Resolve device paths in kernel and initrd locations.

[petitboot] / devices / udev-helper.c

diff --git a/devices/udev-helper.c b/devices/udev-helper.c
index 4ec054b38411ad8e053a2f3171de89dc2e865e84..661fb08b4ef9c2021984109b78d2d3af68fe9943 100644 (file)
--- a/devices/udev-helper.c
+++ b/devices/udev-helper.c
@@ -1,4 +1,6 @@
 
+#define _GNU_SOURCE
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdarg.h>
@@ -181,28 +183,92 @@ int connect_to_socket()
 #endif
 }
 
-int mount_device(const char *dev_path, char *mount_path)
+struct device_map {
+       char *dev, *mnt;
+};
+
+#define DEVICE_MAP_SIZE 32
+static struct device_map device_map[DEVICE_MAP_SIZE];
+
+const char *mountpoint_for_device(const char *dev_path)
 {
-       char *dir;
+       int i;
        const char *basename;
-       int pid, status, rc = -1;
 
-       basename = strrchr(dev_path, '/');
-       if (basename)
-               basename++;
-       else
+       /* shorten '/dev/foo' to 'foo' */
+       basename = strrchr(dev_path, '/');
+       if (basename)
+               basename++;
+       else
                basename = dev_path;
- 
-       /* create a unique mountpoint */
-       dir = malloc(strlen(TMP_DIR) + 13 + strlen(basename));
-       sprintf(dir, "%s/mnt-%s-XXXXXX", TMP_DIR, basename);
-
-       if (!mkdtemp(dir)) {
-               pb_log("failed to create temporary directory in %s: %s",
-                               TMP_DIR, strerror(errno));
-               goto out;
+
+       /* check existing entries in the map */
+       for (i = 0; (i < DEVICE_MAP_SIZE) && device_map[i].dev; i++)
+               if (!strcmp(device_map[i].dev, basename))
+                       return device_map[i].mnt;
+
+       if (i == DEVICE_MAP_SIZE)
+               return NULL;
+
+       device_map[i].dev = strdup(dev_path);
+       asprintf(&device_map[i].mnt, "%s/%s", TMP_DIR, basename);
+       return device_map[i].mnt;
+}
+
+/**
+ * Resolve a path given in a config file, to a path in the local filesystem.
+ * Paths may be of the form:
+ *  device:path (eg /dev/sda:/boot/vmlinux)
+ *
+ * or just a path:
+ *  /boot/vmlinux
+ * - in this case, the default mountpoint is used.
+ *
+ * Returns a newly-allocated string containing a full path to the file in path
+ */
+char *resolve_path(const char *path, const char *default_mountpoint)
+{
+       char *ret;
+       const char *devpath, *sep;
+
+       sep = strchr(path, ':');
+       if (!sep) {
+               devpath = default_mountpoint;
+               asprintf(&ret, "%s/%s", devpath, path);
+       } else {
+               /* copy just the device name into tmp */
+               char *dev = strndup(path, sep - path);
+               devpath = mountpoint_for_device(dev);
+               asprintf(&ret, "%s/%s", devpath, sep + 1);
+               free(dev);
        }
 
+       return ret;
+}
+
+int mount_device(const char *dev_path)
+{
+       const char *dir;
+       int pid, status, rc = -1;
+       struct stat statbuf;
+
+       dir = mountpoint_for_device(dev_path);
+
+       if (stat(dir, &statbuf)) {
+               if (mkdir(dir, 0755)) {
+                       pb_log("couldn't create directory %s: %s\n",
+                                       dir, strerror(errno));
+                       goto out;
+               }
+       } else {
+               if (!S_ISDIR(statbuf.st_mode)) {
+                       pb_log("mountpoint %s exists, "
+                                       "but isn't a directory\n", dir);
+                       goto out;
+               }
+       }
+
+
        pid = fork();
        if (pid == -1) {
                pb_log("%s: fork failed: %s\n", __FUNCTION__, strerror(errno));
@@ -220,13 +286,10 @@ int mount_device(const char *dev_path, char *mount_path)
                goto out;
        }
 
-       if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
-               strcpy(mount_path, dir);
+       if (WIFEXITED(status) && WEXITSTATUS(status) == 0)
                rc = 0;
-       }
 
 out:
-       free(dir);
        return rc;
 }
 
@@ -348,9 +411,9 @@ static int is_ignored_device(const char *devname)
 
 static int found_new_device(const char *dev_path)
 {
-       char mountpoint[PATH_MAX];
+       const char *mountpoint = mountpoint_for_device(dev_path);
 
-       if (mount_device(dev_path, mountpoint)) {
+       if (mount_device(dev_path)) {
                pb_log("failed to mount %s\n", dev_path);
                return EXIT_FAILURE;
        }