Merge pull request #686 from Knogle/persistent-device-paths

Enhances the --exclude option to match devices by their underlying block

src/device.c

@@ -50,6 +50,119 @@
 int check_device( nwipe_context_t*** c, PedDevice* dev, int dcount );
 char* trim( char* str );
 
+/*
+ * Resolve a device path (including /dev/disk/by-* symlinks) to its
+ * underlying block device id (dev_t).
+ *
+ * Returns 0 on success and fills *out_rdev.
+ * Returns -1 on error or if the path is not a block device.
+ */
+static int nwipe_path_to_rdev( const char* path, dev_t* out_rdev )
+{
+    struct stat st;
+
+    if( path == NULL || out_rdev == NULL )
+    {
+        errno = EINVAL;
+        return -1;
+    }
+
+    /*
+     * stat() follows symlinks by default, which is what we want for
+     * persistent names in /dev/disk/by-id, /dev/disk/by-path, etc.
+     */
+    if( stat( path, &st ) != 0 )
+    {
+        return -1;
+    }
+
+    if( !S_ISBLK( st.st_mode ) )
+    {
+        /* Not a block device node. */
+        errno = ENOTBLK;
+        return -1;
+    }
+
+    *out_rdev = st.st_rdev;
+    return 0;
+}
+
+/*
+ * Check whether a candidate device node should be excluded based on the
+ * --exclude list. Matching is done primarily by device identity
+ * (major/minor via st_rdev), so persistent names like /dev/disk/by-id/*
+ * are safe. We keep legacy string-based matching as a fallback.
+ *
+ * Returns 1 if the candidate should be excluded, 0 otherwise.
+ */
+static int nwipe_is_excluded_device( const char* candidate_devnode )
+{
+    dev_t cand_rdev;
+    int have_cand_rdev;
+    int i;
+
+    /* Try to resolve the candidate device to a dev_t. */
+    have_cand_rdev = ( nwipe_path_to_rdev( candidate_devnode, &cand_rdev ) == 0 );
+
+    for( i = 0; i < MAX_NUMBER_EXCLUDED_DRIVES; i++ )
+    {
+        const char* ex = nwipe_options.exclude[i];
+        dev_t ex_rdev;
+        int have_ex_rdev;
+        const char* base;
+
+        /* Empty slot in the exclude array. */
+        if( ex == NULL || ex[0] == 0 )
+        {
+            continue;
+        }
+
+        /*
+         * First try: both candidate and exclude entry resolve to block
+         * devices; compare device ids (major/minor).
+         */
+        have_ex_rdev = ( nwipe_path_to_rdev( ex, &ex_rdev ) == 0 );
+        if( have_cand_rdev && have_ex_rdev && ex_rdev == cand_rdev )
+        {
+            nwipe_log( NWIPE_LOG_NOTICE, "Device %s excluded as per command line option -e", candidate_devnode );
+            return 1;
+        }
+
+        /*
+         * Fallback 1: exact string match. This keeps compatibility with
+         * older usage like --exclude=/dev/sda or --exclude=/dev/mapper/cryptswap1.
+         */
+        if( strcmp( candidate_devnode, ex ) == 0 )
+        {
+            nwipe_log( NWIPE_LOG_NOTICE, "Device %s excluded as per command line option -e", candidate_devnode );
+            return 1;
+        }
+
+        /*
+         * Fallback 2: match against the basename only, so that an
+         * exclude entry like "sda" still works even if the full path is
+         * /dev/sda.
+         */
+        base = strrchr( candidate_devnode, '/' );
+        if( base != NULL )
+        {
+            base++;
+        }
+        else
+        {
+            base = candidate_devnode;
+        }
+
+        if( strcmp( base, ex ) == 0 )
+        {
+            nwipe_log( NWIPE_LOG_NOTICE, "Device %s excluded as per command line option -e", candidate_devnode );
+            return 1;
+        }
+    }
+
+    return 0;
+}
+
 extern int terminate_signal;
 
 int nwipe_device_scan( nwipe_context_t*** c )
@@ -138,15 +251,11 @@ int check_device( nwipe_context_t*** c, PedDevice* dev, int dcount )
 
     bus = 0;
 
-    /* Check whether this drive is on the excluded drive list ? */
-    idx = 0;
-    while( idx < MAX_NUMBER_EXCLUDED_DRIVES )
+    /* Check whether this drive is on the excluded drive list. */
+    if( nwipe_is_excluded_device( dev->path ) )
     {
-        if( !strcmp( dev->path, nwipe_options.exclude[idx++] ) )
-        {
-            nwipe_log( NWIPE_LOG_NOTICE, "Device %s excluded as per command line option -e", dev->path );
-            return 0;
-        }
+        /* Already logged inside nwipe_is_excluded_device(). */
+        return 0;
     }
 
     /* Check whether the user has specified using the --nousb option

src/options.c

@@ -789,6 +789,8 @@ void display_help()
     puts( "                           --exclude=/dev/sdc" );
     puts( "                           --exclude=/dev/sdc,/dev/sdd" );
     puts( "                           --exclude=/dev/sdc,/dev/sdd,/dev/mapper/cryptswap1\n" );
+    puts( "                           --exclude=/dev/disk/by-id/ata-XXXXXXXX" );
+    puts( "                           --exclude=/dev/disk/by-path/pci-0000:00:17.0-ata-1\n" );
     puts( "" );
     exit( EXIT_SUCCESS );
 }