[linux-2.6-block.git] / lib / glob.c

#include <linux/module.h>
#include <linux/glob.h>

/*
 * The only reason this code can be compiled as a module is because the
 * ATA code that depends on it can be as well.  In practice, they're
 * both usually compiled in and the module overhead goes away.
 */
MODULE_DESCRIPTION("glob(7) matching");
MODULE_LICENSE("Dual MIT/GPL");

/**
 * glob_match - Shell-style pattern matching, like !fnmatch(pat, str, 0)
 * @pat: Shell-style pattern to match, e.g. "*.[ch]".
 * @str: String to match.  The pattern must match the entire string.
 *
 * Perform shell-style glob matching, returning true (1) if the match
 * succeeds, or false (0) if it fails.  Equivalent to !fnmatch(@pat, @str, 0).
 *
 * Pattern metacharacters are ?, *, [ and \.
 * (And, inside character classes, !, - and ].)
 *
 * This is small and simple implementation intended for device blacklists
 * where a string is matched against a number of patterns.  Thus, it
 * does not preprocess the patterns.  It is non-recursive, and run-time
 * is at most quadratic: strlen(@str)*strlen(@pat).
 *
 * An example of the worst case is glob_match("*aaaaa", "aaaaaaaaaa");
 * it takes 6 passes over the pattern before matching the string.
 *
 * Like !fnmatch(@pat, @str, 0) and unlike the shell, this does NOT
 * treat / or leading . specially; it isn't actually used for pathnames.
 *
 * Note that according to glob(7) (and unlike bash), character classes
 * are complemented by a leading !; this does not support the regex-style
 * [^a-z] syntax.
 *
 * An opening bracket without a matching close is matched literally.
 */
bool __pure glob_match(char const *pat, char const *str)
{
	/*
	 * Backtrack to previous * on mismatch and retry starting one
	 * character later in the string.  Because * matches all characters
	 * (no exception for /), it can be easily proved that there's
	 * never a need to backtrack multiple levels.
	 */
	char const *back_pat = NULL, *back_str = back_str;

	/*
	 * Loop over each token (character or class) in pat, matching
	 * it against the remaining unmatched tail of str.  Return false
	 * on mismatch, or true after matching the trailing nul bytes.
	 */
	for (;;) {
		unsigned char c = *str++;
		unsigned char d = *pat++;

		switch (d) {
		case '?':	/* Wildcard: anything but nul */
			if (c == '\0')
				return false;
			break;
		case '*':	/* Any-length wildcard */
			if (*pat == '\0')	/* Optimize trailing * case */
				return true;
			back_pat = pat;
			back_str = --str;	/* Allow zero-length match */
			break;
		case '[': {	/* Character class */
			bool match = false, inverted = (*pat == '!');
			char const *class = pat + inverted;
			unsigned char a = *class++;

			/*
			 * Iterate over each span in the character class.
			 * A span is either a single character a, or a
			 * range a-b.  The first span may begin with ']'.
			 */
			do {
				unsigned char b = a;

				if (a == '\0')	/* Malformed */
					goto literal;

				if (class[0] == '-' && class[1] != ']') {
					b = class[1];

					if (b == '\0')
						goto literal;

					class += 2;
					/* Any special action if a > b? */
				}
				match |= (a <= c && c <= b);
			} while ((a = *class++) != ']');

