move code to repository c_cpp_code

assets/Linux-UNIX系统编程手册(上下册合集)_1694420599654_0.edn

@@ -824,4 +824,4 @@
                           :page 146},
                :content {:text "[:span]", :image 1694614015805},
                :properties {:color "purple"}}],
- :extra {:page 165}}
+ :extra {:page 164}}

code/CSAPP/Chapter01/hello.c

-#include <stdio.h>
-
-int main() {
-    printf("Hello, world\n");
-    return 0;
-}
\ No newline at end of file

code/CSAPP/Chapter02/LowBit.c

-/*
-位操作练习题
-*/
-
-#include <stdio.h>
-#include <stdlib.h>
-
-/*
-* LowBit - return value of low-order 1 bit
-*   Examples: LowBit(0x1F) = 0x1
-*             LowBit(0x300) = 0x100
-*             LowBit(0x0) = 0x0
-*/
-unsigned int LowBit(unsigned int x) {
-    return x & (~x + 1);
-}
-
-/*
-* hexAllLetter - return 1 when all 4 hex digits are letters
-*   Examples: hexAllLetter(0x1234) = 0
-*             hexAllLetter(0x1ABF) = 0
-*             hexAllLetter(0xABCD) = 1
-A hexadecimal number orresponding to the four binary number x3x2x1x0
-Let's check whether the hexadecimal number is a letter
-
-            x3x2=00   x3x2=01   x3x2=10   x3x2=11
-x1x0= 00       0        0         0         1
-x1x0= 01       0        0         0         1
-x1x0= 10       0        0         1         1
-x1x0= 11       0        1         1         1
-*/
-unsigned hexAllLetter(unsigned x) {
-    // x3 x2 x1 x0  ->  hex
-    // 0  0  1  0   ->  hex constent 0x2
-    unsigned x1 = x & 0x22222222;           // ...xxxx0010
-    // 0  1  0  0   ->  hex constent 0x4    // ...xxxx0100
-    unsigned x2 = x & 0x44444444;           // ...xxxx1000
-    // 1  0  0  0   ->  hex constent 0x8
-    unsigned x3 = x & 0x88888888;           // ...xxx10000
-    // x3 * (x1 + x2)  ==> x3 & (x1 + x2)
-    unsigned a = (x3 >> 3) & ((x2 >> 2) | (x1 >> 1));
-    return a;
-}
-
-
-int main() {
-    printf("%#x\n", LowBit(0xf)); // 0xf = 1111 -> 0x1
-    printf("%#x, is letter %#x\n", 0xabcdefab, hexAllLetter(0xabcdefab));
-    printf("%#x, is letter %#x\n", 0x11111111, hexAllLetter(0x11111111));
-    printf("%#x, is letter %#x\n", 0xa0a0a0a0, hexAllLetter(0xa0a0a0a0));
-    return 0;
-}
-

code/CSAPP/Chapter02/byte_order.c

-/*
-查看字节序
-*/
-
-#include <stdio.h>
-#include <stdbool.h>
-
-
-void show_byte_order(void) {
-    int a = 0x1100;
-    char *p = (char *)&a;
-    if (p[0] == 0x00) {
-        printf("little endian\n");
-    } else {
-        printf("big endian\n");
-    }
-}
-
-int main() {
-    int a = 0x12345678;
-    char *p = (char *)&a;
-    printf("%x %x %x %x\n", p[0], p[1], p[2], p[3]);  // 78 56 34 12 小端字节序
-    show_byte_order();
-    return 0;
-}
\ No newline at end of file

code/CSAPP/Chapter02/integer_arithmetic.c

-/*
-整数运算
-*/
-
-#include <stdio.h>
-#include <limits.h>
-
-int main() {
-    /* 无符号数加法 */
-    unsigned char us1 = 255;  // UCHAR_MAX 2^8 - 1
-    unsigned char us2 = 2;
-    
-    printf("us1 + us2 = %d\n", us1 + us2 - (UCHAR_MAX + 1)); /*溢出*/
-
-    /*无符号数求反*/
-    unsigned char us3 = 1;
-    printf("~us3 = %hhu\n", (UCHAR_MAX + 1)-us3);
-    
-    return 0;
-}
\ No newline at end of file

code/CSAPP/Chapter02/show_bytes.c

-#include <stdio.h>
-
-typedef unsigned char *byte_pointer;
-
-void show_bytes(byte_pointer start, size_t len)
-{
-    // start 就是传递对象的最低地址
-    size_t i;
-    for (i = 0; i < len; i++)
-    {
-        printf("%.2x ", start[i]);
-    }
-    printf("\n");
-}
-
-void show_int(int x)
-{
-    printf("show bytes(int): ");
-    show_bytes((byte_pointer)&x, sizeof(int));
-    // (byte_pointer) &x: 表示将 &x 视为指向对象的字节序列，而不是指向源数据的指针。
-}
-
-void show_float(float x)
-{
-    printf("show bytes(float): ");
-    show_bytes((byte_pointer)&x, sizeof(float));
-}
-
-void show_pointer(void *x)
-{
-    printf("show bytes(pointer): ");
-    show_bytes((byte_pointer)&x, sizeof(void *));
-}
-
-void test_show_bytes(int val)
-{
-    int ival = val;
-    float fval = (float)ival;
-    int *pval = &ival;
-    show_int(ival);     // show bytes(int): 39 30 00 00 
-    show_float(fval);   // show bytes(float): 00 e4 40 46
-    show_pointer(pval); // show bytes(pointer): 8c fa df 0a 77 00 00 00
-}
-
-int main()
-{
-    test_show_bytes(0x00003039);
-    return 0;
-}
\ No newline at end of file

code/CSAPP/Chapter02/signed2unsigned.c

-#include <stdio.h>
-
-int main() {
-    int tx, ty;
-    unsigned ux, uy;
-    // tx = (int) ux;
-    // uy = (unsigned) ty;
-
-    // tx = ux;
-    // uy = ty;
-
-    int x = -1;
-    unsigned u = 2147483648;
-    printf("x = %u = %d\n", x, x);  // x = 4294967295 = -1
-    printf("u = %u = %d\n", u, u);  // u = 2147483648 = -2147483648
-    return 0;
-}

code/CSAPP/Chapter02/sum.c

-int sum(int x, int y) {
-    return x + y;
-}
-
-
-int main() {
-    int val = sum(1, 2);
-    return 0;
-}

code/CSAPP/Chapter02/uint2float.c

-#include <stdio.h>
-#include <stdlib.h>
-#include <stdint.h>
-
-#define unlikely(x) __builtin_expect(!!(x), 0) // 期望 !!(x) == 0 为真
-
-uint32_t uint2float(uint32_t u)
-{
-    // 32 个 0
-    if (u == 0x0000000)
-    {
-        return 0x00000000;
-    }
-
-    // 计算最高位为1的位置
-    int n = 31;
-    while (0 <= n && (((u >> n) & 0x1) == 0x0))
-    {
-        n = n - 1;
-    }
-    // printf("n = %d\n", n);
-
-    uint32_t f; // 尾数
-    uint32_t e; // 指数
-
-    // <= 0000 0000 1.111 1111 1111 1111 1111 1111  尾数刚好24位，最高位 1 隐含表示刚好能表示尾数，因此不需要舍入
-    // <= 0x00ffffff
-    if (u <= 0x00ffffff)
-    {
-        uint32_t mask = 0xffffffff >> (32 - n);
-        f = (u & mask) << (23 - n);
-        e = n + 127;
-        return (e << 23) | f;
-    }
-    // >= 0000 0001 0000 0000 0000 0000 0000 0000 尾数超过24位，最高位 1 隐含表示也不能完全表示尾数，因此需要舍入
-    // >= 0x01000000 
-    else
-    {
-        // 扩展到64位
-        uint64_t a = 0;
-        a += u;
-        // GRS舍入规则
-        uint32_t g = (a >> (n - 23)) & 0x1;   // 最后一个保留的位
-        uint32_t r = (a >> (n - 24)) & 0x1;   // 第一个丢弃的位
-        uint32_t s = 0x0;
-        // 计算要丢弃的第一个位之后所有位的或
-        for (int j = 0; j < n - 24; ++j)
-        {
-            s = s | ((u >> j) & 0x1);
-        }
-
-        //   0   1    2  ? ... ?
-        // [24] [23] [22] ... [0]
-        a = a >> (n - 23);
-        if (r & (g | s) == 0x1)
-        {
-            a += 1; // f+1可能跑到了第24位
-        }
-        /* 没有溢出 */
-        if ((a >> 23) == 0x1)
-        {
-            //   0   1    1  ? ... ?
-            // [24] [23] [22] ... [0]
-            f = a & 0x007fffff;  // 取后23位
-            e = n + 127;    // 指数
-            return (e << 23) | f;
-        }
-        /* 溢出 */
-        else if ((a >> 23) == 0x2)
-        {
-            //   1   0    0   ...  0
-            // [24] [23] [22] ... [0]
-            e = n + 1 + 127;
-            return (e << 23);
-        }
-    }
-    // inf 默认错误
-    return 0x7f800000; // 0 1111 1111 000 0000 0000 0000 0000 0000
-}
-
-int main()
-{
-    uint32_t uf;
-    float f;
-    for (uint32_t u = 0x00ffffff; u <= 0xffffffff; u += 0xf)
-    {
-        uf = uint2float(u);
-        f = (float)u;
-        if (unlikely(uf != *(uint32_t *)&f))
-        {
-            printf("fail\n");
-            return 0;
-        }
-        printf("u=%#x, f=%#x,uf=%#x\n", u, *(uint32_t *)&f, uf);
-    }
-    printf("pass\n");
-    return 0;
-}

code/CSAPP/Chapter03/AssemblySimulator/add.c

-/*
-加法
-*/
-#include <stdio.h>
-#include <stdlib.h>
-#include <stdint.h>
-
-uint64_t add(uint64_t a, uint64_t b) {
-    return a + b;
-}
-
-
-int main() {
-    uint64_t a = 0xab;
-    uint64_t b = 0xac;
-    uint64_t c = add(a, b);
-    return 0;
-}

code/CSAPP/Chapter03/AssemblySimulator/cpu.c

-#include <stdio.h>
-
-#include "cpu.h"
-
-int main() {
-    cpu_t cpu;
-    cpu.rax = 0x1234abcd5678ffaaU;
-    printf("rax: %x\n", cpu.rax);
-    printf("eax: %x\n", cpu.eax);    
-    printf("ax: %x\n", cpu.ax);
-    printf("al: %x\n", cpu.al); 
-    return 0;
-}
\ No newline at end of file

