block/partitions/cmdline.c

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