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authorAndy Shevchenko <andriy.shevchenko@linux.intel.com>2013-04-30 15:27:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-04-30 17:04:03 -0700
commit16c7fa05829e8b91db48e3539c5d6ff3c2b18a23 (patch)
tree6658e9f27c033e5f6de19284fe9a6b8485360aa6
parente1d12f327037a59e06c66520951ab4e0bd29f9c4 (diff)
downloadlinux-16c7fa05829e8b91db48e3539c5d6ff3c2b18a23.tar.gz
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: Andy 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--drivers/char/random.c1
-rw-r--r--include/linux/string_helpers.h58
-rw-r--r--lib/Kconfig.debug3
-rw-r--r--lib/Makefile4
-rw-r--r--lib/string_helpers.c133
-rw-r--r--lib/test-string_helpers.c103
6 files changed, 301 insertions, 1 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 32a6c576495..cd9a6211dca 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -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
diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h
index a3eb2f65b65..3eeee9672a4 100644
--- a/include/linux/string_helpers.h
+++ b/include/linux/string_helpers.h
@@ -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
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 28be08c09ba..77ebaa3dfa1 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -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"
diff --git a/lib/Makefile b/lib/Makefile
index 6e2cc561f76..23c9a0fe74f 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -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
diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index 1cffc223bff..ed5c1454dd6 100644
--- a/lib/string_helpers.c
+++ b/lib/string_helpers.c
@@ -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);
diff --git a/lib/test-string_helpers.c b/lib/test-string_helpers.c
new file mode 100644
index 00000000000..6ac48de04c0
--- /dev/null
+++ b/lib/test-string_helpers.c
@@ -0,0 +1,103 @@
+/*
+ * 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");