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>
diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index 1cffc22..ed5c145 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 @@
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);
