libc glob: Avoid pathological exponential behavior
Adapt glob's match() routine to use a greedy algorithm that avoids exponential runtime in byzantine inputs. While here, add a testcase for the byzantine input. Prompted by: https://research.swtch.com/glob Authored by: Yves Orton <demerphq at gmail.com> Obtained from: Perl (33252c318625f3c6c89b816ee88481940e3e6f95) Sponsored by: Dell EMC Isilon
This commit is contained in:
Conrad Meyer
parent
702eb303ff
commit
241eb37e29
@ -903,61 +903,73 @@ globextend(const Char *path, glob_t *pglob, struct glob_limit *limit,
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}
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/*
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* pattern matching function for filenames. Each occurrence of the *
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* pattern causes a recursion level.
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* pattern matching function for filenames.
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*/
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static int
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match(Char *name, Char *pat, Char *patend)
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{
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int ok, negate_range;
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Char c, k;
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Char c, k, *nextp, *nextn;
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struct xlocale_collate *table =
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(struct xlocale_collate*)__get_locale()->components[XLC_COLLATE];
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while (pat < patend) {
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c = *pat++;
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switch (c & M_MASK) {
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case M_ALL:
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if (pat == patend)
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return (1);
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do
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if (match(name, pat, patend))
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return (1);
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while (*name++ != EOS);
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return (0);
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case M_ONE:
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if (*name++ == EOS)
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return (0);
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break;
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case M_SET:
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ok = 0;
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if ((k = *name++) == EOS)
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return (0);
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if ((negate_range = ((*pat & M_MASK) == M_NOT)) != 0)
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++pat;
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while (((c = *pat++) & M_MASK) != M_END)
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if ((*pat & M_MASK) == M_RNG) {
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if (table->__collate_load_error ?
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CHAR(c) <= CHAR(k) &&
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CHAR(k) <= CHAR(pat[1]) :
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__wcollate_range_cmp(CHAR(c),
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CHAR(k)) <= 0 &&
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__wcollate_range_cmp(CHAR(k),
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CHAR(pat[1])) <= 0)
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nextn = NULL;
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nextp = NULL;
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while (1) {
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while (pat < patend) {
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c = *pat++;
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switch (c & M_MASK) {
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case M_ALL:
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if (pat == patend)
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return (1);
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if (*name == EOS)
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return (0);
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nextn = name + 1;
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nextp = pat - 1;
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break;
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case M_ONE:
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if (*name++ == EOS)
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goto fail;
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break;
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case M_SET:
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ok = 0;
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if ((k = *name++) == EOS)
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goto fail;
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if ((negate_range = ((*pat & M_MASK) == M_NOT)) != 0)
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++pat;
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while (((c = *pat++) & M_MASK) != M_END)
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if ((*pat & M_MASK) == M_RNG) {
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if (table->__collate_load_error ?
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CHAR(c) <= CHAR(k) &&
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CHAR(k) <= CHAR(pat[1]) :
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__wcollate_range_cmp(CHAR(c),
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CHAR(k)) <= 0 &&
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__wcollate_range_cmp(CHAR(k),
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CHAR(pat[1])) <= 0)
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ok = 1;
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pat += 2;
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} else if (c == k)
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ok = 1;
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pat += 2;
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} else if (c == k)
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ok = 1;
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if (ok == negate_range)
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return (0);
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break;
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default:
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if (*name++ != c)
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return (0);
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break;
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if (ok == negate_range)
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goto fail;
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break;
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default:
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if (*name++ != c)
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goto fail;
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break;
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}
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}
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if (*name == EOS)
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return (1);
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fail:
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if (nextn == NULL)
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break;
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pat = nextp;
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name = nextn;
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}
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return (*name == EOS);
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return (0);
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}
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/* Free allocated data belonging to a glob_t structure. */
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@ -8,6 +8,7 @@ ATF_TESTS_C+= fmtmsg_test
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ATF_TESTS_C+= fnmatch2_test
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ATF_TESTS_C+= fpclassify2_test
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ATF_TESTS_C+= ftw_test
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ATF_TESTS_C+= glob2_test
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ATF_TESTS_C+= popen_test
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ATF_TESTS_C+= posix_spawn_test
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ATF_TESTS_C+= wordexp_test
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114
lib/libc/tests/gen/glob2_test.c
Normal file
114
lib/libc/tests/gen/glob2_test.c
Normal file
@ -0,0 +1,114 @@
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/*
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* Copyright (c) 2017 Dell EMC Isilon
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <glob.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include <unistd.h>
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#include <atf-c.h>
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/*
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* Derived from Russ Cox' pathological case test program used for the
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* https://research.swtch.com/glob article.
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*/
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ATF_TC_WITHOUT_HEAD(glob_pathological_test);
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ATF_TC_BODY(glob_pathological_test, tc)
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{
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struct timespec t, t2;
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glob_t g;
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const char *longname = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
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"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
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char pattern[1000], *p;
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double dt;
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unsigned i, j, k, mul;
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int fd, rc;
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fd = open(longname, O_CREAT | O_RDWR, 0666);
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ATF_REQUIRE(fd >= 0);
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/*
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* Test up to 100 a* groups. Exponential implementations typically go
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* bang at i=7 or 8.
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*/
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for (i = 0; i < 100; i++) {
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/*
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* Create a*...b pattern with i 'a*' groups.
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*/
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p = pattern;
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for (k = 0; k < i; k++) {
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*p++ = 'a';
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*p++ = '*';
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}
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*p++ = 'b';
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*p = '\0';
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clock_gettime(CLOCK_REALTIME, &t);
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for (j = 0; j < mul; j++) {
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memset(&g, 0, sizeof g);
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rc = glob(pattern, 0, 0, &g);
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if (rc == GLOB_NOSPACE || rc == GLOB_ABORTED) {
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ATF_REQUIRE_MSG(rc == GLOB_NOMATCH,
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"an unexpected error occurred: "
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"rc=%d errno=%d", rc, errno);
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/* NORETURN */
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}
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ATF_CHECK_MSG(rc == GLOB_NOMATCH,
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"A bogus match occurred: '%s' ~ '%s'", pattern,
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g.gl_pathv[0]);
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globfree(&g);
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}
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clock_gettime(CLOCK_REALTIME, &t2);
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t2.tv_sec -= t.tv_sec;
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t2.tv_nsec -= t.tv_nsec;
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dt = t2.tv_sec + (double)t2.tv_nsec/1e9;
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dt /= mul;
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ATF_CHECK_MSG(dt < 1, "glob(3) took far too long: %d %.9f", i,
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dt);
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if (dt >= 0.0001)
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mul = 1;
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}
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}
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ATF_TP_ADD_TCS(tp)
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{
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ATF_TP_ADD_TC(tp, glob_pathological_test);
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return (atf_no_error());
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}
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