libext2fs: fix potential divide by zero bug caused by a lxcfs bug

[thirdparty/e2fsprogs.git] / debugfs / set_fields.c

/*
 * set_fields.c --- set a superblock value
 *
 * Copyright (C) 2000, 2001, 2002, 2003, 2004 by Theodore Ts'o.
 *
 * %Begin-Header%
 * This file may be redistributed under the terms of the GNU Public
 * License.
 * %End-Header%
 */

#define _XOPEN_SOURCE 600 /* for inclusion of strptime() and strtoull */

#ifdef HAVE_STRTOULL
#define STRTOULL strtoull
#else
#define STRTOULL strtoul
#endif

#include "config.h"
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include <strings.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#include <assert.h>
#if HAVE_STRINGS_H
#include <strings.h>
#endif
#include <fcntl.h>
#include <utime.h>

#include "debugfs.h"
#include "uuid/uuid.h"
#include "e2p/e2p.h"
#include "support/quotaio.h"

static struct ext2_super_block set_sb;
static struct ext2_inode_large set_inode;
static struct ext2_group_desc set_gd;
static struct ext4_group_desc set_gd4;
static struct mmp_struct set_mmp;
static dgrp_t set_bg;
static ext2_ino_t set_ino;
static int array_idx;

#define FLAG_ARRAY      0x0001
#define FLAG_ALIAS      0x0002  /* Data intersects with other field */
#define FLAG_CSUM       0x0004

struct field_set_info {
        const char      *name;
        void    *ptr;
        void    *ptr2;
        unsigned int    size;
        errcode_t (*func)(struct field_set_info *info, char *field, char *arg);
        int flags;
        int max_idx;
};

static errcode_t parse_uint(struct field_set_info *info, char *field, char *arg);
static errcode_t parse_int(struct field_set_info *info, char *field, char *arg);
static errcode_t parse_string(struct field_set_info *info, char *field, char *arg);
static errcode_t parse_uuid(struct field_set_info *info, char *field, char *arg);
static errcode_t parse_hashalg(struct field_set_info *info, char *field, char *arg);
static errcode_t parse_time(struct field_set_info *info, char *field, char *arg);
static errcode_t parse_bmap(struct field_set_info *info, char *field, char *arg);
static errcode_t parse_gd_csum(struct field_set_info *info, char *field, char *arg);
static errcode_t parse_inode_csum(struct field_set_info *info, char *field,
                                  char *arg);
static errcode_t parse_mmp_clear(struct field_set_info *info, char *field,
                                 char *arg);

#if __GNUC_PREREQ (4, 6) || defined(__clang__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wmissing-field-initializers"
#endif

