添加文件操作

data/3.C语言高阶/5.文件/1.文件的基本操作/file01.c

+#include <stdio.h>
+
+int main(int argc, char **args) {
+  FILE *file = fopen("/tmp/hello.txt", "w+");
+  fputs("Hello,World!\n", file);
+  fclose(file);
+  return 0;
+}
\ No newline at end of file

data/3.C语言高阶/5.文件/1.文件的基本操作/file01.json

+{
+    "type": "code_options",
+    "author": "幻灰龙",
+    "source": "file01.md"
+}
\ No newline at end of file

data/3.C语言高阶/5.文件/1.文件的基本操作/file01.md

+# 写入字符串到文件(1)
+
+下面正确将"Hello,World!"写入到文件的代码是？
+
+## 答案
+
+```c
+#include <stdio.h>
+
+int main(int argc, char **args) {
+  FILE *file = fopen("/tmp/hello.txt", "w+");
+  fputs("Hello,World!\n", file);
+  fclose(file);
+  return 0;
+}
+```
+
+## 选项
+
+### 选项1
+
+```c
+#include <stdio.h>
+
+int main(int argc, char **args) {
+  FILE *file = fopen("/tmp/hello.txt", "r+");
+  fputs("Hello,World!\n", file);
+  fclose(file);
+  return 0;
+}
+```
+
+### 选项2
+
+```c
+#include <stdio.h>
+
+int main(int argc, char **args) {
+  FILE *file = fopen("/tmp/hello.txt", "w+");
+  fputs("Hello,World!\n", file);
+  return 0;
+}
+```
+
+### 选项3
+
+```c
+#include <stdio.h>
+
+int main(int argc, char **args) {
+  FILE *file = fopen("/tmp/hello.txt", "w+");
+  fputs(file, "Hello,World!\n");
+  fclose(file);
+  return 0;
+}
+```
\ No newline at end of file

data/3.C语言高阶/5.文件/1.文件的基本操作/file02.c

+#include <stdio.h>
+
+int main(int argc, char **args) {
+  // 写入
+  FILE *f1 = fopen("/tmp/hello.txt", "w+");
+  fputs("Hello,World!\n", f1);
+  fclose(f1);
+
+  // 读取
+  FILE *f2 = fopen("/tmp/hello.txt", "r+");
+  char buff[1024];
+  fgets(buff, 1024, f2);
+  fclose(f2);
+
+  // 打印
+  printf("%s", buff);
+
+  return 0;
+}
\ No newline at end of file

data/3.C语言高阶/5.文件/1.文件的基本操作/file02.json

+{
+    "type": "code_options",
+    "author": "幻灰龙",
+    "source": "file02.md"
+}
\ No newline at end of file

data/3.C语言高阶/5.文件/1.文件的基本操作/file02.md

+# 写入字符串到文件(2)
+
+下面正确将"Hello,World!"写入文件，并再次打开读取出来的代码是？
+
+## 答案
+
+```c
+#include <stdio.h>
+
+int main(int argc, char **args) {
+  // 写入
+  FILE *f1 = fopen("/tmp/hello.txt", "w+");
+  fputs("Hello,World!\n", f1);
+  fclose(f1);
+
+  // 读取
+  FILE *f2 = fopen("/tmp/hello.txt", "r+");
+  char buff[1024];
+  fgets(buff, 1024, f2);
+  fclose(f2);
+
+  // 打印
+  printf("%s", buff);
+
+  return 0;
+}
+```
+
+## 选项
+
+### 选项1
+
+```c
+#include <stdio.h>
+
+int main(int argc, char **args) {
+  // 写入
+  FILE *f1 = fopen("/tmp/hello.txt", "r+");
+  fputs("Hello,World!\n", f1);
+  fclose(f1);
+
+  // 读取
+  FILE *f2 = fopen("/tmp/hello.txt", "w+");
+  char buff[1024];
+  fgets(buff, 1024, f2);
+  fclose(f2);
+
+  // 打印
+  printf("%s", buff);
+
+  return 0;
+}
+```
+
+### 选项2
+
+```c
+#include <stdio.h>
+
+int main(int argc, char **args) {
+  // 写入
+  FILE *f1 = fopen("/tmp/hello.txt", "w+");
+  fputs("Hello,World!\n", f1);
+  fclose(f1);
+
+  // 读取
+  FILE *f2 = fopen("/tmp/hello.txt", "r+");
+  char buff[1024];
+  fgets(f2, buff, 1024);
+  fclose(f2);
+
+  // 打印
+  printf("%s", buff);
+
+  return 0;
+}
+```
+
+### 选项3
+
+```c
+#include <stdio.h>
+
+int main(int argc, char **args) {
+  // 写入
+  FILE *f1 = fopen("/tmp/hello.txt", "w+");
+  fputs("Hello,World!\n", f1);
+  fclose(f1);
+
+  // 读取
+  FILE *f2 = fopen("/tmp/hello.txt", "r+");
+  char buff[1024];
+  fgets(buff, 1024, f2);
+
+  // 打印
+  printf("%s", buff);
+
+  return 0;
+}
+```
\ No newline at end of file

