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// SPDX-License-Identifier: (GPL-2.0 OR MIT)
#include <linux/module.h>
#include <linux/glob.h>
#include <linux/export.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");
static bool __pure glob_match_str(char const *pat, char const *str,
char const *str_end);
/**
* 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 a small and simple implementation intended for device denylists
* 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)
{
return glob_match_str(pat, str, NULL);
}
EXPORT_SYMBOL(glob_match);
/**
* glob_match_len - glob match against a length-bounded string
* @pat: Shell-style pattern to match.
* @str: String to match. Need not be NUL-terminated.
* @len: Number of bytes of @str that may be read.
*
* Like glob_match(), but @str is only read up to @len bytes, so it can be
* used on buffers that are not NUL-terminated (e.g. trace event fields).
* A NUL byte within @len still terminates the string.
*/
bool __pure glob_match_len(char const *pat, char const *str, size_t len)
{
return glob_match_str(pat, str, str + len);
}
EXPORT_SYMBOL(glob_match_len);
static bool __pure glob_match_str(char const *pat, char const *str,
char const *str_end)
{
/*
* 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 = NULL;
/*
* 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_end && str >= str_end) ? '\0' : *str;
unsigned char d = *pat++;
str++;
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 */
if (c == '\0') /* No possible match */
return false;
bool match = false, inverted = (*pat == '!');
char const *class = inverted ? pat + 1 : pat;
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? */
}
if (a <= c && c <= b)
match = true;
} 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;
}
}
}
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