static struct field_set_info super_fields[] = {
        { "inodes_count", &set_sb.s_inodes_count, NULL, 4, parse_uint },
        { "blocks_count", &set_sb.s_blocks_count, &set_sb.s_blocks_count_hi,
                4, parse_uint },
        { "r_blocks_count", &set_sb.s_r_blocks_count,
                &set_sb.s_r_blocks_count_hi, 4, parse_uint },
        { "free_blocks_count", &set_sb.s_free_blocks_count,
                &set_sb.s_free_blocks_hi, 4, parse_uint },
        { "free_inodes_count", &set_sb.s_free_inodes_count, NULL, 4, parse_uint },
        { "first_data_block", &set_sb.s_first_data_block, NULL, 4, parse_uint },
        { "log_block_size", &set_sb.s_log_block_size, NULL, 4, parse_uint },
        { "log_cluster_size", &set_sb.s_log_cluster_size, NULL, 4, parse_int },
        { "blocks_per_group", &set_sb.s_blocks_per_group, NULL, 4, parse_uint },
        { "clusters_per_group", &set_sb.s_clusters_per_group, NULL, 4, parse_uint },
        { "inodes_per_group", &set_sb.s_inodes_per_group, NULL, 4, parse_uint },
        { "mtime", &set_sb.s_mtime, NULL, 4, parse_time },
        { "wtime", &set_sb.s_wtime, NULL, 4, parse_time },
        { "mnt_count", &set_sb.s_mnt_count, NULL, 2, parse_uint },
        { "max_mnt_count", &set_sb.s_max_mnt_count, NULL, 2, parse_int },
        /* s_magic */
        { "state", &set_sb.s_state, NULL, 2, parse_uint },
        { "errors", &set_sb.s_errors, NULL, 2, parse_uint },
        { "minor_rev_level", &set_sb.s_minor_rev_level, NULL, 2, parse_uint },
        { "lastcheck", &set_sb.s_lastcheck, NULL, 4, parse_time },
        { "checkinterval", &set_sb.s_checkinterval, NULL, 4, parse_uint },
        { "creator_os", &set_sb.s_creator_os, NULL, 4, parse_uint },
        { "rev_level", &set_sb.s_rev_level, NULL, 4, parse_uint },
        { "def_resuid", &set_sb.s_def_resuid, NULL, 2, parse_uint },
        { "def_resgid", &set_sb.s_def_resgid, NULL, 2, parse_uint },
        { "first_ino", &set_sb.s_first_ino, NULL, 4, parse_uint },
        { "inode_size", &set_sb.s_inode_size, NULL, 2, parse_uint },
        { "block_group_nr", &set_sb.s_block_group_nr, NULL, 2, parse_uint },
        { "feature_compat", &set_sb.s_feature_compat, NULL, 4, parse_uint },
        { "feature_incompat", &set_sb.s_feature_incompat, NULL, 4, parse_uint },
        { "feature_ro_compat", &set_sb.s_feature_ro_compat, NULL, 4, parse_uint },
        { "uuid", &set_sb.s_uuid, NULL, 16, parse_uuid },
        { "volume_name",  &set_sb.s_volume_name, NULL, 16, parse_string },
        { "last_mounted",  &set_sb.s_last_mounted, NULL, 64, parse_string },
        { "algorithm_usage_bitmap", &set_sb.s_algorithm_usage_bitmap, NULL,
                  4, parse_uint },
        { "prealloc_blocks", &set_sb.s_prealloc_blocks, NULL, 1, parse_uint },
        { "prealloc_dir_blocks", &set_sb.s_prealloc_dir_blocks, NULL, 1,
                  parse_uint },
        { "reserved_gdt_blocks", &set_sb.s_reserved_gdt_blocks, NULL, 2,
                  parse_uint },
        { "journal_uuid", &set_sb.s_journal_uuid, NULL, 16, parse_uuid },
        { "journal_inum", &set_sb.s_journal_inum, NULL, 4, parse_uint },
        { "journal_dev", &set_sb.s_journal_dev, NULL, 4, parse_uint },
        { "last_orphan", &set_sb.s_last_orphan, NULL, 4, parse_uint },
        { "hash_seed", &set_sb.s_hash_seed, NULL, 16, parse_uuid },
        { "def_hash_version", &set_sb.s_def_hash_version, NULL, 1, parse_hashalg },
        { "jnl_backup_type", &set_sb.s_jnl_backup_type, NULL, 1, parse_uint },
        { "desc_size", &set_sb.s_desc_size, NULL, 2, parse_uint },
        { "default_mount_opts", &set_sb.s_default_mount_opts, NULL, 4, parse_uint },
        { "first_meta_bg", &set_sb.s_first_meta_bg, NULL, 4, parse_uint },
        { "mkfs_time", &set_sb.s_mkfs_time, NULL, 4, parse_time },
        { "jnl_blocks", &set_sb.s_jnl_blocks[0], NULL, 4, parse_uint, FLAG_ARRAY,
          17 },
        { "min_extra_isize", &set_sb.s_min_extra_isize, NULL, 2, parse_uint },
        { "want_extra_isize", &set_sb.s_want_extra_isize, NULL, 2, parse_uint },
        { "flags", &set_sb.s_flags, NULL, 4, parse_uint },
        { "raid_stride", &set_sb.s_raid_stride, NULL, 2, parse_uint },
        { "mmp_interval", &set_sb.s_mmp_update_interval, NULL, 2, parse_uint },
        { "mmp_block", &set_sb.s_mmp_block, NULL, 8, parse_uint },
        { "raid_stripe_width", &set_sb.s_raid_stripe_width, NULL, 4, parse_uint },
        { "log_groups_per_flex", &set_sb.s_log_groups_per_flex, NULL, 1, parse_uint },
        { "kbytes_written", &set_sb.s_kbytes_written, NULL, 8, parse_uint },
        { "snapshot_inum", &set_sb.s_snapshot_inum, NULL, 4, parse_uint },
        { "snapshot_id", &set_sb.s_snapshot_id, NULL, 4, parse_uint },
        { "snapshot_r_blocks_count", &set_sb.s_snapshot_r_blocks_count,
          NULL, 8, parse_uint },
        { "snapshot_list", &set_sb.s_snapshot_list, NULL, 4, parse_uint },
        { "mount_opts",  &set_sb.s_mount_opts, NULL, 64, parse_string },
        { "usr_quota_inum", &set_sb.s_usr_quota_inum, NULL, 4, parse_uint },
        { "grp_quota_inum", &set_sb.s_grp_quota_inum, NULL, 4, parse_uint },
        { "prj_quota_inum", &set_sb.s_prj_quota_inum, NULL, 4, parse_uint },
        { "overhead_blocks", &set_sb.s_overhead_blocks, NULL, 4, parse_uint },
        { "backup_bgs", &set_sb.s_backup_bgs[0], NULL, 4, parse_uint,
          FLAG_ARRAY, 2 },
        { "checksum", &set_sb.s_checksum, NULL, 4, parse_uint },
        { "checksum_type", &set_sb.s_checksum_type, NULL, 1, parse_uint },
        { "encryption_level", &set_sb.s_encryption_level, NULL, 1, parse_uint },
        { "error_count", &set_sb.s_error_count, NULL, 4, parse_uint },
        { "first_error_time", &set_sb.s_first_error_time, NULL, 4, parse_time },
        { "first_error_ino", &set_sb.s_first_error_ino, NULL, 4, parse_uint },
        { "first_error_block", &set_sb.s_first_error_block, NULL, 8, parse_uint },
        { "first_error_func", &set_sb.s_first_error_func, NULL, 32, parse_string },
        { "first_error_line", &set_sb.s_first_error_line, NULL, 4, parse_uint },
        { "last_error_time", &set_sb.s_last_error_time, NULL, 4, parse_time },
        { "last_error_ino", &set_sb.s_last_error_ino, NULL, 4, parse_uint },
        { "last_error_block", &set_sb.s_last_error_block, NULL, 8, parse_uint },
        { "last_error_func", &set_sb.s_last_error_func, NULL, 32, parse_string },
        { "last_error_line", &set_sb.s_last_error_line, NULL, 4, parse_uint },
        { "encrypt_algos", &set_sb.s_encrypt_algos, NULL, 1, parse_uint,
          FLAG_ARRAY, 4 },
        { "encrypt_pw_salt", &set_sb.s_encrypt_pw_salt, NULL, 16, parse_uuid },
        { "lpf_ino", &set_sb.s_lpf_ino, NULL, 4, parse_uint },
        { "checksum_seed", &set_sb.s_checksum_seed, NULL, 4, parse_uint },
        { 0, 0, 0, 0 }
};

