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