New commands: 'ln', 'ln-f', 'ln-s', 'ln-sf' and 'readlink'.

These commands can be used to make hard and symbolic links.  The
readlink command is used to read existing symbolic links.

1 files changed, 137 insertions, 0 deletions

diff --git a/daemon/link.c b/daemon/link.c
new file mode 100644
index 00000000..57e35384
--- /dev/null
+++ b/daemon/link.c
@@ -0,0 +1,137 @@
+/* libguestfs - the guestfsd daemon
+ * Copyright (C) 2009 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <limits.h>
+
+#include "daemon.h"
+#include "actions.h"
+
+char *
+do_readlink (char *path)
+{
+  ssize_t r;
+  char *ret;
+  char link[PATH_MAX];
+
+  NEED_ROOT (NULL);
+  ABS_PATH (path, NULL);
+
+  CHROOT_IN;
+  r = readlink (path, link, sizeof link);
+  CHROOT_OUT;
+  if (r == -1) {
+    reply_with_perror ("readlink");
+    return NULL;
+  }
+
+  ret = strndup (link, r);
+  if (ret == NULL) {
+    reply_with_perror ("strndup");
+    return NULL;
+  }
+
+  return ret;			/* caller frees */
+}
+
+static int
+_link (const char *flag, int symbolic, const char *target, const char *linkname)
+{
+  int r;
+  char *err;
+  char *buf_linkname;
+  char *buf_target;
+
+  NEED_ROOT (-1);
+  ABS_PATH (linkname, -1);
+  /* but target does not need to be absolute */
+
+  /* Prefix linkname with sysroot. */
+  buf_linkname = sysroot_path (linkname);
+  if (!buf_linkname) {
+    reply_with_perror ("malloc");
+    return -1;
+  }
+
+  /* Only prefix target if it's _not_ a symbolic link, and if
+   * the target is absolute.  Note that the resulting link will
+   * always be "broken" from the p.o.v. of the appliance, ie:
+   * /a -> /b but the path as seen here is /sysroot/b
+   */
+  buf_target = NULL;
+  if (!symbolic && target[0] == '/') {
+    buf_target = sysroot_path (target);
+    if (!buf_target) {
+      reply_with_perror ("malloc");
+      free (buf_linkname);
+      return -1;
+    }
+  }
+
+  if (flag)
+    r = command (NULL, &err,
+		 "ln", flag, "--", /* target could begin with '-' */
+		 buf_target ? : target, buf_linkname, NULL);
+  else
+    r = command (NULL, &err,
+		 "ln", "--",
+		 buf_target ? : target, buf_linkname, NULL);
+  free (buf_linkname);
+  free (buf_target);
+  if (r == -1) {
+    reply_with_error ("ln%s%s: %s: %s: %s",
+		      flag ? " " : "",
+		      flag ? : "",
+		      target, linkname, err);
+    free (err);
+    return -1;
+  }
+
+  free (err);
+
+  return 0;
+}
+
+int
+do_ln (char *target, char *linkname)
+{
+  return _link (NULL, 0, target, linkname);
+}
+
+int
+do_ln_f (char *target, char *linkname)
+{
+  return _link ("-f", 0, target, linkname);
+}
+
+int
+do_ln_s (char *target, char *linkname)
+{
+  return _link ("-s", 1, target, linkname);
+}
+
+int
+do_ln_sf (char *target, char *linkname)
+{
+  return _link ("-sf", 1, target, linkname);
+}