static struct field_set_info inode_fields[] = {
        { "mode", &set_inode.i_mode, NULL, 2, parse_uint },
        { "uid", &set_inode.i_uid, &set_inode.osd2.linux2.l_i_uid_high,
                2, parse_uint },
        { "size", &set_inode.i_size, &set_inode.i_size_high, 4, parse_uint },
        { "atime", &set_inode.i_atime, &set_inode.i_atime_extra,
                4, parse_time },
        { "ctime", &set_inode.i_ctime, &set_inode.i_ctime_extra,
                4, parse_time },
        { "mtime", &set_inode.i_mtime, &set_inode.i_mtime_extra,
                4, parse_time },
        { "dtime", &set_inode.i_dtime, NULL,
                4, parse_time },
        { "gid", &set_inode.i_gid, &set_inode.osd2.linux2.l_i_gid_high,
                2, parse_uint },
        { "links_count", &set_inode.i_links_count, NULL, 2, parse_uint },
        /* Special case: i_blocks is 4 bytes, i_blocks_high is 2 bytes */
        { "blocks", &set_inode.i_blocks, &set_inode.osd2.linux2.l_i_blocks_hi,
                6, parse_uint },
        { "flags", &set_inode.i_flags, NULL, 4, parse_uint },
        { "version", &set_inode.osd1.linux1.l_i_version,
                &set_inode.i_version_hi, 4, parse_uint },
        { "translator", &set_inode.osd1.hurd1.h_i_translator, NULL,
                4, parse_uint, FLAG_ALIAS },
        { "block", &set_inode.i_block[0], NULL, 4, parse_uint, FLAG_ARRAY,
          EXT2_NDIR_BLOCKS },
        { "block[IND]", &set_inode.i_block[EXT2_IND_BLOCK], NULL, 4, parse_uint },
        { "block[DIND]", &set_inode.i_block[EXT2_DIND_BLOCK], NULL, 4, parse_uint },
        { "block[TIND]", &set_inode.i_block[EXT2_TIND_BLOCK], NULL, 4, parse_uint },
        { "generation", &set_inode.i_generation, NULL, 4, parse_uint },
        /* Special case: i_file_acl_high is 2 bytes */
        { "file_acl", &set_inode.i_file_acl, 
                &set_inode.osd2.linux2.l_i_file_acl_high, 6, parse_uint },
        { "faddr", &set_inode.i_faddr, NULL, 4, parse_uint },
        { "frag", &set_inode.osd2.hurd2.h_i_frag, NULL, 1, parse_uint, FLAG_ALIAS },
        { "fsize", &set_inode.osd2.hurd2.h_i_fsize, NULL, 1, parse_uint },
        { "checksum", &set_inode.osd2.linux2.l_i_checksum_lo, 
                &set_inode.i_checksum_hi, 2, parse_inode_csum, FLAG_CSUM },
        { "author", &set_inode.osd2.hurd2.h_i_author, NULL,
                4, parse_uint, FLAG_ALIAS },
        { "extra_isize", &set_inode.i_extra_isize, NULL,
                2, parse_uint },
        { "ctime_extra", &set_inode.i_ctime_extra, NULL,
                4, parse_uint, FLAG_ALIAS },
        { "mtime_extra", &set_inode.i_mtime_extra, NULL,
                4, parse_uint, FLAG_ALIAS  },
        { "atime_extra", &set_inode.i_atime_extra, NULL,
                4, parse_uint, FLAG_ALIAS },
        { "crtime", &set_inode.i_crtime, &set_inode.i_crtime_extra,
                4, parse_time },
        { "crtime_extra", &set_inode.i_crtime_extra, NULL,
                4, parse_uint, FLAG_ALIAS },
        { "projid", &set_inode.i_projid, NULL, 4, parse_uint },
        { "bmap", NULL, NULL, 4, parse_bmap, FLAG_ARRAY },
        { 0, 0, 0, 0 }
};

