1 files changed, 115 insertions, 0 deletions
diff --git a/src/with-dev-root-do.c b/src/with-dev-root-do.c
new file mode 100644
index 0000000..e822d00
--- /dev/null
+++ b/src/with-dev-root-do.c
@@ -0,0 +1,115 @@
+/* -*- c-basic-offset: 8 -*- */
+/*
+ * Query udev for the real name of the device currently mounted
+ * as root filesystem and use it as an argument for a command.
+ *
+ * Copyright (C) 2012 Samsung Electronics
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ * Author: Łukasz Stelmach <l.stelmach@samsung.com>
+ *
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <libudev.h>
+#include <stdlib.h>
+#include <string.h>
+
+void usage() {
+	fprintf(stderr, "Usage:\n\n  with-dev-root-do <cmdline>\n\n");
+	fprintf(stderr, "Execute the cmdline with the real name of the device currently mounted\n");
+	fprintf(stderr, "as root file-system appended at the end or substituted for '{}'. Examples\n");
+	fprintf(stderr, "assuming /dev/sda1 holds root file-system:\n\n");
+	fprintf(stderr, "  with-dev-root-do /sbin/fsck\n\n");
+	fprintf(stderr, "runs \"/sbin/fsck /dev/sda1\"\n\n");
+	fprintf(stderr, "  with-dev-root-do /sbin/e2image {} /tmp/root.e2img\n\n");
+	fprintf(stderr, "runs \"/sbin/e2image /dev/sda1 /tmp/root.e2img\"\n");
+}
+
+const char* find_node() {
+	struct stat s;
+	struct udev* udev=NULL;
+        struct udev_device *udev_device = NULL;
+	const char* node=NULL;
+
+	if(stat("/", &s) < 0) {
+		perror("stat");
+		return NULL;
+	}
+
+	if (s.st_dev == 0)
+		return NULL;
+
+	udev=udev_new();
+	if(udev==NULL) {
+		fprintf(stderr, "I don't remember.\n");
+		return NULL;
+	}
+
+	udev_device=udev_device_new_from_devnum(udev, 'b', s.st_dev);
+	if(udev_device==NULL) {
+		fprintf(stderr, "Where do we come from?\n");
+		return NULL;
+	}
+
+	node=udev_device_get_devnode(udev_device);
+	if(node==NULL) {
+		fprintf(stderr, "Where are we going to?\n");
+		return NULL;
+	}
+	return node;
+}
+
+int main(int argc, char* argv[]) {
+	const char** cmdline;
+	const char* node;
+	int i;
+	int placeholder_found=0;
+
+	if(argc < 2) {
+		usage();
+		fprintf(stderr, "\nI don't want to be alone.\n");
+		exit(1);
+	}
+
+	cmdline=malloc((1+argc) * sizeof(char*));
+	if(cmdline==NULL) {
+		perror("malloc");
+		exit(1);
+	}
+	memset((char*)cmdline, 0, (1+argc) * sizeof(char*));
+
+	if((node=find_node())==NULL) {
+		free(cmdline);
+		exit(1);
+	}
+
+	for (i=0; i < argc && argv[i+1]; i++) {
+		if(strncmp("{}", argv[i+1], 3)==0) {
+			placeholder_found=1;
+			cmdline[i] = node;
+		} else
+			cmdline[i] = argv[i+1];
+	}
+
+	if (!placeholder_found)
+		cmdline[i]=node;
+
+	execv(cmdline[0], (char**) cmdline);
+	return 1;
+}