[PATCH 1/4] lib/string_helpers: introduce generic string_unescape

[PATCH 1/4] lib/string_helpers: introduce generic string_unescape

[Andy Shevchenko]

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.

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>
---
 include/linux/string_helpers.h |  58 ++++++++++++++++++
 lib/Kconfig.debug              |   3 +
 lib/Makefile                   |   4 +-
 lib/string_helpers.c           | 133 +++++++++++++++++++++++++++++++++++++++++
 lib/test-string_helpers.c      | 103 +++++++++++++++++++++++++++++++
 5 files changed, 300 insertions(+), 1 deletion(-)
 create mode 100644 lib/test-string_helpers.c

diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h
index a3eb2f6..c18df71 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'.
+ *
+ * Due to size of output will be the same or smaller the translation could be
+ * done 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 ae80518..770a422 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1481,5 +1481,8 @@ 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 10facc6..370a1d6 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -23,8 +23,10 @@ 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 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 @@ 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 0000000..6ac48de
--- /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");
-- 
1.8.2.rc0.22.gb3600c3

[PATCH 2/4] staging: speakup: remove custom string_unescape_any_inplace

[Andy Shevchenko]

There is generic implementation of the function to unescape strings.

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: speakup@braille.uwo.ca
Cc: devel@driverdev.osuosl.org
---
 drivers/staging/speakup/kobjects.c    |  6 +++--
 drivers/staging/speakup/speakup.h     |  1 -
 drivers/staging/speakup/varhandlers.c | 46 -----------------------------------
 3 files changed, 4 insertions(+), 49 deletions(-)

diff --git a/drivers/staging/speakup/kobjects.c b/drivers/staging/speakup/kobjects.c
index d6d9264..943b6c1 100644
--- a/drivers/staging/speakup/kobjects.c
+++ b/drivers/staging/speakup/kobjects.c
@@ -15,6 +15,7 @@
 #include <linux/kernel.h>
 #include <linux/kobject.h>
 #include <linux/string.h>
+#include <linux/string_helpers.h>
 #include <linux/sysfs.h>
 #include <linux/ctype.h>
 
@@ -417,7 +418,7 @@ static ssize_t synth_direct_store(struct kobject *kobj,
 		bytes = min_t(size_t, len, 250);
 		strncpy(tmp, ptr, bytes);
 		tmp[bytes] = '\0';
-		spk_xlate(tmp);
+		string_unescape_any_inplace(tmp);
 		synth_printf("%s", tmp);
 		ptr += bytes;
 		len -= bytes;
@@ -605,7 +606,8 @@ ssize_t spk_var_store(struct kobject *kobj, struct kobj_attribute *attr,
 	if (param->data == NULL)
 		return 0;
 	ret = 0;
-	cp = spk_xlate((char *) buf);
+	cp = (char *)buf;
+	string_unescape_any_inplace(cp);
 
 	spk_lock(flags);
 	switch (param->var_type) {
diff --git a/drivers/staging/speakup/speakup.h b/drivers/staging/speakup/speakup.h
index c387a02..0126f71 100644
--- a/drivers/staging/speakup/speakup.h
+++ b/drivers/staging/speakup/speakup.h
@@ -54,7 +54,6 @@ void spk_get_index_count(int *linecount, int *sentcount);
 extern int spk_set_key_info(const u_char *key_info, u_char *k_buffer);
 extern char *spk_strlwr(char *s);
 extern char *spk_s2uchar(char *start, char *dest);
-extern char *spk_xlate(char *s);
 extern int speakup_kobj_init(void);
 extern void speakup_kobj_exit(void);
 extern int spk_chartab_get_value(char *keyword);
diff --git a/drivers/staging/speakup/varhandlers.c b/drivers/staging/speakup/varhandlers.c
index 0099cb1..7f6288f 100644
--- a/drivers/staging/speakup/varhandlers.c
+++ b/drivers/staging/speakup/varhandlers.c
@@ -328,49 +328,3 @@ char *spk_s2uchar(char *start, char *dest)
 	*dest = (u_char)val;
 	return start;
 }
-
-char *spk_xlate(char *s)
-{
-	static const char finds[] = "nrtvafe";
-	static const char subs[] = "\n\r\t\013\001\014\033";
-	static const char hx[] = "0123456789abcdefABCDEF";
-	char *p = s, *p1, *p2, c;
-	int num;
-	while ((p = strchr(p, '\\'))) {
-		p1 = p+1;
-		p2 = strchr(finds, *p1);
-		if (p2) {
-			*p++ = subs[p2-finds];
-			p1++;
-		} else if (*p1 >= '0' && *p1 <= '7') {
-			num = (*p1++)&7;
-			while (num < 32 && *p1 >= '0' && *p1 <= '7') {
-				num <<= 3;
-				num += (*p1++)&7;
-			}
-			*p++ = num;
-		} else if (*p1 == 'x' &&
-				strchr(hx, p1[1]) && strchr(hx, p1[2])) {
-			p1++;
-			c = *p1++;
-			if (c > '9')
-				c = (c - '7') & 0x0f;
-			else
-				c -= '0';
-			num = c << 4;
-			c = *p1++;
-			if (c > '9')
-				c = (c-'7')&0x0f;
-			else
-				c -= '0';
-			num += c;
-			*p++ = num;
-		} else
-			*p++ = *p1++;
-		p2 = p;
-		while (*p1)
-			*p2++ = *p1++;
-		*p2 = '\0';
-	}
-	return s;
-}
-- 
1.8.2.rc0.22.gb3600c3

