[v3] trace-cmd: Move trace_msg cache file to memfd

Commit Message

Joel Fernandes April 5, 2022, 7:22 p.m. UTC

This is cleaner and also fixes issues in Android where /tmp does not
exist.

With this, host-guest tracing works on Android VM running on ChromeOS
Linux.

Signed-off-by: Joel Fernandes <[e-mail]>
---
 lib/trace-cmd/include/private/trace-cmd-private.h | 2 --
 lib/trace-cmd/trace-msg.c                         | 5 ++---
 2 files changed, 2 insertions(+), 5 deletions(-)

Patch

diff --git a/lib/trace-cmd/include/private/trace-cmd-private.h b/lib/trace-cmd/include/private/trace-cmd-private.h
index 6934376..3aee139 100644
--- a/lib/trace-cmd/include/private/trace-cmd-private.h
+++ b/lib/trace-cmd/include/private/trace-cmd-private.h
@@ -377,7 +377,6 @@  enum tracecmd_msg_flags {
 };
 
 /* for both client and server */
-#define MSG_CACHE_FILE "/tmp/trace_msg_cacheXXXXXX"
 struct tracecmd_msg_handle {
 	int			fd;
 	short			cpu_count;
@@ -386,7 +385,6 @@  struct tracecmd_msg_handle {
 	bool			done;
 	bool			cache;
 	int			cfd;
-	char			cfile[sizeof(MSG_CACHE_FILE)];
 };
 
 struct tracecmd_tsync_protos {
diff --git a/lib/trace-cmd/trace-msg.c b/lib/trace-cmd/trace-msg.c
index 03b853e..bb559c8 100644
--- a/lib/trace-cmd/trace-msg.c
+++ b/lib/trace-cmd/trace-msg.c
@@ -19,6 +19,7 @@ 
 #include <string.h>
 #include <unistd.h>
 #include <arpa/inet.h>
+#include <sys/mman.h>
 #include <sys/types.h>
 #include <linux/types.h>
 
@@ -593,11 +594,9 @@  tracecmd_msg_handle_alloc(int fd, unsigned long flags)
 int tracecmd_msg_handle_cache(struct tracecmd_msg_handle *msg_handle)
 {
 	if (msg_handle->cfd < 0) {
-		strcpy(msg_handle->cfile, MSG_CACHE_FILE);
-		msg_handle->cfd = mkstemp(msg_handle->cfile);
+		msg_handle->cfd = memfd_create("trace_msg_cache", 0);
 		if (msg_handle->cfd < 0)
 			return -1;
-		unlink(msg_handle->cfile);
 	}
 	msg_handle->cache = true;
 	return 0;