457 lines
15 KiB
C
457 lines
15 KiB
C
// ext2.c
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// Author: Josh Holtrop
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// Date: 08/22/04
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// Modified: 12/24/04
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#include "hos_defines.h"
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#include "fs/devices.h"
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#include "kout.h"
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#include "ext2.h"
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#include "mm/vmm.h"
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#include "fs/vfs.h"
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#include "lang/lang.h"
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#include "functions.h"
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/* Turning an inode number into a (group, inode_index) pair:
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* group = (inode - 1) / s_inodes_per_group
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* index = (inode - 1) % s_inodes_per_group
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*/
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vfs_fs_t ext2_driver = {ext2_mount_super, ext2_umount_super, ext2_stat,
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ext2__open_dir, ext2__read_dir, ext2__close_dir,
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ext2__open_file, ext2__read_file, ext2__close_file,
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ext2__open_block_file, ext2__read_block_file, ext2__close_block_file};
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// initialize the filesystem driver
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int ext2_init(int fsID)
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{
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vfs_fs_t *fs;
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if (( fs = New(vfs_fs_t) )) // give the VFS system our FS structure
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{
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*fs = ext2_driver;
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vfs_register_fs(fsID, fs);
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return 0;
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}
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return -1;
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}
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// mount the superblock of the filesystem and return a pointer to it, if valid
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void *ext2_mount_super(major_t major, minor_t minor)
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{
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ext2_super_block_t *super = kmalloc(1024);
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block_read(major, minor, 2, 2, super);
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if (super->s_magic != EXT2_MAGIC) // not an ext2 filesystem
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{
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kfree(super);
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return NULL;
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}
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return super;
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}
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// called when we are unmounting this filesystem mount
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int ext2_umount_super(vfs_mount_t *mount)
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{
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return kfree(mount->super); // free memory that the superblock was taking
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}
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// stat a file, return a structure of info about it
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int ext2_stat(vfs_mount_t *mount, char *file, vfs_stat_t *stat)
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{
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u32_t inode_number = ext2_get_inode_number(mount, file);
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if (!inode_number)
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return -1;
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ext2_inode_t inode = ext2_get_inode(mount, inode_number);
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switch(inode.i_mode & EXT2_I_MODE_TYPE_MASK)
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{
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case EXT2_I_MODE_FIFO: stat->type = VFS_FT_FIFO; break;
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case EXT2_I_MODE_CHAR: stat->type = VFS_FT_CHAR; break;
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case EXT2_I_MODE_DIR: stat->type = VFS_FT_DIR; break;
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case EXT2_I_MODE_BLOCK: stat->type = VFS_FT_BLOCK; break;
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case EXT2_I_MODE_FILE: stat->type = VFS_FT_FILE; break;
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case EXT2_I_MODE_SYM: stat->type = VFS_FT_SYMLINK; break;
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case EXT2_I_MODE_SOCK: stat->type = VFS_FT_SOCK; break;
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default: stat->type = VFS_FT_UNKNOWN; break;
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}
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stat->size = inode.i_size;
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stat->inode = inode_number;
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stat->permissions = inode.i_mode & EXT2_I_MODE_ATTR_MASK;
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stat->uid = inode.i_uid;
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stat->gid = inode.i_gid;
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stat->atime = inode.i_atime;
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stat->mtime = inode.i_mtime;
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stat->ctime = inode.i_ctime;
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stat->links = inode.i_links_count;
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return 0;
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}
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// returns the inode number that the given file name points to
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u32_t ext2_get_inode_number(vfs_mount_t *mount, char *file)
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{
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if (file[0] != '/')
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return 0;
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if (strlen(file) == 1)
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return 2; // root inode number
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char *fil = kmalloc(strlen(file));
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strcpy(fil, file + 1);
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int subs = str_split(fil, '/'); // how many levels are there to do lookups on?