static struct field_set_info ext2_bg_fields[] = {
        { "block_bitmap", &set_gd.bg_block_bitmap, NULL, 4, parse_uint },
        { "inode_bitmap", &set_gd.bg_inode_bitmap, NULL, 4, parse_uint },
        { "inode_table", &set_gd.bg_inode_table, NULL, 4, parse_uint },
        { "free_blocks_count", &set_gd.bg_free_blocks_count, NULL, 2, parse_uint },
        { "free_inodes_count", &set_gd.bg_free_inodes_count, NULL, 2, parse_uint },
        { "used_dirs_count", &set_gd.bg_used_dirs_count, NULL, 2, parse_uint },
        { "flags", &set_gd.bg_flags, NULL, 2, parse_uint },
        { "itable_unused", &set_gd.bg_itable_unused, NULL, 2, parse_uint },
        { "checksum", &set_gd.bg_checksum, NULL, 2, parse_gd_csum },
        { 0, 0, 0, 0 }
};

static struct field_set_info ext4_bg_fields[] = {
        { "block_bitmap", &set_gd4.bg_block_bitmap,
                &set_gd4.bg_block_bitmap_hi, 4, parse_uint },
        { "inode_bitmap", &set_gd4.bg_inode_bitmap,
                &set_gd4.bg_inode_bitmap_hi, 4, parse_uint },
        { "inode_table", &set_gd4.bg_inode_table,
                &set_gd4.bg_inode_table_hi, 4, parse_uint },
        { "free_blocks_count", &set_gd4.bg_free_blocks_count,
                &set_gd4.bg_free_blocks_count_hi, 2, parse_uint },
        { "free_inodes_count", &set_gd4.bg_free_inodes_count,
                &set_gd4.bg_free_inodes_count_hi, 2, parse_uint },
        { "used_dirs_count", &set_gd4.bg_used_dirs_count,
                &set_gd4.bg_used_dirs_count_hi, 2, parse_uint },
        { "flags", &set_gd4.bg_flags, NULL, 2, parse_uint },
        { "exclude_bitmap", &set_gd4.bg_exclude_bitmap_lo,
                &set_gd4.bg_exclude_bitmap_hi, 4, parse_uint },
        { "block_bitmap_csum", &set_gd4.bg_block_bitmap_csum_lo,
                &set_gd4.bg_block_bitmap_csum_hi, 2, parse_uint },
        { "inode_bitmap_csum", &set_gd4.bg_inode_bitmap_csum_lo,
                &set_gd4.bg_inode_bitmap_csum_hi, 2, parse_uint },
        { "itable_unused", &set_gd4.bg_itable_unused,
                &set_gd4.bg_itable_unused_hi, 2, parse_uint },
        { "checksum", &set_gd4.bg_checksum, NULL, 2, parse_gd_csum },
        { 0, 0, 0, 0 }
};

static struct field_set_info mmp_fields[] = {
        { "clear", &set_mmp.mmp_magic, NULL, sizeof(set_mmp),
                parse_mmp_clear, FLAG_ALIAS },
        { "magic", &set_mmp.mmp_magic, NULL, 4, parse_uint },
        { "seq", &set_mmp.mmp_seq, NULL, 4, parse_uint },
        { "time", &set_mmp.mmp_time, NULL, 8, parse_uint },
        { "nodename", &set_mmp.mmp_nodename, NULL, sizeof(set_mmp.mmp_nodename),
                parse_string },
        { "bdevname", &set_mmp.mmp_bdevname, NULL, sizeof(set_mmp.mmp_bdevname),
                parse_string },
        { "check_interval", &set_mmp.mmp_check_interval, NULL, 2, parse_uint },
        { "checksum", &set_mmp.mmp_checksum, NULL, 4, parse_uint },
        { 0, 0, 0, 0 }
};
#if __GNUC_PREREQ (4, 6)
#pragma GCC diagnostic pop
#endif

#ifdef UNITTEST


static void do_verify_field_set_info(struct field_set_info *fields,
                const void *data, size_t size)
{
        struct field_set_info *ss, *ss2;
        const char *begin = (char *)data;
        const char *end = begin + size;

        for (ss = fields ; ss->name ; ss++) {
                const char *ptr;

                /* Check pointers */
                ptr = ss->ptr;
                assert(!ptr || (ptr >= begin && ptr < end));
                ptr = ss->ptr2;
                assert(!ptr || (ptr >= begin && ptr < end));

                /* Check function */
                assert(ss->func);

                for (ss2 = fields ; ss2 != ss ; ss2++) {
                        /* Check duplicate names */
                        assert(strcmp(ss->name, ss2->name));

                        if (ss->flags & FLAG_ALIAS || ss2->flags & FLAG_ALIAS)
                                continue;
                        /* Check false aliases, might be copy-n-paste error */
                        assert(!ss->ptr || (ss->ptr != ss2->ptr &&
                                            ss->ptr != ss2->ptr2));
                        assert(!ss->ptr2 || (ss->ptr2 != ss2->ptr &&
                                             ss->ptr2 != ss2->ptr2));
                }
        }
}

int main(int argc, char **argv)
{
        do_verify_field_set_info(super_fields, &set_sb, sizeof(set_sb));
        do_verify_field_set_info(inode_fields, &set_inode, sizeof(set_inode));
        do_verify_field_set_info(ext2_bg_fields, &set_gd, sizeof(set_gd));
        do_verify_field_set_info(ext4_bg_fields, &set_gd4, sizeof(set_gd4));
        do_verify_field_set_info(mmp_fields, &set_mmp, sizeof(set_mmp));
        return 0;
}

ext2_filsys current_fs;
ext2_ino_t root, cwd;

