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ext2_parser/main.c

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8.3 KiB
C
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#include <stdio.h>
#include <stdint.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include "ext2_structs.h"
char img[33554432];
ext2_superblock* supblk;
uint32_t blk_size;
blk_grp** blk_grps;
void show_supblk_info(int num_blk_grps) {
printf("Num block groups:%d\n",num_blk_grps);
printf("Number of blocks per group:%d\n",supblk->s_blocks_per_group);
printf("Number of inodes per group:%d\n",supblk->s_inodes_per_group);
printf("Number of unallocated blocks:%d\n",supblk->s_free_blocks_count);
printf("Number of unallocated inodes:%d\n",supblk->s_free_inodes_count);
printf("Optional features:");
if ((supblk->s_feature_compat&EXT2_FEATURE_COMPAT_DIR_PREALLOC)!=0) {
printf("DIR_PREALLOC ");
}
if ((supblk->s_feature_compat&EXT2_FEATURE_COMPAT_IMAGIC_INODES)!=0) {
printf("IMAGIC_INODES ");
}
if ((supblk->s_feature_compat&EXT2_FEATURE_COMPAT_HAS_JOURNAL)!=0) {
printf("HAS_JOURNAL ");
}
if ((supblk->s_feature_compat&EXT2_FEATURE_COMPAT_EXT_ATTR)!=0) {
printf("EXT_ATTR ");
}
if ((supblk->s_feature_compat&EXT2_FEATURE_COMPAT_RESIZE_INO)!=0) {
printf("RESIZE_INO ");
}
if ((supblk->s_feature_compat&EXT2_FEATURE_COMPAT_DIR_INDEX)!=0) {
printf("DIR_INDEX ");
}
printf("\n");
printf("Required features:");
if ((supblk->s_feature_incompat&EXT2_FEATURE_INCOMPAT_COMPRESSION)!=0) {
printf("COMPRESSION ");
}
if ((supblk->s_feature_incompat&EXT2_FEATURE_INCOMPAT_FILETYPE)!=0) {
printf("FILETYPE ");
}
if ((supblk->s_feature_incompat&EXT2_FEATURE_INCOMPAT_RECOVER)!=0) {
printf("RECOVER ");
}
if ((supblk->s_feature_incompat&EXT2_FEATURE_INCOMPAT_JOURNAL_DEV)!=0) {
printf("JOURNAL_DEV ");
}
printf("\n");
printf("Readonly features:");
if ((supblk->s_feature_ro_compat&EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)!=0) {
printf("SPARSE_SUPER ");
}
if ((supblk->s_feature_ro_compat&EXT2_FEATURE_RO_COMPAT_LARGE_FILE)!=0) {
printf("LARGE_FILE ");
}
if ((supblk->s_feature_ro_compat&EXT2_FEATURE_RO_COMPAT_BTREE_DIR)!=0) {
printf("BTREE_DIR ");
}
printf("\n");
}
void show_inode_info(inode inod) {
printf("Flags:");
if ((inod.i_flags&EXT2_SECRM_FL)!=0) {
printf("SECRM_FL");
}
if ((inod.i_flags&EXT2_UNRM_FL)!=0) {
printf("UNRM_FL");
}
if ((inod.i_flags&EXT2_COMPR_FL)!=0) {
printf("COMPR_FL");
}
if ((inod.i_flags&EXT2_SYNC_FL)!=0) {
printf("SYNC_FL");
}
if ((inod.i_flags&EXT2_IMMUTABLE_FL)!=0) {
printf("IMMUTABLE_FL");
}
if ((inod.i_flags&EXT2_APPEND_FL)!=0) {
printf("APPEND_FL");
}
if ((inod.i_flags&EXT2_NODUMP_FL)!=0) {
printf("NODUMP_FL");
}
if ((inod.i_flags&EXT2_NOATIME_FL)!=0) {
printf("NOATIME_FL");
}
if ((inod.i_flags&EXT2_DIRTY_FL)!=0) {
printf("DIRTY_FL");
}
if ((inod.i_flags&EXT2_COMPRBLK_FL)!=0) {
printf("COMPRBLK_FL");
}
if ((inod.i_flags&EXT2_NOCOMPR_FL)!=0) {
printf("NOCOMPR_FL");
}
if ((inod.i_flags&EXT2_ECOMPR_FL)!=0) {
printf("ECOMPR_FL");
}
if ((inod.i_flags&EXT2_BTREE_FL)!=0) {
printf("BTREE_FL");
}
if ((inod.i_flags&EXT2_INDEX_FL)!=0) {
printf("INDEX_FL");
}
if ((inod.i_flags&EXT2_IMAGIC_FL)!=0) {
printf("IMAGIC_FL");
}
if ((inod.i_flags&EXT2_JOURNAL_DATA_FL)!=0) {
printf("JOURNAL_DATA_FL");
}
if ((inod.i_flags&EXT2_RESERVED_FL)!=0) {
printf("RESERVED_FL");
}
printf("\n");
}
void* read_blk(blknum) {
return (void*)(&img[blknum*1024]);
}
inode read_inode(uint32_t inode_num) {
uint32_t grp=(inode_num-1)/supblk->s_inodes_per_group;
uint32_t index=(inode_num-1)%supblk->s_inodes_per_group;
uint32_t starting_blk=blk_grps[grp]->bg_inode_table;
inode* inodes=read_blk(starting_blk);
return inodes[index];
}
char** get_dir_listing(uint32_t inode_num) {
char** names=malloc(sizeof(char*)*100);
int num_entries_used=0;
int max_len=100;
inode dir_inode=read_inode(inode_num);
uint32_t size=dir_inode.i_size;
uint32_t tot_size=0;
dir_entry* dir=read_blk(dir_inode.i_block[0]);
