From: Rich Felker <dalias@aerifal.cx>
Date: Fri, 7 Feb 2014 06:16:53 +0000 (-0500)
Subject: in fdopen, avoid setting O_APPEND flag if it's already set
X-Git-Tag: v1.0.0~72
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=758ab35a167ac17a4e3102cee5d16b75053842a7;p=oweals%2Fmusl.git

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

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.
---

diff --git a/src/stdio/__fdopen.c b/src/stdio/__fdopen.c
index a2ca62b1..a6ae73a2 100644
--- a/src/stdio/__fdopen.c
+++ b/src/stdio/__fdopen.c
@@ -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;
 	}