git/wildmatch.c

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/*
** Do shell-style pattern matching for ?, \, [], and * characters.
** It is 8bit clean.
**
** Written by Rich $alz, mirror!rs, Wed Nov 26 19:03:17 EST 1986.
** Rich $alz is now <rsalz@bbn.com>.
**
** Modified by Wayne Davison to special-case '/' matching, to make '**'
** work differently than '*', and to fix the character-class code.
*/
#include "git-compat-util.h"
#include "wildmatch.h"
typedef unsigned char uchar;
/* Internal return values */
#define WM_ABORT_ALL -1
#define WM_ABORT_TO_STARSTAR -2
/* What character marks an inverted character class? */
#define NEGATE_CLASS '!'
#define NEGATE_CLASS2 '^'
#define CC_EQ(class, len, litmatch) ((len) == sizeof (litmatch)-1 \
&& *(class) == *(litmatch) \
&& strncmp((char*)class, litmatch, len) == 0)
#if defined STDC_HEADERS || !defined isascii
# define ISASCII(c) 1
#else
# define ISASCII(c) isascii(c)
#endif
#ifdef isblank
# define ISBLANK(c) (ISASCII(c) && isblank(c))
#else
# define ISBLANK(c) ((c) == ' ' || (c) == '\t')
#endif
#ifdef isgraph
# define ISGRAPH(c) (ISASCII(c) && isgraph(c))
#else
# define ISGRAPH(c) (ISASCII(c) && isprint(c) && !isspace(c))
#endif
#define ISPRINT(c) (ISASCII(c) && isprint(c))
#define ISDIGIT(c) (ISASCII(c) && isdigit(c))
#define ISALNUM(c) (ISASCII(c) && isalnum(c))
#define ISALPHA(c) (ISASCII(c) && isalpha(c))
#define ISCNTRL(c) (ISASCII(c) && iscntrl(c))
#define ISLOWER(c) (ISASCII(c) && islower(c))
#define ISPUNCT(c) (ISASCII(c) && ispunct(c))
#define ISSPACE(c) (ISASCII(c) && isspace(c))
#define ISUPPER(c) (ISASCII(c) && isupper(c))
#define ISXDIGIT(c) (ISASCII(c) && isxdigit(c))
/* Match pattern "p" against "text" */
static int dowild(const uchar *p, const uchar *text, unsigned int flags)
{
uchar p_ch;
const uchar *pattern = p;
for ( ; (p_ch = *p) != '\0'; text++, p++) {
int matched, match_slash, negated;
uchar t_ch, prev_ch;
if ((t_ch = *text) == '\0' && p_ch != '*')
return WM_ABORT_ALL;
if ((flags & WM_CASEFOLD) && ISUPPER(t_ch))
t_ch = tolower(t_ch);
if ((flags & WM_CASEFOLD) && ISUPPER(p_ch))
p_ch = tolower(p_ch);
switch (p_ch) {
case '\\':
/* Literal match with following character. Note that the test
* in "default" handles the p[1] == '\0' failure case. */
p_ch = *++p;
/* FALLTHROUGH */
default:
if (t_ch != p_ch)
return WM_NOMATCH;
continue;
case '?':
/* Match anything but '/'. */
if ((flags & WM_PATHNAME) && t_ch == '/')
return WM_NOMATCH;
continue;
case '*':
if (*++p == '*') {
const uchar *prev_p = p;
while (*++p == '*') {}
if (!(flags & WM_PATHNAME))
/* without WM_PATHNAME, '*' == '**' */
match_slash = 1;
else if ((prev_p - pattern < 2 || *(prev_p - 2) == '/') &&
(*p == '\0' || *p == '/' ||
(p[0] == '\\' && p[1] == '/'))) {
/*
* Assuming we already match 'foo/' and are at
* <star star slash>, just assume it matches
* nothing and go ahead match the rest of the
* pattern with the remaining string. This
* helps make foo/<*><*>/bar (<> because
* otherwise it breaks C comment syntax) match
* both foo/bar and foo/a/bar.
