[RFC][PATCH] Read/print contents of fifo.

[Sukadev Bhattiprolu]

To test that checkpoint/restart of pipes is working, read
one byte at a time from the pipe and write to stdout.

After checkpoint, both the checkpointed application and the
restarted application should continue reading from the checkpoint.

The '-e' option to the program, tests with an empty pipe.

Signed-off-by: Sukadev Bhattiprolu <sukadev at us.ibm.com>
---
 tests/pipe.c |   32 ++++++++++++++++++++++++++++----
 1 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/tests/pipe.c b/tests/pipe.c
index cc3cdfd..0812cb3 100644
--- a/tests/pipe.c
+++ b/tests/pipe.c
@@ -3,25 +3,49 @@
 #include <unistd.h>
 #include <stdlib.h>
 #include <string.h>
+#include <errno.h>
+#include <sys/fcntl.h>
 
-int main()
+int main(int argc, char *argv[])
 {
 	int i = 0;
+	int rc;
 	int fds[2];
+	int c;
+	int empty;
 	char *buf = "abcdefghijklmnopqrstuvwxyz";
 
+	/*
+	 * -e: test with an empty pipe
+	 */
+	empty = 0;
+	if (argc > 1 && strcmp(argv[1], "-e") == 0)
+		empty = 1;
+
 	if (pipe(fds) < 0) {
 		perror("pipe()");
 		exit(1);
 	}
 
-	write(fds[1], buf, strlen(buf));
+	if (!empty)
+		write(fds[1], buf, strlen(buf));
 
+	if (fcntl(fds[0], F_SETFL, O_NONBLOCK) < 0) {
+		perror("fcntl()");
+		exit(1);
+	}
 	printf("Running as %d\n", getpid());
 	while (i<100) {
 		sleep(1);
-		if (i%5 == 0)
-			printf("i is %d (pid %d)\n", i, getpid());
+		if (i%5 == 0) {
+			c = errno = 0;
+			rc = read(fds[0], &c, 1);
+			if (rc != 1) {
+				perror("read() failed");
+			}
+			printf("i is %d (pid %d), c is %c\n", i, getpid(), c);
+
+		}
 		i++;
 	}
 }
-- 
1.5.2.5