cregit-Linux how code gets into the kernel

Release 4.11 lib/glob.c

Directory: lib
#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; } } }

Contributors

PersonTokensPropCommitsCommitProp
George Spelvin292100.00%1100.00%
Total292100.00%1100.00%

EXPORT_SYMBOL(glob_match);

Overall Contributors

PersonTokensPropCommitsCommitProp
George Spelvin315100.00%1100.00%
Total315100.00%1100.00%
Directory: lib
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