From: Sebastian Harl <sh@tokkee.org>
Date: Thu, 19 Dec 2013 20:41:38 +0000 (+0100)
Subject: proto utils: Added sdb_proto_select().
X-Git-Tag: sysdb-0.1.0~306
X-Git-Url: https://git.tokkee.org/?p=sysdb.git;a=commitdiff_plain;h=0e9ae0a6da794b4c6f514c123d2a0ab9527ad592

proto utils: Added sdb_proto_select().

This is a simple wrapper around select(2) to be used in cases where we only
care about a single file-descriptor being ready for a particular operation.
---

diff --git a/src/include/utils/proto.h b/src/include/utils/proto.h
index 372e34d..f3f1a87 100644
--- a/src/include/utils/proto.h
+++ b/src/include/utils/proto.h
@@ -37,6 +37,25 @@
 extern "C" {
 #endif
 
+enum {
+	SDB_PROTO_SELECTIN = 0,
+	SDB_PROTO_SELECTOUT,
+	SDB_PROTO_SELECTERR,
+};
+
+/*
+ * sdb_proto_select:
+ * Wait for a file-descriptor to become ready for I/O operations of the
+ * specified type. This is a simple wrapper around the select() system call.
+ * The type argument may be any of the SDB_PROTO_SELECT* constants.
+ *
+ * Returns:
+ *  - the number of file descriptors ready for I/O
+ *  - a negative value on error
+ */
+int
+sdb_proto_select(int fd, int type);
+
 ssize_t
 sdb_proto_send(int fd, size_t msg_len, const char *msg);
 
diff --git a/src/utils/proto.c b/src/utils/proto.c
index 29783ef..404d2a3 100644
--- a/src/utils/proto.c
+++ b/src/utils/proto.c
@@ -36,10 +36,57 @@
 #include <string.h>
 #include <unistd.h>
 
+#include <sys/select.h>
+
 /*
  * public API
  */
 
+int
+sdb_proto_select(int fd, int type)
+{
+	fd_set fds;
+	fd_set *readfds = NULL;
+	fd_set *writefds = NULL;
+	fd_set *exceptfds = NULL;
+
+	if (fd < 0) {
+		errno = EBADF;
+		return -1;
+	}
+
+	FD_ZERO(&fds);
+
+	switch (type) {
+		case SDB_PROTO_SELECTIN:
+			readfds = &fds;
+			break;
+		case SDB_PROTO_SELECTOUT:
+			writefds = &fds;
+			break;
+		case SDB_PROTO_SELECTERR:
+			exceptfds = &fds;
+			break;
+		default:
+			errno = EINVAL;
+			return -1;
+	}
+
+	FD_SET(fd, &fds);
+
+	while (42) {
+		int n;
+		errno = 0;
+		n = select(fd + 1, readfds, writefds, exceptfds, NULL);
+
+		if ((n < 0) && (errno != EINTR))
+			return (ssize_t)n;
+		if (n > 0)
+			break;
+	}
+	return 0;
+} /* sdb_proto_select */
+
 ssize_t
 sdb_proto_send(int fd, size_t msg_len, const char *msg)
 {
@@ -56,7 +103,8 @@ sdb_proto_send(int fd, size_t msg_len, const char *msg)
 	while (len > 0) {
 		ssize_t status;
 
-		/* XXX: use select() */
+		if (sdb_proto_select(fd, SDB_PROTO_SELECTOUT))
+			return -1;
 
 		errno = 0;
 		status = write(fd, buf, len);