[PATCH 6/6] cmd: Add MBR partition layout control utility
Heinrich Schuchardt
xypron.glpk at gmx.de
Fri Dec 18 01:42:40 CET 2020
Am 17. Dezember 2020 12:27:39 MEZ schrieb Marek Szyprowski <m.szyprowski at samsung.com>:
>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
It is good to have this information in the commit message. But we cannot expect a user to look at commit messages.
Please, provide a man-page in doc/usage/. You can use this patch as template:
https://lists.denx.de/pipermail/u-boot/2020-December/435144.html
Use 'make htmldocs' to build and check the documentation.
Once your patch is merged the documentation will be published at
https://u-boot.readthedocs.io/
Best regards
Heinrich
>
>Signed-off-by: Marek Szyprowski <m.szyprowski at samsung.com>
>---
> cmd/Kconfig | 8 ++
> cmd/Makefile | 1 +
> cmd/mbr.c | 308 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 317 insertions(+)
> create mode 100644 cmd/mbr.c
>
>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..25a3f694d3
>--- /dev/null
>+++ b/cmd/mbr.c
>@@ -0,0 +1,308 @@
>+// 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 <malloc.h>
>+#include <command.h>
>+#include <part.h>
>+
>+/**
>+ * extract_val(): Extract value from a key=value pair list (comma
>separated).
>+ * Only value for the given key is returend.
>+ * Function allocates memory for the value, remember to
>free!
>+ *
>+ * @param str - pointer to string with key=values pairs
>+ * @param key - pointer to the key to search for
>+ *
>+ * @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(): Found key without value in parameter list (comma
>separated).
>+ *
>+ * @param str - pointer to string with key
>+ * @param key - pointer to the key to search for
>+ *
>+ * @return - true on found key
>+ */
>+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_partition_info(const char *str_part, 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 / 512;
>+ }
>+ 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 / 512;
>+ 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 count;
>+
>+ if (str_to_partition_info(str, &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 count, i, ret = 1;
>+
>+ if (str_to_partition_info(str, &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"
>+);
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