From a121cabf70b992c7b2a2e49a27b059aac9987a10 Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Sat, 25 Dec 2010 13:49:15 -0800 Subject: [PATCH] utimens: configure better on hosts with NFS clock skew * m4/utimes.m4 (gl_FUNC_UTIMES): Don't assume that utimes (f, NULL) uses the clock of the local host. It might use the clock of the NFS server. Reported for Linux 2.4.21 client by Bruno Haible in . --- ChangeLog | 8 ++++++++ m4/utimes.m4 | 54 +++++++++++++++++++++++++++++++++++++++--------------- 2 files changed, 47 insertions(+), 15 deletions(-) diff --git a/ChangeLog b/ChangeLog index c4e609cc5..18cd30ecf 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,11 @@ +2010-12-25 Paul Eggert + + utimens: configure better on hosts with NFS clock skew + * m4/utimes.m4 (gl_FUNC_UTIMES): Don't assume that utimes (f, NULL) + uses the clock of the local host. It might use the clock of the + NFS server. Reported for Linux 2.4.21 client by Bruno Haible in + . + 2010-12-25 Bruno Haible ptsname test: Avoid failure on Solaris. diff --git a/m4/utimes.m4 b/m4/utimes.m4 index dc93cf863..81865cb5a 100644 --- a/m4/utimes.m4 +++ b/m4/utimes.m4 @@ -34,15 +34,21 @@ AC_DEFUN([gl_FUNC_UTIMES], #include #include +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"; + static struct timeval timeval[2] = {{9, 10}, {999999, 999999}}; /* Test whether utimes() essentially works. */ { - static struct timeval timeval[2] = {{9, 10}, {999999, 999999}}; struct stat sbuf; FILE *f = fopen (file, "w"); if (f == NULL) @@ -56,37 +62,54 @@ main () else if (!(sbuf.st_atime == timeval[0].tv_sec && sbuf.st_mtime == timeval[1].tv_sec)) result |= 4; - unlink (file); + if (unlink (file) != 0) + result |= 1; } /* Test whether utimes() with a NULL argument sets the file's timestamp - to the current time. Note that this test fails on NFS file systems + 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. */ { - struct stat sbuf; - FILE *f = fopen (file, "w"); - if (f == NULL) - result |= 1; - else if (fclose (f) != 0) + int fd = open (file, O_WRONLY|O_CREAT, 0644); + if (fd < 0) result |= 1; else { - time_t now; - if (time (&now) == (time_t)-1) + 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) + result |= 2; else if (utimes (file, NULL) != 0) result |= 8; - else if (lstat (file, &sbuf) != 0) + 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 { - if (!(now - sbuf.st_atime <= 2)) + int a_ok_POSIX = inorder (t0, st1.st_atime, t2); + int m_ok_POSIX = inorder (t0, st1.st_mtime, t2); + int a_ok_NFS = inorder (st0.st_mtime, st1.st_atime, st2.st_mtime); + int m_ok_NFS = inorder (st0.st_mtime, st1.st_mtime, st2.st_mtime); + if (! ((a_ok_POSIX || a_ok_NFS) && st1.st_atime == st1.st_mtime)) result |= 16; - if (!(now - sbuf.st_mtime <= 2)) + if (! (a_ok_POSIX ? m_ok_POSIX : m_ok_NFS)) result |= 32; } + if (close (fd) != 0) + result |= 1; } - unlink (file); + if (unlink (file) != 0) + result |= 1; } /* Test whether utimes() with a NULL argument works on read-only files. */ @@ -98,7 +121,8 @@ main () result |= 1; else if (utimes (file, NULL) != 0) result |= 64; - unlink (file); + if (unlink (file) != 0) + result |= 1; } return result; -- 2.11.0