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in fdopen, avoid setting O_APPEND flag if it's already set

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this saves a syscall in the case where the underlying open already
took place with O_APPEND, which is common because fopen with append
modes sets O_APPEND at the time of open before passing the file
descriptor to __fdopen.
This commit is contained in:
Rich Felker 2014-02-07 01:16:53 -05:00
commit 758ab35a16
1 changed files with 2 additions and 1 deletions
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3
src/stdio/__fdopen.c
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@ -32,7 +32,8 @@ FILE *__fdopen(int fd, const char *mode)
/* Set append mode on fd if opened for append */
if (*mode == 'a') {
int flags = __syscall(SYS_fcntl, fd, F_GETFL);
__syscall(SYS_fcntl, fd, F_SETFL, flags | O_APPEND);
if (!(flags & O_APPEND))
__syscall(SYS_fcntl, fd, F_SETFL, flags | O_APPEND);
f->flags |= F_APP;
}