124 lines
3.5 KiB
C
124 lines
3.5 KiB
C
#include <linux/module.h>
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#include <linux/glob.h>
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/*
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* The only reason this code can be compiled as a module is because the
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* ATA code that depends on it can be as well. In practice, they're
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* both usually compiled in and the module overhead goes away.
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*/
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MODULE_DESCRIPTION("glob(7) matching");
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MODULE_LICENSE("Dual MIT/GPL");
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/**
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* glob_match - Shell-style pattern matching, like !fnmatch(pat, str, 0)
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* @pat: Shell-style pattern to match, e.g. "*.[ch]".
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* @str: String to match. The pattern must match the entire string.
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*
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* Perform shell-style glob matching, returning true (1) if the match
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* succeeds, or false (0) if it fails. Equivalent to !fnmatch(@pat, @str, 0).
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*
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* Pattern metacharacters are ?, *, [ and \.
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* (And, inside character classes, !, - and ].)
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*
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* This is small and simple implementation intended for device blacklists
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* where a string is matched against a number of patterns. Thus, it
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* does not preprocess the patterns. It is non-recursive, and run-time
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* is at most quadratic: strlen(@str)*strlen(@pat).
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*
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* An example of the worst case is glob_match("*aaaaa", "aaaaaaaaaa");
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* it takes 6 passes over the pattern before matching the string.
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*
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* Like !fnmatch(@pat, @str, 0) and unlike the shell, this does NOT
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* treat / or leading . specially; it isn't actually used for pathnames.
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*
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* Note that according to glob(7) (and unlike bash), character classes
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* are complemented by a leading !; this does not support the regex-style
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* [^a-z] syntax.
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*
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* An opening bracket without a matching close is matched literally.
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*/
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bool __pure glob_match(char const *pat, char const *str)
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{
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/*
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* Backtrack to previous * on mismatch and retry starting one
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* character later in the string. Because * matches all characters
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* (no exception for /), it can be easily proved that there's
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* never a need to backtrack multiple levels.
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*/
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char const *back_pat = NULL, *back_str = back_str;
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/*
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* Loop over each token (character or class) in pat, matching
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* it against the remaining unmatched tail of str. Return false
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* on mismatch, or true after matching the trailing nul bytes.
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*/
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for (;;) {
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unsigned char c = *str++;
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unsigned char d = *pat++;
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switch (d) {
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case '?': /* Wildcard: anything but nul */
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if (c == '\0')
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return false;
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break;
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case '*': /* Any-length wildcard */
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if (*pat == '\0') /* Optimize trailing * case */
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return true;
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back_pat = pat;
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back_str = --str; /* Allow zero-length match */
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break;
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case '[': { /* Character class */
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bool match = false, inverted = (*pat == '!');
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char const *class = pat + inverted;
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unsigned char a = *class++;
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/*
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* Iterate over each span in the character class.
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* A span is either a single character a, or a
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* range a-b. The first span may begin with ']'.
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*/
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do {
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unsigned char b = a;
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if (a == '\0') /* Malformed */
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goto literal;
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if (class[0] == '-' && class[1] != ']') {
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b = class[1];
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if (b == '\0')
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goto literal;
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class += 2;
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/* Any special action if a > b? */
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}
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match |= (a <= c && c <= b);
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} while ((a = *class++) != ']');
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if (match == inverted)
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goto backtrack;
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pat = class;
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}
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break;
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case '\\':
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d = *pat++;
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/*FALLTHROUGH*/
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default: /* Literal character */
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literal:
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if (c == d) {
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if (d == '\0')
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return true;
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break;
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}
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backtrack:
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if (c == '\0' || !back_pat)
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return false; /* No point continuing */
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/* Try again from last *, one character later in str. */
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pat = back_pat;
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str = ++back_str;
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break;
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}
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}
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}
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EXPORT_SYMBOL(glob_match);
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