#endif /* UNITTEST */

static int check_suffix(const char *field)
{
        int len = strlen(field);

        if (len <= 3)
                return 0;
        field += len-3;
        if (!strcmp(field, "_lo"))
                return 1;
        if (!strcmp(field, "_hi"))
                return 2;
        return 0;
}

static struct field_set_info *find_field(struct field_set_info *fields,
                                         char *field)
{
        struct field_set_info *ss;
        const char      *prefix;
        char            *arg, *delim, *idx, *tmp;
        int             suffix, prefix_len;

        if (fields == super_fields)
                prefix = "s_";
        else if (fields == inode_fields)
                prefix = "i_";
        else
                prefix = "bg_";
        prefix_len = strlen(prefix);
        if (strncmp(field, prefix, prefix_len) == 0)
                field += prefix_len;

        arg = malloc(strlen(field)+1);
        if (!arg)
                return NULL;
        strcpy(arg, field);

        idx = strchr(arg, '[');
        if (idx) {
                *idx++ = 0;
                delim = idx + strlen(idx) - 1;
                if (!*idx || *delim != ']')
                        idx = 0;
                else
                        *delim = 0;
        }
        /*
         * Can we parse the number?
         */
        if (idx) {
                array_idx = strtol(idx, &tmp, 0);
                if (*tmp) {
                        *(--idx) = '[';
                        *delim = ']';
                        idx = 0;
                }
        }

        /*
         * If there is a valid _hi or a _lo suffix, strip it off
         */
        suffix = check_suffix(arg);
        if (suffix > 0)
                arg[strlen(arg)-3] = 0;

        for (ss = fields ; ss->name ; ss++) {
                if (suffix && ss->ptr2 == 0)
                        continue;
                if (ss->flags & FLAG_ARRAY) {
                        if (!idx || (strcmp(ss->name, arg) != 0))
                                continue;
                        if (ss->max_idx > 0 && array_idx >= ss->max_idx)
                                continue;
                } else {
                        if (strcmp(ss->name, arg) != 0)
                                continue;
                }
                free(arg);
                return ss;
        }
        free(arg);
        return NULL;
}

/*
 * Note: info->size == 6 is special; this means a base size 4 bytes,
 * and secondary (high) size of 2 bytes.  This is needed for the
 * special case of i_blocks_high and i_file_acl_high.
 */
static errcode_t parse_uint(struct field_set_info *info, char *field,
                            char *arg)
{
        unsigned long long n, num, mask, limit;
        int suffix = check_suffix(field);
        char *tmp;
        void *field1 = info->ptr, *field2 = info->ptr2;
        int size = (info->size == 6) ? 4 : info->size;
        union {
                __u64   *ptr64;
                __u32   *ptr32;
                __u16   *ptr16;
                __u8    *ptr8;
        } u;

        if (suffix == 1)
                field2 = 0;
        if (suffix == 2) {
                field1 = field2;
                field2 = 0;
        }

        u.ptr8 = (__u8 *) field1;
        if (info->flags & FLAG_ARRAY)
                u.ptr8 += array_idx * info->size;

        errno = 0;
        num = STRTOULL(arg, &tmp, 0);
        if (*tmp || errno) {
                fprintf(stderr, "Couldn't parse '%s' for field %s.\n",
                        arg, info->name);
                return EINVAL;
        }
        mask = ~0ULL >> ((8 - size) * 8);
        limit = ~0ULL >> ((8 - info->size) * 8);
        if (field2 && info->size != 6)
                limit = ~0ULL >> ((8 - info->size*2) * 8);

        if (num > limit) {
                fprintf(stderr, "Value '%s' exceeds field %s maximum %llu.\n",
                        arg, info->name, limit);
                return EINVAL;
        }
        n = num & mask;
        switch (size) {
        case 8:
                /* Should never get here */
                fprintf(stderr, "64-bit field %s has a second 64-bit field\n"
                        "defined; BUG?!?\n", info->name);
                *u.ptr64 = 0;
                break;
        case 4:
                *u.ptr32 = n;
                break;
        case 2:
                *u.ptr16 = n;
                break;
        case 1:
                *u.ptr8 = n;
                break;
        }
        if (!field2)
                return 0;
        n = (size == 8) ? 0 : (num >> (size*8));
        u.ptr8 = (__u8 *) field2;
        if (info->size == 6)
                size = 2;
        switch (size) {
        case 8:
                *u.ptr64 = n;
                break;
        case 4:
                *u.ptr32 = n;
                break;
        case 2:
                *u.ptr16 = n;
                break;
        case 1:
                *u.ptr8 = n;
                break;
        }
        return 0;
}

static errcode_t parse_int(struct field_set_info *info,
                           char *field EXT2FS_ATTR((unused)), char *arg)
{
        long    num;
        char *tmp;
        __s32   *ptr32;
        __s16   *ptr16;
        __s8    *ptr8;

