New API: get-sockdir

Introduce a new read-only API to get a path where to store temporary
sockets: this is different from tmpdir, as we need short paths for
sockets (due to sockaddr_un::sun_path), and it is either
XDG_RUNTIME_DIR if set, or /tmp; adapt guestfs_int_create_socketname
to create sockets in that location.

Furthermore, print sockdir and XDG_RUNTIME_DIR in test-tool for
debugging.

fish/guestfish.pod

@@ -1519,6 +1519,17 @@ about kernel selection, see L<supermin(1)>.
 
 See L</LIBGUESTFS_CACHEDIR>, L</LIBGUESTFS_TMPDIR>.
 
+=item XDG_RUNTIME_DIR
+
+This directory represents a user-specific directory for storing
+non-essential runtime files.
+
+If it is set, then is used to store temporary sockets.  Otherwise,
+F</tmp> is used.
+
+See also L</get-sockdir>,
+L<http://www.freedesktop.org/wiki/Specifications/basedir-spec/>.
+
 =back
 
 =head1 FILES

generator/actions.ml

@@ -3504,6 +3504,22 @@ call it returns a simple true/false boolean result, instead
 of throwing an exception if a feature is not found.  For
 other documentation see C<guestfs_available>." };
 
+  { defaults with
+    name = "get_sockdir"; added = (1, 33, 8);
+    style = RString "sockdir", [], [];
+    blocking = false;
+    shortdesc = "get the temporary directory for sockets";
+    longdesc = "\
+Get the directory used by the handle to store temporary socket files.
+
+This is different from C<guestfs_tmpdir>, as we need shorter paths for
+sockets (due to the limited buffers of filenames for UNIX sockets),
+and C<guestfs_tmpdir> may be too long for them.
+
+The environment variable C<XDG_RUNTIME_DIR> controls the default
+value: If C<XDG_RUNTIME_DIR> is set, then that is the default.
+Else F</tmp> is the default." };
+
 ]
 
 (* daemon_functions are any functions which cause some action

src/guestfs-internal.h

@@ -434,8 +434,10 @@ struct guestfs_h
    * handle, you have to call guestfs_int_lazy_make_tmpdir.
    */
   char *tmpdir;
-  /* Environment variables that affect tmpdir/cachedir locations. */
+  char *sockdir;
+  /* Environment variables that affect tmpdir/cachedir/sockdir locations. */
   char *env_tmpdir;             /* $TMPDIR (NULL if not set) */
+  char *env_runtimedir;         /* $XDG_RUNTIME_DIR (NULL if not set)*/
   char *int_tmpdir;   /* $LIBGUESTFS_TMPDIR or guestfs_set_tmpdir or NULL */
   char *int_cachedir; /* $LIBGUESTFS_CACHEDIR or guestfs_set_cachedir or NULL */
 
@@ -757,8 +759,11 @@ extern void guestfs_int_call_callbacks_array (guestfs_h *g, uint64_t event, cons
 
 /* tmpdirs.c */
 extern int guestfs_int_set_env_tmpdir (guestfs_h *g, const char *tmpdir);
+extern int guestfs_int_set_env_runtimedir (guestfs_h *g, const char *runtimedir);
 extern int guestfs_int_lazy_make_tmpdir (guestfs_h *g);
+extern int guestfs_int_lazy_make_sockdir (guestfs_h *g);
 extern void guestfs_int_remove_tmpdir (guestfs_h *g);
+extern void guestfs_int_remove_sockdir (guestfs_h *g);
 extern void guestfs_int_recursive_remove_dir (guestfs_h *g, const char *dir);
 
 /* whole-file.c */

src/guestfs.pod

@@ -3482,6 +3482,17 @@ about kernel selection, see L<supermin(1)>.
 
 See L</LIBGUESTFS_CACHEDIR>, L</LIBGUESTFS_TMPDIR>.
 
+=item XDG_RUNTIME_DIR
+
+This directory represents a user-specific directory for storing
+non-essential runtime files.
+
+If it is set, then is used to store temporary sockets.  Otherwise,
+F</tmp> is used.
+
+See also L</get-sockdir>,
+L<http://www.freedesktop.org/wiki/Specifications/basedir-spec/>.
+
 =back
 
 =head1 SEE ALSO

src/handle.c

@@ -273,6 +273,10 @@ parse_environment (guestfs_h *g,
       return -1;
   }
 
+  str = do_getenv (data, "XDG_RUNTIME_DIR");
+  if (guestfs_int_set_env_runtimedir (g, str) == -1)
+    return -1;
+
   return 0;
 }
 
@@ -347,8 +351,9 @@ guestfs_close (guestfs_h *g)
   if (g->test_fp != NULL)
     fclose (g->test_fp);
 
