lib: Remove guestfs_int_qemu_version

This function is now only used in one place, to print the version of
qemu in direct mode, when debugging is enabled.

Remove this function and replace with a direct command invocation
('qemu --version').  We only need to run this command when debugging
is enabled, and we copy all of the output to the debug channel.

I have made the assumption here that qemu -version does not try to
create a display device.  (The previous invocation of qemu -help
actually ran 'qemu -display none -help' indicating that this was not
always the case.)

This is actually an improvement on before, since now we get to see the
full output of 'qemu --version'.  The new output looks like:

  libguestfs: begin testing qemu features
  libguestfs: command: run: /usr/bin/qemu-kvm
  libguestfs: command: run: \ -version
  libguestfs: qemu: QEMU emulator version 10.1.0 (qemu-10.1.0-8.fc44)
  libguestfs: qemu: Copyright (c) 2003-2025 Fabrice Bellard and the QEMU Project developers

lib/guestfs-internal.h

@@ -793,7 +793,6 @@ void guestfs_int_init_libvirt_backend (void) __attribute__((constructor));
 /* qemu.c */
 struct qemu_data;
 extern struct qemu_data *guestfs_int_test_qemu (guestfs_h *g);
-extern struct version guestfs_int_qemu_version (guestfs_h *g, struct qemu_data *);
 extern int guestfs_int_qemu_supports_device (guestfs_h *g, const struct qemu_data *, const char *device_name);
 extern bool guestfs_int_platform_has_kvm (guestfs_h *g, const struct qemu_data *data);
 extern char *guestfs_int_drive_source_qemu_param (guestfs_h *g, const struct drive_source *src);

lib/launch-direct.c

@@ -61,6 +61,13 @@ struct backend_direct_data {
   char guestfsd_sock[UNIX_PATH_MAX]; /* Path to daemon socket. */
 };
 
+/* Helper that sends all output from a command to debug. */
+static void
+debug_lines (guestfs_h *g, void *retv, const char *buf, size_t len)
+{
+  debug (g, "qemu: %s", buf);
+}
+
 static char *
 create_cow_overlay_direct (guestfs_h *g, void *datav, struct drive *drv)
 {
@@ -479,16 +486,21 @@ launch_direct (guestfs_h *g, void *datav, const char *arg)
 
   debug (g, "begin testing qemu features");
 
-  /* Get qemu help text and version. */
+  /* If debugging, print the qemu version. */
-  if (data->qemu_data == NULL) {
+  if (g->verbose) {
-    struct version qemu_version;
+    CLEANUP_CMD_CLOSE struct command *cmd = guestfs_int_new_command (g);
 
+    guestfs_int_cmd_add_arg (cmd, g->hv);
+    guestfs_int_cmd_add_arg (cmd, "-version");
+    guestfs_int_cmd_set_stdout_callback (cmd, debug_lines, NULL, 0);
+    guestfs_int_cmd_run (cmd);
+  }
+
+  /* Get qemu help text. */
+  if (data->qemu_data == NULL) {
     data->qemu_data = guestfs_int_test_qemu (g);
     if (data->qemu_data == NULL)
       goto cleanup0;
-    qemu_version = guestfs_int_qemu_version (g, data->qemu_data);
-    debug (g, "qemu version: %d.%d",
-           qemu_version.v_major, qemu_version.v_minor);
   }
 
   /* Work out if KVM is supported or if the user wants to force TCG. */

lib/qemu.c

@@ -65,7 +65,6 @@ struct qemu_data {
   char *query_kvm;              /* Output of QMP query-kvm. */
 
   /* The following fields are derived from the fields above. */
-  struct version qemu_version;  /* Parsed qemu version number. */
   bool has_kvm;                 /* If KVM is available. */
 };
 
@@ -81,7 +80,6 @@ static int read_cache_query_kvm (guestfs_h *g, struct qemu_data *data, const cha
 static int write_cache_query_kvm (guestfs_h *g, const struct qemu_data *data, const char *filename);
 static int read_cache_qemu_stat (guestfs_h *g, struct qemu_data *data, const char *filename);
 static int write_cache_qemu_stat (guestfs_h *g, const struct qemu_data *data, const char *filename);
-static void parse_qemu_version (guestfs_h *g, const char *, struct version *qemu_version);
 static void parse_has_kvm (guestfs_h *g, const char *, bool *);
 static void read_all (guestfs_h *g, void *retv, const char *buf, size_t len);
 static int generic_read_cache (guestfs_h *g, const char *filename, char **strp);
@@ -218,7 +216,6 @@ guestfs_int_test_qemu (guestfs_h *g)
 
  out:
   /* Derived fields. */
-  parse_qemu_version (g, data->qemu_help, &data->qemu_version);
   parse_has_kvm (g, data->query_kvm, &data->has_kvm);
 
   return data;
@@ -392,23 +389,6 @@ write_cache_qemu_stat (guestfs_h *g, const struct qemu_data *data,
   return 0;
 }
 
-/**
- * Parse the first line of C<qemu_help> into the major and minor
- * version of qemu, but don't fail if parsing is not possible.
- */
-static void
-parse_qemu_version (guestfs_h *g, const char *qemu_help,
-                    struct version *qemu_version)
-{
-  version_init_null (qemu_version);
-
-  if (guestfs_int_version_from_x_y (g, qemu_version, qemu_help) < 1) {
-    debug (g, "%s: failed to parse qemu version string from the first line of the output of '%s -help'.  When reporting this bug please include the -help output.",
-           __func__, g->hv);
-    return;
-  }
-}
-
 /**
  * Parse the json output from QMP query-kvm to find out if KVM is
  * enabled on this machine.  Don't fail if parsing is not possible,
@@ -579,15 +559,6 @@ read_all (guestfs_h *g, void *retv, const char *buf, size_t len)
   *ret = safe_strndup (g, buf, len);
 }
 
-/**
- * Return the parsed version of qemu.
- */
-struct version
-guestfs_int_qemu_version (guestfs_h *g, struct qemu_data *data)
-{
-  return data->qemu_version;
-}
-
 /**
  * Test if device is supported by qemu (currently just greps the
  * C<qemu -device ?> output).