[PATCH v2 6/6] cmd: Add MBR partition layout control utility
Heinrich Schuchardt
xypron.glpk at gmx.de
Tue Dec 22 18:53:15 CET 2020
On 12/22/20 3:09 PM, Marek Szyprowski wrote:
> Add a 'mbr' command to let user create or verify MBR partition layout
> based on the provided text description. The partition layout is
> altearnatively read from 'mbr_parts' environment variable. This can be
> used in scripts to help system image flashing tools to ensure proper
> partition layout.
>
> The syntax of the text description of the partition list is similar to
> the one used by the 'gpt' command. Supported parameters are: name
> (currently ignored), start (partition start offset in bytes), size (in
> bytes or '-' to expand it to the whole free area), bootable (boolean
> flag) and id (MBR partition system ID). If one wants to create more than
> 4 partitions, an 'Extended' primary partition (with 0x05 ID) has to be
> explicitely provided as a one of the first 4 entries.
>
> Here is the example how to create a 6 partitions (3 on the 'extended
> volume'), some of the predefined sizes:
>
>> setenv mbr_parts 'name=boot,start=4M,size=128M,bootable,id=0x0e;
> name=rootfs,size=3072M,id=0x83;
> name=system-data,size=512M,id=0x83;
> name=[ext],size=-,id=0x05;
> name=user,size=-,id=0x83;
> name=modules,size=100M,id=0x83;
> name=ramdisk,size=8M,id=0x83'
>> mbr write mmc 0
>
> Signed-off-by: Marek Szyprowski <m.szyprowski at samsung.com>
> ---
> cmd/Kconfig | 8 ++
> cmd/Makefile | 1 +
> cmd/mbr.c | 314 ++++++++++++++++++++++++++++++++++++++++++++
> doc/usage/index.rst | 1 +
> doc/usage/mbr.rst | 93 +++++++++++++
> 5 files changed, 417 insertions(+)
> create mode 100644 cmd/mbr.c
> create mode 100644 doc/usage/mbr.rst
>
> diff --git a/cmd/Kconfig b/cmd/Kconfig
> index 1595de999b..2c3358e359 100644
> --- a/cmd/Kconfig
> +++ b/cmd/Kconfig
> @@ -1025,6 +1025,14 @@ config CMD_LSBLK
> Print list of available block device drivers, and for each, the list
> of known block devices.
>
> +config CMD_MBR
> + bool "MBR (Master Boot Record) command"
> + select DOS_PARTITION
> + select HAVE_BLOCK_DEVICE
> + help
> + Enable the 'mbr' command to ready and write MBR (Master Boot Record)
> + style partition tables.
> +
> config CMD_MISC
> bool "misc"
> depends on MISC
> diff --git a/cmd/Makefile b/cmd/Makefile
> index dd86675bf2..41379d9a0e 100644
> --- a/cmd/Makefile
> +++ b/cmd/Makefile
> @@ -178,6 +178,7 @@ obj-$(CONFIG_CMD_ZFS) += zfs.o
>
> obj-$(CONFIG_CMD_DFU) += dfu.o
> obj-$(CONFIG_CMD_GPT) += gpt.o
> +obj-$(CONFIG_CMD_MBR) += mbr.o
> obj-$(CONFIG_CMD_ETHSW) += ethsw.o
> obj-$(CONFIG_CMD_AXI) += axi.o
> obj-$(CONFIG_CMD_PVBLOCK) += pvblock.o
> diff --git a/cmd/mbr.c b/cmd/mbr.c
> new file mode 100644
> index 0000000000..da2e3a4722
> --- /dev/null
> +++ b/cmd/mbr.c
> @@ -0,0 +1,314 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * cmd_mbr.c -- MBR (Master Boot Record) handling command
> + *
> + * Copyright (C) 2020 Samsung Electronics
> + * author: Marek Szyprowski <m.szyprowski at samsung.com>
> + *
> + * based on the gpt command.
> + */
> +
> +#include <common.h>
> +#include <blk.h>
> +#include <command.h>
> +#include <malloc.h>
> +#include <part.h>
> +
> +/**
> + * extract_val() - Extract a value from the key=value pair list
> + * @str: pointer to string with key=values pairs
> + * @key: pointer to the key to search for
> + *
> + * The list of parameters is come separated, only a value for
> + * the given key is returend.
