diff options
| -rw-r--r-- | rootdev.c | 61 | ||||
| -rw-r--r-- | rootdev.h | 5 |
2 files changed, 45 insertions, 21 deletions
@@ -1,4 +1,4 @@ -/* Copyright (c) 2010 The Chromium OS Authors. All rights reserved. +/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved. * Use of this source code is governed by a BSD-style license that can be * found in the LICENSE file. * @@ -21,6 +21,13 @@ #include <sys/types.h> #include <unistd.h> +/* + * A depth of more than about 4 slave devices + * will run out of kernel stack space, so setting + * the serach depth to 8 covers all possible cases. + */ +#define MAX_SLAVE_DEPTH 8 + static const char *kDefaultSearchPath = "/sys/block"; static const char *kDefaultDevPath = "/dev"; @@ -75,9 +82,10 @@ static dev_t devt_from_file(const char *file) { return dev; } -/* Walks sysfs and will recurse into any directory/link that represents - * a block device to find sub-devices (partitions). - * If dev == 0, the first device in the directory will be returned. */ +/* Walks sysfs and recurses into any directory/link that represents + * a block device to find sub-devices (partitions) for dev. + * If dev == 0, the name fo the first device in the directory will be returned. + * Returns the device's name in "name" */ static int match_sysfs_device(char *name, size_t name_len, const char *basedir, dev_t *dev, int depth) { int found = -1; @@ -253,25 +261,42 @@ int rootdev_get_device(char *dst, size_t size, dev_t dev, return 0; } -int rootdev_get_device_slave(char *slave, size_t size, dev_t *dev, - const char *device, const char *search) { +/* + * rootdev_get_device_slave returns results in slave which + * may be the original device or the name of the slave. + * + * Because slave and device may point to the same data, + * must be careful how they are handled because slave + * is modified (can't use snprintf). + */ +void rootdev_get_device_slave(char *slave, size_t size, dev_t *dev, + const char *device, const char *search) { char dst[PATH_MAX]; int len = 0; + int i; if (search == NULL) search = kDefaultSearchPath; - /* So far, I've only seen top-level block devices with slaves. */ - len = snprintf(dst, sizeof(dst), "%s/%s/slaves", search, device); - if (len < 0 || len != strlen(device) + strlen(search) + 8) { - warnx("rootdev_get_device_slave: device name too long"); - return -1; + /* + * With stacked device mappers, we have to chain through all the levels + * and find the last device. For example, verity can be stacked on bootcache + * that is stacked on a disk partition. + */ + strncpy(slave, device, size); + slave[size - 1] = '\0'; + for (i = 0; i < MAX_SLAVE_DEPTH; i++) { + len = snprintf(dst, sizeof(dst), "%s/%s/slaves", search, slave); + if (len != strlen(device) + strlen(search) + 8) { + warnx("rootdev_get_device_slave: device name too long"); + return; + } + *dev = 0; + if (match_sysfs_device(slave, size, dst, dev, 0) <= 0) { + return; + } } - *dev = 0; - if (match_sysfs_device(slave, size, dst, dev, 0) <= 0) - return -1; - - return 0; + warnx("slave depth greater than %d at %s", i, slave); } int rootdev_create_devices(const char *name, dev_t dev, bool symlink) { @@ -358,8 +383,8 @@ int rootdev_wrapper(char *path, size_t size, return res; if (full) - res = rootdev_get_device_slave(devname, sizeof(devname), dev, devname, - search); + rootdev_get_device_slave(devname, sizeof(devname), dev, devname, + search); /* TODO(wad) we should really just track the block dev, partition number, and * dev path. When we rewrite this, we can track all the sysfs info @@ -61,11 +61,10 @@ int rootdev_get_device(char *dst, size_t size, dev_t dev, * @device: name of the device to probe, like "sdb" * @search: path to search under. NULL for default. * - * Returns 0 on success, non-zero on failure. * It is safe for @device == @slave. */ -int rootdev_get_device_slave(char *slave, size_t size, dev_t *dev, - const char *device, const char *search); +void rootdev_get_device_slave(char *slave, size_t size, dev_t *dev, + const char *device, const char *search); /** * rootdev_get_path: converts a device name to a path in the device tree |