提交 16c7fa05 编写于 作者: A Andy Shevchenko 提交者: Linus Torvalds

lib/string_helpers: introduce generic string_unescape

There are several places in kernel where modules unescapes input to convert
C-Style Escape Sequences into byte codes.

The patch provides generic implementation of such approach. Test cases are
also included into the patch.

[akpm@linux-foundation.org: clarify comment]
[akpm@linux-foundation.org: export get_random_int() to modules]
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: William Hubbs <w.d.hubbs@gmail.com>
Cc: Chris Brannon <chris@the-brannons.com>
Cc: Kirk Reiser <kirk@braille.uwo.ca>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 e1d12f32
......@@ -1485,6 +1485,7 @@ unsigned int get_random_int(void)
return ret;
}
EXPORT_SYMBOL(get_random_int);
/*
* randomize_range() returns a start address such that
......
......@@ -13,4 +13,62 @@ enum string_size_units {
int string_get_size(u64 size, enum string_size_units units,
char *buf, int len);
#define UNESCAPE_SPACE 0x01
#define UNESCAPE_OCTAL 0x02
#define UNESCAPE_HEX 0x04
#define UNESCAPE_SPECIAL 0x08
#define UNESCAPE_ANY \
(UNESCAPE_SPACE | UNESCAPE_OCTAL | UNESCAPE_HEX | UNESCAPE_SPECIAL)
/**
* string_unescape - unquote characters in the given string
* @src: source buffer (escaped)
* @dst: destination buffer (unescaped)
* @size: size of the destination buffer (0 to unlimit)
* @flags: combination of the flags (bitwise OR):
* %UNESCAPE_SPACE:
* '\f' - form feed
* '\n' - new line
* '\r' - carriage return
* '\t' - horizontal tab
* '\v' - vertical tab
* %UNESCAPE_OCTAL:
* '\NNN' - byte with octal value NNN (1 to 3 digits)
* %UNESCAPE_HEX:
* '\xHH' - byte with hexadecimal value HH (1 to 2 digits)
* %UNESCAPE_SPECIAL:
* '\"' - double quote
* '\\' - backslash
* '\a' - alert (BEL)
* '\e' - escape
* %UNESCAPE_ANY:
* all previous together
*
* Returns amount of characters processed to the destination buffer excluding
* trailing '\0'.
*
* Because the size of the output will be the same as or less than the size of
* the input, the transformation may be performed in place.
*
* Caller must provide valid source and destination pointers. Be aware that
* destination buffer will always be NULL-terminated. Source string must be
* NULL-terminated as well.
*/
int string_unescape(char *src, char *dst, size_t size, unsigned int flags);
static inline int string_unescape_inplace(char *buf, unsigned int flags)
{
return string_unescape(buf, buf, 0, flags);
}
static inline int string_unescape_any(char *src, char *dst, size_t size)
{
return string_unescape(src, dst, size, UNESCAPE_ANY);
}
static inline int string_unescape_any_inplace(char *buf)
{
return string_unescape_any(buf, buf, 0);
}
#endif
......@@ -1463,5 +1463,8 @@ source "lib/Kconfig.kgdb"
source "lib/Kconfig.kmemcheck"
config TEST_STRING_HELPERS
tristate "Test functions located in the string_helpers module at runtime"
config TEST_KSTRTOX
tristate "Test kstrto*() family of functions at runtime"
......@@ -22,8 +22,10 @@ lib-y += kobject.o klist.o
obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o \
string_helpers.o gcd.o lcm.o list_sort.o uuid.o flex_array.o \
gcd.o lcm.o list_sort.o uuid.o flex_array.o \
bsearch.o find_last_bit.o find_next_bit.o llist.o memweight.o kfifo.o
obj-y += string_helpers.o
obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o
obj-y += kstrtox.o
obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o
......
......@@ -2,10 +2,12 @@
* Helpers for formatting and printing strings
*
* Copyright 31 August 2008 James Bottomley
* Copyright (C) 2013, Intel Corporation
*/
#include <linux/kernel.h>
#include <linux/math64.h>
#include <linux/export.h>
#include <linux/ctype.h>
#include <linux/string_helpers.h>
/**
......@@ -66,3 +68,134 @@ int string_get_size(u64 size, const enum string_size_units units,
return 0;
}
EXPORT_SYMBOL(string_get_size);
static bool unescape_space(char **src, char **dst)
{
char *p = *dst, *q = *src;
switch (*q) {