> + *
> + * Function allocates memory for the value, remember to free!
> + *
> + * Return: Pointer to allocated string with the value.
> + */
> +static char *extract_val(const char *str, const char *key)
> +{
> + char *v, *k;
> + char *s, *strcopy;
> + char *new = NULL;
> +
> + strcopy = strdup(str);
> + if (strcopy == NULL)
> + return NULL;
> +
> + s = strcopy;
> + while (s) {
> + v = strsep(&s, ",");
> + if (!v)
> + break;
> + k = strsep(&v, "=");
> + if (!k)
> + break;
> + if (strcmp(k, key) == 0) {
> + new = strdup(v);
> + break;
> + }
> + }
> +
> + free(strcopy);
> +
> + return new;
> +}
> +
> +/**
> + * found_key() - Search for a key without a value in the parameter list
> + * @str: pointer to string with key
> + * @key: pointer to the key to search for
> + *
> + * The list of parameters is come separated.
> + *
> + * Return: True if key has been found.
> + */
> +static bool found_key(const char *str, const char *key)
> +{
> + char *k;
> + char *s, *strcopy;
> + bool result = false;
> +
> + strcopy = strdup(str);
> + if (!strcopy)
> + return NULL;
> +
> + s = strcopy;
> + while (s) {
> + k = strsep(&s, ",");
> + if (!k)
> + break;
> + if (strcmp(k, key) == 0) {
> + result = true;
> + break;
> + }
> + }
> +
> + free(strcopy);
> +
> + return result;
> +}
> +
> +static int str_to_partitions(const char *str_part, int blksz,
> + unsigned long *disk_uuid, struct disk_partition **partitions,
> + int *parts_count)
> +{
> + char *tok, *str, *s;
> + int i;
> + char *val, *p;
> + int p_count;
> + struct disk_partition *parts;
> + int errno = 0;
> + uint64_t size_ll, start_ll;
> +
> + if (str_part == NULL)
> + return -1;
> +
> + str = strdup(str_part);
> + if (str == NULL)
> + return -ENOMEM;
> +
> + /* extract disk guid */
> + s = str;
> + val = extract_val(str, "uuid_disk");
> + if (val) {
> + val = strsep(&val, ";");
> + p = val;
> + *disk_uuid = ustrtoull(p, &p, 0);
> + free(val);
> + /* Move s to first partition */
> + strsep(&s, ";");
> + }
> + if (s == NULL) {
> + printf("Error: is the partitions string NULL-terminated?\n");
> + return -EINVAL;
> + }
> +
> + /* remove the optional semicolon at the end of the string */
> + i = strlen(s) - 1;
> + if (s[i] == ';')
> + s[i] = '\0';
> +
> + /* calculate expected number of partitions */
> + p_count = 1;
> + p = s;
> + while (*p) {
> + if (*p++ == ';')
> + p_count++;
> + }
> +
> + /* allocate memory for partitions */
> + parts = calloc(sizeof(struct disk_partition), p_count);
> + if (parts == NULL)
> + return -ENOMEM;
> +
> + /* retrieve partitions data from string */
> + for (i = 0; i < p_count; i++) {
> + tok = strsep(&s, ";");
> +
> + if (tok == NULL)
> + break;
> +
> + /* size */
> + val = extract_val(tok, "size");
> + if (!val) { /* 'size' is mandatory */
> + errno = -4;
> + goto err;
> + }
> + p = val;
> + if ((strcmp(p, "-") == 0)) {
> + /* auto extend the size */
> + parts[i].size = 0;
> + } else {
> + size_ll = ustrtoull(p, &p, 0);
> + parts[i].size = size_ll / blksz;
> + }
> + free(val);
> +
> + /* start address */
> + val = extract_val(tok, "start");
> + if (val) { /* start address is optional */
> + p = val;
> + start_ll = ustrtoull(p, &p, 0);
> + parts[i].start = start_ll / blksz;
> + free(val);
> + }
> +
> + /* system id */
> + val = extract_val(tok, "id");
> + if (!val) { /* '' is mandatory */
> + errno = -4;
> + goto err;
> + }
> + p = val;
> + parts[i].sys_ind = ustrtoul(p, &p, 0);
> + free(val);