code/CSAPP/Chapter03/AssemblySimulator/cpu.h

-#ifndef _CPU_H_
-#define _CPU_H_
-
-#include <stdlib.h>
-#include <stdint.h>
-
-typedef struct CPU_STRUCT
-{
-    union
-    {
-        uint64_t rax;
-        uint32_t eax;
-        uint16_t ax;
-        uint8_t al;
-    };
-
-    union
-    {
-        uint8_t bl;
-        uint16_t bx;
-        uint32_t ebx;
-        uint64_t rbx;
-    };
-
-    union
-    {
-        uint8_t cl;
-        uint16_t cx;
-        uint32_t ecx;
-        uint64_t rcx;
-    };
-    union
-    {
-        uint8_t dl;
-        uint16_t dx;
-        uint32_t edx;
-        uint64_t rdx;
-    };
-
-    union
-    {
-        uint8_t sil;
-        uint16_t si;
-        uint32_t esi;
-        uint64_t rsi;
-    };
-    union
-    {
-        uint8_t dil;
-        uint16_t di;
-        uint32_t edi;
-        uint64_t rdi;
-    };
-
-    union
-    {
-        uint8_t bpl;
-        uint16_t bp;
-        uint32_t ebp;
-        uint64_t rbp;
-    };
-    union
-    {
-        uint8_t spl;
-        uint16_t sp;
-        uint32_t esp;
-        uint64_t rsp;
-    };
-    union
-    {
-        uint8_t r8b;
-        uint16_t r8w;
-        uint32_t r8d;
-        uint64_t r8;
-    };
-    union
-    {
-        uint8_t r9b;
-        uint16_t r9w;
-        uint32_t r9d;
-        uint64_t r9;
-    };
-    union
-    {
-        uint8_t r10b;
-        uint16_t r10w;
-        uint32_t r10d;
-        uint64_t r10;
-    };
-    union
-    {
-        uint8_t r11b;
-        uint16_t r11w;
-        uint32_t r11d;
-        uint64_t r11;
-    };
-    union
-    {
-        uint8_t r12b;
-        uint16_t r12w;
-        uint32_t r12d;
-        uint64_t r12;
-    };
-    union
-    {
-        uint8_t r13b;
-        uint16_t r13w;
-        uint32_t r13d;
-        uint64_t r13;
-    };
-    union
-    {
-        uint8_t r14b;
-        uint16_t r14w;
-        uint32_t r14d;
-        uint64_t r14;
-    };
-    union
-    {
-        uint8_t r15b;
-        uint16_t r15w;
-        uint32_t r15d;
-        uint64_t r15;
-    };
-
-    uint64_t rip;
-} cpu_t;
-#endif

code/CSAPP/Chapter03/arithmetic_logic/arith.c

-/*
-算术操作
-*/
-
-/*
-// long arith(long x, long y, long z)
-// x in %rdi, y in %rsi, z in %rdx                  
-0000000000001119 <arith>:                                        
-    1119:	48 31 f7             	xor    %rsi,%rdi            // %rdi[t1] = x ^ y
-    111c:	48 8d 04 52          	lea    (%rdx,%rdx,2),%rax   // %rax[3 * z]
-    1120:	48 c1 e0 04          	shl    $0x4,%rax            // %rax[t2] = 3 * z << 4 = 48 * z
-    1124:	81 e7 0f 0f 0f 0f    	and    $0xf0f0f0f,%edi      // %edi[t3] = t1 & 0x0f0f0f0f
-    112a:	48 29 f8             	sub    %rdi,%rax            // t4 = t2 - t3
-    112d:	c3                   	ret
-*/
-long arith(long x, long y, long z) {
-    long t1 = x ^ y;
-    long t2 = z * 48;
-    long t3 = t1 & 0x0f0f0f0f;
-    long t4 = t2 - t3;
-    return t4;
-}
-
-int main() {
-    arith(10, 20, 30);
-    return 0;
-}

code/CSAPP/Chapter03/arithmetic_logic/remdiv.c

-/*
-x86-64 除法
-*/
-
-/*
-// void remdiv(long x, long y, long *qp, long *rp)
-// x in %rdi, y in %rsi, qp in %rdx, rp in %rcx
-0000000000001139 <remdiv>:
-    1139:	48 89 f8             	mov    %rdi,%rax    // 移动被除数 x 的低 8 字节到 %rax
-    113c:	49 89 d0             	mov    %rdx,%r8     // 复制 qp 到 %r8
-    113f:	48 99                	cqto                // 将 %rax 的符号位扩展到 %rdx
-    1141:	48 f7 fe             	idiv   %rsi         // %rdx[余数]:%rax[商] <-  x / y
-    1144:	49 89 00             	mov    %rax,(%r8)   // *qp = 商
-    1147:	48 89 11             	mov    %rdx,(%rcx)  // *rp = 余数
-    114a:	c3                   	ret
-*/
-void remdiv(long x, long y, long *qp, long *rp) {
-    long q = x /y;
-    long r = x % y;
-    *qp = q;
-    *rp = r;
-}
-
-int main() {
-    long x = 0x1234567887654321;
-    long y = 0x1111111111111111;
-    long q = 0;
-    long r = 0;
-    remdiv(x, y, &q, &r);
-    return 0;
-}
\ No newline at end of file

code/CSAPP/Chapter03/arithmetic_logic/scale.c

-/*
-leaq 指令：加载有效地址
-    leaq S, D
-    将有效地址S加载到目的操作数D中
-    有效地址：指向一个对象的指针或数组元素的
-*/
-
-/*
-// long scale(long x, long y, long z);
-// x in %rdi, y in %rsi, z in %rdx
-0000000000001119 <scale>:
-    1119:	48 8d 04 b7          	lea    (%rdi,%rsi,4),%rax   // %rax = %rdi[x] + 4 * %rsi[y]
-    111d:	48 8d 14 52          	lea    (%rdx,%rdx,2),%rdx   // %rdx = %rdx[z] +  2 * %rdx[z]
-    1121:	48 8d 04 90          	lea    (%rax,%rdx,4),%rax   // %rax = %rax + 4 * %rdx = %rdi[x] + 4 * %rsi[y] + 4 * (%rdx[z] +  2 * %rdx[z])
-    1125:	c3                   	ret
-*/
-long scale(long x, long y, long z)
-{
-    long t = x + 4 * y + 12 * z;
-    return t;
-}
-
-int main() {
-    long a = 10;
-    long b = 20;
-    long c = 30;
-    long d = scale(a, b, c);
-    return 0;
-}
\ No newline at end of file

code/CSAPP/Chapter03/arithmetic_logic/shift_left_4_rightn.c

-/*
-移位指令
-*/
-
-/*
-// long shift_left_4_rightn(long x, long n)
-// x in %rdi, n in %rsi
-0000000000001119 <shift_left_4_rightn>:
-    1119:	48 89 f8             	mov    %rdi,%rax
-    111c:	48 c1 e0 04          	shl    $0x4,%rax    // 左移 %rax = %rax << 4 
-    1120:	89 f1                	mov    %esi,%ecx    // %ecx = %rsi [%rcx %ecx %cx %cl]
-    1122:	48 d3 f8             	sar    %cl,%rax     // 算术右移 %rax = %rax >> %cl
-    1125:	c3                   	ret
-*/
-long shift_left_4_rightn(long x, long n) {
-    x <<= 4;
-    x >>= n;
-    return x;
-}
-
-int main() {
-    shift_left_4_rightn(0xff, 4);
-    return 0;
-}
\ No newline at end of file

code/CSAPP/Chapter03/arithmetic_logic/store_uprod.c

-/*
-特殊的算术运算
-*/
-
-#include <inttypes.h>
-
-typedef unsigned __int128 uint128_t;
-
-/*
-// void store_uprod(uint128_t *dest, uint128_t x, uint64_t y)
-// dest in %rdi, x in %rsi, y in %rdx
-0000000000001139 <store_uprod>:
-    1139:	48 89 f0             	mov    %rsi,%rax    // %rax <- x
-    113c:	48 f7 e2             	mul    %rdx         // %rdx(高64位):%rax(低64位) <- x * y
-    113f:	48 89 07             	mov    %rax,(%rdi)      // *dest = 低64位
-    1142:	48 89 57 08          	mov    %rdx,0x8(%rdi)   // *(dest + 8) = 高64位
-    1146:	c3                   	ret
-*/
-void store_uprod(uint128_t *dest, uint64_t x, uint64_t y) {
-    *dest = x * (uint128_t) y;
-}
-
-int main() {
-    uint128_t dest;
-    uint64_t x = 0x1234567887654321;
-    uint64_t y = 0x1111111111111111;
-    store_uprod(&dest, x, y);
-    return 0;
-}
\ No newline at end of file

code/CSAPP/Chapter03/array/fix_prod_ele.c

-/*
-定长数组
-*/
-
-#define N 16
-
-typedef int fix_matrix[N][N];
-
-int fix_prod_ele(fix_matrix A, fix_matrix B, long i, long k) {
-    long j;
-    int result = 0;
-    for(j = 0; j < N; j++) {
-        result += A[i][j] * B[j][k];
-    }
-    return result;
-}
-/*
-// int fix_prod_ele(fix_matrix A, fix_matrix B, long i, long k)
-// A in %rdi, B in %rsi, i in %rdx, k in %rcx
-fix_prod_ele:
-	salq	$6, %rdx                // i *= 64
-	addq	%rdx, %rdi              // &A[i][0] (A + 4 * 16  * i)
-	leaq	(%rsi,%rcx,4), %rax     // &B[0][k] (B + 4 * k)
-	leaq	1024(%rax), %rsi        // &B[N][k] (B + 4 * k + 4 * 16 * 16)
-	movl	$0, %ecx                // result = 0
-.L2:
-	movl	(%rdi), %edx            // A[i][0]
-	imull	(%rax), %edx            // A[i][0] * B[0][k]
-	addl	%edx, %ecx              // result += A[i][0] * B[0][k]
-	addq	$4, %rdi                // A[i]++
-	addq	$64, %rax               // B[0][k] + N
-	cmpq	%rsi, %rax              // compare B[0][k] + N and B[N][k]
-	jne	.L2                         // if not equal, jump to .L2
-	movl	%ecx, %eax              // return result
-	ret
-*/
-

