[gnome-multi-writer] trivial: Do not allow probing block devices that are mounted

[Richard Hughes <rhughes src gnome org>]

commit ebe953b2443401e05ca23d020009bc93cccb0e89
Author: Richard Hughes <richard hughsie com>
Date:   Wed Jan 28 20:03:56 2015 +0000

    trivial: Do not allow probing block devices that are mounted

 src/gmw-probe.c |   44 +++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 43 insertions(+), 1 deletions(-)
---
diff --git a/src/gmw-probe.c b/src/gmw-probe.c
index 22973cc..2930c4c 100644
--- a/src/gmw-probe.c
+++ b/src/gmw-probe.c
@@ -24,6 +24,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <glib/gi18n.h>
+#include <glib/gprintf.h>
 #include <glib/gstdio.h>
 #include <gudev/gudev.h>
 #include <linux/fs.h>
@@ -474,6 +475,39 @@ gmw_probe_use_device (GUdevClient *udev_client,
 }
 
 /**
+ * gmw_probe_is_block_device_valid:
+ **/
+static gboolean
+gmw_probe_is_block_device_valid (const gchar *block_device)
+{
+       guint i;
+
+       /* dev prefix */
+       if (!g_str_has_prefix (block_device, "/dev/"))
+               return FALSE;
+
+       /* has no partition number */
+       for (i = 5; block_device[i] != '\0'; i++) {
+               if (g_ascii_isdigit (block_device[i]))
+                       return FALSE;
+       }
+       return TRUE;
+}
+
+
+/**
+ * gmw_probe_is_block_device_mounted:
+ **/
+static gboolean
+gmw_probe_is_block_device_mounted (const gchar *block_device)
+{
+       _cleanup_free_ gchar *data = NULL;
+       if (!g_file_get_contents ("/etc/mtab", &data, NULL, NULL))
+               return FALSE;
+       return g_strrstr (data, block_device) != NULL;
+}
+
+/**
  * main:
  **/
 int
@@ -509,12 +543,20 @@ main (int argc, char **argv)
        if (verbose)
                g_setenv ("G_MESSAGES_DEBUG", "all", TRUE);
 
-       if (argc == 1) {
+       /* valid arguments */
+       if (argc != 2 || !gmw_probe_is_block_device_valid (argv[1])) {
                status = EXIT_FAILURE;
                g_print ("Block device required as argument\n");
                goto out;
        }
 
+       /* already mounted */
+       if (gmw_probe_is_block_device_mounted (argv[1])) {
+               status = EXIT_FAILURE;
+               g_print ("Partition mounted from block device\n");
+               goto out;
+       }
+
        /* probe device */
        cancellable = g_cancellable_new ();
        udev_client = g_udev_client_new (subsystems);