        num = strtol(arg, &tmp, 0);
        if (*tmp) {
                fprintf(stderr, "Couldn't parse '%s' for field %s.\n",
                        arg, info->name);
                return EINVAL;
        }
        switch (info->size) {
        case 4:
                ptr32 = (__s32 *) info->ptr;
                *ptr32 = num;
                break;
        case 2:
                ptr16 = (__s16 *) info->ptr;
                *ptr16 = num;
                break;
        case 1:
                ptr8 = (__s8 *) info->ptr;
                *ptr8 = num;
                break;
        }
        return 0;
}

static errcode_t parse_string(struct field_set_info *info,
                              char *field EXT2FS_ATTR((unused)), char *arg)
{
        char    *cp = (char *) info->ptr;

        if (strlen(arg) >= info->size) {
                fprintf(stderr, "Error maximum size for %s is %d.\n",
                        info->name, info->size);
                return EINVAL;
        }
        strcpy(cp, arg);
        return 0;
}

static errcode_t parse_time(struct field_set_info *info,
                            char *field, char *arg)
{
        __s64           t;
        __u32           t_low, t_high;
        __u32           *ptr_low, *ptr_high;

        if (check_suffix(field))
                return parse_uint(info, field, arg);

        ptr_low  = (__u32 *) info->ptr;
        ptr_high = (__u32 *) info->ptr2;

        t = string_to_time(arg);

        if (t == -1) {
                fprintf(stderr, "Couldn't parse '%s' for field %s.\n",
                        arg, info->name);
                return EINVAL;
        }
        t_low = (__u32) t;
        t_high = ((t - (__s32)t) >> 32) & EXT4_EPOCH_MASK;
        *ptr_low = t_low;
        if (ptr_high)
                *ptr_high = (*ptr_high & ~EXT4_EPOCH_MASK) | t_high;
        return 0;
}

static errcode_t parse_uuid(struct field_set_info *info,
                            char *field EXT2FS_ATTR((unused)), char *arg)
{
        unsigned char * p = (unsigned char *) info->ptr;

        if ((strcasecmp(arg, "null") == 0) ||
            (strcasecmp(arg, "clear") == 0)) {
                uuid_clear(p);
        } else if (strcasecmp(arg, "time") == 0) {
                uuid_generate_time(p);
        } else if (strcasecmp(arg, "random") == 0) {
                uuid_generate(p);
        } else if (uuid_parse(arg, p)) {
                fprintf(stderr, "Invalid UUID format: %s\n", arg);
                return EINVAL;
        }
        return 0;
}

static errcode_t parse_hashalg(struct field_set_info *info,
                               char *field EXT2FS_ATTR((unused)), char *arg)
{
        int     hashv;
        unsigned char   *p = (unsigned char *) info->ptr;

        hashv = e2p_string2hash(arg);
        if (hashv < 0) {
                fprintf(stderr, "Invalid hash algorithm: %s\n", arg);
                return EINVAL;
        }
        *p = hashv;
        return 0;
}

static errcode_t parse_bmap(struct field_set_info *info,
                            char *field EXT2FS_ATTR((unused)), char *arg)
{
        blk64_t         blk;
        errcode_t       retval;
        char            *tmp;

        blk = strtoull(arg, &tmp, 0);
        if (*tmp) {
                fprintf(stderr, "Couldn't parse '%s' for field %s.\n",
                        arg, info->name);
                return EINVAL;
        }

        retval = ext2fs_bmap2(current_fs, set_ino,
                              (struct ext2_inode *) &set_inode,
                              NULL, BMAP_ALLOC | BMAP_SET, array_idx, NULL,
                              &blk);
        if (retval) {
                com_err("set_inode", retval, "while setting block map");
        }
        return retval;
}

static errcode_t parse_gd_csum(struct field_set_info *info, char *field,
                               char *arg)
{
        __u16 *checksum = info->ptr;

        if (strcmp(arg, "calc") == 0) {
                *checksum = ext2fs_group_desc_csum(current_fs, set_bg);
                printf("Checksum set to 0x%04x\n", *checksum);
                return 0;
        }
        return parse_uint(info, field, arg);
}

static errcode_t parse_inode_csum(struct field_set_info *info, char *field,
                                  char *arg)
{
        errcode_t       retval = 0;
        __u32           crc;
        int             is_large_inode = 0;
        struct ext2_inode_large *tmp_inode;

        if (strcmp(arg, "calc") == 0) {
                size_t sz = EXT2_INODE_SIZE(current_fs->super);
                struct ext2_inode_large *tmp_inode = NULL;

                retval = ext2fs_get_mem(sz, &tmp_inode);
                if (retval)
                        goto out;

                retval = ext2fs_read_inode_full(current_fs, set_ino,
                                     (struct ext2_inode *) tmp_inode,
                                     sz);
                if (retval)
                        goto out;

#ifdef WORDS_BIGENDIAN
                ext2fs_swap_inode_full(current_fs, tmp_inode,
                                       tmp_inode, 1, sz);
#endif

                if (sz > EXT2_GOOD_OLD_INODE_SIZE)
                        is_large_inode = 1;

                retval = ext2fs_inode_csum_set(current_fs, set_ino,
                                               tmp_inode);
                if (retval)
                        goto out;
#ifdef WORDS_BIGENDIAN
                crc = set_inode.i_checksum_lo =
                        ext2fs_swab16(tmp_inode->i_checksum_lo);