code/CSAPP/Chapter03/control/absdiff.c

-/*
-条件传送
-*/
-/*
-// long absdiff(long x, long y)
-// x in %rdi, y in %rsi
-absdiff:
-	movq	%rsi, %rdx        // 将 y 存储到 %rdx
-	subq	%rdi, %rdx        // %rdx = y - x
-	movq	%rdi, %rax        // 将 x 存储到 %rax
-	subq	%rsi, %rax        // %rax = x - y
-	cmpq	%rsi, %rdi        // 比较 x 和 y
-	cmovl	%rdx, %rax        // 如果 x < y, 则将 %rdx 的值传送到 %rax
-	ret
-*/
-long absdiff(long x, long y) {
-    long result;
-    if(x < y) {
-        result = y - x;
-    }
-    else {
-        result = x - y;
-    }
-    return result;
-}
-
-int main() {
-    absdiff(2, 3);
-    return 0;
-}
\ No newline at end of file

code/CSAPP/Chapter03/control/absdiff_se.c

-/*
-条件控制
-*/
-
-long lt_cnt = 0;
-long ge_cnt = 0;
-
-/*
-// long absdiff_se(long x, long y)
-// x in %rdi, y in %rsi
-absdiff_se:
-	cmpq	%rsi, %rdi          // 比较 x 和 y
-	jge	.L2                     // 如果 x >= y, 跳转到 .L2
-	addq	$1, lt_cnt(%rip)    // lt_cnt++
-	movq	%rsi, %rax          // 将 y 存储到 %rax
-	subq	%rdi, %rax          // 计算 y - x 并存储到 %rax
-	ret
-.L2:
-	addq	$1, ge_cnt(%rip)    // ge_cnt++
-	movq	%rdi, %rax          // 将 x 存储到 %rax
-	subq	%rsi, %rax          // 计算 x - y 并存储到 %rax
-	ret
-*/
-long absdiff_se(long x, long y) {
-    long result;
-    if (x < y) {
-        lt_cnt++;
-        result = y - x;
-    }
-    else {
-        ge_cnt++;
-        result = x - y;
-    }
-    return result;
-}
-
-int main() {
-    absdiff_se(2, 3);
-    return 0;
-}
\ No newline at end of file

code/CSAPP/Chapter03/control/cread.c

-/*
-条件传送非法示例
-*/
-long cread(long *xp)
-{
-    return (xp ? *xp : 0);
-}
-
-int main() {
-    long a = 0;
-    long *xp = &a;
-    long result = cread(xp);
-    return 0;
-}
-
-// gcc -Og -S cread.c
\ No newline at end of file

code/CSAPP/Chapter03/control/dw_loop.c

-/*
-分析寄存器存放的程序值
-*/
-/*
-// long dw_loop(long x)
-// x in %rdi
-dw_loop:
-	movq	%rdi, %rax          // 将 x 存储到 %rax
-	movq	%rdi, %rcx          // 将 x 存储到 %rcx
-	imulq	%rdi, %rcx          // 将 y=x*x 存储到 %rcx
-	leaq	(%rdi,%rdi), %rdx   // 将 n=2*x 存储到 %rdx
-.L2:
-	leaq	1(%rcx,%rax), %rax  // x += y, (*p)++
-	subq	$1, %rdx            // n--
-	testq	%rdx, %rdx          // 测试 n & n 是否为 0
-	jg	.L2
-	ret
-*/
-long dw_loop(long x) {
-    long y = x * x;
-    long *p = &x;
-    long n = 2 * x;
-    do {
-        x += y;
-        (*p)++;
-        n--;
-    } while(n > 0);
-    return x;
-}
-
-int main() {
-    dw_loop(3);
-    return 0;
-}
\ No newline at end of file

code/CSAPP/Chapter03/control/fact_do.c

-/*
-do-while 循环
-*/
-/*
-// long fact_do(long n)
-// n in %rdi
-fact_do:
-	movl	$1, %eax    // result = 1
-.L2:
-	imulq	%rdi, %rax  // result *= n
-	subq	$1, %rdi    // n = n - 1
-	cmpq	$1, %rdi    // 比较 n 和 1
-	jg	.L2             // 如果 n > 1, 则跳转到 .L2
-	ret
-*/
-long fact_do(long n) {
-    long result = 1;
-    do {
-        result *= n;
-        n = n - 1;
-    } while (n > 1);
-    return result;
-}
-
-int main() {
-    fact_do(3);
-    return 0;
-}

code/CSAPP/Chapter03/control/fact_for.c

-/*
-for 循环：GCC 为 for 循环产生代码是 while 循环的两种翻译方式之一
-
-这里我们看第一种：跳转到中间
-*/
-
-/*
-// gcc -Og -S fact_for.c
-// long fact_for(long n)
-// n in %rdi
-fact_for:
-	movl	$2, %eax    // i = 2
-	movl	$1, %edx    // result = 1
-	jmp	.L2             // 跳转到 .L2
-.L3:
-	imulq	%rax, %rdx  // result *= i
-	addq	$1, %rax    // i++
-.L2:
-	cmpq	%rdi, %rax  // 测试 i - n 
-	jle	.L3             // 如果 i - n <= 0, 跳转到 .L3
-	movq	%rdx, %rax  
-	ret
-*/
-long fact_for(long n)
-{
-    long result = 1;
-    long i;
-    for (i = 2; i <= n; i++)
-    {
-        result *= i;
-    }
-    return result;
-}
-
-int main()
-{
-    fact_for(3);
-    return 0;
-}
-
-

code/CSAPP/Chapter03/control/fact_while.c

-/*
-while 循环的第一种翻译方法
-*/
-
-/*
-// gcc -Og -S fact_while.c
-// long fact_while(long n)
-// n in %rdi
-fact_while:
-	movl	$1, %eax    // result = 1
-	jmp	.L2             // 跳转到 .L2
-.L3:
-	imulq	%rdi, %rax  // result *= n
-	subq	$1, %rdi    // n--
-.L2:
-	cmpq	$1, %rdi    // 测试 n - 1 是否为 0
-	jg	.L3             // 如果 n - 1 > 0, 跳转到 .L3
-	ret
-*/
-long fact_while(long n) {
-    long result = 1;
-    while (n > 1)
-    {
-        result *= n;
-        n = n - 1;
-    }
-    return result;
-}
-
-int main() {
-    fact_while(3);
-    return 0;
-}
\ No newline at end of file

code/CSAPP/Chapter03/control/fact_while2.c

-/*
-while 循环的第二种翻译方法
-*/
-
-/*
-// gcc -O1 -S fact_while.c
-// long fact_while(long n)
-// n in %rdi
-fact_while:
-	cmpq	$1, %rdi    // 测试 n - 1 是否为 0
-	jle	.L4             // 如果 n - 1 <= 0, 跳转到 .L4
-	movl	$1, %eax    // result = 1
-.L3:
-	imulq	%rdi, %rax  // result *= n
-	subq	$1, %rdi    // n--
-	cmpq	$1, %rdi    // 测试 n - 1 是否为 0
-	jne	.L3             // 如果 n - 1 != 0, 跳转到 .L3
-	ret
-.L4:
-	movl	$1, %eax    // result = 1
-	ret
-*/
-long fact_while(long n) {
-    long result = 1;
-    while (n > 1)
-    {
-        result *= n;
-        n = n - 1;
-    }
-    return result;
-}
-
-int main() {
-    fact_while(3);
-    return 0;
-}
\ No newline at end of file

code/CSAPP/Chapter03/control/gotodiff_se.c

-/*
-// long absdiff_se(long x, long y)
-// x in %rdi, y in %rsi
-absdiff_se:
-	cmpq	%rsi, %rdi          // 比较 x 和 y
-	jge	.L2                     // 如果 x >= y, 跳转到 .L2
-	addq	$1, lt_cnt(%rip)    // lt_cnt++
-	movq	%rsi, %rax          // 将 y 存储到 %rax
-	subq	%rdi, %rax          // 计算 y - x 并存储到 %rax
-	ret
-.L2:
-	addq	$1, ge_cnt(%rip)    // ge_cnt++
-	movq	%rdi, %rax          // 将 x 存储到 %rax
-	subq	%rsi, %rax          // 计算 x - y 并存储到 %rax
-	ret
-*/
-
-long lt_cnt = 0;
-long ge_cnt = 0;
-
-long gotodiff_se(long x, long y) {
-    long result;
-    if(x >= y) {
-        goto x_ge_y;
-    }
-    lt_cnt++;
-    result = y - x;
-    return result;
-x_ge_y:
-    ge_cnt++;
-    result = x - y;
-    return result;
-}
-
-int main() {
-    gotodiff_se(2, 3);
-    return 0;
-}

code/CSAPP/Chapter03/control/switch_eg.c

-/*
-switch 语句的翻译
-*/
-
-/*
-// gcc -Og -S switch_eg.c
-// void switch_eg(long x, long n, long *dest)
-// x in %rdi, n in %rsi, dest in %rdx
-switch_eg:
-	subq	$100, %rsi          // index = n - 100
-	cmpq	$6, %rsi            // 比较 n - 100 和 6
-	ja	.L8                     // 如果 n - 100 > 6, 跳转到 .L8
-	leaq	.L4(%rip), %rcx     // 将 .L4 的地址存入 %rcx
-	movslq	(%rcx,%rsi,4), %rax // 将 %rcx + index * 4 的值存入 %rax
-	addq	%rcx, %rax          // 将 %rcx + %rcx + index * 4 存入 %rax
-	jmp	*%rax                   // 跳转到 %rax 指向的地址
-    .section	.rodata
-	.align 4
-	.align 4
-.L4:
-	.long	.L7-.L4            // .L7 - .L4 = 0x0 case 100
-	.long	.L8-.L4            // .L8 - .L4 = 0x4 default
-	.long	.L6-.L4            // .L6 - .L4 = 0x8 case 102
-	.long	.L5-.L4            // .L5 - .L4 = 0xc case 103
-	.long	.L3-.L4            // .L3 - .L4 = 0x10 case 104
-	.long	.L8-.L4            // .L8 - .L4 = 0x14 default
-	.long	.L3-.L4            // .L3 - .L4 = 0x18 case 106
-	.text
-.L7:
-	leaq	(%rdi,%rdi,2), %rax
-	leaq	(%rdi,%rax,4), %rdi
-	jmp	.L2
-.L6:
-	addq	$10, %rdi
-.L5:
-	addq	$11, %rdi
-.L2:
-	movq	%rdi, (%rdx)    // 将 %rdi 的值存入 %rdx 指向的地址
-	ret
-.L3:
-	imulq	%rdi, %rdi
-	jmp	.L2
-.L8:
-	movl	$0, %edi
-	jmp	.L2
-*/
-void switch_eg(long x, long n, long *dest) {
-    long val = x;
-    switch (n) {
-        case 100:
-            val *= 13;
-            break;
-        case 102:
-            val += 10;
-            /*Fall through*/
-        case 103:
-            val += 11;
-            break;
-        case 104:
-        case 106:
-            val *= val;
-            break;
-        default:
-            val = 0;
-    }
-    *dest = val;
-}
-
-int main() {
-    long x = 1;
-    long n = 100;
-    long *dest = &x;
-    switch_eg(x, n, dest);
-    return 0;
-}