> +
> + /* bootable */
> + if (found_key(tok, "bootable"))
> + parts[i].bootable = PART_BOOTABLE;
> + }
> +
> + *parts_count = p_count;
> + *partitions = parts;
> + free(str);
> +
> + return 0;
> +err:
> + free(str);
> + free(parts);
> +
> + return errno;
> +}
> +
> +static int do_write_mbr(struct blk_desc *dev, const char *str)
> +{
> + unsigned long disk_uuid = 0;
> + struct disk_partition *partitions;
> + int blksz = dev->blksz;
> + int count;
> +
> + if (str_to_partitions(str, blksz, &disk_uuid, &partitions, &count)) {
> + printf("MBR: failed to setup partitions from \"%s\"\n", str);
> + return -1;
> + }
> +
> + if (layout_mbr_partitions(partitions, count, dev->lba)) {
> + printf("MBR: failed to layout partitions on the device\n");
> + free(partitions);
> + return -1;
> + }
> +
> + if (write_mbr_partitions(dev, partitions, count, disk_uuid)) {
> + printf("MBR: failed to write partitions to the device\n");
> + free(partitions);
> + return -1;
> + }
> +
> + return 0;
> +}
> +
> +static int do_verify_mbr(struct blk_desc *dev, const char *str)
> +{
> + unsigned long disk_uuid = 0;
> + struct disk_partition *partitions;
> + int blksz = dev->blksz;
> + int count, i, ret = 1;
> +
> + if (str_to_partitions(str, blksz, &disk_uuid, &partitions, &count)) {
> + printf("MBR: failed to setup partitions from \"%s\"\n", str);
> + return -1;
> + }
> +
> + for (i = 0; i < count; i++) {
> + struct disk_partition p;
> +
> + if (part_get_info(dev, i+1, &p))
> + goto fail;
> +
> + if ((partitions[i].size && p.size < partitions[i].size) ||
> + (partitions[i].start && p.start < partitions[i].start) ||
> + (p.sys_ind != partitions[i].sys_ind))
> + goto fail;
> + }
> + ret = 0;
> +fail:
> + free(partitions);
> + return ret;
> +}
> +
> +static int do_mbr(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
> +{
> + const char *parts = NULL;
> + int ret = CMD_RET_SUCCESS;
> + int dev = 0;
> + char *ep;
> + struct blk_desc *blk_dev_desc = NULL;
> +
> + if (argc != 4 && argc != 5)
> + return CMD_RET_USAGE;
> +
> + dev = (int)simple_strtoul(argv[3], &ep, 10);
> + if (!ep || ep[0] != '\0') {
> + printf("'%s' is not a number\n", argv[3]);
> + return CMD_RET_USAGE;
> + }
> + blk_dev_desc = blk_get_dev(argv[2], dev);
> + if (!blk_dev_desc) {
> + printf("%s: %s dev %d NOT available\n",
> + __func__, argv[2], dev);
> + return CMD_RET_FAILURE;
> + }
> +
> + if ((strcmp(argv[1], "write") == 0)) {
> + parts = (argc == 5) ? argv[4] : env_get("mbr_parts");
> + printf("MBR: write ");
> + ret = do_write_mbr(blk_dev_desc, parts);
> + } else if ((strcmp(argv[1], "verify") == 0)) {
> + printf("MBR: verify ");
> + parts = (argc == 5) ? argv[4] : env_get("mbr_parts");
> + ret = do_verify_mbr(blk_dev_desc, parts);
> + } else {
> + return CMD_RET_USAGE;
> + }
> +
> + if (ret) {
> + printf("error!\n");
> + return CMD_RET_FAILURE;
> + }
> +
> + printf("success!\n");
> + return CMD_RET_SUCCESS;
> +}
> +
> +U_BOOT_CMD(mbr, CONFIG_SYS_MAXARGS, 1, do_mbr,
> + "MBR (Master Boot Record)",
> + "<command> <interface> <dev> <partitions_list>\n"
> + " - MBR partition table restoration utility\n"
> + " Restore or check partition information on a device connected\n"
> + " to the given block interface\n"
> + " Example usage:\n"
> + " mbr write mmc 0 [\"${mbr_parts}\"]\n"
> + " mbr verify mmc 0 [\"${partitions}\"]\n"
> +);
> diff --git a/doc/usage/index.rst b/doc/usage/index.rst
> index fbb2c0481c..5869fba189 100644
