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Diffstat (limited to 'm4/utimes.m4')
| -rw-r--r-- | m4/utimes.m4 | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/m4/utimes.m4 b/m4/utimes.m4 new file mode 100644 index 0000000..e1056bb --- /dev/null +++ b/m4/utimes.m4 @@ -0,0 +1,160 @@ +# Detect some bugs in glibc's implementation of utimes. +# serial 7 + +dnl Copyright (C) 2003-2005, 2009-2020 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. + +# See if we need to work around bugs in glibc's implementation of +# utimes from 2003-07-12 to 2003-09-17. +# First, there was a bug that would make utimes set mtime +# and atime to zero (1970-01-01) unconditionally. +# Then, there was code to round rather than truncate. +# Then, there was an implementation (sparc64, Linux-2.4.28, glibc-2.3.3) +# that didn't honor the NULL-means-set-to-current-time semantics. +# Finally, there was also a version of utimes that failed on read-only +# files, while utime worked fine (linux-2.2.20, glibc-2.2.5). +# +# From Jim Meyering, with suggestions from Paul Eggert. + +AC_DEFUN([gl_FUNC_UTIMES], +[ + AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles + AC_CACHE_CHECK([whether the utimes function works], + [gl_cv_func_working_utimes], + [AC_RUN_IFELSE([AC_LANG_SOURCE([[ +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> +#include <sys/time.h> +#include <time.h> +#include <unistd.h> +#include <stdlib.h> +#include <stdio.h> +#include <utime.h> +#include <errno.h> + +static int +inorder (time_t a, time_t b, time_t c) +{ + return a <= b && b <= c; +} + +int +main () +{ + int result = 0; + char const *file = "conftest.utimes"; + /* On OS/2, file timestamps must be on or after 1980 in local time, + with an even number of seconds. */ + static struct timeval timeval[2] = {{315620000 + 10, 10}, + {315620000 + 1000000, 999998}}; + + /* Test whether utimes() essentially works. */ + { + struct stat sbuf; + FILE *f = fopen (file, "w"); + if (f == NULL) + result |= 1; + else if (fclose (f) != 0) + result |= 1; + else if (utimes (file, timeval) != 0) + result |= 2; + else if (lstat (file, &sbuf) != 0) + result |= 1; + else if (!(sbuf.st_atime == timeval[0].tv_sec + && sbuf.st_mtime == timeval[1].tv_sec)) + result |= 4; + if (unlink (file) != 0) + result |= 1; + } + + /* Test whether utimes() with a NULL argument sets the file's timestamp + to the current time. Use 'fstat' as well as 'time' to + determine the "current" time, to accommodate NFS file systems + if there is a time skew between the host and the NFS server. */ + { + int fd = open (file, O_WRONLY|O_CREAT, 0644); + if (fd < 0) + result |= 1; + else + { + time_t t0, t2; + struct stat st0, st1, st2; + if (time (&t0) == (time_t) -1) + result |= 1; + else if (fstat (fd, &st0) != 0) + result |= 1; + else if (utimes (file, timeval) != 0 + && (errno != EACCES + /* OS/2 kLIBC utimes fails on opened files. */ + || close (fd) != 0 + || utimes (file, timeval) != 0 + || (fd = open (file, O_WRONLY)) < 0)) + result |= 2; + else if (utimes (file, NULL) != 0 + && (errno != EACCES + /* OS/2 kLIBC utimes fails on opened files. */ + || close (fd) != 0 + || utimes (file, NULL) != 0 + || (fd = open (file, O_WRONLY)) < 0)) + result |= 8; + else if (fstat (fd, &st1) != 0) + result |= 1; + else if (write (fd, "\n", 1) != 1) + result |= 1; + else if (fstat (fd, &st2) != 0) + result |= 1; + else if (time (&t2) == (time_t) -1) + result |= 1; + else + { + int m_ok_POSIX = inorder (t0, st1.st_mtime, t2); + int m_ok_NFS = inorder (st0.st_mtime, st1.st_mtime, st2.st_mtime); + if (! (st1.st_atime == st1.st_mtime)) + result |= 16; + if (! (m_ok_POSIX || m_ok_NFS)) + result |= 32; + } + if (close (fd) != 0) + result |= 1; + } + if (unlink (file) != 0) + result |= 1; + } + + /* Test whether utimes() with a NULL argument works on read-only files. */ + { + int fd = open (file, O_WRONLY|O_CREAT, 0444); + if (fd < 0) + result |= 1; + else if (close (fd) != 0) + result |= 1; + else if (utimes (file, NULL) != 0) + result |= 64; + if (unlink (file) != 0) + result |= 1; + } + + return result; +} + ]])], + [gl_cv_func_working_utimes=yes], + [gl_cv_func_working_utimes=no], + [case "$host_os" in + # Guess yes on musl systems. + *-musl*) gl_cv_func_working_utimes="guessing yes" ;; + # Guess no on native Windows. + mingw*) gl_cv_func_working_utimes="guessing no" ;; + *) gl_cv_func_working_utimes="$gl_cross_guess_normal" ;; + esac + ]) + ]) + + case "$gl_cv_func_working_utimes" in + *yes) + AC_DEFINE([HAVE_WORKING_UTIMES], [1], [Define if utimes works properly.]) + ;; + esac +]) |