code/CSAPP/Chapter03/control/switch_eg_goto.c

-void switch_eg_impl(long x, long n, long *dest) {
-    /*Table of code pointers*/
-    static void *jt[7] = {
-        &&loc_A, &&loc_def,&&loc_B,
-        &&loc_C, &&loc_D,&&loc_def,
-        &&loc_D
-    }; // && gcc 提供的运算符，它创建一个指向代码的指针
-    unsigned long index = n - 100;
-    long val;
-    // 超出范围 执行 default
-    if(index > 6) {
-        goto loc_def;
-    }
-    goto *jt[index];
-    loc_A: /*case 100*/
-        val = x * 13;
-        goto done;
-    loc_B: /*case 102*/
-        x = x + 10;
-        /*Fall through*/
-    loc_C: /*case 103*/
-        val = x + 11;
-        goto done;
-    loc_D: /*case 104, 106*/
-        val = x * x;
-    loc_def: /*default*/
-        val = 0;
-    done:
-        *dest = val;
-}
\ No newline at end of file

code/CSAPP/Chapter03/float/float_mov.c

-/*
-浮点数数传送指令
-*/
-
-float float_mov(float v1, float *src, float *dst) {
-    float v2 = *src;
-    *dst = v1;
-    return v2;
-}
-
-/*
-// float float_mov(float v1, float *src, float *dst)
-// v1 in %xmm0, src in %rdi, dest in %rsi
-float_mov:
-	movaps	%xmm0, %xmm1        // xmm1 = xmm0
-	movss	(%rdi), %xmm0       // xmm0 = *src
-	movss	%xmm1, (%rsi)       // *dst = xmm1
-	ret
-*/
-
-int main() {
-    float v1 = 1.0;
-    float src = 10.0;
-    float dst;
-    float v2 = float_mov(v1, &src, &dst);
-
-    return 0;
-}
\ No newline at end of file

code/CSAPP/Chapter03/mov/decode1.c

-/** 将下面汇编代码转为 C 代码
-    xp in %rdi, yp in %rsi, zp in %rdx
-    movq (%rdi), %r8  |读出xp指向的内容，并写入到 %r8
-    movq (%rsi), %rcx |读出yp指向的内容，并写入到 %rcx
-    movq (%rdx), %rax |读出zp指向的内容，并写入到 %rax
-    movq %r8, (%rsi)  |读出 %r8 的内容，写入到 yp 指向的内存中
-    movq %rcx, (%rdx) |读出 %rcx 的内容，写入到 zp 指向的内存中
-    movq %rax, (%rdi) |读出 %rax 的内容，写入到 xp 指向的内存中
-    ret 返回
-*/
-
-void decode1(long *xp, long *yp, long *zp) {
-    long x = *xp;
-    long y = *yp;
-    long z = *zp;
-    *yp = x;
-    *zp = y;
-    *xp = z;
-}
-
-int main() {
-    long a = 10;
-    long b = 20;
-    long c = 30;
-    decode1(&a, &b, &c);
-    printf("a = %ld, b = %ld, c = %ld\n", a, b, c);
-    return 0;
-}
\ No newline at end of file

code/CSAPP/Chapter03/mov/exchange.c

-/*
-mov 指令示例
-*/
-
-#include <stdio.h>
-
-/*
-// long exchange(long *xp, long y)
-// xp in %rdi , y in %rsi
-0000000000001149 <exchange>:
-    1149:	48 8b 07             	mov    (%rdi),%rax      // 从 xp 中获取 x, 并设置返回值
-    114c:	48 89 37             	mov    %rsi,(%rdi)      // 将 y 存入 xp
-    114f:	c3                   	ret                     // 函数返回
-*/
-long exchange(long *xp, long y)
-{
-    long x = *xp;
-    *xp = y;
-    return x;
-}
-
-
-int main() {
-    long a = 10;
-    long b = 20;
-    b = exchange(&a, b);
-    printf("a = %d, b = %d\n", a, b);
-}

code/CSAPP/Chapter03/mstore/main.c

-#include <stdio.h>
-void multstore(long , long , long *);
-int main() {
-    long d;
-    multstore(2,3,&d);
-    printf("2 * 3 ---> %ld\n", d);
-    return 0;
-}
-long mult2(long l1,long l2){
-    long s = l1 * l2;
-    return s;
-}
\ No newline at end of file

code/CSAPP/Chapter03/mstore/mstore.c

-long mult2(long l1,long l2);
-
-void multstore(long x, long y, long *dest) {
-    long t = mult2(x, y);
-    *dest = t;
-}
\ No newline at end of file

code/CSAPP/Chapter03/process/local.c

-/*
-寄存器中的局部存储空间：调用者保存寄存器和被调用者保存寄存器
-*/
-#include <stdio.h>
-
-long Q(long x) {
-    long val = 8 * x;
-    return val;
-}
-
-long P(long x, long y) {
-    long u = Q(y);
-    long v = Q(x);
-    return u + v;
-}
-/*
-// long Q(long x)
-// x in %rdi
-Q:
-	leaq	0(,%rdi,8), %rax
-	ret
-
-// long P(long x, long y)
-// x in %rdi, y in %rsi
-P:
-	pushq	%rbp        // save caller's %rbp (frame pointer)
-	pushq	%rbx        // save caller's %rbx
-	movq	%rdi, %rbp  // save x in %rbp
-	movq	%rsi, %rdi  // save y in %rdi
-	call	Q           // call Q(y)
-	movq	%rax, %rbx  // save Q(y) in %rbx
-	movq	%rbp, %rdi  // restore x in %rdi
-	call	Q           // call Q(x)
-	addq	%rbx, %rax  // add Q(y) to Q(x)
-	popq	%rbx        // restore caller's %rbx
-	popq	%rbp        // restore caller's %rbp
-	ret
-
-main:
-	subq	$8, %rsp
-	movl	$3, %esi
-	movl	$2, %edi
-	call	P
-*/
-
-int main() {
-    long x = P(2, 3);
-    printf("%ld\n", x);
-    return 0;
-}
-
-

code/CSAPP/Chapter03/process/mstore/main.c

-/*
-转移控制
-*/
-
-#include <stdio.h>
-
-void multstore(long, long, long *);
-
-int main()
-{
-    long d;
-    multstore(2, 3, &d);
-    printf("2 * 3 ---> %ld\n", d);
-    return 0;
-}
-
-long mult2(long l1, long l2)
-{
-    long s = l1 * l2;
-    return s;
-}
\ No newline at end of file

code/CSAPP/Chapter03/process/mstore/mstore.c

-long mult2(long l1,long l2);
-
-void multstore(long x, long y, long *dest) {
-    long t = mult2(x, y);
-    *dest = t;
-}
\ No newline at end of file