[PATCH 3/4] dynamic_debug: reuse generic string_unescape function

[Andy Shevchenko]

There is kernel function to do the job in generic way. Let's use it.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Jason Baron <jbaron@redhat.com>
---
 lib/dynamic_debug.c | 48 +++++-------------------------------------------
 1 file changed, 5 insertions(+), 43 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 4603245..99fec3a 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -24,6 +24,7 @@
 #include <linux/sysctl.h>
 #include <linux/ctype.h>
 #include <linux/string.h>
+#include <linux/string_helpers.h>
 #include <linux/uaccess.h>
 #include <linux/dynamic_debug.h>
 #include <linux/debugfs.h>
@@ -276,47 +277,6 @@ static inline int parse_lineno(const char *str, unsigned int *val)
 	return 0;
 }
 
-/*
- * Undo octal escaping in a string, inplace.  This is useful to
- * allow the user to express a query which matches a format
- * containing embedded spaces.
- */
-static char *unescape(char *str)
-{
-	char *in = str;
-	char *out = str;
-
-	while (*in) {
-		if (*in == '\\') {
-			if (in[1] == '\\') {
-				*out++ = '\\';
-				in += 2;
-				continue;
-			} else if (in[1] == 't') {
-				*out++ = '\t';
-				in += 2;
-				continue;
-			} else if (in[1] == 'n') {
-				*out++ = '\n';
-				in += 2;
-				continue;
-			} else if (isodigit(in[1]) &&
-				   isodigit(in[2]) &&
-				   isodigit(in[3])) {
-				*out++ = (((in[1] - '0') << 6) |
-					  ((in[2] - '0') << 3) |
-					  (in[3] - '0'));
-				in += 4;
-				continue;
-			}
-		}
-		*out++ = *in++;
-	}
-	*out = '\0';
-
-	return str;
-}
-
 static int check_set(const char **dest, char *src, char *name)
 {
 	int rc = 0;
@@ -370,8 +330,10 @@ static int ddebug_parse_query(char *words[], int nwords,
 		} else if (!strcmp(words[i], "module")) {
 			rc = check_set(&query->module, words[i+1], "module");
 		} else if (!strcmp(words[i], "format")) {
-			rc = check_set(&query->format, unescape(words[i+1]),
-				       "format");
+			string_unescape_inplace(words[i+1], UNESCAPE_SPACE |
+							    UNESCAPE_OCTAL |
+							    UNESCAPE_SPECIAL);
+			rc = check_set(&query->format, words[i+1], "format");
 		} else if (!strcmp(words[i], "line")) {
 			char *first = words[i+1];
 			char *last = strchr(first, '-');
-- 
1.8.2.rc0.22.gb3600c3

[PATCH 4/4] binfmt_misc: reuse string_unescape_inplace()

[Andy Shevchenko]

There is string_unescape_inplace() function which decodes strings in generic
way. Let's use it.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
---
 fs/binfmt_misc.c | 24 ++++--------------------
 1 file changed, 4 insertions(+), 20 deletions(-)

diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index 751df5e..1c740e1 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -23,6 +23,7 @@
 #include <linux/binfmts.h>
 #include <linux/slab.h>
 #include <linux/ctype.h>
+#include <linux/string_helpers.h>
 #include <linux/file.h>
 #include <linux/pagemap.h>
 #include <linux/namei.h>
@@ -234,24 +235,6 @@ static char *scanarg(char *s, char del)
 	return s;
 }
 
-static int unquote(char *from)
-{
-	char c = 0, *s = from, *p = from;
-
-	while ((c = *s++) != '\0') {
-		if (c == '\\' && *s == 'x') {
-			s++;
-			c = toupper(*s++);
-			*p = (c - (isdigit(c) ? '0' : 'A' - 10)) << 4;
-			c = toupper(*s++);
-			*p++ |= c - (isdigit(c) ? '0' : 'A' - 10);
-			continue;
-		}
-		*p++ = c;
-	}
-	return p - from;
-}
-
 static char * check_special_flags (char * sfs, Node * e)
 {
 	char * p = sfs;
@@ -354,8 +337,9 @@ static Node *create_entry(const char __user *buffer, size_t count)
 		p[-1] = '\0';
 		if (!e->mask[0])
 			e->mask = NULL;
-		e->size = unquote(e->magic);
-		if (e->mask && unquote(e->mask) != e->size)
+		e->size = string_unescape_inplace(e->magic, UNESCAPE_HEX);
+		if (e->mask &&
+		    string_unescape_inplace(e->mask, UNESCAPE_HEX) != e->size)
 			goto Einval;
 		if (e->size + e->offset > BINPRM_BUF_SIZE)
 			goto Einval;
-- 
1.8.2.rc0.22.gb3600c3