data/3.C语言高阶/5.文件/1.文件的基本操作/file03.c

+#include <stdio.h>
+
+int main(int argc, char **args) {
+  // 写入
+  FILE *f1 = fopen("/tmp/hello.txt", "w+");
+  fputs("Hello,World!\n", f1);
+  fclose(f1);
+
+  // 追加
+  FILE *f2 = fopen("/tmp/hello.txt", "a+");
+  fputs("Hello,World!\n", f1);
+  fclose(f2);
+
+  // 读取
+  FILE *f3 = fopen("/tmp/hello.txt", "r+");
+  char buff[1024];
+
+  fgets(buff, 1024, f3);
+  printf("%s", buff);
+
+  fgets(buff, 1024, f3);
+  printf("%s", buff);
+
+  fclose(f3);
+
+  return 0;
+}
\ No newline at end of file

data/3.C语言高阶/5.文件/1.文件的基本操作/file03.json

+{
+    "type": "code_options",
+    "author": "幻灰龙",
+    "source": "file03.md"
+}
\ No newline at end of file

data/3.C语言高阶/5.文件/1.文件的基本操作/file03.md

+# 写入字符串到文件(3)
+
+下面正确将"Hello,World!"写入文件，并再次打开追加写入"Hello,World!"，最后一次打开并读取出来打印两行"Hello,World!"的代码是？
+
+## 答案
+
+```c
+#include <stdio.h>
+
+int main(int argc, char **args) {
+  // 写入
+  FILE *f1 = fopen("/tmp/hello.txt", "w+");
+  fputs("Hello,World!\n", f1);
+  fclose(f1);
+
+  // 追加
+  FILE *f2 = fopen("/tmp/hello.txt", "a+");
+  fputs("Hello,World!\n", f1);
+  fclose(f2);
+
+  // 读取
+  FILE *f3 = fopen("/tmp/hello.txt", "r+");
+  char buff[1024];
+
+  fgets(buff, 1024, f3);
+  printf("%s", buff);
+
+  fgets(buff, 1024, f3);
+  printf("%s", buff);
+
+  fclose(f3);
+
+  return 0;
+}
+```
+
+## 选项
+
+### 选项1
+
+```c
+#include <stdio.h>
+
+int main(int argc, char **args) {
+  // 写入
+  FILE *f1 = fopen("/tmp/hello.txt", "w+");
+  fputs("Hello,World!\n", f1);
+  fclose(f1);
+
+  // 追加
+  FILE *f2 = fopen("/tmp/hello.txt", "w+");
+  fputs("Hello,World!\n", f1);
+  fclose(f2);
+
+  // 读取
+  FILE *f3 = fopen("/tmp/hello.txt", "r+");
+  char buff[1024];
+
+  fgets(buff, 1024, f3);
+  printf("%s", buff);
+
+  fgets(buff, 1024, f3);
+  printf("%s", buff);
+
+  fclose(f3);
+
+  return 0;
+}
+```
+
+### 选项2
+
+```c
+#include <stdio.h>
+
+int main(int argc, char **args) {
+  // 写入
+  FILE *f1 = fopen("/tmp/hello.txt", "w+");
+  fputs("Hello,World!\n", f1);
+  fclose(f1);
+
+  // 追加
+  FILE *f1 = fopen("/tmp/hello.txt", "w+");
+  fputs("Hello,World!\n", f1);
+  fclose(f1);
+
+  // 读取
+  FILE *f3 = fopen("/tmp/hello.txt", "r+");
+  char buff[1024];
+
+  fgets(buff, 1024, f3);
+  printf("%s", buff);
+
+  fgets(buff, 1024, f3);
+  printf("%s", buff);
+
+  fclose(f3);
+
+  return 0;
+}
+```
+
+### 选项3
+
+```c
+#include <stdio.h>
+
+int main(int argc, char **args) {
+  // 写入
+  FILE *f1 = fopen("/tmp/hello.txt", "w+");
+  fputs("Hello,World!\n", f1);
+  fclose(f1);
+
+  // 追加
+  FILE *f2 = fopen("/tmp/hello.txt", "a+");
+  fputs("Hello,World!\n", f1);
+  fclose(f2);
+
+  // 读取
+  FILE *f3 = fopen("/tmp/hello.txt", "r+");
+  char buff[1024];
+
+  fgets(buff, 1024, f3);
+  printf("%s", buff);
+
+  fclose(f3);
+
+  return 0;
+}
+```
\ No newline at end of file