-  /* Remove temporary directory. */
+  /* Remove temporary directories. */
   guestfs_int_remove_tmpdir (g);
+  guestfs_int_remove_sockdir (g);
 
   /* Mark the handle as dead and then free up all memory. */
   g->state = NO_HANDLE;
@@ -377,7 +382,9 @@ guestfs_close (guestfs_h *g)
   if (g->pda)
     hash_free (g->pda);
   free (g->tmpdir);
+  free (g->sockdir);
   free (g->env_tmpdir);
+  free (g->env_runtimedir);
   free (g->int_tmpdir);
   free (g->int_cachedir);
   free (g->last_error);

src/launch.c

@@ -425,12 +425,15 @@ int
 guestfs_int_create_socketname (guestfs_h *g, const char *filename,
                                char (*sockpath)[UNIX_PATH_MAX])
 {
-  if (strlen (g->tmpdir) + 1 + strlen (filename) > UNIX_PATH_MAX-1) {
-    error (g, _("socket path too long: %s/%s"), g->tmpdir, filename);
+  if (guestfs_int_lazy_make_sockdir (g) == -1)
+    return -1;
+
+  if (strlen (g->sockdir) + 1 + strlen (filename) > UNIX_PATH_MAX-1) {
+    error (g, _("socket path too long: %s/%s"), g->sockdir, filename);
     return -1;
   }
 
-  snprintf (*sockpath, UNIX_PATH_MAX, "%s/%s", g->tmpdir, filename);
+  snprintf (*sockpath, UNIX_PATH_MAX, "%s/%s", g->sockdir, filename);
 
   return 0;
 }

src/tmpdirs.c

@@ -75,6 +75,12 @@ guestfs_int_set_env_tmpdir (guestfs_h *g, const char *tmpdir)
   return set_abs_path (g, tmpdir, &g->env_tmpdir);
 }
 
+int
+guestfs_int_set_env_runtimedir (guestfs_h *g, const char *runtimedir)
+{
+  return set_abs_path (g, runtimedir, &g->env_runtimedir);
+}
+
 int
 guestfs_impl_set_tmpdir (guestfs_h *g, const char *tmpdir)
 {
@@ -119,6 +125,20 @@ guestfs_impl_get_cachedir (guestfs_h *g)
   return safe_strdup (g, str);
 }
 
+/* Note this actually calculates the sockdir, so it never returns NULL. */
+char *
+guestfs_impl_get_sockdir (guestfs_h *g)
+{
+  const char *str;
+
+  if (g->env_runtimedir)
+    str = g->env_runtimedir;
+  else
+    str = "/tmp";
+
+  return safe_strdup (g, str);
+}
+
 static int
 lazy_make_tmpdir (guestfs_h *g, char *(*getdir) (guestfs_h *g), char **dest)
 {
@@ -145,6 +165,12 @@ guestfs_int_lazy_make_tmpdir (guestfs_h *g)
   return lazy_make_tmpdir (g, guestfs_get_tmpdir, &g->tmpdir);
 }
 
+int
+guestfs_int_lazy_make_sockdir (guestfs_h *g)
+{
+  return lazy_make_tmpdir (g, guestfs_get_sockdir, &g->sockdir);
+}
+
 /* Recursively remove a temporary directory.  If removal fails, just
  * return (it's a temporary directory so it'll eventually be cleaned
  * up by a temp cleaner).  This is done using "rm -rf" because that's
@@ -167,3 +193,10 @@ guestfs_int_remove_tmpdir (guestfs_h *g)
   if (g->tmpdir)
     guestfs_int_recursive_remove_dir (g, g->tmpdir);
 }
+
+void
+guestfs_int_remove_sockdir (guestfs_h *g)
+{
+  if (g->sockdir)
+    guestfs_int_recursive_remove_dir (g, g->sockdir);
+}

test-tool/test-tool.c

@@ -210,6 +210,9 @@ main (int argc, char *argv[])
   p = getenv ("PATH");
   if (p)
     printf ("PATH=%s\n", p);
+  p = getenv ("XDG_RUNTIME_DIR");
+  if (p)
+    printf ("XDG_RUNTIME_DIR=%s\n", p);
 
   /* Print SELinux mode (don't worry if this fails, or if the command
    * doesn't even exist).
@@ -255,6 +258,9 @@ main (int argc, char *argv[])
   printf ("guestfs_get_recovery_proc: %d\n", guestfs_get_recovery_proc (g));
   printf ("guestfs_get_selinux: %d\n", guestfs_get_selinux (g));
   printf ("guestfs_get_smp: %d\n", guestfs_get_smp (g));
+  p = guestfs_get_sockdir (g);
+  printf ("guestfs_get_sockdir: %s\n", p ? : "(null)");
+  free (p);
   p = guestfs_get_tmpdir (g);
   printf ("guestfs_get_tmpdir: %s\n", p ? : "(null)");
   free (p);