干杯， 所以基本上我需要创建一个名为my_open，my_read，my_write和my_close的函数来操作Ext2文件系统映像。这一切都需要用C语言（我所知道的唯一语言）来完成。 我编写了一些代码来打印源自文件系统中根目录的所有目录和文件，但我希望能够使用此代码来操作文件系统。这是我的代码：
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include "/include/ext2.h"
#define BASE_OFFSET 1024
#define BLOCK_OFFSET(block) (BASE_OFFSET+(block-1)*block_size)
#define NAMELEN 255
unsigned int block_size = 0;
void read_inode(int, int, const struct ext2_group_desc*, struct ext2_inode*);
void read_dir(int, struct ext2_inode*, const struct ext2_group_desc*, char *);
int main(int argc, char *argv[]) {
char imgname[BASE_OFFSET];
struct ext2_super_block super_block;
struct ext2_group_desc block_group;
struct ext2_inode inode;
int fd;
if (argc > 1)
strcpy(imgname, argv[1]);
else
fprintf(stderr, " Command Usage: step1 %s ", imgname);
if ((fd = open(imgname, O_RDONLY)) < 0) {
fprintf(stderr, "Usage: step1 %s", argv[1]);
exit(1);
}
fd = open(imgname, O_RDONLY);
if(lseek(fd, BASE_OFFSET, SEEK_SET) < 0) {
fprintf(stderr,"unable to seek\n");
exit(0);
}
/* read super-block */
lseek(fd, BASE_OFFSET, SEEK_SET);
read(fd, &super_block, sizeof(super_block));
block_size = 1024 << super_block.s_log_block_size;
/* read group descriptor */
lseek(fd, BASE_OFFSET + block_size, SEEK_SET);
read(fd, &block_group, sizeof(block_group));
/* show entries in the root directory */
read_inode(fd, 2, &block_group, &inode); /* read inode 2 (root directory) */
read_dir(fd, &inode, &block_group, "/");
close(fd);
exit(0);
}
void read_inode(int fd, int inode_no, const struct ext2_group_desc *block_group, struct ext2_inode *inode)
{
lseek(fd, BLOCK_OFFSET(block_group->bg_inode_table)+(inode_no-1)*sizeof(struct ext2_inode),
SEEK_SET);
read(fd, inode, sizeof(struct ext2_inode));
}
void read_dir(int fd, struct ext2_inode *inode, const struct ext2_group_desc *block_group, char *prefix)
{
void *block;
if (S_ISDIR(inode->i_mode)) {
struct ext2_dir_entry_2 *entry;
unsigned int size = 0;
char *tmpprefix;
//prefix = malloc (siozeof(char) * BASE_OFFSET);
if ((block = malloc(block_size)) == NULL) {
fprintf(stderr, "Not enough Memory.\n");
close(fd);
exit(1);
}
lseek(fd, BLOCK_OFFSET(inode->i_block[0]), SEEK_SET);
read(fd, block, block_size);
entry = (struct ext2_dir_entry_2 *) block; /* first entry in the directory */
//entry (entry->inode == NULL)
while((size < inode->i_size) && entry->inode) {
char file_name[NAMELEN+1];
memcpy(file_name, entry->name, entry->name_len);
file_name[entry->name_len] = 0; /* append null character */
if (*file_name != '.')