code/CSAPP/Chapter03/process/proc.c

-/*
-数据传送：寄存器可以直接传送 6 个整型参数（包括指针），其他参数通过栈传送
-*/
-
-void proc(long a1, long *a1p, int a2, int *a2p, short a3, short *a3p, char a4, char *a4p)
-{
-    *a1p += a1;
-    *a2p += a2;
-    *a3p += a3;
-    *a4p += a4;
-}
-
-
-int main() {
-    long    a1 = 0;
-    int     a2 = 0;
-    short   a3 = 0;
-    char    a4 = 0;
-    proc(0x4d2l, &a1, 0x20, &a2, (short) 0xc, &a3, (char) 0x60, &a4);
-    return 0;
-}
-/*
-// void proc(long a1, long *a1p, int a2, int *a2p, short a3, short *a3p, char a4, char *a4p)
-// a1  	in 	%rdi 		(64 bits)
-// a1p 	in 	%rsi 		(64 bits)
-// a2  	in 	%edx 		(32 bits)
-// a2p 	in 	%rcx 		(64 bits)
-// a3  	in 	%r8w 		(16 bits)
-// a3p 	in 	%r9  		(64 bits)
-// a4  	in 	%rsp + 8 	(8 bits)
-// a4p 	in 	%rsp + 16 	(64 bits)
-0000000000001139 <proc>:
-    1139:	48 8b 44 24 10       	mov    0x10(%rsp),%rax  // 读取 a4p 的值存入 %rax
-    113e:	48 01 3e             	add    %rdi,(%rsi)      // *a1p += a1
-    1141:	01 11                	add    %edx,(%rcx)      // *a2p += a2
-    1143:	66 45 01 01          	add    %r8w,(%r9)       // *a3p += a3
-    1147:	8b 54 24 08          	mov    0x8(%rsp),%edx   // 将栈中的 0x8(%rsp) 的值存入 %edx
-    114b:	00 10                	add    %dl,(%rax)       // *a4p += a4
-    114d:	c3                   	ret
-
-000000000000114e <main>:
-    114e:	48 83 ec 28          	sub    $0x28,%rsp       // 为栈分配 0x28 字节的空间
-    1152:	64 48 8b 04 25 28 00 	mov    %fs:0x28,%rax
-    1159:	00 00 
-    115b:	48 89 44 24 18       	mov    %rax,0x18(%rsp)
-    1160:	31 c0                	xor    %eax,%eax        // 将 %eax 置为 0：开始准备参数
-    1162:	48 c7 44 24 10 00 00 	movq   $0x0,0x10(%rsp)  // a1 = 0
-    1169:	00 00 
-    116b:	c7 44 24 0c 00 00 00 	movl   $0x0,0xc(%rsp)   // a2 = 0
-    1172:	00 
-    1173:	66 c7 44 24 0a 00 00 	movw   $0x0,0xa(%rsp)   // a3 = 0
-    117a:	c6 44 24 09 00       	movb   $0x0,0x9(%rsp)   // a4 = 0
-    117f:	48 8d 4c 24 0c       	lea    0xc(%rsp),%rcx   // 将栈中的 0xc(%rsp) 的地址存入 %rcx  第四个参数(a2p)
-    1184:	48 8d 74 24 10       	lea    0x10(%rsp),%rsi  // 将栈中的 0x10(%rsp) 的地址存入 %rsi 第二个参数(a1p)
-    1189:	48 8d 44 24 09       	lea    0x9(%rsp),%rax   // 将栈中的 0x9(%rsp) 的地址存入 %rax
-    118e:	50                   	push   %rax             // 将 %rax 的值存入栈中  第八个参数(a4p) %rsp = %rsp - 0x8
-    118f:	6a 60                	push   $0x60            // 将 $0x60 的值存入栈中 第七个参数(a4)  %rsp = %rsp - 0x8
-    1191:	4c 8d 4c 24 1a       	lea    0x1a(%rsp),%r9   // 将栈中的 0x1a(%rsp) 的地址存入 %r9 第六个参数(a3p) 
-    1196:	41 b8 0c 00 00 00    	mov    $0xc,%r8d        // 第五个参数(a3)
-    119c:	ba 20 00 00 00       	mov    $0x20,%edx       // 第三个参数(a2)
-    11a1:	bf d2 04 00 00       	mov    $0x4d2,%edi      // 第一个参数(a1) 参数准备完毕
-    11a6:	e8 8e ff ff ff       	call   1139 <proc>      // 调用 proc 函数，将返回地址存入栈中
-    11ab:	48 83 c4 10          	add    $0x10,%rsp       // 返回地址
-*/
-
-/*
-高地址   栈帧                       %rsp 的变化         main 指令            进入 proc 时 %rsp 位置
-|---------------------------|                   |                       |
-|                           |                   |                       |
-|---------------------------|                   |                       |
-|                           |                   |                       |
-|---------------------------|                   |                       |
-|                           |                   |                       |
-|---------------------------|                   |                       |
-|                           |                   |                       |
-|---------------------------| <- %rsp + 0x18    |                       |
-|       long a1 = 0         |                   |                       |
-|---------------------------| <- %rsp + 0x10    |movq   $0x0,0x10(%rsp) |
-|        int a2 = 0         |                   |                       |
-|---------------------------| <- %rsp + 0xc     |movl   $0x0,0xc(%rsp)  |
-|      short a3 = 0         |                   |                       |
-|---------------------------| <- %rsp + 0xa     |movw   $0x0,0xa(%rsp)  |
-|      char a4 = 0          |                   |                       |
-|---------------------------| <- %rsp + 0x9     |movb   $0x0,0x9(%rsp)  |
-|                           |                   |                       |
-|---------------------------|                   |                       |
-|                           |                   |                       |
-|---------------------------|                   |                       |
-|                           |                   |                       |
-|---------------------------| <- %rsp           |                       |
-|       0x9(%rsp) &a4       |                   |                       |
-|---------------------------| <- %rsp - 0x8     | push   %rax           |
-|       0x60                |                   |                       |
-|---------------------------| <- %rsp - 0x10    | push   $0x60          |
-|       0x11ab              |                   |                       |
-|---------------------------| <- %rsp - 0x18    | call   1139 <proc>    | <- %rsp
-*/
\ No newline at end of file

code/CSAPP/Chapter03/process/rfact.c

-/*
-递归过程
-*/
-
-/*
-rfact:
-	cmpq	$1, %rdi        // 比较 n 和 1
-	jg	.L8                 // 如果 n > 1，跳转到 .L8
-	movl	$1, %eax        // 如果 n <= 1，返回 1
-	ret
-.L8:
-	pushq	%rbx            // 保存 callee's %rbx
-	movq	%rdi, %rbx      // 保存 n in %rbx
-	leaq	-1(%rdi), %rdi  // n = n - 1
-	call	rfact           // 调用 rfact(n-1)
-	imulq	%rbx, %rax      // result = n * rfact(n-1)
-	popq	%rbx            // 恢复 callee's %rbx
-	ret
-*/
-long rfact(long n) {
-    long result;
-    if(n <= 1) {
-        result = 1;
-    } else {
-        result = n * rfact(n-1);
-    }
-    return result;
-}
-
-int main() {
-    long result = rfact(5);
-    return 0;
-}

code/CSAPP/Chapter03/process/swap_add.c

-/*
-栈上的局部存储：有时候局部数据必须存储在内存中
-    1. 寄存器不足够存放所有本地数据
-    2. 对局部变量使用 取地址运算符&
-    3. 局部变量是数组或结构
-*/
-
-/*
-本例中，处理取地址运算符&
-*/
-
-long swap_add(long *xp, long *yp) {
-    long x = *xp;
-    long y = *yp;
-    *xp = y;
-    *yp = x;
-    return x + y;
-}
-
-long caller() {
-    long arg1 = 534;    // 0x216
-    long arg2 = 1057;   // 0x421
-    long sum = swap_add(&arg1, &arg2);
-    long diff = arg1 - arg2;
-    return sum * diff;
-}
-
-/*
-0000000000001139 <swap_add>:
-    1139:	48 8b 07             	mov    (%rdi),%rax
-    113c:	48 8b 16             	mov    (%rsi),%rdx
-    113f:	48 89 17             	mov    %rdx,(%rdi)
-    1142:	48 89 06             	mov    %rax,(%rsi)
-    1145:	48 01 d0             	add    %rdx,%rax
-    1148:	c3                   	ret
-
-0000000000001149 <caller>:
-    1149:	48 83 ec 28          	sub    $0x28,%rsp           // 在栈上分配 0x28 = 40 字节的空间
-    114d:	64 48 8b 04 25 28 00 	mov    %fs:0x28,%rax        // 获取栈底指针
-    1154:	00 00 
-    1156:	48 89 44 24 18       	mov    %rax,0x18(%rsp)      // 保存栈底指针
-    115b:	31 c0                	xor    %eax,%eax            // 将 %eax 置为 0
-    115d:	48 c7 44 24 08 16 02 	movq   $0x216,0x8(%rsp)     // arg1 = 534
-    1164:	00 00 
-    1166:	48 c7 44 24 10 21 04 	movq   $0x421,0x10(%rsp)    // arg2 = 1057
-    116d:	00 00 
-    116f:	48 8d 74 24 10       	lea    0x10(%rsp),%rsi      // &arg2
-    1174:	48 8d 7c 24 08       	lea    0x8(%rsp),%rdi       // &arg1
-    1179:	e8 bb ff ff ff       	call   1139 <swap_add>      // swap_add(&arg1, &arg2)
-    117e:	48 8b 54 24 08       	mov    0x8(%rsp),%rdx       // 
-    1183:	48 2b 54 24 10       	sub    0x10(%rsp),%rdx
-    1188:	48 0f af c2          	imul   %rdx,%rax
-    ...
-*/
-
-int main() {
-    caller();
-    return 0;
-}

code/CSAPP/Chapter06/dotprod.c

-/*
-冲突不命中：计算两个向量的点积
-*/
-
-float dotprod(float x[8], float y[8]) {
-    float sum = 0.0;
-    int i;
-    for(i = 0; i < 8; i++) {
-        sum += x[i] * y[i];
-    }
-    return sum;
-}

code/CSAPP/Chapter06/sumvec.c

-/*
-局部性
-*/
-
-#include <stdio.h>
-
-#define N 10
-#define M 10
-
-int sumvec(int v[N]) {
-    int i, sum = 0;
-    for(i = 0; i < N; i++) {
-        sum += v[i];
-    }
-    return sum;
-}
-
-int sumarrayrows(int a[M][N]) {
-    int i, j, sum = 0;
-    for(i = 0; i < M; i++) {
-        for(j = 0; j < N; j++) {
-            sum += a[i][j];
-        }
-    }
-    return sum;
-}
-
-int sumarraycols(int a[M][N]) {
-    int i, j, sum = 0;
-    for(j = 0; j < N; j++) {
-        for(i = 0; i < M; i++) {
-            sum += a[i][j];
-        }
-    }
-    return sum;
-}
-int main() {
-
-    int v[N] = {1,2,3,4,5,6,7,8,9,10};
-    int sum = sumvec(v);
-    printf("sum = %d\n", sum);
-    return 0;
-}
\ No newline at end of file

code/USP/IO/file_IO/atomic.c

-/* 一独占方式打开文件 */
-
-#include <fcntl.h>
-#include <unistd.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <errno.h>
-
-int main(int argc, char *argv[]) {
-    int fd = open(argv[1], O_WRONLY);
-    if(fd != -1) {
-        fprintf(stdout, "[PID %ld] File \"%s\" already exists\n", (long)getpid(), argv[1]);
-        close(fd);
-    } else {
-        /* No such file or directory */
-        if(errno != ENOENT) {
-            perror("open: ");
-            exit(EXIT_FAILURE);
-        } else {
-            /* */
-            fd = open(argv[1], O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR);
-            if(fd == -1) {
-                perror("open: ");
-                exit(EXIT_FAILURE);
-            }
-            fprintf(stdout, "[PID %ld] File \"%s\" already exists\n", (long)getpid(), argv[1]);
-        }
-    }
-    return 0;
-}

code/USP/IO/file_IO/copy_fd.c

-/* 复制文件描述符 */
-
-#define _GNU_SOURCE
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <errno.h>
-
-/* open close*/
-#include <fcntl.h>
-
-
-/* read write close lseek dup dup2*/
-#include <unistd.h>
-
-int main() {
-    int fd;
-//    close(2);  // 关闭 文件描述符 2
-//    fd = dup(1); // 复制文件描述符 1
-//    printf("%d\n", fd); // 2
-    fd = dup2(2, 1);
-    fd = fcntl(1, F_DUPFD, 2);
-    dup3();
-    return 0;
-}
-