*/
if (p[0] == '/' &&
dowild(p + 1, text, flags) == WM_MATCH)
return WM_MATCH;
match_slash = 1;
} else /* WM_PATHNAME is set */
match_slash = 0;
} else
/* without WM_PATHNAME, '*' == '**' */
match_slash = flags & WM_PATHNAME ? 0 : 1;
if (*p == '\0') {
/* Trailing "**" matches everything. Trailing "*" matches
* only if there are no more slash characters. */
if (!match_slash) {
if (strchr((char *)text, '/'))
wildmatch: fix exponential behavior When dowild() cannot match a '*' or '/**/' wildcard then it must return WM_ABORT_TO_STARSTAR or WM_ABORT_ALL respectively. Failure to observe this results in unnecessary backtracking and the time taken for a failed match increases exponentially with the number of wildcards in the pattern [1]. Unfortunately in some instances dowild() returns WM_NOMATCH for a failed match resulting in long match times for patterns containing multiple wildcards as can be seen in the following benchmark. (Note that the timings in the Benchmark 1 are really measuring the time to execute test-tool rather than the time to match the pattern) Benchmark 1: t/helper/test-tool wildmatch wildmatch aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab "*a" Time (mean ± σ): 22.8 ms ± 1.7 ms [User: 12.1 ms, System: 10.6 ms] Range (min … max): 19.4 ms … 26.9 ms 113 runs Warning: Ignoring non-zero exit code. Benchmark 2: t/helper/test-tool wildmatch wildmatch aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab "*a*a*a*a*a*a*a*a*a" Time (mean ± σ): 5.244 s ± 0.228 s [User: 5.229 s, System: 0.010 s] Range (min … max): 4.969 s … 5.707 s 10 runs Warning: Ignoring non-zero exit code. Summary 't/helper/test-tool wildmatch wildmatch aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab "*a"' ran 230.37 ± 20.04 times faster than 't/helper/test-tool wildmatch wildmatch aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab "*a*a*a*a*a*a*a*a*a"' The security implications are limited as it only affects operations that are potentially DoS vectors. For example by creating a blob containing such a pattern a malicious user can exploit this behavior to use large amounts of CPU time on a remote server by pushing the blob and then creating a new clone with --filter=sparse:oid. However this filter type is usually disabled as it is known to consume large amounts of CPU time even without this bug. The WM_MATCH changed in the first hunk of this patch comes from the original implementation imported from rsync in 5230f605e1 (Import wildmatch from rsync, 2012-10-15). Compared to the others converted here it is fairly harmless as it only triggers at the end of the pattern and so will only cause a single unnecessary backtrack. The others introduced by 6f1a31f0aa (wildmatch: advance faster in <asterisk> + <literal> patterns, 2013-01-01) and 46983441ae (wildmatch: make a special case for "*/" with FNM_PATHNAME, 2013-01-01) are more pernicious and will cause exponential behavior. A new test is added to protect against future regressions. [1] https://research.swtch.com/glob Helped-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-03-20 16:10:00 +00:00
return WM_ABORT_TO_STARSTAR;
}
return WM_MATCH;
} else if (!match_slash && *p == '/') {
/*
* _one_ asterisk followed by a slash
* with WM_PATHNAME matches the next
* directory
*/
const char *slash = strchr((char*)text, '/');
if (!slash)
wildmatch: fix exponential behavior When dowild() cannot match a '*' or '/**/' wildcard then it must return WM_ABORT_TO_STARSTAR or WM_ABORT_ALL respectively. Failure to observe this results in unnecessary backtracking and the time taken for a failed match increases exponentially with the number of wildcards in the pattern [1]. Unfortunately in some instances dowild() returns WM_NOMATCH for a failed match resulting in long match times for patterns containing multiple wildcards as can be seen in the following benchmark. (Note that the timings in the Benchmark 1 are really measuring the time to execute test-tool rather than the time to match the pattern) Benchmark 1: t/helper/test-tool wildmatch wildmatch aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab "*a" Time (mean ± σ): 22.8 ms ± 1.7 ms [User: 12.1 ms, System: 10.6 ms] Range (min … max): 19.4 ms … 26.9 ms 113 runs Warning: Ignoring non-zero exit code. Benchmark 2: t/helper/test-tool wildmatch wildmatch aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab "*a*a*a*a*a*a*a*a*a" Time (mean ± σ): 5.244 s ± 0.228 s [User: 5.229 s, System: 0.010 s] Range (min … max): 4.969 s … 5.707 s 10 runs Warning: Ignoring non-zero exit code. Summary 't/helper/test-tool wildmatch wildmatch aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab "*a"' ran 230.37 ± 20.04 times faster than 't/helper/test-tool wildmatch wildmatch aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab "*a*a*a*a*a*a*a*a*a"' The security implications are limited as it only affects operations that are potentially DoS vectors. For example by creating a blob containing such a pattern a malicious user can exploit this behavior to use large amounts of CPU time on a remote server by pushing the blob and then creating a new clone with --filter=sparse:oid. However this filter type is usually disabled as it is known to consume large amounts of CPU time even without this bug. The WM_MATCH changed in the first hunk of this patch comes from the original implementation imported from rsync in 5230f605e1 (Import wildmatch from rsync, 2012-10-15). Compared to the others converted here it is fairly harmless as it only triggers at the end of the pattern and so will only cause a single unnecessary backtrack. The others introduced by 6f1a31f0aa (wildmatch: advance faster in <asterisk> + <literal> patterns, 2013-01-01) and 46983441ae (wildmatch: make a special case for "*/" with FNM_PATHNAME, 2013-01-01) are more pernicious and will cause exponential behavior. A new test is added to protect against future regressions. [1] https://research.swtch.com/glob Helped-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-03-20 16:10:00 +00:00
return WM_ABORT_ALL;
text = (const uchar*)slash;
/* the slash is consumed by the top-level for loop */
break;
}
while (1) {
if (t_ch == '\0')
break;
/*
* Try to advance faster when an asterisk is
* followed by a literal. We know in this case
* that the string before the literal
* must belong to "*".
* If match_slash is false, do not look past
* the first slash as it cannot belong to '*'.
*/
if (!is_glob_special(*p)) {
p_ch = *p;
if ((flags & WM_CASEFOLD) && ISUPPER(p_ch))
p_ch = tolower(p_ch);
while ((t_ch = *text) != '\0' &&
(match_slash || t_ch != '/')) {
if ((flags & WM_CASEFOLD) && ISUPPER(t_ch))
t_ch = tolower(t_ch);
if (t_ch == p_ch)
break;
text++;
}
wildmatch: fix exponential behavior When dowild() cannot match a '*' or '/**/' wildcard then it must return WM_ABORT_TO_STARSTAR or WM_ABORT_ALL respectively. Failure to observe this results in unnecessary backtracking and the time taken for a failed match increases exponentially with the number of wildcards in the pattern [1]. Unfortunately in some instances dowild() returns WM_NOMATCH for a failed match resulting in long match times for patterns containing multiple wildcards as can be seen in the following benchmark. (Note that the timings in the Benchmark 1 are really measuring the time to execute test-tool rather than the time to match the pattern) Benchmark 1: t/helper/test-tool wildmatch wildmatch aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab "*a" Time (mean ± σ): 22.8 ms ± 1.7 ms [User: 12.1 ms, System: 10.6 ms] Range (min … max): 19.4 ms … 26.9 ms 113 runs Warning: Ignoring non-zero exit code. Benchmark 2: t/helper/test-tool wildmatch wildmatch aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab "*a*a*a*a*a*a*a*a*a" Time (mean ± σ): 5.244 s ± 0.228 s [User: 5.229 s, System: 0.010 s] Range (min … max): 4.969 s … 5.707 s 10 runs Warning: Ignoring non-zero exit code. Summary 't/helper/test-tool wildmatch wildmatch aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab "*a"' ran 230.37 ± 20.04 times faster than 't/helper/test-tool wildmatch wildmatch aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab "*a*a*a*a*a*a*a*a*a"' The security implications