data/3.C语言高阶/5.文件/2.文件的读写/config.json

@@ -5,5 +5,7 @@
     "C语言"
   ],
   "children": [],
-  "export": []
+  "export": [
+      "file_hash.json"
+  ]
 }
\ No newline at end of file

data/3.C语言高阶/5.文件/2.文件的读写/file_hash.c

+/*
+    MIT License
+    Copyright (c) 2020 LekKit https://github.com/LekKit
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to
+   deal in the Software without restriction, including without limitation the
+   rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+   sell copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+    The above copyright notice and this permission notice shall be included in
+   all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED
+   "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
+   LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+   PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+   ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+   WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+/* Details of the implementation, etc can be found here:
+   https://en.wikipedia.org/wiki/SHA-2 See sha256.h for short documentation on
+   library usage */
+
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct sha256_buff {
+  uint64_t data_size;
+  uint32_t h[8];
+  uint8_t last_chunk[64];
+  uint8_t chunk_size;
+};
+
+void sha256_init(struct sha256_buff *buff) {
+  buff->h[0] = 0x6a09e667;
+  buff->h[1] = 0xbb67ae85;
+  buff->h[2] = 0x3c6ef372;
+  buff->h[3] = 0xa54ff53a;
+  buff->h[4] = 0x510e527f;
+  buff->h[5] = 0x9b05688c;
+  buff->h[6] = 0x1f83d9ab;
+  buff->h[7] = 0x5be0cd19;
+  buff->data_size = 0;
+  buff->chunk_size = 0;
+}
+
+const static uint32_t k[64] = {
+    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1,
+    0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
+    0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786,
+    0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
+    0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147,
+    0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
+    0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b,
+    0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
+    0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a,
+    0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
+    0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2};
+
+#define rotate_r(val, bits) (val >> bits | val << (32 - bits))
+
+static void sha256_calc_chunk(struct sha256_buff *buff, const uint8_t *chunk) {
+  uint32_t w[64];
+  uint32_t tv[8];
+  uint32_t i;
+
+  for (i = 0; i < 16; ++i) {
+    w[i] = (uint32_t)chunk[0] << 24 | (uint32_t)chunk[1] << 16 |
+           (uint32_t)chunk[2] << 8 | (uint32_t)chunk[3];
+    chunk += 4;
+  }
+
+  for (i = 16; i < 64; ++i) {
+    uint32_t s0 =
+        rotate_r(w[i - 15], 7) ^ rotate_r(w[i - 15], 18) ^ (w[i - 15] >> 3);
+    uint32_t s1 =
+        rotate_r(w[i - 2], 17) ^ rotate_r(w[i - 2], 19) ^ (w[i - 2] >> 10);
+    w[i] = w[i - 16] + s0 + w[i - 7] + s1;
+  }
+
+  for (i = 0; i < 8; ++i)
+    tv[i] = buff->h[i];
+
+  for (i = 0; i < 64; ++i) {
+    uint32_t S1 =
+        rotate_r(tv[4], 6) ^ rotate_r(tv[4], 11) ^ rotate_r(tv[4], 25);
+    uint32_t ch = (tv[4] & tv[5]) ^ (~tv[4] & tv[6]);
+    uint32_t temp1 = tv[7] + S1 + ch + k[i] + w[i];
+    uint32_t S0 =
