[stgt] [PATCH] fixes in call_program (closing pipe fds, waitpid interrupted by a signal)

[Alexander Nezhinsky]

Some fixes in call_program():
1) if fork() fails, previously open pipe file descriptors should be closed.
2) the redirect script is invoked from a fork'ed process so tgt has to wait
for its child. Currently this is done synchronously using waitpid().
Sometimes the system call is interrupted by a signal (most probably by
a SIGCHLD signal from the very process that is being waited upon).
To overcome this waitpid() is called repeatedly while the error code
is "Interrupted by a signal".

Signed-off-by: Alexander Nezhinsky <alexandern at voltaire.com>
---
 usr/tgtd.c |   20 +++++++++++++++-----
 1 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/usr/tgtd.c b/usr/tgtd.c
index c3abca8..619ecb0 100644
--- a/usr/tgtd.c
+++ b/usr/tgtd.c
@@ -285,14 +285,20 @@ int call_program(const char *cmd, void (*callback)(void *data, int result),
 	argv[i] =  NULL;
 
 	ret = pipe(fds);
-	if (ret < 0)
+	if (ret < 0) {
+		eprintf("pipe create failed for %s, %m\n", cmd);
 		return ret;
+	}
 
-	eprintf("%d %d\n", fds[0], fds[1]);
+	dprintf("%s, pipe: %d %d\n", cmd, fds[0], fds[1]);
 
 	pid = fork();
-	if (pid < 0)
+	if (pid < 0) {
+		eprintf("fork failed for: %s, %m\n", cmd);
+		close(fds[0]);
+		close(fds[1]);
 		return pid;
+	}
 
 	if (!pid) {
 		close(1);
@@ -302,10 +308,14 @@ int call_program(const char *cmd, void (*callback)(void *data, int result),
 		exit(-1);
 	} else {
 		close(fds[1]);
-		waitpid(pid, &i, 0);
+		do {
+			ret = waitpid(pid, &i, 0);
+			if (ret < 0 && errno != EINTR)
+				eprintf("waitpid failed for: %s, %m\n", cmd);
+		} while (ret < 0 && errno == EINTR);
 		ret = read(fds[0], output, op_len);
 		if (ret < 0)
-			eprintf("failed to get the output from <%s>.", cmd);
+			eprintf("failed to get the output from: %s\n", cmd);
 
 		if (callback)
 			callback(data, WEXITSTATUS(i));
--
1.6.5.5
--
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