Add a function to test if a fd has data to be read.

1 files changed, 20 insertions, 0 deletions

diff --git a/common.c b/common.c
index 32df8844..7eeb1d9d 100644
--- a/common.c
+++ b/common.c
@@ -33,6 +33,7 @@
 #ifdef BSD
 #  include <paths.h>
 #endif
+#include <poll.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -151,6 +152,25 @@ close_fds(void)
 }
 
 int
+fd_hasdata(int fd)
+{
+	struct pollfd fds;
+	int retval;
+
+	if (fd == -1)
+		return -1;
+	fds.fd = fd;
+	fds.events = POLLIN;
+	fds.revents = 0;
+	retval = poll(&fds, 1, 0);
+	if (retval == -1)
+		return -1;
+	if (retval > 0 && fds.revents & POLLIN)
+		return retval;
+	return 0;
+}
+
+int
 close_on_exec(int fd)
 {
 	int flags;