[1/3] libata: glob_match for ata_device_blacklist (v2)

Message ID 4C2D13AE.6090701@teksavvy.com
State Not Applicable
Delegated to: David Miller
Headers show

Commit Message

Mark Lord July 1, 2010, 10:16 p.m.
Replace rudimentry pattern matching with more capable shell-style globbing.
This will enable shrinking ata_device_blacklist[] table in subsequent patches,
and helps with future editions to the table, such as matching only the end
of a firmware revision string etc..

Signed-off-by: Mark Lord <mlord@pobox.com>
---

(re-diff'd against latest -git, and also attached to bypass mailer issues)

Eventually, this function should move out of libata into lib/string.c or similar (?).
But since following patches in this series require it for libata,
let's start with it there, and move things later on.

Patch

Replace rudimentry pattern matching with more capable shell-style globbing.
This will enable shrinking ata_device_blacklist[] table in subsequent patches,
and helps with future editions to the table, such as matching only the end
of a firmware revision string etc..

Signed-off-by: Mark Lord <mlord@pobox.com>
---

Eventually, this function should move out of libata into lib/string.c or similar (?).
But since following patches in this series require it for libata,
let's start with it there, and move things later on.

--- linux-2.6.35-rc3/drivers/ata/libata-core.c	2010-06-11 22:14:04.000000000 -0400
+++ linux/drivers/ata/libata-core.c	2010-07-01 18:11:25.801348855 -0400
@@ -4326,29 +4326,65 @@ 
 	{ }
 };
 
-static int strn_pattern_cmp(const char *patt, const char *name, int wildchar)
+/**
+ *	glob_match - match a text string against a glob-style pattern
+ *	@text: the string to be examined
+ *	@pattern: the glob-style pattern to be matched against
+ *
+ *	Either/both of text and pattern can be empty strings.
+ *
+ *	Match text against a glob-style pattern, with wildcards and simple sets:
+ *
+ *		?	matches any single character.
+ *		*	matches any run of characters.
+ *		[xyz]	matches a single character from the set: x, y, or z.
+ *
+ *	Note: hyphenated ranges [0-9] are _not_ supported here.
+ *	The special characters ?, [, or *, can be matched using a set, eg. [*]
+ *
+ *	Example patterns:  "SD1?",  "SD1[012345]",  "*R0",  SD*1?[012]*xx"
+ *
+ *	This function uses one level of recursion per '*' in pattern.
+ *	Since it calls _nothing_ else, and has _no_ explicit local variables,
+ *	this will not cause stack problems for any reasonable use here.
+ *
+ *	RETURNS:
+ *	0 on match, 1 otherwise.
+ */
+static int glob_match (const char *text, const char *pattern)
 {
-	const char *p;
-	int len;
+	do {
+		/* Match single character or a '?' wildcard */
+		if (*text == *pattern || *pattern == '?') {
+			if (!*pattern++)
+				return 0;  /* End of both strings: match */
+		} else {
+			/* Match single char against a '[' bracketed ']' pattern set */
+			if (!*text || *pattern != '[')
+				break;  /* Not a pattern set */
+			while (*++pattern && *pattern != ']' && *text != *pattern);
+			if (!*pattern || *pattern == ']')
+				return 1;  /* No match */
+			while (*pattern && *pattern++ != ']');
+		}
+	} while (*++text && *pattern);
 
-	/*
-	 * check for trailing wildcard: *\0
-	 */
-	p = strchr(patt, wildchar);
-	if (p && ((*(p + 1)) == 0))
-		len = p - patt;
-	else {
-		len = strlen(name);
-		if (!len) {
-			if (!*patt)
-				return 0;
-			return -1;
+	/* Match any run of chars against a '*' wildcard */
+	if (*pattern == '*') {
+		if (!*++pattern)
+			return 0;  /* Match: avoid recursion at end of pattern */
+		/* Loop to handle additional pattern chars after the wildcard */
+		while (*text) {
+			if (glob_match(text, pattern) == 0)
+				return 0;  /* Remainder matched */
+			++text;  /* Absorb (match) this char and try again */
 		}
 	}
-
-	return strncmp(patt, name, len);
+	if (!*text && !*pattern)
+		return 0;  /* End of both strings: match */
+	return 1;  /* No match */
 }
-
+ 
 static unsigned long ata_dev_blacklisted(const struct ata_device *dev)
 {
 	unsigned char model_num[ATA_ID_PROD_LEN + 1];
@@ -4359,10 +4395,10 @@ 
 	ata_id_c_string(dev->id, model_rev, ATA_ID_FW_REV, sizeof(model_rev));
 
 	while (ad->model_num) {
-		if (!strn_pattern_cmp(ad->model_num, model_num, '*')) {
+		if (!glob_match(model_num, ad->model_num)) {
 			if (ad->model_rev == NULL)
 				return ad->horkage;
-			if (!strn_pattern_cmp(ad->model_rev, model_rev, '*'))
+			if (!glob_match(model_rev, ad->model_rev))
 				return ad->horkage;
 		}
 		ad++;