code/USP/IO/file_IO/cp.c

-/*编写一个类似于 cp 命令的程序，当使用该程序复制一个包含空洞（连续的空字节）的普通文件时，要求目标文件的空洞与源文件保持一致*/
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <errno.h>
-
-/* open close*/
-#include <fcntl.h>
-
-/* read write close lseek */
-#include <unistd.h>
-
-
-#define BUFFER_SIZE 1
-
-int main(int argc, char *argv[]) {
-    if (argc != 3) {
-        fprintf(stderr, "Usage: %s source dest\n", argv[0]);
-        exit(EXIT_FAILURE);
-    }
-
-    char *source_file = argv[1];
-    char *destination_file = argv[2];
-
-    int source_fd = open(source_file, O_RDONLY);
-    if (source_fd == -1) {
-        fprintf(stderr, "open: %s", strerror(errno));
-        exit(EXIT_FAILURE);
-    }
-
-    int dest_fd = open(destination_file, O_WRONLY | O_CREAT | O_TRUNC, 0644);
-    if (dest_fd == -1) {
-        fprintf(stderr, "open: %s", strerror(errno));
-        close(source_fd);
-        exit(EXIT_FAILURE);
-    }
-
-    char buffer[BUFFER_SIZE];
-    ssize_t bytes_read;
-    while ((bytes_read = read(source_fd, buffer, BUFFER_SIZE)) > 0) {
-        if(bytes_read == - 1) {
-            fprintf(stderr, "read: %s", strerror(errno));
-            close(source_fd);
-            close(dest_fd);
-            exit(EXIT_FAILURE);
-        }
-        /* check file hole */
-        if(buffer[0] == '\0') {
-            lseek(dest_fd, 1, SEEK_CUR);
-            continue;
-        }
-        ssize_t bytes_written = write(dest_fd, buffer, bytes_read);
-        if (bytes_written == -1) {
-            fprintf(stderr, "write: %s", strerror(errno));
-            close(source_fd);
-            close(dest_fd);
-            exit(EXIT_FAILURE);
-        }
-    }
-
-    if (bytes_read == -1) {
-        fprintf(stderr, "read: %s", strerror(errno));
-        close(source_fd);
-        close(dest_fd);
-        exit(EXIT_FAILURE);
-    }
-
-    close(source_fd);
-    close(dest_fd);
-
-    fprintf(stdout, "copy file from %s to %s finished\n", source_file, destination_file);
-
-    return 0;
-}

code/USP/IO/file_IO/file_cntl.c

-/* 文件控制操作 */
-
-#include <fcntl.h>
-#include <unistd.h>
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <errno.h>
-#include <string.h>
-
-int main() {
-    int flag, access_mode;
-    int fd = open("test.txt", O_RDONLY | O_SYNC);
-    flag = fcntl(fd, F_GETFL);  /* 第三个参数不需要 */
-    /* 测试文件是否以同步方式打开 */
-    if(flag & O_SYNC) {
-        fprintf(stdout, "SYNC\n");
-    }
-    /* 判断文件是否可读 */
-    access_mode = flag & O_ACCMODE;
-    if(access_mode == O_RDONLY || access_mode == O_RDWR) {
-        fprintf(stdout, "READ\n");
-    }
-    /*添加 O_APPEND 标志 */
-    flag |= O_APPEND;
-    if(fcntl(fd, F_SETFL, flag) == -1) {
-        fprintf(stderr, "fcntl: %s\n", strerror(errno));
-        exit(EXIT_FAILURE);
-    }
-    return 0;
-}
-

code/USP/IO/file_IO/file_void.c

-/* 文件空洞 */
-
-/* open create */
-#include <sys/stat.h>
-#include <fcntl.h>
-
-/* read write close lseek*/
-#include <unistd.h>
-
-/* ioctl */
-#include <sys/ioctl.h>
-
-#include <stdio.h>
-#include <string.h>
-#include <errno.h>
-
-int main() {
-    ssize_t file_end, file_cur;
-
-    int fd = open("./test.txt", O_RDWR);
-    if(fd == -1) {
-        fprintf(stderr, "open: %s", strerror(errno));
-        return -1;
-    }
-
-    file_end = lseek(fd, 0, SEEK_END);
-    file_cur = lseek(fd, 10, SEEK_END);
-    write(fd, "hello\n", 6);
-    close(fd);
-    return 0;
-}
-
-

code/USP/IO/file_IO/offset_io.c

-/* 在文件特定偏移量处的 I/O：`pread()` 和 `pwrite()` */
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <errno.h>
-
-#include <fcntl.h>
-#include <unistd.h>
-
-int main() {
-    int fd;
-    pread(fd)
-    return 0;
-}
-
-

code/USP/IO/file_IO/readv_writev.c

-/* 分散输入和集中输出 */
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <sys/stat.h>
-#include <sys/uio.h>
-
-#include <fcntl.h>
-#include <unistd.h>
-
-#include <errno.h>
-
-int main(int argc, char *argv[]) {
-
-    int fd;
-    struct iovec iov[3];
-    struct stat my_struct;
-    int x;
-#define STR_SIZE 100
-    char str[STR_SIZE];
-    ssize_t num_read, tot_required;
-    if(argc != 2 || strcmp(argv[1], "--help") == 0) {
-        fprintf(stderr, "Usage: %s file", argv[0]);
-        exit(EXIT_FAILURE);
-    }
-    fd = open(argv[1], O_RDONLY);
-    if(fd == -1) {
-        fprintf(stderr, "open: %s", strerror(errno));
-        exit(EXIT_FAILURE);
-    }
-
-    tot_required = 0;
-    iov[0].iov_base = &my_struct;
-    iov[0].iov_len = sizeof(struct stat);
-    tot_required += iov[0].iov_len;
-
-    iov[1].iov_base = &x;
-    iov[1].iov_len = sizeof(x);
-    tot_required += iov[1].iov_len;
-
-    iov[2].iov_base = str;
-    iov[2].iov_len = STR_SIZE;
-    tot_required += iov[2].iov_len;
-    num_read = readv(fd, iov, 3);
-
-    if(num_read == -1) {
-        fprintf(stderr, "readv: %s", strerror(errno));
-        exit(EXIT_FAILURE);
-    }
-
-    if(num_read < tot_required) {
-        printf("Read fewer bytes than requested\n");
-    }
-    printf("total bytes requested: %ld; bytes read %ld\n", (long) tot_required, (long ) num_read);
-
-    return 0;
-}

code/USP/IO/file_IO/truncate_file.c

-/* 截断文件：truncate()和 ftruncate()系统调用 */
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <sys/stat.h>
-#include <sys/uio.h>
-
-#include <fcntl.h>
-#include <unistd.h>
-
-#include <errno.h>
-
-int main() {
-    truncate();
-    ftruncate();
-    return 0;
-}
-
-

code/USP/IO/general_IO/copy.c

-/* 使用 I/O 系统调用编写 copy 例程 */
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <errno.h>
-
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <unistd.h>
-
-#define BUFFER_SIZE 1024
-
-int main(int argc, char *argv[]) {
-    int in_fd, out_fd;
-    ssize_t read_bytes;
-    char buf[BUFFER_SIZE];
-
-    if(argc != 3 || strcmp(argv[1], "--help") == 0) {
-        fprintf(stderr, "%s oldfile newfile", argv[0]);
-        exit(EXIT_FAILURE);
-    }
-    in_fd = open(argv[1], O_RDONLY);
-    if (in_fd == -1) {
-        fprintf(stderr, "open:%s", strerror(errno));
-    }
-
-    out_fd = open(argv[2], O_WRONLY|O_CREAT, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
-    if (out_fd == -1) {
-        fprintf(stderr, "open:%s", strerror(errno));
-    }
-
-    errno = 0;
-    while ((read_bytes = read(in_fd, buf, BUFFER_SIZE)) > 0) {
-        if(write(out_fd, buf, read_bytes) != read_bytes) {
-            fprintf(stderr, "write: %s", strerror(errno));
-        }
-    }
-    errno = 0;
-    if(read_bytes == -1) {
-        fprintf(stderr, "read: %s", strerror(errno));
-        exit(EXIT_FAILURE);
-    }
-    errno = 0;
-    if(close(in_fd) == -1) {
-        fprintf(stderr, "close: %s", strerror(errno));
-        exit(EXIT_FAILURE);
-    }
-    errno = 0;
-    if(close(out_fd) == -1) {
-        fprintf(stderr, "close: %s", strerror(errno));
-        exit(EXIT_FAILURE);
-    }
-    return  0;
-}
-
-

code/USP/IO/general_IO/io.c

-/* IO 系统调用 */
-
-/* open create */
-#include <sys/stat.h>
-#include <fcntl.h>
-
-/* read write close lseek*/
-#include <unistd.h>
-
-/* ioctl */
-#include <sys/ioctl.h>
-
-int main() {
-    open();
-    creat();
-    read();
-    write();
-    close();
-    lseek()
-    ioctl();
-    return 0;
-}
-

code/USP/IO/general_IO/io_new.c

-/* IO 系统调用 */
-
-/* open create */
-#include <sys/stat.h>
-#include <fcntl.h>
-
-/* read write close lseek*/
-#include <unistd.h>
-
-int main() {
-    open();
-    creat();
-    read();
-    write();
-    close();
-    lseek()
-    return 0;
-}
-

code/USP/IO/general_IO/tee.c

-/* tee 命令是从标准输入中读取数据，直至文件结尾，随后将数据写入标准输出和命令行参数所指定的文件 */
-
-/* open create */
-#include <sys/stat.h>
-#include <fcntl.h>
-
-/* read write close lseek*/
-#include <unistd.h>
-
-#include <stdio.h>
-#include <string.h>
-#include <errno.h>
-
-#define BUFF_SIZE 1024
-
-extern int errno;
-
-int main(int argc, const char *argv[]) {
-    int out_fd;
-    ssize_t read_bytes_num;
-    char buf[BUFF_SIZE];
-
-    if(argc != 2 || strcmp(argv[1], "--help") == 0) {
-        fprintf(stderr, "%s out-file\n", argv[0]);
-        return -1;
-    }
-    errno = 0;
-    out_fd = open(argv[1], O_WRONLY | O_CREAT, S_IWUSR);
-    if(out_fd == -1) {
-        fprintf(stderr, "open: %s\n", strerror(errno));
-        return -1;
-    }
-
-    while ((read_bytes_num = read(STDIN_FILENO, buf, BUFF_SIZE)) > 0) {
-        if(read_bytes_num == -1) {
-            fprintf(stderr, "read: %s\n", strerror(errno));
-        }
-        if(write(STDOUT_FILENO, buf, read_bytes_num) != read_bytes_num || write(out_fd, buf, read_bytes_num) != read_bytes_num) {
-            fprintf(stderr, "write: %s\n", strerror(errno));
-        }
-    }
-
-    errno = 0;
-    if(close(out_fd) == -1) {
-        fprintf(stderr, "close: %s\n", strerror(errno));
-        return -1;
-    }
-
-    return 0;
-}
-

