LXR linux/block/partitions/cmdline.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (C) 2013 HUAWEI
   4 * Author: Cai Zhiyong <caizhiyong@huawei.com>
   5 *
   6 * Read block device partition table from the command line.
   7 * Typically used for fixed block (eMMC) embedded devices.
   8 * It has no MBR, so saves storage space. Bootloader can be easily accessed
   9 * by absolute address of data on the block device.
  10 * Users can easily change the partition.
  11 *
  12 * The format for the command line is just like mtdparts.
  13 *
  14 * For further information, see "Documentation/block/cmdline-partition.txt"
  15 *
  16 */
  17
  18#include <linux/cmdline-parser.h>
  19
  20#include "check.h"
  21#include "cmdline.h"
  22
  23static char *cmdline;
  24static struct cmdline_parts *bdev_parts;
  25
  26static int add_part(int slot, struct cmdline_subpart *subpart, void *param)
  27{
  28        int label_min;
  29        struct partition_meta_info *info;
  30        char tmp[sizeof(info->volname) + 4];
  31        struct parsed_partitions *state = (struct parsed_partitions *)param;
  32
  33        if (slot >= state->limit)
  34                return 1;
  35
  36        put_partition(state, slot, subpart->from >> 9,
  37                      subpart->size >> 9);
  38
  39        info = &state->parts[slot].info;
  40
  41        label_min = min_t(int, sizeof(info->volname) - 1,
  42                          sizeof(subpart->name));
  43        strncpy(info->volname, subpart->name, label_min);
  44        info->volname[label_min] = '\0';
  45
  46        snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
  47        strlcat(state->pp_buf, tmp, PAGE_SIZE);
  48
  49        state->parts[slot].has_info = true;
  50
  51        return 0;
  52}
  53
  54static int __init cmdline_parts_setup(char *s)
  55{
  56        cmdline = s;
  57        return 1;
  58}
  59__setup("blkdevparts=", cmdline_parts_setup);
  60
  61/*
  62 * Purpose: allocate cmdline partitions.
  63 * Returns:
  64 * -1 if unable to read the partition table
  65 *  0 if this isn't our partition table
  66 *  1 if successful
  67 */
  68int cmdline_partition(struct parsed_partitions *state)
  69{
  70        sector_t disk_size;
  71        char bdev[BDEVNAME_SIZE];
  72        struct cmdline_parts *parts;
  73
  74        if (cmdline) {
  75                if (bdev_parts)
  76                        cmdline_parts_free(&bdev_parts);
  77
  78                if (cmdline_parts_parse(&bdev_parts, cmdline)) {
  79                        cmdline = NULL;
  80                        return -1;
  81                }
  82                cmdline = NULL;
  83        }
  84
  85        if (!bdev_parts)
  86                return 0;
  87
  88        bdevname(state->bdev, bdev);
  89        parts = cmdline_parts_find(bdev_parts, bdev);
  90        if (!parts)
  91                return 0;
  92
  93        disk_size = get_capacity(state->bdev->bd_disk) << 9;
  94
  95        cmdline_parts_set(parts, disk_size, 1, add_part, (void *)state);
  96
  97        strlcat(state->pp_buf, "\n", PAGE_SIZE);
  98
  99        return 1;
 100}
 101