6 files changed, 301 insertions, 1 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 32a6c5764950..cd9a6211dcad 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 a3eb2f65b656..3eeee9672a4a 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 28be08c09bab..77ebaa3dfa12 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 6e2cc561f761..23c9a0fe74fc 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 1cffc223bff5..ed5c1454dd62 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 000000000000..6ac48de04c0e
--- /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");