fix: Work around Big Sur read buffer tracking

As noted by @koekeishiya on yabai#714, it seems a bug was introduced
in Big Sur which causes `read` calls to track buffers incorrectly.
These changes (taken from koekeishiya/yabai@4f8be49) work around this.

Closes #41

makefile

@@ -4,10 +4,10 @@ BUILD_FLAGS    = -std=c99 -Wall -DDEBUG -g -O0 -fvisibility=hidden -mmacosx-vers
 BUILD_PATH     = ./bin
 DOC_PATH       = ./doc
 SMP_PATH       = ./examples
-SPACEBAR_SRC      = ./src/manifest.m
+SPACEBAR_SRC   = ./src/manifest.m
 BINS           = $(BUILD_PATH)/spacebar
 
-.PHONY: all clean install sign archive man
+.PHONY: all clean install archive man
 
 all: clean $(BINS)
 

src/misc/socket.c

@@ -14,6 +14,19 @@ char *socket_read(int sockfd, int *len)
         result = temp;
         memcpy(result+cursor, buffer, bytes_read);
         cursor += bytes_read;
+
+        if (((result+cursor)[-1] == '\0') &&
+            ((result+cursor)[-2] == '\0')) {
+
+            // NOTE(cmacrae): if our message ends with double null-terminator we
+            // have successfully received the entire message. this was added because
+            // on macOS Big Sur we would in a few rare cases read the message AND YET
+            // still enter another call to *read* above that would block, because the
+            // client was finished sending its message and is blocking in a poll loop
+            // waiting for a response.
+
+            break;
+        }
     }
 
     if (result && bytes_read != -1) {

src/spacebar.c

@@ -54,7 +54,7 @@ static int client_send_message(int argc, char **argv)
         error("spacebar-msg: failed to connect to socket..\n");
     }
 
-    int message_length = argc - 1;
+    int message_length = argc;
     int argl[argc];
 
     for (int i = 1; i < argc; ++i) {
@@ -70,6 +70,7 @@ static int client_send_message(int argc, char **argv)
         temp += argl[i];
         *temp++ = '\0';
     }
+    *temp++ = '\0';
 
     if (!socket_write_bytes(sockfd, message, message_length)) {
         error("spacebar-msg: failed to send data..\n");