> --- a/doc/usage/index.rst
> +++ b/doc/usage/index.rst
> @@ -14,4 +14,5 @@ Shell commands
> bootefi
> bootmenu
> button
> + mbr
> pstore
> diff --git a/doc/usage/mbr.rst b/doc/usage/mbr.rst
> new file mode 100644
> index 0000000000..ee27b00c75
> --- /dev/null
> +++ b/doc/usage/mbr.rst
> @@ -0,0 +1,93 @@
> +.. SPDX-License-Identifier: GPL-2.0+
> +
> +mbr command
> +===========
> +
> +Synopsis
> +--------
> +
> +::
> +
> + mbr verify [interface] [device no] [partition list]
> + mbr write [interface] [device no] [partition list]
> +
> +Description
> +-----------
> +
> +The mbr command lets user to create or verify MBR partition layout
allows the user to create
or
lets users create
create or verify the MBR
> +based on the provided text description. The partition layout is
> +altearnatively read from 'mbr_parts' environment variable. This can be
alternatively read from the
> +used in scripts to help system image flashing tools to ensure proper
> +partition layout.
> +
> +The syntax of the text description of the partition list is similar to
> +the one used by the 'gpt' command.
> +
> +Supported partition parameters are:
> +
> +* name (currently ignored)
> +* start (partition start offset in bytes)
> +* size (in bytes or '-' to expand it to the whole free area)
> +* bootable (boolean flag)
> +* id (MBR partition system ID)
fdisk calls this 'partition type'.
The word ID does not make sense because all four partitions may have the
same value.
> +
> +If one wants to create more than 4 partitions, an 'Extended' primary
> +partition (with 0x05 ID) has to be explicitely provided as a one of the
explicitly
> +first 4 entries.
> +
> +Here is the example how to create a 6 partitions (3 on the 'extended
an example
> +volume'), some of the predefined sizes:
> +
> +::
> +
> + => setenv mbr_parts 'name=boot,start=4M,size=128M,bootable,id=0x0e;
> + name=rootfs,size=3072M,id=0x83;
> + name=system-data,size=512M,id=0x83;
> + name=[ext],size=-,id=0x05;
> + name=user,size=-,id=0x83;
> + name=modules,size=100M,id=0x83;
> + name=ramdisk,size=8M,id=0x83'
> + => mbr write mmc 0
> +
> +To check if the layout on the MMC #0 storage device matches the provided
> +text description one has to issue following command (assuming that
> +mbr_parts environment variable is set):
> +
> +::
> +
> + => mbr verify mmc 0
> +
> +The verify sub-command is especially useful in the system update scripts:
> +
> +::
> + => if mbr verify mmc 0; then
> + echo MBR layout needs to be updated
> + ...
> + fi
> +
> +The 'mbr write' command returns 0 on success write or -1 on failure.
> +
> +The 'mbr verify' returns 0 if the layout matches the one on the storage
> +device or -1 if not.
CMD_RET_FAILURE has value 1 not -1. See you table below.
Best regards
Heinrich
> +
> +Configuration
> +-------------
> +
> +To use the mbr command you must specify CONFIG_CMD_MBR=y.
> +
> +Return value
> +------------
> +
> +The variable *$?* takes the following values
> +
> ++---+------------------------------+
> +| 0 | mbr write was succesful |
> ++---+------------------------------+
> +| 1 | mbr write failed |
> ++---+------------------------------+
> +| 0 | mbr verify was succesful |
> ++---+------------------------------+
> +| 1 | mbr verify was not succesful |
> ++---+------------------------------+
> +|-1 | invalid arguments |
> ++---+------------------------------+
>
More information about the U-Boot
mailing list