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| author | Siddhesh Poyarekar <siddhesh@redhat.com> | 2014-03-17 18:42:53 +0530 |
|---|---|---|
| committer | Siddhesh Poyarekar <siddhesh@redhat.com> | 2014-03-17 21:24:02 +0530 |
| commit | ae42bbc55a9e05976269026ddabcfb917f6e922f (patch) | |
| tree | 3d5c26ff77263cada4610720a1ea591c63185b1d /libio/iofdopen.c | |
| parent | ea33158c96c53a64402a772186956c1f5cb556ae (diff) | |
| download | glibc-ae42bbc55a9e05976269026ddabcfb917f6e922f.tar.gz | |
Change offset in fdopen only if setting O_APPEND
fdopen should only be allowed to change the offset in the file it
attaches to if it is setting O_APPEND. If O_APPEND is already set, it
should not change the state of the handle.
Diffstat (limited to 'libio/iofdopen.c')
| -rw-r--r-- | libio/iofdopen.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/libio/iofdopen.c b/libio/iofdopen.c index 843a4fa65c..b36d21d041 100644 --- a/libio/iofdopen.c +++ b/libio/iofdopen.c @@ -59,6 +59,11 @@ _IO_new_fdopen (fd, mode) int i; int use_mmap = 0; + /* Decide whether we modify the offset of the file we attach to and seek to + the end of file. We only do this if the mode is 'a' and if the file + descriptor did not have O_APPEND in its flags already. */ + bool do_seek = false; + switch (*mode) { case 'r': @@ -128,6 +133,7 @@ _IO_new_fdopen (fd, mode) */ if ((posix_mode & O_APPEND) && !(fd_flags & O_APPEND)) { + do_seek = true; #ifdef F_SETFL if (_IO_fcntl (fd, F_SETFL, fd_flags | O_APPEND) == -1) #endif @@ -167,10 +173,11 @@ _IO_new_fdopen (fd, mode) _IO_mask_flags (&new_f->fp.file, read_write, _IO_NO_READS+_IO_NO_WRITES+_IO_IS_APPENDING); - /* For append mode, set the file offset to the end of the file. Don't - update the offset cache though, since the file handle is not active. */ - if ((read_write & (_IO_IS_APPENDING | _IO_NO_READS)) - == (_IO_IS_APPENDING | _IO_NO_READS)) + /* For append mode, set the file offset to the end of the file if we added + O_APPEND to the file descriptor flags. Don't update the offset cache + though, since the file handle is not active. */ + if (do_seek && ((read_write & (_IO_IS_APPENDING | _IO_NO_READS)) + == (_IO_IS_APPENDING | _IO_NO_READS))) { _IO_off64_t new_pos = _IO_SYSSEEK (&new_f->fp.file, 0, _IO_seek_end); if (new_pos == _IO_pos_BAD && errno != ESPIPE) |