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
  23 static char *cmdline;
  24 static struct cmdline_parts *bdev_parts;
  25
  26 static 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
  54 static 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  */
  68 int 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 }