[v2,10/17] gdbstub: Allow the %d placeholder in the socket path

Commit Message

Alex Bennée Feb. 7, 2025, 3:31 p.m. UTC

From: Ilya Leoshkevich <[e-mail]>

Just like for QEMU_LOG_FILENAME, replace %d with PID in the GDB socket
path. This allows running multi-process applications with, e.g.,
export QEMU_GDB=/tmp/qemu-%d.sock. Currently this is not possible,
since the first process will cause the subsequent ones to fail due to
not being able to bind() the GDB socket.

Reviewed-by: Richard Henderson <[e-mail]>
Reviewed-by: Warner Losh <[e-mail]>
Signed-off-by: Ilya Leoshkevich <[e-mail]>
Message-Id: <[e-mail]>
Signed-off-by: Alex Bennée <[e-mail]>
---
 gdbstub/user.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

Patch

diff --git a/gdbstub/user.c b/gdbstub/user.c
index c2bdfc3d49..fd29d595f4 100644
--- a/gdbstub/user.c
+++ b/gdbstub/user.c
@@ -317,9 +317,19 @@  static bool gdb_accept_socket(int gdb_fd)
 
 static int gdbserver_open_socket(const char *path)
 {
+    g_autoptr(GString) buf = g_string_new("");
     struct sockaddr_un sockaddr = {};
+    char *pid_placeholder;
     int fd, ret;
 
+    pid_placeholder = strstr(path, "%d");
+    if (pid_placeholder != NULL) {
+        g_string_append_len(buf, path, pid_placeholder - path);
+        g_string_append_printf(buf, "%d", qemu_get_thread_id());
+        g_string_append(buf, pid_placeholder + 2);
+        path = buf->str;
+    }
+
     fd = socket(AF_UNIX, SOCK_STREAM, 0);
     if (fd < 0) {
         perror("create socket");