//if (strcmp(file_name,".") == 0 || strcmp(file_name,"..")== 0) continue;
if (entry->file_type == 2) {
printf("%10u %s%s/\n", entry->inode, prefix,file_name);
read_inode(fd, entry->inode, block_group, inode);
tmpprefix = (char *)malloc(strlen(file_name)+strlen(prefix)+2);
sprintf(tmpprefix, "%s%s/",prefix,file_name);
read_dir(fd, inode, block_group, tmpprefix);
free(tmpprefix);
}
else {
printf("%10u %s%s\n", entry->inode, prefix, file_name);
}
entry = (void*) entry + entry->rec_len;
size += entry->rec_len;
}
free(block);
}
}
/*
my_open(char *fn, int mode)
{
}
my_close(char *fn, descriptor)
{
}
my_read()
{
}
my_write()
{
}
*/
这是我的Header文件，其结构为：
/*
__u32 * Structure of the super block
*/
#include <linux/types.h>
#define EXT2_NDIR_BLOCKS 12
#define EXT2_IND_BLOCK EXT2_NDIR_BLOCKS
#define EXT2_DIND_BLOCK (EXT2_IND_BLOCK + 1)
#define EXT2_TIND_BLOCK (EXT2_DIND_BLOCK + 1)
#define EXT2_N_BLOCKS (EXT2_TIND_BLOCK + 1)
#define EXT2_NAME_LEN 255
struct ext2_super_block
{
__u32 s_inodes_count; /* Inodes count */
__u32 s_blocks_count; /* Blocks count */
__u32 s_r_blocks_count; /* Reserved blocks count */
__u32 s_free_blocks_count; /* Free blocks count */
__u32 s_free_inodes_count; /* Free inodes */
__u32 s_first_data_block; /* First Data Block */
__u32 s_log_block_size; /* Block size */
__u32 s_log_frag_size; /* Fragment size */
__u32 s_blocks_per_group; /* # Blocks per group */
__s32 s_frags_per_group; /* # Fragments per group */
__u32 s_inodes_per_group; /* # Inodes per group */
__u32 s_mtime; /* Mount time */
__u32 s_wtime; /* Write time */
__u16 s_mnt_count; /* Mount count */
__s16 s_max_mnt_count; /* Maximal mount count */
__u16 s_magic; /* Magic signature */
__u16 s_state; /* File system state */
__u16 s_errors; /* Behaviour when detecting errors */
__u16 s_minor_rev_level; /* minor revision level */
__u32 s_lastcheck; /* time of last check */
__u32 s_checkinterval; /* max. time between checks */
__u32 s_creator_os; /* OS */
__u32 s_rev_level; /* Revision level */
__u16 s_def_resuid; /* Default uid for reserved blocks */
__u16 s_def_resgid; /* Default gid for reserved blocks */
__u32 s_first_ino; /* First non-reserved inode */
__u16 s_inode_size; /* size of inode structure */
__u16 s_block_group_nr; /* block group # of this superblock */
__u32 s_feature_compat; /* compatible feature set */
__u32 s_feature_incompat; /* incompatible feature set */
/*
__u32 * Structure of the super block
*/
#include <linux/types.h>
#define EXT2_NDIR_BLOCKS 12
#define EXT2_IND_BLOCK EXT2_NDIR_BLOCKS
#define EXT2_DIND_BLOCK (EXT2_IND_BLOCK + 1)
#define EXT2_TIND_BLOCK (EXT2_DIND_BLOCK + 1)
#define EXT2_N_BLOCKS (EXT2_TIND_BLOCK + 1)
#define EXT2_NAME_LEN 255
struct ext2_super_block
{
__u32 s_inodes_count; /* Inodes count */
__u32 s_blocks_count; /* Blocks count */
__u32 s_r_blocks_count; /* Reserved blocks count */
__u32 s_free_blocks_count; /* Free blocks count */
__u32 s_free_inodes_count; /* Free inodes */
__u32 s_first_data_block; /* First Data Block */
__u32 s_log_block_size; /* Block size */
__u32 s_log_frag_size; /* Fragment size */
__u32 s_blocks_per_group; /* # Blocks per group */
__s32 s_frags_per_group; /* # Fragments per group */
__u32 s_inodes_per_group; /* # Inodes per group */
__u32 s_mtime; /* Mount