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u32_t on_dir = 2; // start on the root directory
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char *lookupName = fil;
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ext2_dir_entry_t dentry;
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while (subs--)
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{
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if (ext2_dir_lookup(mount, on_dir, lookupName, &dentry))
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{
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kfree(fil);
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return 0; // entry not found
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}
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on_dir = dentry.inode;
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lookupName = str_advance(lookupName);
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}
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kfree(fil);
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return on_dir;
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}
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// lookup a file name in a directory and store the directory entry for it
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int ext2_dir_lookup(vfs_mount_t *mount, u32_t dir_inode, char *fileName, ext2_dir_entry_t *direntry)
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{
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ext2_open_dir_t *dir = ext2_open_dir(mount, dir_inode);
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if (!dir)
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return -1; // bad directory inode number
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ext2_dir_entry_t dentry;
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while (!ext2_dir_read_entry(mount, dir, &dentry))
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{
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char *dentryName = kcalloc(1, dentry.name_length + 1);
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memcpy(dentryName, dentry.name, dentry.name_length);
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int res = strcmp(fileName, dentryName);
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kfree(dentryName);
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if (!res)
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{
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*direntry = dentry;
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ext2_close_dir(mount, dir);
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return 0;
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}
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}
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ext2_close_dir(mount, dir);
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return -2;
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}
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// open a directory by inode number for reading
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ext2_open_dir_t *ext2_open_dir(vfs_mount_t *mount, u32_t inode_number)
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{
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ext2_open_dir_t *open_dir = New(ext2_open_dir_t);
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ext2_open_inode_t *open_inode = ext2_open_inode(mount, inode_number);
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if (!open_inode || ((open_inode->inode.i_mode & EXT2_I_MODE_TYPE_MASK) != EXT2_I_MODE_DIR))
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{
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kfree(open_dir);
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return NULL;
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}
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open_dir->open_inode = open_inode;
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open_dir->position = 0;
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return open_dir;
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}
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int ext2_dir_read_entry(vfs_mount_t *mount, ext2_open_dir_t *open_dir, ext2_dir_entry_t *dentry)
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{
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ext2_super_block_t *super = mount->super;
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if (open_dir->position >= open_dir->open_inode->inode.i_size)
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return -1; // EOF
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u32_t dir_block = open_dir->position >> (10 + super->s_log_block_size);
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char *block = kmalloc(2048 << super->s_log_block_size);
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ext2_inode_seek(mount, open_dir->open_inode, dir_block);
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if (ext2_read_inode_block(mount, open_dir->open_inode, block))
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ext2_read_inode_block(mount, open_dir->open_inode, block + (1024 << super->s_log_block_size));
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ext2_dir_entry_t *dir_entry = (ext2_dir_entry_t *)(block + open_dir->position % (1024 << super->s_log_block_size));
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if (!dir_entry->inode)
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{
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kfree(block);
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return -2; // EOF
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}
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memcpy(dentry, dir_entry, min(dir_entry->length, sizeof(ext2_dir_entry_t)));
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open_dir->position += dir_entry->length;
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kfree(block);
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return 0;
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}
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int ext2_close_dir(vfs_mount_t *mount, ext2_open_dir_t *open_dir)
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{
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ext2_close_inode(mount, open_dir->open_inode);
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kfree(open_dir);
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return 0;
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}
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// open an inode for reading
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ext2_open_inode_t *ext2_open_inode(vfs_mount_t *mount, u32_t inode_number)
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{
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if (ext2_inode_status(mount, inode_number) != 1)
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return NULL;
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ext2_inode_t inode = ext2_get_inode(mount, inode_number);
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ext2_open_inode_t *open_inode = New(ext2_open_inode_t);
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open_inode->inode = inode;
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open_inode->block = 0;
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open_inode->block_pointers = NULL;
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open_inode->block_pointers_start = 0;
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mount->refs++;
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return open_inode;
