ipc_recv_message: store message_type, don’t compare. add distinct EOF retval

[i3/i3] / libi3 / ipc_recv_message.c

diff --git a/libi3/ipc_recv_message.c b/libi3/ipc_recv_message.c
index f5c4a62b69dc7ba8742ce1832b4e22422fcc05a3..8fd438e3455f2bf1456e1f52fdd18d442bd0aefb 100644 (file)
--- a/libi3/ipc_recv_message.c
+++ b/libi3/ipc_recv_message.c
@@ -2,7 +2,7 @@
  * vim:ts=4:sw=4:expandtab
  *
  * i3 - an improved dynamic tiling window manager
- * © 2009-2011 Michael Stapelberg and contributors (see also: LICENSE)
+ * © 2009-2013 Michael Stapelberg and contributors (see also: LICENSE)
  *
  */
 #include <string.h>
@@ -10,6 +10,7 @@
 #include <stdio.h>
 #include <stdint.h>
 #include <unistd.h>
+#include <errno.h>
 
 #include <i3/ipc.h>
 
@@ -20,57 +21,56 @@
  * (reply_length) as well as a pointer to its contents (reply).
  *
  * Returns -1 when read() fails, errno will remain.
- * Returns -2 when the IPC protocol is violated (invalid magic, unexpected
+ * Returns -2 on EOF.
+ * Returns -3 when the IPC protocol is violated (invalid magic, unexpected
  * message type, EOF instead of a message). Additionally, the error will be
  * printed to stderr.
  * Returns 0 on success.
  *
  */
-int ipc_recv_message(int sockfd, uint32_t message_type,
+int ipc_recv_message(int sockfd, uint32_t *message_type,
                      uint32_t *reply_length, uint8_t **reply) {
     /* Read the message header first */
-    uint32_t to_read = strlen(I3_IPC_MAGIC) + sizeof(uint32_t) + sizeof(uint32_t);
+    const uint32_t to_read = strlen(I3_IPC_MAGIC) + sizeof(uint32_t) + sizeof(uint32_t);
     char msg[to_read];
     char *walk = msg;
 
     uint32_t read_bytes = 0;
     while (read_bytes < to_read) {
-        int n = read(sockfd, msg + read_bytes, to_read);
+        int n = read(sockfd, msg + read_bytes, to_read - read_bytes);
         if (n == -1)
             return -1;
         if (n == 0) {
-            fprintf(stderr, "IPC: received EOF instead of reply\n");
+            ELOG("IPC: received EOF instead of reply\n");
             return -2;
         }
 
         read_bytes += n;
-        to_read -= n;
     }
 
     if (memcmp(walk, I3_IPC_MAGIC, strlen(I3_IPC_MAGIC)) != 0) {
-        fprintf(stderr, "IPC: invalid magic in reply\n");
-        return -2;
+        ELOG("IPC: invalid magic in reply\n");
+        return -3;
     }
 
     walk += strlen(I3_IPC_MAGIC);
     *reply_length = *((uint32_t*)walk);
     walk += sizeof(uint32_t);
-    if (*((uint32_t*)walk) != message_type) {
-        fprintf(stderr, "IPC: unexpected reply type (got %d, expected %d)\n", *((uint32_t*)walk), message_type);
-        return -2;
-    }
+    if (message_type != NULL)
+        *message_type = *((uint32_t*)walk);
 
     *reply = smalloc(*reply_length);
 
-    to_read = *reply_length;
     read_bytes = 0;
-    while (read_bytes < to_read) {
-        int n = read(sockfd, *reply + read_bytes, to_read);
-        if (n == -1)
+    int n;
+    while (read_bytes < *reply_length) {
+        if ((n = read(sockfd, *reply + read_bytes, *reply_length - read_bytes)) == -1) {
+            if (errno == EINTR || errno == EAGAIN)
+                continue;
             return -1;
+        }
 
         read_bytes += n;
-        to_read -= n;
     }
 
     return 0;