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[mirror_ubuntu-artful-kernel.git] / 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 }