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authorAdhemerval Zanella <adhemerval.zanella@linaro.org>2016-09-16 17:44:50 -0300
committerAdhemerval Zanella <adhemerval.zanella@linaro.com>2016-09-28 14:07:35 -0700
commite83be730910c341f2f02ccc207b0586bb04fc21a (patch)
tree6f8ff0de28073a7706be43359fa45fa50ea1b3f3 /sysdeps/unix
parent4b4d4056bb154603f36c6f8845757c1012758158 (diff)
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posix: Fix open file action for posix_spawn on Linux
On posix_spawn open file action (issued by posix_spawn_file_actions_addopen)
POSIX states that if fildes was already an open file descriptor, it shall be
closed before the new file is openedi [1].  This avoid pontential issues when
posix_spawn plus addopen action is called with the process already at maximum
number of file descriptor opened and also for multiple actions on single-open
special paths (like /dev/watchdog).

This fixes its behavior on Linux posix_spawn implementation and also adds
a tests to check for its behavior.

Checked on x86_64.

	* posix/Makefile (tests): Add tst-spawn3.
	* posix/tst-spawn3.c: New file.
	* sysdeps/unix/sysv/linux/spawni.c (__spawni_child): Close file descriptor
	if it is already opened for open action.

[1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_spawn_file_actions_addclose.html
Diffstat (limited to 'sysdeps/unix')
-rw-r--r--sysdeps/unix/sysv/linux/spawni.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/spawni.c b/sysdeps/unix/sysv/linux/spawni.c
index 679534b79d..fda8593287 100644
--- a/sysdeps/unix/sysv/linux/spawni.c
+++ b/sysdeps/unix/sysv/linux/spawni.c
@@ -219,6 +219,14 @@ __spawni_child (void *arguments)
 
 	    case spawn_do_open:
 	      {
+		/* POSIX states that if fildes was already an open file descriptor,
+		   it shall be closed before the new file is opened.  This avoid
+		   pontential issues when posix_spawn plus addopen action is called
+		   with the process already at maximum number of file descriptor
+		   opened and also for multiple actions on single-open special
+		   paths (like /dev/watchdog).  */
+		close_not_cancel (action->action.open_action.fd);
+
 		ret = open_not_cancel (action->action.open_action.path,
 				       action->action.
 				       open_action.oflag | O_LARGEFILE,