[pacman-dev] [PATCH] libalpm: handle syscall interruption correctly

[Dan McGee]

It is possible to throw EINTR from a system call such as open(), close(), or
waitpid() if custom signal handlers are set up and they are not initialized
with the SA_RESTART flag. This was noticed by Andreas Radke when ^C (SIGINT)
was given during the call to waitpid(), causing it to throw the EINTR error
and we could not accommodate it.

Simply wrap these calls in a simple loop that allows us to retry the call if
interrupted.

Signed-off-by: Dan McGee <dan at archlinux.org>
---
This patch should probably be considered for maint. It seems to work correctly
in the normal case, although I have not reproduced it by trying to issue a
SIGINT during the system call itself, which could be tricky.

As a side note, our signal handlers are not async-safe at all and should
probably be looked at sometime.

-Dan

 lib/libalpm/trans.c |    5 ++---
 lib/libalpm/util.c  |    3 ++-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/libalpm/trans.c b/lib/libalpm/trans.c
index d233645..73ae822 100644
--- a/lib/libalpm/trans.c
+++ b/lib/libalpm/trans.c
@@ -30,7 +30,6 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/statvfs.h>
-#include <unistd.h>
 #include <errno.h>
 
 /* libalpm */
@@ -205,7 +204,7 @@ int SYMEXPORT alpm_trans_release()
 
 	/* unlock db */
 	if(handle->lckfd != -1) {
-		close(handle->lckfd);
+		while(close(handle->lckfd) == -1 && errno == EINTR);
 		handle->lckfd = -1;
 	}
 	if(_alpm_lckrm()) {
@@ -567,7 +566,7 @@ int _alpm_runscriptlet(const char *root, const char *installfn,
 		/* this code runs for the parent only (wait on the child) */
 		pid_t retpid;
 		int status;
-		retpid = waitpid(pid, &status, 0);
+		while((retpid = waitpid(pid, &status, 0)) == -1 && errno == EINTR);
 		if(retpid == -1) {
 			_alpm_log(PM_LOG_ERROR, _("call to waitpid failed (%s)\n"),
 			          strerror(errno));
diff --git a/lib/libalpm/util.c b/lib/libalpm/util.c
index b26c970..da3463b 100644
--- a/lib/libalpm/util.c
+++ b/lib/libalpm/util.c
@@ -254,7 +254,8 @@ int _alpm_lckmk()
 	_alpm_makepath(dir);
 	FREE(dir);
 
-	fd = open(file, O_WRONLY | O_CREAT | O_EXCL, 0000);
+	while((fd = open(file, O_WRONLY | O_CREAT | O_EXCL, 0000)) == -1
+			&& errno == EINTR);
 	return(fd > 0 ? fd : -1);
 }
 
-- 
1.6.0.1