code/USP/IO/general_IO/test.txt

-shfkskhfs
-fhsknfs

code/USP/SharedLibraries/dynamic_loading/dynload.c

-/*
-动态加载库：dlopen dlsym dlerror dlclose dladdr
-*/
-#define _GNU_SOURCE
-#include <dlfcn.h>
-#include <stdio.h>
-#include <string.h>
-#include <stdlib.h>
-
-int main(int argc, char * argv[]) {
-    void *lib_handle;  /* Handle for shared library */
-    int ( *func_ptr)(int, int);  /* Pointer to function with 2 int arguments*/
-    int result;
-    const char *err;
-
-    if(argc != 3 || strcmp(argv[1], "--help") == 0) {
-        fprintf(stderr, "%s lib-path func-name\n", argv[0]);
-        exit(EXIT_FAILURE);
-    }
-
-    /* load the shared library and get a handle for later use */
-    lib_handle = dlopen(argv[1], RTLD_LAZY);
-    if (!lib_handle) {
-        fprintf(stderr, "dlopen: %s\n", dlerror());
-        exit(EXIT_FAILURE);
-    }
-
-    /* search library for symbol named in argv[2] */
-    (void) dlerror();  /* clear dlerror()*/
-
-    err = dlerror();
-    func_ptr = dlsym(lib_handle, argv[2]);
-    if(err) {
-        fprintf(stderr, "dlsym: %s\n", err);
-        exit(EXIT_FAILURE);
-    }
-    /* if the address returned by dlsym() is no-NULL, try calling it as a function that takes 2 int arguments */
-    if ( !func_ptr) {
-        fprintf(stderr, "%s is NULL\n", argv[2]);
-        exit(EXIT_FAILURE);
-    }
-    else {
-        result = (*func_ptr)(1, 2);
-    }
-    printf("call %s, result is %d\n", argv[2], result);
-
-    /* dladdr() */
-    Dl_info info;
-    dladdr(func_ptr, &info);
-    printf("info.dli_fname = %s\n", info.dli_fname);
-    printf("info.dli_fbase = %p\n", info.dli_fbase);
-    printf("info.dli_sname = %s\n", info.dli_sname);
-    printf("info.dli_saddr = %p\n", info.dli_saddr);
-    dlclose(lib_handle);
-    return  0;
-}
\ No newline at end of file

code/USP/SharedLibraries/share/calc.c

-#include "calc.h"
-
-extern int add(int a, int b) {
-    return a + b;
-}
-
-extern int sub(int a, int b) {
-    return a - b;
-}

code/USP/SharedLibraries/share/calc.h

-#ifndef _CALC_H_
-#define _CALC_H_
-
-int add(int a, int b);
-int sub(int a, int b);
-
-#endif

code/USP/SharedLibraries/share/main.c

-#include "calc.h"
-#include "show.h"
-
-int main() {
-    int result = add(1, 2);
-    show(1, '+', 2);
-    return 0;
-}

code/USP/SharedLibraries/share/show.c

-
-#include <stdio.h>
-
-#include "show.h"
-#include "calc.h"
-
-#define BUFSIZE 1024
-
-void show(int left, char op, int right) {
-    char buf[BUFSIZ];
-    int result;
-    switch(op) {
-        case '+':
-            result = add(left, right);
-            break;
-        case '-':
-            result = sub(left, right);
-            break;
-        default:
-            fprintf(stderr, "Unknown operator '%c'\n", op);
-            return;
-    }
-    snprintf(buf, BUFSIZ, "%d %c %d = %d\n", left, op, right, result);
-    puts(buf);
-}

code/USP/SharedLibraries/share/show.h

-#ifndef _SHOW_H_
-#define _SHOW_H_
-
-void show(int left, char op, int right);
-
-#endif

code/USP/SharedLibraries/static/calc.c

-#include "calc.h"
-
-extern int add(int a, int b) {
-    return a + b;
-}
-
-extern int sub(int a, int b) {
-    return a - b;
-}

code/USP/SharedLibraries/static/calc.h

-#ifndef _CALC_H_
-#define _CALC_H_
-
-int add(int a, int b);
-int sub(int a, int b);
-
-#endif

code/USP/SharedLibraries/static/main.c

-#include "calc.h"
-#include "show.h"
-
-int main() {
-    int result = add(1, 2);
-    show(1, '+', 2);
-    return 0;
-}

code/USP/SharedLibraries/static/show.c

-
-#include <stdio.h>
-
-#include "show.h"
-#include "calc.h"
-
-#define BUFSIZE 1024
-
-void show(int left, char op, int right) {
-    char buf[BUFSIZ];
-    int result;
-    switch(op) {
-        case '+':
-            result = add(left, right);
-            break;
-        case '-':
-            result = sub(left, right);
-            break;
-        default:
-            fprintf(stderr, "Unknown operator '%c'\n", op);
-            return;
-    }
-    snprintf(buf, BUFSIZ, "%d %c %d = %d\n", left, op, right, result);
-    puts(buf);
-}

code/USP/SharedLibraries/static/show.h

-#ifndef _SHOW_H_
-#define _SHOW_H_
-
-void show(int left, char op, int right);
-
-#endif

code/USP/SharedLibraries/version_script/init_fini/init_fini.c

-
-
-void __attribute__ ((constructor)) some_name_load(void){
-    /* Initialization code */
-}
-
-void __attribute__ ((deprecated)) some_name_unload(void) {
-    /* Finalization code */
-}
\ No newline at end of file

code/USP/SharedLibraries/version_script/symbol_visible/main.c

-//
-// Created by dyp on 9/12/23.
-//
-
-#include <dlfcn.h>
-#include <stdio.h>
-
-int main() {
-    void * handle = dlopen("./libvis.so.1", RTLD_LAZY);
-    void (*fp)() = dlsym(handle, "vis_f1");
-    if(fp == NULL) {
-        fprintf(stderr, "dlsym:%s\n", dlerror());
-        return -1;
-    }
-    fp();
-    return 0;
-}

code/USP/SharedLibraries/version_script/symbol_visible/vis.map

-VER_1 {
-    global:
-        vis_f1;
-        vis_f2;
-    local:
-        *;
-};
\ No newline at end of file

code/USP/SharedLibraries/version_script/symbol_visible/vis_comm.c

-
-
-#include <stdio.h>
-
-
-void vis_comm() {
-    printf("at vis_comm.c");
-}
-
-
-

code/USP/SharedLibraries/version_script/symbol_visible/vis_f1.c

-
-#include <stdio.h>
-
-void vis_comm();
-void vis_f1() {
-    printf("at vis_f1.c call vis_comm()\n");
-    vis_comm();
-}
-

code/USP/SharedLibraries/version_script/symbol_visible/vis_f2.c

-#include <stdio.h>
-
-void vis_comm();
-void vis_f2() {
-    printf("at vis_f2.c call vis_comm()");
-    vis_comm();
-}

code/USP/SharedLibraries/version_script/symbolic_version/sv_lib_v1.c

-
-#include <stdio.h>
-
-void xyz(void) {
-    printf("v1 xyz\n");
-}
-

code/USP/SharedLibraries/version_script/symbolic_version/sv_lib_v2.c

-#include <stdio.h>
-
-__asm__(".symver xyz_old,xyz@VER_1");
-__asm__(".symver xyz_new,xyz@@VER_2");
-
-void xyz_old(void) {
-    printf("v1 xyz\n");
-}
-
-void xyz_new(void) {
-    printf("v2 xyz\n");
-}
-
-void pqr(void) {
-    printf("v2 pqr\n");
-}

code/USP/SharedLibraries/version_script/symbolic_version/sv_prog.c

-#include <stdlib.h>
-
-int main(int argc, char *argv[]) {
-    void xyz(void);
-    xyz();
-    exit(EXIT_SUCCESS);
-}
\ No newline at end of file

code/USP/SharedLibraries/version_script/symbolic_version/sv_v1.map

-VER_1 {
-    global:
-        xyz;
-    local:
-        *;
-};
\ No newline at end of file

code/USP/SharedLibraries/version_script/symbolic_version/sv_v2.map

-VER_1 {
-    global:
-        xyz;
-    local:
-        *;
-};
-
-VER_2 {
-    global:
-        pqr;
-} VER_1;

code/USP/process/base/environ.c

-/* 显示进程环境变量 */
-
-#include <stdio.h>
-#include <stdlib.h>
-
-extern char **environ;  // 获取环境变量
-
-int main(int argc, char *argv[]) {
-    int j;
-    char **ep;
-    // 清除环境变量
-    clearenv();
-    for(j = 1; j < argc; j++) {
-        // putenv 失败返回 非零0 值
-        if(putenv(argv[j]) != 0) {
-            fprintf(stderr, "putenv: fail");
-            exit(EXIT_FAILURE);
-        }
-    }
-    // setenv 失败返回 -1
-    if(setenv("GREET", "HELLO WORLD", 0) == -1) {
-        fprintf(stderr, "setenv: fail");
-        exit(EXIT_FAILURE);
-    }
-    unsetenv("BYE");
-    for(ep = environ; *ep != NULL; ep++) {
-        puts(*ep);
-    }
-
-    return 0;
-}
-

code/USP/process/base/pid.c

-/* 获取进程号 */
-
-#include <unistd.h>
-#include <stdio.h>
-
-int main() {
-    printf("PPID: %d -> PID: %d\n", getppid(), getpid());
-    return 0;
-}

