commit eaa7af65860b4c2091e3e5001679eaee591ef57d
Author: pjht <pjht@users.noreply.github.com>
Date:   Sat Nov 10 11:33:49 2018 -0600

    Initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..5761abc
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+*.o
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..095510f
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,17 @@
+CC = gcc
+CFLAGS = -Wall -g
+SRCS = $(wildcard *.c */*.c */*/*.c)
+OBJS = $(SRCS:.c=.o)
+MAIN = ext2prsr
+.PHONY: clean
+all: $(MAIN)
+run: $(MAIN)
+	./$(MAIN)
+debug: $(MAIN)
+	lldb $(MAIN)
+$(MAIN): $(OBJS)
+	$(CC) $(CFLAGS) -o $(MAIN) $(OBJS)
+.c.o:
+	$(CC) $(CFLAGS) $(INCLUDES) -c $<  -o $@
+clean:
+	$(RM) *.o *~ $(MAIN)
diff --git a/ext2.img b/ext2.img
new file mode 100644
index 0000000..21abeb2
Binary files /dev/null and b/ext2.img differ
diff --git a/ext2prsr b/ext2prsr
new file mode 100755
index 0000000..c334ef0
Binary files /dev/null and b/ext2prsr differ
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..e42d6ad
--- /dev/null
+++ b/main.c
@@ -0,0 +1,321 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <math.h>
+#include <stdlib.h>
+typedef struct {
+  uint32_t s_inodes_count;
+  uint32_t s_blocks_count;
+  uint32_t s_r_blocks_count;
+  uint32_t s_free_blocks_count;
+  uint32_t s_free_inodes_count;
+  uint32_t s_first_data_block;
+  uint32_t s_log_blk_size;
+  uint32_t s_log_frag_size;
+  uint32_t s_blocks_per_group;
+  uint32_t s_frags_per_group;
+  uint32_t s_inodes_per_group;
+  uint32_t s_mtime;
+  uint32_t s_wtime;
+  uint16_t s_mnt_count;
+  uint16_t s_max_mnt_count;
+  uint16_t s_magic;
+  uint16_t s_state;
+  uint16_t s_errors;
+  uint16_t s_minor_rev_level;
+  uint32_t s_lastcheck;
+  uint32_t s_checkinterval;
+  uint32_t s_creator_os;
+  uint32_t s_rev_level;
+  uint16_t s_def_resuid;
+  uint16_t s_def_resgid;
+  uint32_t s_first_ino;
+  uint16_t s_inode_size;
+  uint16_t s_block_group_nr;
+  uint32_t s_feature_compat;
+  uint32_t s_feature_incompat;
+  uint32_t s_feature_ro_compat;
+  char s_uuid[16];
+  char s_volume_name[16];
+  char s_last_mounted[64];
+  uint32_t s_algo_bitmap;
+  char s_prealloc_blocks;
+  char s_prealloc_dir_blocks;
+  char s_journal_uuid[16];
+  uint32_t s_journal_inum;
+  uint32_t s_journal_dev;
+  uint32_t s_last_orphan;
+} __attribute__((packed)) ext2_superblock;
+
+typedef enum {
+  EXT2_FEATURE_COMPAT_DIR_PREALLOC=1,
+  EXT2_FEATURE_COMPAT_IMAGIC_INODES=2,
+  EXT2_FEATURE_COMPAT_HAS_JOURNAL=4,
+  EXT2_FEATURE_COMPAT_EXT_ATTR=8,
+  EXT2_FEATURE_COMPAT_RESIZE_INO=16,
+  EXT2_FEATURE_COMPAT_DIR_INDEX=32
+}  s_feature_compat;
+
+typedef enum {
+  EXT2_FEATURE_INCOMPAT_COMPRESSION=1,
+  EXT2_FEATURE_INCOMPAT_FILETYPE=2,
+  EXT2_FEATURE_INCOMPAT_RECOVER=4,
+  EXT2_FEATURE_INCOMPAT_JOURNAL_DEV=8
+}  s_feature_incompat;
+
+typedef enum {
+  EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER=1,
+  EXT2_FEATURE_RO_COMPAT_LARGE_FILE=2,
+  EXT2_FEATURE_RO_COMPAT_BTREE_DIR=4
+}  s_feature_ro_compat;
+
+typedef struct {
+  uint32_t bg_blk_bitmap;
+  uint32_t bg_inode_bitmap;
+  uint32_t bg_inode_table;
+  uint16_t bg_free_blocks_count;
+  uint16_t bg_free_inodes_count;
+  uint16_t bg_used_dirs_count;