+        rotate_r(tv[0], 2) ^ rotate_r(tv[0], 13) ^ rotate_r(tv[0], 22);
+    uint32_t maj = (tv[0] & tv[1]) ^ (tv[0] & tv[2]) ^ (tv[1] & tv[2]);
+    uint32_t temp2 = S0 + maj;
+
+    tv[7] = tv[6];
+    tv[6] = tv[5];
+    tv[5] = tv[4];
+    tv[4] = tv[3] + temp1;
+    tv[3] = tv[2];
+    tv[2] = tv[1];
+    tv[1] = tv[0];
+    tv[0] = temp1 + temp2;
+  }
+
+  for (i = 0; i < 8; ++i)
+    buff->h[i] += tv[i];
+}
+
+void sha256_update(struct sha256_buff *buff, const void *data, size_t size) {
+  const uint8_t *ptr = (const uint8_t *)data;
+  buff->data_size += size;
+  /* If there is data left in buff, concatenate it to process as new chunk */
+  if (size + buff->chunk_size >= 64) {
+    uint8_t tmp_chunk[64];
+    memcpy(tmp_chunk, buff->last_chunk, buff->chunk_size);
+    memcpy(tmp_chunk + buff->chunk_size, ptr, 64 - buff->chunk_size);
+    ptr += (64 - buff->chunk_size);
+    size -= (64 - buff->chunk_size);
+    buff->chunk_size = 0;
+    sha256_calc_chunk(buff, tmp_chunk);
+  }
+  /* Run over data chunks */
+  while (size >= 64) {
+    sha256_calc_chunk(buff, ptr);
+    ptr += 64;
+    size -= 64;
+  }
+
+  /* Save remaining data in buff, will be reused on next call or finalize */
+  memcpy(buff->last_chunk + buff->chunk_size, ptr, size);
+  buff->chunk_size += size;
+}
+
+void sha256_finalize(struct sha256_buff *buff) {
+  buff->last_chunk[buff->chunk_size] = 0x80;
+  buff->chunk_size++;
+  memset(buff->last_chunk + buff->chunk_size, 0, 64 - buff->chunk_size);
+
+  /* If there isn't enough space to fit int64, pad chunk with zeroes and prepare
+   * next chunk */
+  if (buff->chunk_size > 56) {
+    sha256_calc_chunk(buff, buff->last_chunk);
+    memset(buff->last_chunk, 0, 64);
+  }
+
+  /* Add total size as big-endian int64 x8 */
+  uint64_t size = buff->data_size * 8;
+  int i;
+  for (i = 8; i > 0; --i) {
+    buff->last_chunk[55 + i] = size & 255;
+    size >>= 8;
+  }
+
+  sha256_calc_chunk(buff, buff->last_chunk);
+}
+
+void sha256_read(const struct sha256_buff *buff, uint8_t *hash) {
+  uint32_t i;
+  for (i = 0; i < 8; i++) {
+    hash[i * 4] = (buff->h[i] >> 24) & 255;
+    hash[i * 4 + 1] = (buff->h[i] >> 16) & 255;
+    hash[i * 4 + 2] = (buff->h[i] >> 8) & 255;
+    hash[i * 4 + 3] = buff->h[i] & 255;
+  }
+}
+
+static void bin_to_hex(const void *data, uint32_t len, char *out) {
+  static const char *const lut = "0123456789abcdef";
+  uint32_t i;
+  for (i = 0; i < len; ++i) {
+    uint8_t c = ((uint8_t *)data)[i];
+    out[i * 2] = lut[c >> 4];
+    out[i * 2 + 1] = lut[c & 15];
+  }
+}
+
+void sha256_read_hex(const struct sha256_buff *buff, char *hex) {
+  uint8_t hash[32];
+  sha256_read(buff, hash);
+  bin_to_hex(hash, 32, hex);
+}
+
+int main(int argc, char **argv) {
+  FILE *file = fopen(argv[1], "rb");
+  if (!file) {
+    printf("Cannot open file\n");
+    return 0;
+  }
+  char buffer[1024];
+  size_t size;
+  struct sha256_buff buff;
+  sha256_init(&buff);
+  while (!feof(file)) {
+    /* Hash file by 1kb chunks, instead of loading into RAM at once */
+    size = fread(buffer, 1, 1024, file);
+    sha256_update(&buff, buffer, size);
+  }
+  char hash[65] = {0}; /* hash[64] is null-byte */
+  sha256_finalize(&buff);
+  sha256_read_hex(&buff, hash);
+  printf("%s\n", hash);
+  return 0;
+}
\ No newline at end of file

