From ca4678354c4a7c21bfd184e604ad7a3c8224e10c Mon Sep 17 00:00:00 2001
From: Alexander Irion <alexander_irion@mentor.com>
Date: Mon, 7 Mar 2022 15:49:49 +0100
Subject: [PATCH] connection: Make wl_closure_print output atomic

When multiple threads are used, output from different threads was intermixed in one line. That what breaking parsing of the log messages. Now, intermixing is prevented by using a memstream.

Signed-off-by: Alexander Irion <alexander_irion@mentor.com>
---
 src/connection.c | 44 ++++++++++++++++++++++++++++----------------
 1 file changed, 28 insertions(+), 16 deletions(-)

diff --git a/src/connection.c b/src/connection.c
index 8c51a24e..a2d1b2f2 100644
--- a/src/connection.c
+++ b/src/connection.c
@@ -1272,11 +1272,18 @@ wl_closure_print(struct wl_closure *closure, struct wl_object *target,
 	struct timespec tp;
 	unsigned int time;
 	uint32_t nval;
+	FILE *f;
+	char *buffer;
+	size_t buffer_length;
+
+	f = open_memstream(&buffer, &buffer_length);
+	if (f == NULL)
+		return;
 
 	clock_gettime(CLOCK_REALTIME, &tp);
 	time = (tp.tv_sec * 1000000L) + (tp.tv_nsec / 1000);
 
-	fprintf(stderr, "[%7u.%03u] %s%s%s@%u.%s(",
+	fprintf(f, "[%7u.%03u] %s%s%s@%u.%s(",
 		time / 1000, time % 1000,
 		discarded ? "discarded " : "",
 		send ? " -> " : "",
@@ -1286,41 +1293,41 @@ wl_closure_print(struct wl_closure *closure, struct wl_object *target,
 	for (i = 0; i < closure->count; i++) {
 		signature = get_next_argument(signature, &arg);
 		if (i > 0)
-			fprintf(stderr, ", ");
+			fprintf(f, ", ");
 
 		switch (arg.type) {
 		case 'u':
-			fprintf(stderr, "%u", closure->args[i].u);
+			fprintf(f, "%u", closure->args[i].u);
 			break;
 		case 'i':
-			fprintf(stderr, "%d", closure->args[i].i);
+			fprintf(f, "%d", closure->args[i].i);
 			break;
 		case 'f':
 			/* The magic number 390625 is 1e8 / 256 */
 			if (closure->args[i].f >= 0) {
-				fprintf(stderr, "%d.%08d",
+				fprintf(f, "%d.%08d",
 					closure->args[i].f / 256,
 					390625 * (closure->args[i].f % 256));
 			} else {
 
-				fprintf(stderr, "-%d.%08d",
+				fprintf(f, "-%d.%08d",
 					closure->args[i].f / -256,
 					-390625 * (closure->args[i].f % 256));
 			}
 			break;
 		case 's':
 			if (closure->args[i].s)
-				fprintf(stderr, "\"%s\"", closure->args[i].s);
+				fprintf(f, "\"%s\"", closure->args[i].s);
 			else
-				fprintf(stderr, "nil");
+				fprintf(f, "nil");
 			break;
 		case 'o':
 			if (closure->args[i].o)
-				fprintf(stderr, "%s@%u",
+				fprintf(f, "%s@%u",
 					closure->args[i].o->interface->name,
 					closure->args[i].o->id);
 			else
-				fprintf(stderr, "nil");
+				fprintf(f, "nil");
 			break;
 		case 'n':
 			if (n_parse)
@@ -1328,25 +1335,30 @@ wl_closure_print(struct wl_closure *closure, struct wl_object *target,
 			else
 				nval = closure->args[i].n;
 
-			fprintf(stderr, "new id %s@",
+			fprintf(f, "new id %s@",
 				(closure->message->types[i]) ?
 				 closure->message->types[i]->name :
 				  "[unknown]");
 			if (nval != 0)
-				fprintf(stderr, "%u", nval);
+				fprintf(f, "%u", nval);
 			else
-				fprintf(stderr, "nil");
+				fprintf(f, "nil");
 			break;
 		case 'a':
-			fprintf(stderr, "array[%zu]", closure->args[i].a->size);
+			fprintf(f, "array[%zu]", closure->args[i].a->size);
 			break;
 		case 'h':
-			fprintf(stderr, "fd %d", closure->args[i].h);
+			fprintf(f, "fd %d", closure->args[i].h);
 			break;
 		}
 	}
 
-	fprintf(stderr, ")\n");
+	fprintf(f, ")\n");
+
+	if (fclose(f) == 0) {
+		fprintf(stderr, "%s", buffer);
+		free(buffer);
+	}
 }
 
 static int