time */
__u32 s_wtime; /* Write time */
__u16 s_mnt_count; /* Mount count */
__s16 s_max_mnt_count; /* Maximal mount count */
__u16 s_magic; /* Magic signature */
__u16 s_state; /* File system state */
__u16 s_errors; /* Behaviour when detecting errors */
__u16 s_minor_rev_level; /* minor revision level */
__u32 s_lastcheck; /* time of last check */
__u32 s_checkinterval; /* max. time between checks */
__u32 s_creator_os; /* OS */
__u32 s_rev_level; /* Revision level */
__u16 s_def_resuid; /* Default uid for reserved blocks */
__u16 s_def_resgid; /* Default gid for reserved blocks */
__u32 s_first_ino; /* First non-reserved inode */
__u16 s_inode_size; /* size of inode structure */
__u16 s_block_group_nr; /* block group # of this superblock */
__u32 s_feature_compat; /* compatible feature set */
__u32 s_feature_incompat; /* incompatible feature set */
__u32 s_feature_ro_compat; /* readonly-compatible feature set */
__u8 s_uuid[16]; /* 128-bit uuid for volume */
char s_volume_name[16]; /* volume name */
char s_last_mounted[64]; /* directory where last mounted */
__u32 s_algorithm_usage_bitmap; /* For compression */
__u8 s_prealloc_blocks; /* Nr of blocks to try to preallocate */
__u8 s_prealloc_dir_blocks; /* Nr to preallocate for dirs */
__u16 s_padding1;
__u32 s_reserved[204]; /* Padding to the end of the block */
};
struct ext2_group_desc
{
__u32 bg_block_bitmap; /* Blocks bitmap block */
__u32 bg_inode_bitmap; /* Inodes bitmap block */
__u32 bg_inode_table; /* Inodes table block */
__u16 bg_free_blocks_count; /* Free blocks count */
__u16 bg_free_inodes_count; /* Free inodes count */
__u16 bg_used_dirs_count; /* Directories count */
__u16 bg_pad;
__u32 bg_reserved[3];
};
struct ext2_inode
{
__u16 i_mode; /* File mode */
__u16 i_uid; /* Low 16 bits of Owner Uid */
__u32 i_size; /* Size in bytes */
__u32 i_atime; /* Access time */
__u32 i_ctime; /* Creation time */
__u32 i_mtime; /* Modification time */
__u32 i_dtime; /* Deletion Time */
__u16 i_gid; /* Low 16 bits of Group Id */
__u16 i_links_count; /* Links count */
__u32 i_blocks; /* Blocks count */
__u32 i_flags; /* File flags */
union
{
struct {
__u32 l_i_reserved1;
} linux1;
struct {
__u32 h_i_translator;
} hurd1;
struct {
__u32 m_i_reserved1;
} masix1;
} osd1; /* OS dependent 1 */
__u32 i_block[EXT2_N_BLOCKS]; /* Pointers to blocks */
__u32 i_generation; /* File version (for NFS) */
__u32 i_file_acl; /* File ACL */
__u32 i_dir_acl; /* Directory ACL */
__u32 i_faddr; /* Fragment address */
union {
struct {
__u8 l_i_frag; /* Fragment number */
__u8 l_i_fsize; /* Fragment size */
__u16 i_pad1;
__u16 l_i_uid_high; /* these 2 fields */
__u16 l_i_gid_high; /* were reserved2[0] */
__u32 l_i_reserved2;
} linux2;
struct {
__u8 h_i_frag; /* Fragment number */
__u8 h_i_fsize; /* Fragment size */
__u16 h_i_mode_high;
__u16 h_i_uid_high;
__u16 h_i_gid_high;
__u32 h_i_author;
} hurd2;
struct {
__u8 m_i_frag; /* Fragment number */
__u8 m_i_fsize; /* Fragment size */
__u16 m_pad1;
__u32 m_i_reserved2[2];
} masix2;
} osd2;
};
struct ext2_dir_entry_2
{
__u32 inode; /* Inode number */
__u16 rec_len; /* Directory entry length */
__u8 name_len; /* Name length */
__u8 file_type;
char name[EXT2_NAME_LEN]; /* File name */
};
任何帮助将不胜感激！提前谢谢！