data/3.C语言高阶/5.文件/2.文件的读写/file_hash.json

+{
+    "type": "code_options",
+    "author": "幻灰龙",
+    "source": "file_hash.md"
+}
\ No newline at end of file

data/3.C语言高阶/5.文件/2.文件的读写/file_hash.md

+# 计算文件到 sha256 哈希
+
+下面的代码打开文件、分片读取文件二进制数据，最终计算文件的 sha256 哈希，请选择正确的代码。
+依赖的文件请参考：
+* [sha256.h](https://codechina.csdn.net/csdn/skill_tree_c/-/tree/master/data/3.C%E8%AF%AD%E8%A8%80%E9%AB%98%E9%98%B6/5.%E6%96%87%E4%BB%B6/2.%E6%96%87%E4%BB%B6%E7%9A%84%E8%AF%BB%E5%86%99/sha256.h)
+* [sha256.c](https://codechina.csdn.net/csdn/skill_tree_c/-/tree/master/data/3.C%E8%AF%AD%E8%A8%80%E9%AB%98%E9%98%B6/5.%E6%96%87%E4%BB%B6/2.%E6%96%87%E4%BB%B6%E7%9A%84%E8%AF%BB%E5%86%99/sha256.c)
+
+## 答案
+
+```c
+#include "sha256.h"
+#include <stdio.h>
+
+int main(int argc, char **argv) {
+  FILE *file = fopen(argv[1], "rb");
+  if (!file) {
+    printf("Cannot open file\n");
+    return 0;
+  }
+  char buffer[1024];
+  size_t size;
+  struct sha256_buff buff;
+  sha256_init(&buff);
+  while (!feof(file)) {
+    /* Hash file by 1kb chunks, instead of loading into RAM at once */
+    size = fread(buffer, 1, 1024, file);
+    sha256_update(&buff, buffer, size);
+  }
+  char hash[65] = {0}; /* hash[64] is null-byte */
+  sha256_finalize(&buff);
+  sha256_read_hex(&buff, hash);
+  printf("%s\n", hash);
+  fclose(file);
+  return 0;
+}
+
+```
+
+## 选项
+
+### 选项1
+
+```c
+#include "sha256.h"
+#include <stdio.h>
+
+int main(int argc, char **argv) {
+  FILE *file = fopen(argv[1], "rb");
+  if (!file) {
+    printf("Cannot open file\n");
+    return 0;
+  }
+  char buffer[1024];
+  size_t size;
+  struct sha256_buff buff;
+  sha256_init(&buff);
+  while (!feof(file)) {
+    /* Hash file by 1kb chunks, instead of loading into RAM at once */
+    size = fread(file, buffer, 1, 1024);
+    sha256_update(&buff, buffer, size);
+  }
+  char hash[65] = {0}; /* hash[64] is null-byte */
+  sha256_finalize(&buff);
+  sha256_read_hex(&buff, hash);
+  printf("%s\n", hash);
+  fclose(file);
+  return 0;
+}
+```
+
+### 选项2
+
+```c
+#include "sha256.h"
+#include <stdio.h>
+
+int main(int argc, char **argv) {
+  FILE *file = fopen(argv[1], "rb");
+  if (!file) {
+    printf("Cannot open file\n");
+    return 0;
+  }
+  char buffer[1024];
+  size_t size;
+  struct sha256_buff buff;
+  sha256_init(&buff);
+  while (!feof(file)) {
+    /* Hash file by 1kb chunks, instead of loading into RAM at once */
+    size = fread(buffer, 2, 1024, file);
+    sha256_update(&buff, buffer, size);
+  }
+  char hash[65] = {0}; /* hash[64] is null-byte */
+  sha256_finalize(&buff);
+  sha256_read_hex(&buff, hash);
+  printf("%s\n", hash);
+  fclose(file);
+  return 0;
+}
+
+```
+
+### 选项3
+
+```c
+#include "sha256.h"
+#include <stdio.h>
+
+int main(int argc, char **argv) {
+  FILE *file = fopen(argv[1], "rb");
+  if (!file) {
+    printf("Cannot open file\n");
+    return 0;
+  }
+  char buffer[1024];
+  size_t size;
+  struct sha256_buff buff;
+  sha256_init(&buff);
+  while (!feof(file)) {
+    /* Hash file by 1kb chunks, instead of loading into RAM at once */
+    size = fread(buffer, 1, 1024, file);
+    sha256_update(&buff, buffer, size);
+  }
+  char hash[65] = {0}; /* hash[64] is null-byte */
+  sha256_finalize(&buff);
+  sha256_read_hex(&buff, hash);
+  printf("%s\n", hash);
+  return 0;
+}
+```
\ No newline at end of file

