#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); #ifdef CONFIG_GLOB_SELFTEST #include <linux/printk.h> #include <linux/moduleparam.h> /* Boot with "glob.verbose=1" to show successful tests, too */ static bool verbose = false; module_param(verbose, bool, 0); struct glob_test { char const *pat, *str; bool expected; }; static bool __pure __init test(char const *pat, char const *str, bool expected) { bool match = glob_match(pat, str); bool success = match == expected; /* Can't get string literals into a particular section, so... */ static char const msg_error[] __initconst = KERN_ERR "glob: \"%s\" vs. \"%s\": %s *** ERROR ***\n"; static char const msg_ok[] __initconst = KERN_DEBUG "glob: \"%s\" vs. \"%s\": %s OK\n"; static char const mismatch[] __initconst = "mismatch"; char const *message; if (!success) message = msg_error; else if (verbose) message = msg_ok; else return success; printk(message, pat, str, mismatch + 3*match); return success; } /* * The tests are all jammed together in one array to make it simpler * to place that array in the .init.rodata section. The obvious * "array of structures containing char *" has no way to force the * pointed-to strings to be in a particular section. * * Anyway, a test consists of: * 1. Expected glob_match result: '1' or '0'. * 2. Pattern to match: null-terminated string * 3. String to match against: null-terminated string * * The list of tests is terminated with a final '\0' instead of * a glob_match result character. */ static char const glob_tests[] __initconst = /* Some basic tests */ "1" "a\0" "a\0" "0" "a\0" "b\0" "0" "a\0" "aa\0" "0" "a\0" "\0" "1" "\0" "\0" "0" "\0" "a\0" /* Simple character class tests */ "1" "[a]\0" "a\0" "0" "[a]\0" "b\0" "0" "[!a]\0" "a\0" "1" "[!a]\0" "b\0" "1" "[ab]\0" "a\0" "1" "[ab]\0" "b\0" "0" "[ab]\0" "c\0" "1" "[!ab]\0" "c\0" "1" "[a-c]\0" "b\0" "0" "[a-c]\0" "d\0" /* Corner cases in character class parsing */ "1" "[a-c-e-g]\0" "-\0" "0" "[a-c-e-g]\0" "d\0" "1" "[a-c-e-g]\0" "f\0" "1" "[]a-ceg-ik[]\0" "a\0" "1" "[]a-ceg-ik[]\0" "]\0" "1" "[]a-ceg-ik[]\0" "[\0" "1" "[]a-ceg-ik[]\0" "h\0" "0" "[]a-ceg-ik[]\0" "f\0" "0" "[!]a-ceg-ik[]\0" "h\0" "0" "[!]a-ceg-ik[]\0" "]\0" "1" "[!]a-ceg-ik[]\0" "f\0" /* Simple wild cards */ "1" "?\0" "a\0" "0" "?\0" "aa\0" "0" "??\0" "a\0" "1" "?x?\0" "axb\0" "0" "?x?\0" "abx\0" "0" "?x?\0" "xab\0" /* Asterisk wild cards (backtracking) */ "0" "*??\0" "a\0" "1" "*??\0" "ab\0" "1" "*??\0" "abc\0" "1" "*??\0" "abcd\0" "0" "??*\0" "a\0" "1" "??*\0" "ab\0" "1" "??*\0" "abc\0" "1" "??*\0" "abcd\0" "0" "?*?\0" "a\0" "1" "?*?\0" "ab\0" "1" "?*?\0" "abc\0" "1" "?*?\0" "abcd\0" "1" "*b\0" "b\0" "1" "*b\0" "ab\0" "0" "*b\0" "ba\0" "1" "*b\0" "bb\0" "1" "*b\0" "abb\0" "1" "*b\0" "bab\0" "1" "*bc\0" "abbc\0" "1" "*bc\0" "bc\0" "1" "*bc\0" "bbc\0" "1" "*bc\0" "bcbc\0" /* Multiple asterisks (complex backtracking) */ "1" "*ac*\0" "abacadaeafag\0" "1" "*ac*ae*ag*\0" "abacadaeafag\0" "1" "*a*b*[bc]*[ef]*g*\0" "abacadaeafag\0" "0" "*a*b*[ef]*[cd]*g*\0" "abacadaeafag\0" "1" "*abcd*\0" "abcabcabcabcdefg\0" "1" "*ab*cd*\0" "abcabcabcabcdefg\0" "1" "*abcd*abcdef*\0" "abcabcdabcdeabcdefg\0" "0" "*abcd*\0" "abcabcabcabcefg\0" "0" "*ab*cd*\0" "abcabcabcabcefg\0"; static int __init glob_init(void) { unsigned successes = 0; unsigned n = 0; char const *p = glob_tests; static char const message[] __initconst = KERN_INFO "glob: %u self-tests passed, %u failed\n"; /* * Tests are jammed together in a string. The first byte is '1' * or '0' to indicate the expected outcome, or '\0' to indicate the * end of the tests. Then come two null-terminated strings: the * pattern and the string to match it against. */ while (*p) { bool expected = *p++ & 1; char const *pat = p; p += strlen(p) + 1; successes += test(pat, p, expected); p += strlen(p) + 1; n++; } n -= successes; printk(message, successes, n); /* What's the errno for "kernel bug detected"? Guess... */ return n ? -ECANCELED : 0; } /* We need a dummy exit function to allow unload */ static void __exit glob_fini(void) { } module_init(glob_init); module_exit(glob_fini); #endif /* CONFIG_GLOB_SELFTEST */