+  char unused[14];
+} __attribute__((packed)) blk_grp;
+
+typedef struct {
+  uint16_t i_mode;
+  uint16_t i_uid;
+  uint32_t i_size;
+  uint32_t i_atime;
+  uint32_t i_ctime;
+  uint32_t i_mtime;
+  uint32_t i_dtime;
+  uint16_t i_gid;
+  uint16_t i_links_count;
+  uint32_t i_blocks;
+  uint32_t i_flags;
+  uint32_t i_osd1;
+  uint32_t i_block[15];
+  uint32_t i_generation;
+  uint32_t i_file_acl;
+  uint32_t i_dir_acl;
+  uint32_t i_faddr;
+  uint32_t i_osd2;
+  char unused[8];
+} __attribute__((packed)) inode;
+
+typedef enum {
+  EXT2_S_IFIFO=0x100,
+  EXT2_S_IFCHR=0x2000,
+  EXT2_S_IFDIR=0x4000,
+  EXT2_S_IFBLK=0x6000,
+  EXT2_S_IFREG=0x8000,
+  EXT2_S_IFLNK=0xA000,
+  EXT2_S_IFSOCK=0xC000
+} i_mode;
+
+typedef enum {
+  EXT2_SECRM_FL=0x1,
+  EXT2_UNRM_FL=0x2,
+  EXT2_COMPR_FL=0x4,
+  EXT2_SYNC_FL=0x8,
+  EXT2_IMMUTABLE_FL=0x10,
+  EXT2_APPEND_FL=0x20,
+  EXT2_NODUMP_FL=0x40,
+  EXT2_NOATIME_FL=0x80,
+  EXT2_DIRTY_FL=0x100,
+  EXT2_COMPRBLK_FL=0x200,
+  EXT2_NOCOMPR_FL=0x400,
+  EXT2_ECOMPR_FL=0x800,
+  EXT2_BTREE_FL=0x1000,
+  EXT2_INDEX_FL=0x1000,
+  EXT2_IMAGIC_FL=0x2000,
+  EXT2_JOURNAL_DATA_FL=0x4000,
+  EXT2_RESERVED_FL=0x80000000
+} i_flags;
+
+typedef struct {
+  uint32_t inode;
+  uint16_t rec_len;
+  char name_len;
+  char file_type;
+} __attribute__((packed)) dir_entry;
+
+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];
+}
+
+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++) {
+    printf("Block group %d:\n",i);
+    printf("Number of unallocated blocks:%d\n",blk_group->bg_free_blocks_count);
+    printf("Number of unallocated inodes:%d\n",blk_group->bg_free_inodes_count);
+    blk_grps[i]=blk_group;
+    blk_group++;
+  }
+  printf("root dir:\n");
+  inode root_dir_inode=read_inode(2);
+  show_inode_info(root_dir_inode);
+  dir_entry* root_dir=read_blk(root_dir_inode.i_block[0]);
+  dir_entry* current_entry=root_dir;
+  for(int i=0;;i++) {
+    if (current_entry->file_type==0) {
+      break;
+    }
+    printf("Directory entry %d:\n",i);
+    printf("Directory entry inode:%d\n",current_entry->inode);
+    printf("Length of entry:%d\n",current_entry->rec_len);
+    printf("Length of name:%d\n",current_entry->name_len);
+    printf("File type:%d\n",current_entry->file_type);
+    printf("File name:%s\n",(char*)current_entry+sizeof(dir_entry));
+    current_entry=(dir_entry*)(((uint64_t)current_entry)+current_entry->rec_len);
+  }
+  printf("lost+found:\n");
+  inode lost_dir_inode=read_inode(11);
+  show_inode_info(lost_dir_inode);
+  printf("Block:%d\n",lost_dir_inode.i_block[0]);
+  dir_entry* lost_dir=read_blk(lost_dir_inode.i_block[0]);
+  current_entry=lost_dir;
+  for(int i=0;;i++) {
+    if (current_entry->file_type==0) {
+      break;
+    }
+    printf("Directory entry %d:\n",i);
+    printf("Directory entry inode:%d\n",current_entry->inode);
+    printf("Length of entry:%d\n",current_entry->rec_len);
+    printf("Length of name:%d\n",current_entry->name_len);
+    printf("File type:%d\n",current_entry->file_type);
+    printf("File name:%s\n",(char*)current_entry+sizeof(dir_entry));
+    current_entry=(dir_entry*)(((uint64_t)current_entry)+current_entry->rec_len);
+  }
+}