			if (match == inverted)
				goto backtrack;
			pat = class;
			}
			break;
		case '\\':
			d = *pat++;
			/*FALLTHROUGH*/
		default:	/* Literal character */
literal:
			if (c == d) {
				if (d == '\0')
					return true;
				break;
			}
backtrack:
			if (c == '\0' || !back_pat)
				return false;	/* No point continuing */
			/* Try again from last *, one character later in str. */
			pat = back_pat;
			str = ++back_str;
			break;
		}
	}
}
EXPORT_SYMBOL(glob_match);
Commit	Line	Data
b0125085 GS	1	#include <linux/module.h>
	2	#include <linux/glob.h>
	3
	4	/*
	5	* The only reason this code can be compiled as a module is because the
	6	* ATA code that depends on it can be as well. In practice, they're
	7	* both usually compiled in and the module overhead goes away.
	8	*/
	9	MODULE_DESCRIPTION("glob(7) matching");
	10	MODULE_LICENSE("Dual MIT/GPL");
	11
	12	/**
	13	* glob_match - Shell-style pattern matching, like !fnmatch(pat, str, 0)
	14	* @pat: Shell-style pattern to match, e.g. "*.[ch]".
	15	* @str: String to match. The pattern must match the entire string.
	16	*
	17	* Perform shell-style glob matching, returning true (1) if the match
	18	* succeeds, or false (0) if it fails. Equivalent to !fnmatch(@pat, @str, 0).
	19	*
	20	* Pattern metacharacters are ?, *, [ and \.
	21	* (And, inside character classes, !, - and ].)
	22	*
	23	* This is small and simple implementation intended for device blacklists
	24	* where a string is matched against a number of patterns. Thus, it
	25	* does not preprocess the patterns. It is non-recursive, and run-time
	26	* is at most quadratic: strlen(@str)*strlen(@pat).
	27	*
	28	* An example of the worst case is glob_match("*aaaaa", "aaaaaaaaaa");
	29	* it takes 6 passes over the pattern before matching the string.
	30	*
	31	* Like !fnmatch(@pat, @str, 0) and unlike the shell, this does NOT
	32	* treat / or leading . specially; it isn't actually used for pathnames.
	33	*
	34	* Note that according to glob(7) (and unlike bash), character classes
	35	* are complemented by a leading !; this does not support the regex-style
	36	* [^a-z] syntax.
	37	*
	38	* An opening bracket without a matching close is matched literally.
	39	*/
	40	bool __pure glob_match(char const pat, char const str)
	41	{
	42	/*
	43	* Backtrack to previous * on mismatch and retry starting one
	44	* character later in the string. Because * matches all characters
	45	* (no exception for /), it can be easily proved that there's
	46	* never a need to backtrack multiple levels.
	47	*/
	48	char const back_pat = NULL, back_str = back_str;
	49
	50	/*
	51	* Loop over each token (character or class) in pat, matching
	52	* it against the remaining unmatched tail of str. Return false
	53	* on mismatch, or true after matching the trailing nul bytes.
	54	*/
	55	for (;;) {
	56	unsigned char c = *str++;
	57	unsigned char d = *pat++;
	58
	59	switch (d) {
	60	case '?': /* Wildcard: anything but nul */
	61	if (c == '\0')
	62	return false;
	63	break;
	64	case '': / Any-length wildcard */
65	if (pat == '\0') / Optimize trailing * case */
66	return true;
67	back_pat = pat;
68	back_str = --str; /* Allow zero-length match */
69	break;
70	case '[': { /* Character class */
71	bool match = false, inverted = (*pat == '!');
72	char const *class = pat + inverted;
73	unsigned char a = *class++;
74
75	/*
76	* Iterate over each span in the character class.
77	* A span is either a single character a, or a
78	* range a-b. The first span may begin with ']'.
79	*/
80	do {
81	unsigned char b = a;
82
83	if (a == '\0') /* Malformed */
84	goto literal;
85
86	if (class[0] == '-' && class[1] != ']') {
87	b = class[1];
88
89	if (b == '\0')
90	goto literal;
91
92	class += 2;
93	/* Any special action if a > b? */
94	}
95	match \|= (a <= c && c <= b);
96	} while ((a = *class++) != ']');
97
98	if (match == inverted)
99	goto backtrack;
100	pat = class;
101	}
102	break;
103	case '\\':
104	d = *pat++;
105	/FALLTHROUGH/
106	default: /* Literal character */
107	literal:
108	if (c == d) {
109	if (d == '\0')
110	return true;
111	break;
112	}
113	backtrack:
114	if (c == '\0' \|\| !back_pat)
115	return false; /* No point continuing */
116	/* Try again from last , one character later in str. /
117	pat = back_pat;
118	str = ++back_str;
119	break;
120	}
121	}
122	}
123	EXPORT_SYMBOL(glob_match);