data/3.C语言高阶/5.文件/2.文件的读写/sha256.c

+/*
+    MIT License
+    Copyright (c) 2020 LekKit https://github.com/LekKit
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to
+   deal in the Software without restriction, including without limitation the
+   rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+   sell copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+    The above copyright notice and this permission notice shall be included in
+   all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED
+   "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
+   LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+   PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+   ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+   WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+/* Details of the implementation, etc can be found here:
+   https://en.wikipedia.org/wiki/SHA-2 See sha256.h for short documentation on
+   library usage */
+
+#include "sha256.h"
+
+void sha256_init(struct sha256_buff *buff) {
+  buff->h[0] = 0x6a09e667;
+  buff->h[1] = 0xbb67ae85;
+  buff->h[2] = 0x3c6ef372;
+  buff->h[3] = 0xa54ff53a;
+  buff->h[4] = 0x510e527f;
+  buff->h[5] = 0x9b05688c;
+  buff->h[6] = 0x1f83d9ab;
+  buff->h[7] = 0x5be0cd19;
+  buff->data_size = 0;
+  buff->chunk_size = 0;
+}
+
+const static uint32_t k[64] = {
+    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1,
+    0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
+    0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786,
+    0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
+    0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147,
+    0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
+    0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b,
+    0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
+    0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a,
+    0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
+    0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2};
+
+#define rotate_r(val, bits) (val >> bits | val << (32 - bits))
+
+static void sha256_calc_chunk(struct sha256_buff *buff, const uint8_t *chunk) {
+  uint32_t w[64];
+  uint32_t tv[8];
+  uint32_t i;
+
+  for (i = 0; i < 16; ++i) {
+    w[i] = (uint32_t)chunk[0] << 24 | (uint32_t)chunk[1] << 16 |
+           (uint32_t)chunk[2] << 8 | (uint32_t)chunk[3];
+    chunk += 4;
+  }
+
+  for (i = 16; i < 64; ++i) {
+    uint32_t s0 =
+        rotate_r(w[i - 15], 7) ^ rotate_r(w[i - 15], 18) ^ (w[i - 15] >> 3);
+    uint32_t s1 =
+        rotate_r(w[i - 2], 17) ^ rotate_r(w[i - 2], 19) ^ (w[i - 2] >> 10);
+    w[i] = w[i - 16] + s0 + w[i - 7] + s1;
+  }
+
+  for (i = 0; i < 8; ++i)
+    tv[i] = buff->h[i];
+
+  for (i = 0; i < 64; ++i) {
+    uint32_t S1 =
+        rotate_r(tv[4], 6) ^ rotate_r(tv[4], 11) ^ rotate_r(tv[4], 25);
+    uint32_t ch = (tv[4] & tv[5]) ^ (~tv[4] & tv[6]);
+    uint32_t temp1 = tv[7] + S1 + ch + k[i] + w[i];
+    uint32_t S0 =
+        rotate_r(tv[0], 2) ^ rotate_r(tv[0], 13) ^ rotate_r(tv[0], 22);