code/USP/process/base/var_in_mem.c

-/* 变量在进程内存各段中的位置 */
-
-
-#include <stdio.h>
-#include <stdlib.h>
-
-
-/* 未初始化段 */
-char globBuf[65536];
-
-/* 初始化段 */
-int primes[] = {2, 3, 5, 7};
-
-/* square 在文本段 */
-static int square(int x) {
-    /* x 和 result 在 square 的栈帧中*/
-    int result;
-    result = x * x;
-    return result;  /* 返回值通过 rax 寄存器 */
-}
-
-static void doCalc(int val) {
-    printf("The square of %d is %d\n", val, square(val));
-    if(val < 1000) {
-        int t;
-        t = val * val * val;
-        printf("The cube of %d is %d\n", val, t);
-    }
-}
-
-int main(int argc, char *argv[]) {
-
-    /* 初始化段 */
-    static int key = 9973;
-    /* 未初始化段 */
-    static  char mbuf[10240000];
-
-    char *p;
-    /* 执行 堆 内存空间 */
-    p = malloc(1024);
-
-    doCalc(key);
-    exit(EXIT_SUCCESS);
-}
-

code/USP/process/mem_alloc/alloca.c

-/* 在栈上分配空间：alloca */
-
-#include <alloca.h>
-
-int main() {
-    alloca()
-    return 0;
-}
\ No newline at end of file

code/USP/process/mem_alloc/brk_sbrk.c

-/* 堆上的内存分配：brk 和 sbrk
- * 释放内存时 program break(&end) 的行为
- * */
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <getopt.h>
-
-#include <unistd.h>
-
-#define MAX_ALLOCS 1000000
-
-int main(int argc, char *argv[]) {
-    char *ptr[MAX_ALLOCS];
-    int freeStep, freeMin, freeMax, blockSize, numALLOCS, j;
-    printf("\n");
-
-    if(argc < 3 || strcmp(argv[1], "--help") == 0) {
-        fprintf(stderr, "Usage: %s source dest\n", argv[0]);
-        exit(EXIT_FAILURE);
-    }
-
-    return 0;
-}
-
-

code/USP/process/user_group/crypt_getpass.c

-/* 密码加密与用户认证：crypt 和 getpass */
-#define _XOPEN_SOURCE /* crypt() */
-#define _DEFAULT_SOURCE  /* getpass() */
-#include <unistd.h>
-#include <limits.h>
-#include <pwd.h>
-#include <shadow.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <errno.h>
-#include <stdbool.h>
-
-int main(int argc, char *argv[]) {
-    char *username, *password, *encrypted, *p;
-    struct passwd *pwd;
-    struct spwd *spwd;
-    bool authOk;
-    size_t len;
-    long lnmax;
-    lnmax = sysconf(_SC_LOGIN_NAME_MAX);
-    if(lnmax ==- 1) {
-        lnmax = 256;
-    }
-    /* 为用户名分配空间 */
-    username = malloc(sizeof(char) * lnmax);
-    if(username == NULL) {
-        fprintf(stderr, "malloc: %s\n", strerror(errno));
-        exit(EXIT_FAILURE);
-    }
-    printf("Usename: ");
-    fflush(stdout);
-    /* 读入用户名 */
-    if(fgets(username, lnmax, stdin) == NULL) {
-        fprintf(stdout, "fget: appear error or eof\n");
-        exit(EXIT_FAILURE);
-    }
-    len = strlen(username);
-    if(username[len - 1] == '\n') {
-        username[len - 1] = '\0';
-    }
-    /* 获取/etc/passwd 中获取用户名记录 */
-    pwd = getpwnam(username);
-    if(pwd == NULL) {
-        fprintf(stdout, "getpwnam: get passwd record fail\n");
-        exit(EXIT_FAILURE);
-    }
-    /*获取/etc/shadow 中获取用户名记录*/
-    spwd = getspnam(username);
-    if(spwd == NULL && errno == EACCES) {
-        fprintf(stdout, "getspnam: no permission to read shadow password file\n");
-    }
-    if(spwd != NULL) {
-        pwd->pw_passwd = spwd->sp_pwdp;
-    }
-    /* 读入一行 */
-    password = getpass("Password: ");
-
-    /* 对读入的密码继续加密，salt参数原加密密码的前两位 */
-    encrypted = crypt(password, pwd->pw_passwd);
-    for(p = password; *p != '\0'; ) {
-        *p++ = '\0';
-    }
-
-    if(encrypted == NULL) {
-        fprintf(stdout, "crypt: crypt fail\n");
-        exit(EXIT_FAILURE);
-    }
-    printf("pw_passwd: %s\n", pwd->pw_passwd);
-    printf("encrypted: %s\n", encrypted);
-
-    /* 判断是否一致 */
-    authOk = strcmp(encrypted, pwd->pw_passwd) == 0;
-    if(!authOk) {
-        printf("Incorrect password\n");
-        exit(EXIT_FAILURE);
-    }
-    printf("Successfully authenticated: UID=%d\n", pwd->pw_uid);
-
-    return 0;
-}

code/USP/process/user_group/getgrna_getgrgid.c

-/* 从组文件获取记录：`getgrnam()` 和 `getgrgid()` */
-
-#include <stdio.h>
-#include <grp.h>
-
-int main() {
-    getgrnam();
-    getgrgid();
-    return 0;
-}
-

code/USP/process/user_group/getpwent_setpwent_endpwent.c

-#include <stdio.h>
-#include <stdlib.h>
-
-#include <pwd.h>
-
-int main() {
-
-    struct passwd *pwd;
-
-    while ((pwd = getpwent()) != NULL) {
-        printf("-%8s %5ld\n", pwd->pw_name, (long) pwd->pw_uid);
-    }
-    endpwent();
-}
\ No newline at end of file

code/USP/process/user_group/getpwname_getpwuid.c

-/* 从密码文件获取用户和组的信息: `getpwnam()` 和 `getpwuid()` */
-
-#include <stdio.h>
-
-#include <pwd.h>
-
-#include <errno.h>
-
-int main() {
-//    errno = 0;
-//    struct passwd *pd = getpwnam("dyp");
-//    if(pd == NULL) {
-//        if(errno == 0) {
-//            /* 未发现匹配记录 */
-//        } else {
-//            /* 出错 */
-//        }
-//    }
-//
-//    printf("pw_name:%s\n", pd->pw_name);
-//    printf("pw_passwd:%s\n", pd->pw_passwd);
-//    printf("pw_uid:%d\n", pd->pw_uid);
-
-    printf("%d %d\n", getpwnam("dyp")->pw_uid, getpwnam("git")->pw_uid);
-    return 0;
-}
-
-
-
-
-
-

code/USP/process/user_group/getspnam_getspent_setspent_endspent.c

-
-#include <stdio.h>
-#include <stdlib.h>
-#include <shadow.h>
-
-int main() {
-    struct spwd * sp;
-    sp = getspnam("dyp");
-    printf("sp_name:%s\n", sp->sp_namp);
-    while((sp = getspent()) != NULL) {
-        printf("-%8s %s\n", sp->sp_namp, sp->sp_pwdp);
-    }
-    endspent();
-    return 0;
-}
-

code/USP/process/user_group/my_getpwnam.c

-/* 使用 `setpwent()`、`getpwent()`和 `endpwent()`来实现 `getpwnam()` */
-
-#include <pwd.h>
-#include <unistd.h>
-#include <string.h>
-#include <stdio.h>
-
-struct passwd * my_getpwnam(const char *name) {
-    struct passwd *pwd;
-    while ((pwd = getpwent()) != NULL) {
-        if(strcmp(name, pwd->pw_name) == 0) {
-            endpwent();
-            return pwd;
-        }
-    }
-    endpwent();
-    return NULL;
-}
-
-int main() {
-    struct passwd *pd = my_getpwnam("dyp");
-    if(pd == NULL) {
-        fprintf(stderr, "my_getpwnam: get passwd by name fail\n");
-        return -1;
-    }
-    printf("user:%s -> UID:%d\n", pd->pw_name, pd->pw_uid);
-    return 0;
-}

code/USP/process/user_group/ugid_functions.c

-/*
- * 在用户名/组名和用户 ID/组 ID 之间互相转换的函数
- * */
-
-#include <pwd.h>
-#include <grp.h>
-#include <ctype.h>
-#include <stdlib.h>
-#include <stdio.h>
-
-/* return pointer to username by uid, or NULL on error*/
-char *userNameFromId(uid_t uid) {
-    struct passwd *pwd;
-    pwd = getpwuid(uid);
-    return (pwd == NULL) ? NULL : pwd->pw_name;
-}
-
-/* return uid by username, or -1 on error*/
-uid_t userIdFromName(const char *username) {
-    struct passwd *pwd;
-    uid_t u;
-    char *endptr;
-    if(username == NULL || *username == '\0') {
-        return -1;
-    }
-    u = strtol(username, &endptr, 10);
-    if(*endptr == '\0') {
-        return u;
-    }
-
-    pwd = getpwnam(username);
-    return pwd == NULL ? -1 : pwd->pw_uid;
-}
-
-/* return pointer to groupname by uid, or NULL on error*/
-char *groupNameFromId(gid_t gid) {
-    struct group *grp;
-    grp = getgrgid(gid);
-    return (grp == NULL) ? NULL : grp->gr_name;
-}
-
-/* return gid by gropname, or -1 on error*/
-gid_t groupIdFromName(const char *gname) {
-    struct group *grp;
-    gid_t g;
-    char *endptr;
-    if(gname == NULL || *gname == '\0') {
-        return -1;
-    }
-    g = strtol(gname, &endptr, 10);
-    if(*endptr == '\0') {
-        return g;
-    }
-
-    grp = getgrnam(gname);
-    return grp == NULL ? -1 : grp->gr_gid;
-}
-
-int main() {
-    printf("uid:1000 -> name: %s\n", userNameFromId(1000));
-    printf("name:dyp -> uid:: %d\n", userIdFromName("dyp"));
-    printf("gid:1000 -> gname:%s\n", groupNameFromId(973));
-    printf("gname:git -> gname:%d\n", groupIdFromName("git"));
-
-    return 0;
-}
\ No newline at end of file

code/dsa/ArrayList/ArrayList.c

-#include "ArrayList.h"
-
-
-struct seq_list {
-    elem_t *data;
-    int size;
-    int length;
-};
\ No newline at end of file

code/dsa/ArrayList/ArrayList.h

-/*
-线性表的顺序存储结构
-*/
-
-typedef int elem_t;
-
-typedef struct seq_list List;
-typedef List *list_t;
-
-
-

code/dsa/ChainQueue/Makefile

-main: queue.o main.o
-	gcc -o main queue.o main.o
-
-queue.o: queue.c queue.h
-	gcc -c queue.c
-
-main.o: main.c queue.h
-	gcc -c main.c
-
-.PHONY:clean
-clean:
-	rm *.o
-	rm *.exe