are limited as it only affects operations that are potentially DoS vectors. For example by creating a blob containing such a pattern a malicious user can exploit this behavior to use large amounts of CPU time on a remote server by pushing the blob and then creating a new clone with --filter=sparse:oid. However this filter type is usually disabled as it is known to consume large amounts of CPU time even without this bug. The WM_MATCH changed in the first hunk of this patch comes from the original implementation imported from rsync in 5230f605e1 (Import wildmatch from rsync, 2012-10-15). Compared to the others converted here it is fairly harmless as it only triggers at the end of the pattern and so will only cause a single unnecessary backtrack. The others introduced by 6f1a31f0aa (wildmatch: advance faster in <asterisk> + <literal> patterns, 2013-01-01) and 46983441ae (wildmatch: make a special case for "*/" with FNM_PATHNAME, 2013-01-01) are more pernicious and will cause exponential behavior. A new test is added to protect against future regressions. [1] https://research.swtch.com/glob Helped-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-03-20 16:10:00 +00:00
if (t_ch != p_ch) {
if (match_slash)
return WM_ABORT_ALL;
else
return WM_ABORT_TO_STARSTAR;
}
}
if ((matched = dowild(p, text, flags)) != WM_NOMATCH) {
if (!match_slash || matched != WM_ABORT_TO_STARSTAR)
return matched;
} else if (!match_slash && t_ch == '/')
return WM_ABORT_TO_STARSTAR;
t_ch = *++text;
}
return WM_ABORT_ALL;
case '[':
p_ch = *++p;
#ifdef NEGATE_CLASS2
if (p_ch == NEGATE_CLASS2)
p_ch = NEGATE_CLASS;
#endif
/* Assign literal 1/0 because of "matched" comparison. */
negated = p_ch == NEGATE_CLASS ? 1 : 0;
if (negated) {
/* Inverted character class. */
p_ch = *++p;
}
prev_ch = 0;
matched = 0;
do {
if (!p_ch)
return WM_ABORT_ALL;
if (p_ch == '\\') {
p_ch = *++p;
if (!p_ch)
return WM_ABORT_ALL;
if (t_ch == p_ch)
matched = 1;
} else if (p_ch == '-' && prev_ch && p[1] && p[1] != ']') {
p_ch = *++p;
if (p_ch == '\\') {
p_ch = *++p;
if (!p_ch)
return WM_ABORT_ALL;
}
if (t_ch <= p_ch && t_ch >= prev_ch)
matched = 1;
else if ((flags & WM_CASEFOLD) && ISLOWER(t_ch)) {
uchar t_ch_upper = toupper(t_ch);
if (t_ch_upper <= p_ch && t_ch_upper >= prev_ch)
matched = 1;
}
p_ch = 0; /* This makes "prev_ch" get set to 0. */
} else if (p_ch == '[' && p[1] == ':') {
const uchar *s;
int i;
for (s = p += 2; (p_ch = *p) && p_ch != ']'; p++) {} /*SHARED ITERATOR*/
if (!p_ch)
return WM_ABORT_ALL;
i = p - s - 1;
if (i < 0 || p[-1] != ':') {
/* Didn't find ":]", so treat like a normal set. */
p = s - 2;
p_ch = '[';
if (t_ch == p_ch)
matched = 1;
continue;
}
if (CC_EQ(s,i, "alnum")) {
if (ISALNUM(t_ch))
matched = 1;
} else if (CC_EQ(s,i, "alpha")) {
if (ISALPHA(t_ch))
matched = 1;
} else if (CC_EQ(s,i, "blank")) {
if (ISBLANK(t_ch))
matched = 1;
} else if (CC_EQ(s,i, "cntrl")) {
if (ISCNTRL(t_ch))
matched = 1;
} else if (CC_EQ(s,i, "digit")) {
if (ISDIGIT(t_ch))
matched = 1;
} else if (CC_EQ(s,i, "graph")) {
if (ISGRAPH(t_ch))
matched = 1;
} else if (CC_EQ(s,i, "lower")) {
if (ISLOWER(t_ch))
matched = 1;
} else if (CC_EQ(s,i, "print")) {
if (ISPRINT(t_ch))
matched = 1;
} else if (CC_EQ(s,i, "punct")) {
if (ISPUNCT(t_ch))
matched = 1;
} else if (CC_EQ(s,i, "space")) {
if (ISSPACE(t_ch))
matched = 1;
} else if (CC_EQ(s,i, "upper")) {
if (ISUPPER(t_ch))
matched = 1;
else if ((flags & WM_CASEFOLD) && ISLOWER(t_ch))
matched = 1;
} else if (CC_EQ(s,i, "xdigit")) {
if (ISXDIGIT(t_ch))
matched = 1;
} else /* malformed [:class:] string */
return WM_ABORT_ALL;
p_ch = 0; /* This makes "prev_ch" get set to 0. */
} else if (t_ch == p_ch)
matched = 1;
} while (prev_ch = p_ch, (p_ch = *++p) != ']');
if (matched == negated ||
((flags & WM_PATHNAME) && t_ch == '/'))
return WM_NOMATCH;
continue;
}
}
return *text ? WM_NOMATCH : WM_MATCH;
}
/* Match the "pattern" against the "text" string. */
int wildmatch(const char *pattern, const char *text, unsigned int flags)
{
int res = dowild((const uchar*)pattern, (const uchar*)text, flags);
return res == WM_MATCH ? WM_MATCH : WM_NOMATCH;
}