+    uint32_t maj = (tv[0] & tv[1]) ^ (tv[0] & tv[2]) ^ (tv[1] & tv[2]);
+    uint32_t temp2 = S0 + maj;
+
+    tv[7] = tv[6];
+    tv[6] = tv[5];
+    tv[5] = tv[4];
+    tv[4] = tv[3] + temp1;
+    tv[3] = tv[2];
+    tv[2] = tv[1];
+    tv[1] = tv[0];
+    tv[0] = temp1 + temp2;
+  }
+
+  for (i = 0; i < 8; ++i)
+    buff->h[i] += tv[i];
+}
+
+void sha256_update(struct sha256_buff *buff, const void *data, size_t size) {
+  const uint8_t *ptr = (const uint8_t *)data;
+  buff->data_size += size;
+  /* If there is data left in buff, concatenate it to process as new chunk */
+  if (size + buff->chunk_size >= 64) {
+    uint8_t tmp_chunk[64];
+    memcpy(tmp_chunk, buff->last_chunk, buff->chunk_size);
+    memcpy(tmp_chunk + buff->chunk_size, ptr, 64 - buff->chunk_size);
+    ptr += (64 - buff->chunk_size);
+    size -= (64 - buff->chunk_size);
+    buff->chunk_size = 0;
+    sha256_calc_chunk(buff, tmp_chunk);
+  }
+  /* Run over data chunks */
+  while (size >= 64) {
+    sha256_calc_chunk(buff, ptr);
+    ptr += 64;
+    size -= 64;
+  }
+
+  /* Save remaining data in buff, will be reused on next call or finalize */
+  memcpy(buff->last_chunk + buff->chunk_size, ptr, size);
+  buff->chunk_size += size;
+}
+
+void sha256_finalize(struct sha256_buff *buff) {
+  buff->last_chunk[buff->chunk_size] = 0x80;
+  buff->chunk_size++;
+  memset(buff->last_chunk + buff->chunk_size, 0, 64 - buff->chunk_size);
+
+  /* If there isn't enough space to fit int64, pad chunk with zeroes and prepare
+   * next chunk */
+  if (buff->chunk_size > 56) {
+    sha256_calc_chunk(buff, buff->last_chunk);
+    memset(buff->last_chunk, 0, 64);
+  }
+
+  /* Add total size as big-endian int64 x8 */
+  uint64_t size = buff->data_size * 8;
+  int i;
+  for (i = 8; i > 0; --i) {
+    buff->last_chunk[55 + i] = size & 255;
+    size >>= 8;
+  }
+
+  sha256_calc_chunk(buff, buff->last_chunk);
+}
+
+void sha256_read(const struct sha256_buff *buff, uint8_t *hash) {
+  uint32_t i;
+  for (i = 0; i < 8; i++) {
+    hash[i * 4] = (buff->h[i] >> 24) & 255;
+    hash[i * 4 + 1] = (buff->h[i] >> 16) & 255;
+    hash[i * 4 + 2] = (buff->h[i] >> 8) & 255;
+    hash[i * 4 + 3] = buff->h[i] & 255;
+  }
+}
+
+static void bin_to_hex(const void *data, uint32_t len, char *out) {
+  static const char *const lut = "0123456789abcdef";
+  uint32_t i;
+  for (i = 0; i < len; ++i) {
+    uint8_t c = ((uint8_t *)data)[i];
+    out[i * 2] = lut[c >> 4];
+    out[i * 2 + 1] = lut[c & 15];
+  }
+}
+
+void sha256_read_hex(const struct sha256_buff *buff, char *hex) {
+  uint8_t hash[32];
+  sha256_read(buff, hash);
+  bin_to_hex(hash, 32, hex);
+}
+
+void sha256_easy_hash(const void *data, size_t size, uint8_t *hash) {
+  struct sha256_buff buff;
+  sha256_init(&buff);
+  sha256_update(&buff, data, size);
+  sha256_finalize(&buff);
+  sha256_read(&buff, hash);
+}
+
+void sha256_easy_hash_hex(const void *data, size_t size, char *hex) {
+  uint8_t hash[32];
+  sha256_easy_hash(data, size, hash);
+  bin_to_hex(hash, 32, hex);
+}
\ No newline at end of file