#else
                crc = set_inode.i_checksum_lo = tmp_inode->i_checksum_lo;
#endif
                if (is_large_inode &&
                    set_inode.i_extra_isize >=
                                (offsetof(struct ext2_inode_large,
                                          i_checksum_hi) -
                                 EXT2_GOOD_OLD_INODE_SIZE)) {
#ifdef WORDS_BIGENDIAN
                        set_inode.i_checksum_lo =
                                ext2fs_swab16(tmp_inode->i_checksum_lo);
#else
                        set_inode.i_checksum_hi = tmp_inode->i_checksum_hi;
#endif
                        crc |= ((__u32)set_inode.i_checksum_hi) << 16;
                }
                printf("Checksum set to 0x%08x\n", crc);
        out:
                ext2fs_free_mem(&tmp_inode);
                return retval;
        }
        return parse_uint(info, field, arg);
}

static void print_possible_fields(struct field_set_info *fields)
{
        struct field_set_info *ss;
        const char      *type, *cmd;
        FILE *f;
        char name[40], idx[40];

        if (fields == super_fields) {
                type = "Superblock";
                cmd = "set_super_value";
        } else if (fields == inode_fields) {
                type = "Inode";
                cmd = "set_inode";
        } else if (fields == mmp_fields) {
                type = "MMP";
                cmd = "set_mmp_value";
        } else {
                type = "Block group descriptor";
                cmd = "set_block_group";
        }
        f = open_pager();

        fprintf(f, "%s fields supported by the %s command:\n", type, cmd);

        for (ss = fields ; ss->name ; ss++) {
                type = "unknown";
                if (ss->func == parse_string)
                        type = "string";
                else if (ss->func == parse_int)
                        type = "integer";
                else if (ss->func == parse_uint)
                        type = "unsigned integer";
                else if (ss->func == parse_uuid)
                        type = "UUID";
                else if (ss->func == parse_hashalg)
                        type = "hash algorithm";
                else if (ss->func == parse_time)
                        type = "date/time";
                else if (ss->func == parse_bmap)
                        type = "set physical->logical block map";
                else if (ss->func == parse_gd_csum)
                        type = "unsigned integer OR \"calc\"";
                strcpy(name, ss->name);
                if (ss->flags & FLAG_ARRAY) {
                        if (ss->max_idx > 0)
                                sprintf(idx, "[%d]", ss->max_idx);
                        else
                                strcpy(idx, "[]");
                        strcat(name, idx);
                }
                if (ss->ptr2)
                        strcat(name, "[_hi|_lo]");
                fprintf(f, "\t%-25s\t%s\n", name, type);
        }
        close_pager(f);
}


void do_set_super(int argc, char *argv[], int sci_idx EXT2FS_ATTR((unused)),
                  void *infop EXT2FS_ATTR((unused)))
{
        const char *usage = "<field> <value>\n"
                "\t\"set_super_value -l\" will list the names of "
                "superblock fields\n\twhich can be set.";
        static struct field_set_info *ss;

        if ((argc == 2) && !strcmp(argv[1], "-l")) {
                print_possible_fields(super_fields);
                return;
        }

        if (common_args_process(argc, argv, 3, 3, "set_super_value",
                                usage, CHECK_FS_RW))
                return;

        if ((ss = find_field(super_fields, argv[1])) == 0) {
                com_err(argv[0], 0, "invalid field specifier: %s", argv[1]);
                return;
        }
        set_sb = *current_fs->super;
        if (ss->func(ss, argv[1], argv[2]) == 0) {
                *current_fs->super = set_sb;
                ext2fs_mark_super_dirty(current_fs);
        }
}

void do_set_inode(int argc, char *argv[], int sci_idx EXT2FS_ATTR((unused)),
                  void *infop EXT2FS_ATTR((unused)))
{
        const char *usage = "<inode> <field> <value>\n"
                "\t\"set_inode_field -l\" will list the names of "
                "the fields in an ext2 inode\n\twhich can be set.";
        static struct field_set_info *ss;

        if ((argc == 2) && !strcmp(argv[1], "-l")) {
                print_possible_fields(inode_fields);
                return;
        }

        if (common_args_process(argc, argv, 4, 4, "set_inode",
                                usage, CHECK_FS_RW))
                return;

        if ((ss = find_field(inode_fields, argv[2])) == 0) {
                com_err(argv[0], 0, "invalid field specifier: %s", argv[2]);
                return;
        }

        set_ino = string_to_inode(argv[1]);
        if (!set_ino)
                return;

        if (debugfs_read_inode2(set_ino,
                                (struct ext2_inode *) &set_inode, argv[1],
                                sizeof(set_inode),
                                (ss->flags & FLAG_CSUM) ?
                                READ_INODE_NOCSUM : 0))
                return;

        if (ss->func(ss, argv[2], argv[3]) == 0) {
                debugfs_write_inode2(set_ino,
                                     (struct ext2_inode *) &set_inode,
                                     argv[1], sizeof(set_inode),
                                     (ss->flags & FLAG_CSUM) ?
                                     WRITE_INODE_NOCSUM : 0);
        }
}

void do_set_block_group_descriptor(int argc, char *argv[],
                                   int sci_idx EXT2FS_ATTR((unused)),
                                   void *infop EXT2FS_ATTR((unused)))
{
        const char *usage = "<bg number> <field> <value>\n"
                "\t\"set_block_group -l\" will list the names of "
                "the fields in a block group descriptor\n\twhich can be set.";
        struct field_set_info   *table;
        struct field_set_info   *ss;
        char                    *end;
        void                    *edit, *target;
        int                     size;