dir_entry* current_entry=dir;
for(int i=0;tot_size<size;i++) {
if (current_entry->file_type==0) {
break;
}
if(num_entries_used==max_len) {
max_len+=100;
names=realloc(names,sizeof(char*)*max_len);
}
names[num_entries_used]=malloc(current_entry->name_len+1);
strcpy(names[num_entries_used],current_entry->file_name);
names[num_entries_used][current_entry->name_len]='\0';
num_entries_used++;
tot_size+=current_entry->rec_len;
current_entry=(dir_entry*)(((uint64_t)current_entry)+current_entry->rec_len);
}
if(num_entries_used==max_len) {
max_len+=1;
names=realloc(names,sizeof(char*)*max_len);
}
names[num_entries_used]=NULL;
return names;
}
void free_dir_listing(char** names) {
for(int i=0;names[i]!=NULL;i++) {
free(names[i]);
}
free(names);
}
dir_entry* read_dir_entry(uint32_t inode_num,uint32_t dir_entry_num) {
inode dir_inode=read_inode(inode_num);
uint32_t size=dir_inode.i_size;
uint32_t tot_size=0;
uint32_t ent_num=0;
dir_entry* dir=read_blk(dir_inode.i_block[0]);
dir_entry* current_entry=dir;
for(int i=0;tot_size<size;i++) {
if (current_entry->file_type==0) {
break;
}
if(ent_num==dir_entry_num) {
return current_entry;
}
ent_num++;
tot_size+=current_entry->rec_len;
current_entry=(dir_entry*)(((uint64_t)current_entry)+current_entry->rec_len);
}
return NULL;
}
uint32_t inode_for_fname(uint32_t dir_inode_num, char* name, char* got_inode) {
uint32_t inode=0;
*got_inode=0;
char** names=get_dir_listing(dir_inode_num);
for(int i=0;names[i]!=NULL;i++) {
if (strcmp(names[i],name)==0) {
dir_entry* entry=read_dir_entry(dir_inode_num,i);
inode=entry->inode;
*got_inode=1;
break;
}
}
free_dir_listing(names);
return inode;
}
char* fname_for_inode(uint32_t dir_inode_num, uint32_t inode_num) {
for(int i=0;;i++) {
dir_entry* entry=read_dir_entry(dir_inode_num,i);
if (entry) {
if (entry->inode==inode_num) {
char* name=malloc(strlen(entry->file_name)+1);
strcpy(name,entry->file_name);
return name;
}
} else {
break;
}
}
return NULL;
}
int main() {
FILE* f=fopen("ext2.img","rb");
if (f) {
fread(img,1,32*1024*1024,f);
fclose(f);
}
supblk=read_blk(1);
blk_size=1024<<(supblk->s_log_blk_size);
double num_blk_grps_dbl=supblk->s_blocks_count/(double)supblk->s_blocks_per_group;
uint32_t num_blk_grps=ceil(num_blk_grps_dbl);
// show_supblk_info(num_blk_grps);
blk_grps=malloc(sizeof(blk_grp*)*num_blk_grps);
blk_grp* blk_group=read_blk(2);
for (int i=0;i<num_blk_grps;i++) {
blk_grps[i]=blk_group;
blk_group++;
};
uint32_t cwi=2;
while(1) {
printf(">");
char line[256];
fgets(line,256,stdin);
line[strlen(line)-1]='\0';
char* cmd=strtok(line," ");
if (strcmp(cmd,"ls")==0) {
char** names=get_dir_listing(cwi);
for(int i=0;names[i]!=NULL;i++) {
printf("%s ",names[i]);
}
printf("\n");
free_dir_listing(names);
} else if (strcmp(cmd,"inode")==0) {
char* name=strtok(NULL," ");
char got_inode;
uint32_t inode=inode_for_fname(cwi,name,&got_inode);
if (got_inode) {
printf("Inode for %s:%d\n",name,inode);
} else {
printf("inode: %s: No such file or directory\n",name);
}
} else if (strcmp(cmd,"cd")==0) {
char* name=strtok(NULL," ");
char got_inode;
uint32_t inode_num=inode_for_fname(cwi,name,&got_inode);
if (got_inode) {
inode dir_inode=read_inode(inode_num);
if ((dir_inode.i_mode&EXT2_S_IFDIR)!=0) {
cwi=inode_num;
} else {
printf("cd: %s: Not a directory\n",name);
}
} else {
printf("cd: %s: No such file or directory\n",name);
}
} else if (strcmp(cmd,"pwi")==0) {
printf("%d\n",cwi);
} else if (strcmp(cmd,"cat")==0) {
char* name=strtok(NULL," ");
char got_inode;
uint32_t inode_num=inode_for_fname(cwi,name,&got_inode);
if (got_inode) {
inode file_inode=read_inode(inode_num);
char* contents=read_blk(file_inode.i_block[0]);
printf("%s",contents);
} else {
printf("type: %s: No such file or directory\n",name);
}
} else if (strcmp(cmd,"quit")==0) {
exit(0);
} else {
printf("%s: Comand not found\n",cmd);
}
}
}
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