126 lines · c
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 the6 * ATA code that depends on it can be as well. In practice, they're7 * both usually compiled in and the module overhead goes away.8 */9MODULE_DESCRIPTION("glob(7) matching");10MODULE_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 match18 * 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 blacklists24 * where a string is matched against a number of patterns. Thus, it25 * does not preprocess the patterns. It is non-recursive, and run-time26 * 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 NOT32 * treat / or leading . specially; it isn't actually used for pathnames.33 *34 * Note that according to glob(7) (and unlike bash), character classes35 * are complemented by a leading !; this does not support the regex-style36 * [^a-z] syntax.37 *38 * An opening bracket without a matching close is matched literally.39 */40bool __pure glob_match(char const *pat, char const *str)41{42 /*43 * Backtrack to previous * on mismatch and retry starting one44 * character later in the string. Because * matches all characters45 * (no exception for /), it can be easily proved that there's46 * never a need to backtrack multiple levels.47 */48 char const *back_pat = NULL, *back_str;49 50 /*51 * Loop over each token (character or class) in pat, matching52 * it against the remaining unmatched tail of str. Return false53 * 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 if (c == '\0') /* No possible match */72 return false;73 bool match = false, inverted = (*pat == '!');74 char const *class = pat + inverted;75 unsigned char a = *class++;76 77 /*78 * Iterate over each span in the character class.79 * A span is either a single character a, or a80 * range a-b. The first span may begin with ']'.81 */82 do {83 unsigned char b = a;84 85 if (a == '\0') /* Malformed */86 goto literal;87 88 if (class[0] == '-' && class[1] != ']') {89 b = class[1];90 91 if (b == '\0')92 goto literal;93 94 class += 2;95 /* Any special action if a > b? */96 }97 match |= (a <= c && c <= b);98 } while ((a = *class++) != ']');99 100 if (match == inverted)101 goto backtrack;102 pat = class;103 }104 break;105 case '\\':106 d = *pat++;107 fallthrough;108 default: /* Literal character */109literal:110 if (c == d) {111 if (d == '\0')112 return true;113 break;114 }115backtrack:116 if (c == '\0' || !back_pat)117 return false; /* No point continuing */118 /* Try again from last *, one character later in str. */119 pat = back_pat;120 str = ++back_str;121 break;122 }123 }124}125EXPORT_SYMBOL(glob_match);126