case 'n':
*p = '\n';
break;
case 'r':
*p = '\r';
break;
case 't':
*p = '\t';
break;
case 'v':
*p = '\v';
break;
case 'f':
*p = '\f';
break;
default:
return false;
}
*dst += 1;
*src += 1;
return true;
}
static bool unescape_octal(char **src, char **dst)
{
char *p = *dst, *q = *src;
u8 num;
if (isodigit(*q) == 0)
return false;
num = (*q++) & 7;
while (num < 32 && isodigit(*q) && (q - *src < 3)) {
num <<= 3;
num += (*q++) & 7;
}
*p = num;
*dst += 1;
*src = q;
return true;
}
static bool unescape_hex(char **src, char **dst)
{
char *p = *dst, *q = *src;
int digit;
u8 num;
if (*q++ != 'x')
return false;
num = digit = hex_to_bin(*q++);
if (digit < 0)
return false;
digit = hex_to_bin(*q);
if (digit >= 0) {
q++;
num = (num << 4) | digit;
}
*p = num;
*dst += 1;
*src = q;
return true;
}
static bool unescape_special(char **src, char **dst)
{
char *p = *dst, *q = *src;
switch (*q) {
case '\"':
*p = '\"';
break;
case '\\':
*p = '\\';
break;
case 'a':
*p = '\a';
break;
case 'e':
*p = '\e';
break;
default:
return false;
}
*dst += 1;
*src += 1;
return true;
}
int string_unescape(char *src, char *dst, size_t size, unsigned int flags)
{
char *out = dst;
while (*src && --size) {
if (src[0] == '\\' && src[1] != '\0' && size > 1) {
src++;
size--;
if (flags & UNESCAPE_SPACE &&
unescape_space(&src, &out))
continue;
if (flags & UNESCAPE_OCTAL &&
unescape_octal(&src, &out))
continue;
if (flags & UNESCAPE_HEX &&
unescape_hex(&src, &out))
continue;
if (flags & UNESCAPE_SPECIAL &&
unescape_special(&src, &out))
continue;
*out++ = '\\';
}
*out++ = *src++;
}
*out = '\0';
return out - dst;
}
EXPORT_SYMBOL(string_unescape);
/*
* Test cases for lib/string_helpers.c module.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/string.h>
#include <linux/string_helpers.h>
struct test_string {
const char *in;
const char *out;
unsigned int flags;
};
static const struct test_string strings[] __initconst = {
{
.in = "\\f\\ \\n\\r\\t\\v",
.out = "\f\\ \n\r\t\v",
.flags = UNESCAPE_SPACE,
},
{
.in = "\\40\\1\\387\\0064\\05\\040\\8a\\110\\777",
.out = " \001\00387\0064\005 \\8aH?7",
.flags = UNESCAPE_OCTAL,
},
{
.in = "\\xv\\xa\\x2c\\xD\\x6f2",
.out = "\\xv\n,\ro2",
.flags = UNESCAPE_HEX,
},
{
.in = "\\h\\\\\\\"\\a\\e\\",
.out = "\\h\\\"\a\e\\",
.flags = UNESCAPE_SPECIAL,
},
};
static void __init test_string_unescape(unsigned int flags, bool inplace)
{
char in[256];
char out_test[256];
char out_real[256];
int i, p = 0, q_test = 0, q_real = sizeof(out_real);
for (i = 0; i < ARRAY_SIZE(strings); i++) {
const char *s = strings[i].in;
int len = strlen(strings[i].in);
/* Copy string to in buffer */
memcpy(&in[p], s, len);
p += len;
/* Copy expected result for given flags */
if (flags & strings[i].flags) {
s = strings[i].out;
len = strlen(strings[i].out);
}
memcpy(&out_test[q_test], s, len);
q_test += len;
}
in[p++] = '\0';
/* Call string_unescape and compare result */
if (inplace) {
memcpy(out_real, in, p);
if (flags == UNESCAPE_ANY)
q_real = string_unescape_any_inplace(out_real);
else
q_real = string_unescape_inplace(out_real, flags);
} else if (flags == UNESCAPE_ANY) {
q_real = string_unescape_any(in, out_real, q_real);
} else {
q_real = string_unescape(in, out_real, q_real, flags);
}
if (q_real != q_test || memcmp(out_test, out_real, q_test)) {
pr_warn("Test failed: flags = %u\n", flags);
print_hex_dump(KERN_WARNING, "Input: ",
DUMP_PREFIX_NONE, 16, 1, in, p - 1, true);
print_hex_dump(KERN_WARNING, "Expected: ",
DUMP_PREFIX_NONE, 16, 1, out_test, q_test, true);
print_hex_dump(KERN_WARNING, "Got: ",
DUMP_PREFIX_NONE, 16, 1, out_real, q_real, true);
}
}
static int __init test_string_helpers_init(void)
{
unsigned int i;
pr_info("Running tests...\n");
for (i = 0; i < UNESCAPE_ANY + 1; i++)
test_string_unescape(i, false);
test_string_unescape(get_random_int() % (UNESCAPE_ANY + 1), true);
return -EINVAL;
}
module_init(test_string_helpers_init);
MODULE_LICENSE("Dual BSD/GPL");
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