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![Cai Zhiyong](/assets/img/avatar_default.png)
Read block device partition table from command line. The partition used for fixed block device (eMMC) embedded device. It is no MBR, save storage space. Bootloader can be easily accessed by absolute address of data on the block device. Users can easily change the partition. This code reference MTD partition, source "drivers/mtd/cmdlinepart.c" About the partition verbose reference "Documentation/block/cmdline-partition.txt" [akpm@linux-foundation.org: fix printk text] [yongjun_wei@trendmicro.com.cn: fix error return code in parse_parts()] Signed-off-by: Cai Zhiyong <caizhiyong@huawei.com> Cc: Karel Zak <kzak@redhat.com> Cc: "Wanglin (Albert)" <albert.wanglin@huawei.com> Cc: Marius Groeger <mag@sysgo.de> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Brian Norris <computersforpeace@gmail.com> Cc: Artem Bityutskiy <dedekind@infradead.org> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
250 lines
4.8 KiB
C
250 lines
4.8 KiB
C
/*
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* Parse command line, get partition information
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*
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* Written by Cai Zhiyong <caizhiyong@huawei.com>
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*
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*/
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#include <linux/buffer_head.h>
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#include <linux/module.h>
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#include <linux/cmdline-parser.h>
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static int parse_subpart(struct cmdline_subpart **subpart, char *partdef)
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{
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int ret = 0;
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struct cmdline_subpart *new_subpart;
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*subpart = NULL;
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new_subpart = kzalloc(sizeof(struct cmdline_subpart), GFP_KERNEL);
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if (!new_subpart)
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return -ENOMEM;
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if (*partdef == '-') {
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new_subpart->size = (sector_t)(~0ULL);
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partdef++;
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} else {
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new_subpart->size = (sector_t)memparse(partdef, &partdef);
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if (new_subpart->size < (sector_t)PAGE_SIZE) {
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pr_warn("cmdline partition size is invalid.");
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ret = -EINVAL;
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goto fail;
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}
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}
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if (*partdef == '@') {
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partdef++;
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new_subpart->from = (sector_t)memparse(partdef, &partdef);
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} else {
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new_subpart->from = (sector_t)(~0ULL);
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}
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if (*partdef == '(') {
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int length;
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char *next = strchr(++partdef, ')');
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if (!next) {
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pr_warn("cmdline partition format is invalid.");
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ret = -EINVAL;
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goto fail;
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}
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length = min_t(int, next - partdef,
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sizeof(new_subpart->name) - 1);
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strncpy(new_subpart->name, partdef, length);
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new_subpart->name[length] = '\0';
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partdef = ++next;
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} else
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new_subpart->name[0] = '\0';
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new_subpart->flags = 0;
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if (!strncmp(partdef, "ro", 2)) {
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new_subpart->flags |= PF_RDONLY;
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partdef += 2;
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}
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if (!strncmp(partdef, "lk", 2)) {
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new_subpart->flags |= PF_POWERUP_LOCK;
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partdef += 2;
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}
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*subpart = new_subpart;
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return 0;
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fail:
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kfree(new_subpart);
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return ret;
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}
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static void free_subpart(struct cmdline_parts *parts)
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{
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struct cmdline_subpart *subpart;
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while (parts->subpart) {
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subpart = parts->subpart;
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parts->subpart = subpart->next_subpart;
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kfree(subpart);
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}
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}
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static int parse_parts(struct cmdline_parts **parts, const char *bdevdef)
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{
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int ret = -EINVAL;
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char *next;
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int length;
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struct cmdline_subpart **next_subpart;
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struct cmdline_parts *newparts;
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char buf[BDEVNAME_SIZE + 32 + 4];
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*parts = NULL;
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newparts = kzalloc(sizeof(struct cmdline_parts), GFP_KERNEL);
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if (!newparts)
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return -ENOMEM;
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next = strchr(bdevdef, ':');
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if (!next) {
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pr_warn("cmdline partition has no block device.");
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goto fail;
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}
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length = min_t(int, next - bdevdef, sizeof(newparts->name) - 1);
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strncpy(newparts->name, bdevdef, length);
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newparts->name[length] = '\0';
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newparts->nr_subparts = 0;
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next_subpart = &newparts->subpart;
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while (next && *(++next)) {
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bdevdef = next;
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next = strchr(bdevdef, ',');
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length = (!next) ? (sizeof(buf) - 1) :
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min_t(int, next - bdevdef, sizeof(buf) - 1);
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strncpy(buf, bdevdef, length);
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buf[length] = '\0';
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ret = parse_subpart(next_subpart, buf);
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if (ret)
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goto fail;
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newparts->nr_subparts++;
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next_subpart = &(*next_subpart)->next_subpart;
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}
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if (!newparts->subpart) {
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pr_warn("cmdline partition has no valid partition.");
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ret = -EINVAL;
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goto fail;
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}
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*parts = newparts;
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return 0;
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fail:
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free_subpart(newparts);
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kfree(newparts);
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return ret;
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}
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void cmdline_parts_free(struct cmdline_parts **parts)
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{
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struct cmdline_parts *next_parts;
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while (*parts) {
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next_parts = (*parts)->next_parts;
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free_subpart(*parts);
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kfree(*parts);
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*parts = next_parts;
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}
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}
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int cmdline_parts_parse(struct cmdline_parts **parts, const char *cmdline)
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{
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int ret;
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char *buf;
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char *pbuf;
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char *next;
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struct cmdline_parts **next_parts;
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*parts = NULL;
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next = pbuf = buf = kstrdup(cmdline, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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next_parts = parts;
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while (next && *pbuf) {
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next = strchr(pbuf, ';');
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if (next)
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*next = '\0';
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ret = parse_parts(next_parts, pbuf);
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if (ret)
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goto fail;
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if (next)
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pbuf = ++next;
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next_parts = &(*next_parts)->next_parts;
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}
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if (!*parts) {
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pr_warn("cmdline partition has no valid partition.");
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ret = -EINVAL;
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goto fail;
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}
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ret = 0;
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done:
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kfree(buf);
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return ret;
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fail:
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cmdline_parts_free(parts);
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goto done;
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}
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struct cmdline_parts *cmdline_parts_find(struct cmdline_parts *parts,
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const char *bdev)
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{
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while (parts && strncmp(bdev, parts->name, sizeof(parts->name)))
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parts = parts->next_parts;
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return parts;
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}
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/*
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* add_part()
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* 0 success.
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* 1 can not add so many partitions.
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*/
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void cmdline_parts_set(struct cmdline_parts *parts, sector_t disk_size,
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int slot,
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int (*add_part)(int, struct cmdline_subpart *, void *),
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void *param)
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{
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sector_t from = 0;
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struct cmdline_subpart *subpart;
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for (subpart = parts->subpart; subpart;
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subpart = subpart->next_subpart, slot++) {
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if (subpart->from == (sector_t)(~0ULL))
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subpart->from = from;
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else
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from = subpart->from;
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if (from >= disk_size)
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break;
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if (subpart->size > (disk_size - from))
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subpart->size = disk_size - from;
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from += subpart->size;
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if (add_part(slot, subpart, param))
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break;
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}
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}
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