data/3.C语言高阶/5.文件/2.文件的读写/sha256.h

+/*
+    MIT License
+    Copyright (c) 2020 LekKit https://github.com/LekKit
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to
+   deal in the Software without restriction, including without limitation the
+   rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+   sell copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+    The above copyright notice and this permission notice shall be included in
+   all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED
+   "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
+   LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+   PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+   ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+   WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+#ifndef SHA256_H
+#define SHA256_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+struct sha256_buff {
+  uint64_t data_size;
+  uint32_t h[8];
+  uint8_t last_chunk[64];
+  uint8_t chunk_size;
+};
+
+/* Initialization, must be called before any further use */
+void sha256_init(struct sha256_buff *buff);
+
+/* Process block of data of arbitary length, can be used on data streams (files,
+ * etc) */
+void sha256_update(struct sha256_buff *buff, const void *data, size_t size);
+
+/* Produces final hash values (digest) to be read
+   If the buffer is reused later, init must be called again */
+void sha256_finalize(struct sha256_buff *buff);
+
+/* Read digest into 32-byte binary array */
+void sha256_read(const struct sha256_buff *buff, uint8_t *hash);
+
+/* Read digest into 64-char string as hex (without null-byte) */
+void sha256_read_hex(const struct sha256_buff *buff, char *hex);
+
+/* Hashes single contiguous block of data and reads digest into 32-byte binary
+ * array */
+void sha256_easy_hash(const void *data, size_t size, uint8_t *hash);
+
+/* Hashes single contiguous block of data and reads digest into 64-char string
+ * (without null-byte) */
+void sha256_easy_hash_hex(const void *data, size_t size, char *hex);
+
+#ifdef __cplusplus
+}
+
+#include <string>
+
+class SHA256 {
+private:
+  struct sha256_buff buff;
+
+public:
+  SHA256() { sha256_init(&buff); }
+
+  void update(const void *data, std::size_t size) {
+    sha256_update(&buff, data, size);
+  }
+
+  std::string hash() {
+    char hash[64];
+    sha256_finalize(&buff);
+    sha256_read_hex(&buff, hash);
+    sha256_init(&buff);
+    return std::string(hash, 64);
+  }
+
+  static std::string hashString(const std::string &str) {
+    char hash[64];
+    sha256_easy_hash_hex(str.c_str(), str.length(), hash);
+    return std::string(hash, 64);
+  }
+};
+
+#endif
+
+#endif
\ No newline at end of file