        /*
         * Determine whether we are editing an ext2 or ext4 block group
         * descriptor.  Descriptors larger than ext4_group_desc cannot
         * have their fields edited yet, because they do not have any
         * names assigned.  When that happens, this function needs to
         * be updated for the new descriptor struct and fields.
         */
        if (current_fs &&
            EXT2_DESC_SIZE(current_fs->super) >= EXT2_MIN_DESC_SIZE_64BIT) {
                table = ext4_bg_fields;
                edit = &set_gd4;
                size = sizeof(set_gd4);
        } else {
                table = ext2_bg_fields;
                edit = &set_gd;
                size = sizeof(set_gd);
        }

        if ((argc == 2) && !strcmp(argv[1], "-l")) {
                print_possible_fields(table);
                return;
        }

        if (common_args_process(argc, argv, 4, 4, "set_block_group",
                                usage, CHECK_FS_RW))
                return;

        set_bg = strtoul(argv[1], &end, 0);
        if (*end) {
                com_err(argv[0], 0, "invalid block group number: %s", argv[1]);
                return;
        }

        if (set_bg >= current_fs->group_desc_count) {
                com_err(argv[0], 0, "block group number too big: %d", set_bg);
                return;
        }

        if ((ss = find_field(table, argv[2])) == 0) {
                com_err(argv[0], 0, "invalid field specifier: %s", argv[2]);
                return;
        }

        target = ext2fs_group_desc(current_fs, current_fs->group_desc, set_bg);
        memcpy(edit, target, size);
        if (ss->func(ss, argv[2], argv[3]) == 0) {
                memcpy(target, edit, size);
                ext2fs_mark_super_dirty(current_fs);
        }
}

static errcode_t parse_mmp_clear(struct field_set_info *info,
                                 char *field EXT2FS_ATTR((unused)),
                                 char *arg EXT2FS_ATTR((unused)))
{
        errcode_t retval;

        retval = ext2fs_mmp_clear(current_fs);
        if (retval != 0)
                com_err("set_mmp_value", retval, "while clearing MMP block\n");
        else
                memcpy(info->ptr, current_fs->mmp_buf, info->size);

        return 1; /* we don't need the MMP block written again */
}

#ifdef CONFIG_MMP
void do_set_mmp_value(int argc, char *argv[], int sci_idx EXT2FS_ATTR((unused)),
                      void *infop EXT2FS_ATTR((unused)))
{
        const char *usage = "<field> <value>\n"
                "\t\"set_mmp_value -l\" will list the names of "
                "MMP fields\n\twhich can be set.";
        static struct field_set_info *smmp;
        struct mmp_struct *mmp_s;
        errcode_t retval;

        if (argc == 2 && strcmp(argv[1], "-l") == 0) {
                print_possible_fields(mmp_fields);
                return;
        }

        if (check_fs_open(argv[0]))
                return;

        if (current_fs->super->s_mmp_block == 0) {
                com_err(argv[0], 0, "no MMP block allocated\n");
                return;
        }

        if (common_args_process(argc, argv, 2, 3, "set_mmp_value",
                                usage, CHECK_FS_RW))
                return;

        mmp_s = current_fs->mmp_buf;
        if (mmp_s == NULL) {
                retval = ext2fs_get_mem(current_fs->blocksize, &mmp_s);
                if (retval) {
                        com_err(argv[0], retval, "allocating MMP buffer\n");
                        return;
                }
                retval = ext2fs_mmp_read(current_fs,
                                         current_fs->super->s_mmp_block, mmp_s);
                if (retval) {
                        com_err(argv[0], retval, "reading MMP block %llu.\n",
                                (long long)current_fs->super->s_mmp_block);
                        ext2fs_free_mem(&mmp_s);
                        return;
                }
                current_fs->mmp_buf = mmp_s;
        }

        smmp = find_field(mmp_fields, argv[1]);
        if (smmp == 0) {
                com_err(argv[0], 0, "invalid field specifier: %s", argv[1]);
                return;
        }

        set_mmp = *mmp_s;
        if (smmp->func(smmp, argv[1], argv[2]) == 0) {
                ext2fs_mmp_write(current_fs, current_fs->super->s_mmp_block,
                                 &set_mmp);
                *mmp_s = set_mmp;
        }
}
#else
void do_set_mmp_value(int argc EXT2FS_ATTR((unused)),
                      char *argv[] EXT2FS_ATTR((unused)),
                      int sci_idx EXT2FS_ATTR((unused)),
                      void *infop EXT2FS_ATTR((unused)))
{
        fprintf(stdout, "MMP is unsupported, please recompile with "
                        "--enable-mmp\n");
}
#endif