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# getcwd-abort-bug.m4
# serial 18
dnl Copyright (C) 2006, 2009-2024 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
# Determine whether getcwd aborts when the length of the working directory
# name is unusually large. Any length between 4k and 16k trigger the bug
# when using glibc-2.4.90-9 or older.
# From Jim Meyering
# gl_FUNC_GETCWD_ABORT_BUG([ACTION-IF-BUGGY[, ACTION-IF-WORKS]])
AC_DEFUN([gl_FUNC_GETCWD_ABORT_BUG],
[
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CHECK_DECLS_ONCE([getcwd])
AC_CHECK_HEADERS_ONCE([unistd.h])
AC_REQUIRE([gl_PATHMAX_SNIPPET_PREREQ])
AC_CACHE_CHECK([whether getcwd succeeds when 4k < cwd_length < 16k],
[gl_cv_func_getcwd_succeeds_beyond_4k],
[# Remove any remnants of a previous test.
rm -rf confdir-14B---
# Arrange for deletion of the temporary directory this test creates.
ac_clean_files="$ac_clean_files confdir-14B---"
dnl Please keep this in sync with tests/test-getcwd.c.
AC_RUN_IFELSE(
[AC_LANG_SOURCE(
[[
#include <errno.h>
#include <stdlib.h>
#if HAVE_UNISTD_H
# include <unistd.h>
#else /* on Windows with MSVC */
# include <direct.h>
#endif
#include <string.h>
#include <sys/stat.h>
]gl_PATHMAX_SNIPPET[
]GL_MDA_DEFINES[
#ifndef S_IRWXU
# define S_IRWXU 0700
#endif
/* This size is chosen to be larger than PATH_MAX (4k), yet smaller than
the 16kB pagesize on ia64 linux. Those conditions make the code below
trigger a bug in glibc's getcwd implementation before 2.4.90-10. */
#define TARGET_LEN (5 * 1024)
int
main ()
{
char *cwd;
size_t initial_cwd_len;
int fail = 0;
/* The bug is triggered when PATH_MAX < page size, so skip
this relatively expensive and invasive test if that's not true. */
#if defined PATH_MAX && defined _SC_PAGESIZE
int bug_possible = PATH_MAX < sysconf (_SC_PAGESIZE);
#else
int bug_possible = 0;
#endif
if (! bug_possible)
return 0;
cwd = getcwd (NULL, 0);
if (cwd == NULL)
return 2;
initial_cwd_len = strlen (cwd);
free (cwd);
if (1)
{
static char const dir_name[] = "confdir-14B---";
size_t desired_depth = ((TARGET_LEN - 1 - initial_cwd_len)
/ sizeof dir_name);
size_t d;
for (d = 0; d < desired_depth; d++)
{
if (mkdir (dir_name, S_IRWXU) < 0 || chdir (dir_name) < 0)
{
if (! (errno == ERANGE || errno == ENAMETOOLONG
|| errno == ENOENT))
fail = 3; /* Unable to construct deep hierarchy. */
break;
}
}
/* If libc has the bug in question, this invocation of getcwd
results in a failed assertion. */
cwd = getcwd (NULL, 0);
if (cwd == NULL)
fail = 4; /* getcwd didn't assert, but it failed for a long name
where the answer could have been learned. */
free (cwd);
/* Call rmdir first, in case the above chdir failed. */
rmdir (dir_name);
while (0 < d--)
{
if (chdir ("..") < 0)
{
fail = 5;
break;
}
rmdir (dir_name);
}
}
return fail;
}
]])],
[gl_cv_func_getcwd_succeeds_beyond_4k=yes],
[dnl An abort will provoke an exit code of something like 134 (128 + 6).
dnl An exit code of 4 can also occur (for example in
dnl musl libc 1.2.2/powerpc64le, NetBSD 10.0, OpenBSD 6.7:
dnl getcwd (NULL, 0) fails rather than returning a string longer than
dnl PATH_MAX. This may be POSIX compliant (in some interpretations of
dnl POSIX). But gnulib's getcwd module wants to provide a non-NULL
dnl value in this case.
ret=$?
if test $ret -ge 128 || test $ret = 4; then
gl_cv_func_getcwd_succeeds_beyond_4k=no
else
gl_cv_func_getcwd_succeeds_beyond_4k=yes
fi
],
[case "$host_os" in
# Guess no otherwise, even on glibc systems and musl systems.
*) gl_cv_func_getcwd_succeeds_beyond_4k="guessing no"
esac
])
])
case "$gl_cv_func_getcwd_succeeds_beyond_4k" in
*no)
$1
;;
*)
$2
;;
esac
])
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