lib: Add guestfs___remove_tmpdir helper function.

This function does 'rm -rf <dir>' for temporary directories, safely
working if '<dir>' contains shell meta-characters.

Replace existing code for removing directories with this.

src/appliance.c

@@ -534,7 +534,7 @@ build_supermin_appliance (guestfs_h *g,
     return -1;
   }
 
-  rmdir (tmpcd);
+  guestfs___remove_tmpdir (tmpcd);
 
   /* Now finish off by linking to the cached appliance and returning it. */
   if (hard_link_to_cached_appliance (g, cachedir,

src/filearch.c

@@ -213,12 +213,7 @@ cpio_arch (guestfs_h *g, const char *file, const char *path)
   error (g, "file_architecture: could not determine architecture of cpio archive");
 
  out:
-  /* Free up the temporary directory.  Note the directory name cannot
-   * contain shell meta-characters because of the way it was
-   * constructed above.
-   */
-  snprintf (cmd, cmd_len, "rm -rf %s", dir);
-  ignore_value (system (cmd));
+  guestfs___remove_tmpdir (dir);
 
   return ret;
 #undef dir_len

src/guestfs-internal.h

@@ -374,6 +374,7 @@ extern void guestfs___debug (guestfs_h *g, const char *fs, ...)
 extern void guestfs___trace (guestfs_h *g, const char *fs, ...)
   __attribute__((format (printf,2,3)));
 extern const char *guestfs___persistent_tmpdir (void);
+extern void guestfs___remove_tmpdir (const char *dir);
 extern void guestfs___print_timestamped_message (guestfs_h *g, const char *fs, ...);
 extern void guestfs___free_inspect_info (guestfs_h *g);
 extern void guestfs___free_drives (struct drive **drives);

src/guestfs.c

@@ -72,7 +72,6 @@
 #include "guestfs_protocol.h"
 
 static void default_error_cb (guestfs_h *g, void *data, const char *msg);
-static void remove_tmpdir (guestfs_h *g);
 static void close_handles (void);
 
 gl_lock_define_initialized (static, handles_lock);
@@ -224,7 +223,8 @@ guestfs_close (guestfs_h *g)
   if (g->recoverypid > 0) waitpid (g->recoverypid, NULL, 0);
 
   /* Remove whole temporary directory. */
-  remove_tmpdir (g);
+  guestfs___remove_tmpdir (g->tmpdir);
+  free (g->tmpdir);
 
   if (g->cmdline) {
     size_t i;
@@ -260,43 +260,6 @@ guestfs_close (guestfs_h *g)
   free (g);
 }
 
-/* g->tmpdir can contain any files (but not subdirectories).  Remove
- * those and the directory itself.  Note that errors in this function
- * aren't really that important: if we end up not deleting temporary
- * files it's only annoying.
- */
-static void
-remove_tmpdir (guestfs_h *g)
-{
-  DIR *dir;
-  struct dirent *d;
-
-  if (!g->tmpdir)
-    return;
-
-  dir = opendir (g->tmpdir);
-  if (dir == NULL) {
-    perror (g->tmpdir);
-    return;
-  }
-
-  while ((d = readdir (dir)) != NULL) {
-    if (STRNEQ (d->d_name, ".") && STRNEQ (d->d_name, "..")) {
-      if (unlinkat (dirfd (dir), d->d_name, 0) == -1)
-        perror (d->d_name);
-    }
-  }
-
-  if (closedir (dir) == -1)
-    perror (g->tmpdir);
-
-  if (rmdir (g->tmpdir) == -1)
-    perror (g->tmpdir);
-
-  free (g->tmpdir);
-  g->tmpdir = NULL;
-}
-
 /* Close all open handles (called from atexit(3)). */
 static void
 close_handles (void)

src/launch.c

@@ -32,6 +32,8 @@
 #include <time.h>
 #include <sys/stat.h>
 #include <sys/select.h>
+#include <sys/types.h>
+#include <sys/wait.h>
 #include <dirent.h>
 #include <signal.h>
 #include <assert.h>
@@ -1092,6 +1094,34 @@ guestfs___persistent_tmpdir (void)
   return tmpdir;
 }
 
+/* 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
+ * simpler and safer, but we have to exec to ensure that paths don't
+ * need to be quoted.
+ */
+void
+guestfs___remove_tmpdir (const char *dir)
+{
+  pid_t pid = fork ();
+
+  if (pid == -1) {
+    perror ("remove tmpdir: fork");
+    return;
+  }
+  if (pid == 0) {
+    execlp ("rm", "rm", "-rf", dir, NULL);
+    perror ("remove tmpdir: exec: rm");
+    _exit (EXIT_FAILURE);
+  }
+
+  /* Parent. */
+  if (waitpid (pid, NULL, 0) == -1) {
+    perror ("remove tmpdir: waitpid");
+    return;
+  }
+}
+
 /* Compute Y - X and return the result in milliseconds.
  * Approximately the same as this code:
  * http://www.mpp.mpg.de/~huber/util/timevaldiff.c