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}
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// seek to a certain block of an open inode
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int ext2_inode_seek(vfs_mount_t *mount, ext2_open_inode_t *open_inode, u32_t block_number)
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{
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ext2_super_block_t *super = mount->super;
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if (open_inode->inode.i_size <= (block_number << (10 + super->s_log_block_size)))
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return -1; // at or past EOF
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open_inode->block = block_number;
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return 0;
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}
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// returns number of bytes read
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int ext2_read_inode_block(vfs_mount_t *mount, ext2_open_inode_t *open_inode, void *block)
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{
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ext2_super_block_t *super = mount->super;
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if (open_inode->inode.i_size <= (open_inode->block << (10 + super->s_log_block_size)))
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return 0; // at or past EOF
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u32_t leftover_bytes = open_inode->inode.i_size - (open_inode->block << (10 + super->s_log_block_size));
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u32_t block_number = ext2_block_number(mount, open_inode);
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block_read(mount->major, mount->minor, ext2_FSToDiskBlock(block_number, super),
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2 << super->s_log_block_size, block);
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open_inode->block++;
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return min(leftover_bytes, 1024 << super->s_log_block_size);
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}
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// close an open inode
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int ext2_close_inode(vfs_mount_t *mount, ext2_open_inode_t *open_inode)
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{
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mount->refs--;
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if (open_inode->block_pointers)
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kfree(open_inode->block_pointers); // free the block pointers cache
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kfree(open_inode);
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return 0;
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}
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// check the status of an inode
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// -1: invalid inode number
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// 0: free inode
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// 1: allocated inode
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int ext2_inode_status(vfs_mount_t *mount, u32_t inode_number)
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{
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ext2_super_block_t *super = mount->super;
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if (inode_number < 1 || inode_number > super->s_inodes_count) // inode number invalid
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return -1;
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inode_number--; // turn inode_number into a 0-based index
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u32_t group = inode_number / super->s_inodes_per_group;
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u32_t index = inode_number % super->s_inodes_per_group;
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u32_t inode_bitmap_block = ext2_get_group_desc(mount, group).bg_inode_bitmap + (index >> (13 + super->s_log_block_size));
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u32_t bitmap_index = index % (8192 << super->s_log_block_size);
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u8_t *inode_bitmap = kmalloc(1024 << super->s_log_block_size);
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block_read(mount->major, mount->minor,
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ext2_FSToDiskBlock(inode_bitmap_block, super), 2 << super->s_log_block_size, inode_bitmap);
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int inode_status = (inode_bitmap[bitmap_index >> 3] >> (bitmap_index & 0x7)) & 1;
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kfree(inode_bitmap);
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return inode_status;
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}
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// check the status of a block
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// -1: invalid block number
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// 0: free block
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// 1: allocated block
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int ext2_block_status(vfs_mount_t *mount, u32_t block_number)
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{
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ext2_super_block_t *super = mount->super;
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if (block_number < super->s_first_data_block || block_number > super->s_blocks_count) // block number invalid
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return -1;
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block_number -= super->s_first_data_block;
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u32_t group = block_number / super->s_blocks_per_group;
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u32_t index = block_number % super->s_blocks_per_group;
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u32_t block_bitmap_block = ext2_get_group_desc(mount, group).bg_block_bitmap + (index >> (13 + super->s_log_block_size));
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u32_t bitmap_index = index % (8192 << super->s_log_block_size);
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u8_t *block_bitmap = kmalloc(1024 << super->s_log_block_size);
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block_read(mount->major, mount->minor,
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ext2_FSToDiskBlock(block_bitmap_block, super), 2 << super->s_log_block_size, block_bitmap);
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int block_status = (block_bitmap[bitmap_index >> 3] >> (bitmap_index & 0x7)) & 1;
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kfree(block_bitmap);
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return block_status;
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}
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// transform open_inode->block (a relative block number) to an absolute block number for the filesystem
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u32_t ext2_block_number(vfs_mount_t *mount, ext2_open_inode_t *open_inode)
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{
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if (open_inode->block < 12)
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return open_inode->inode.i_block[open_inode->block];
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ext2_super_block_t *super = mount->super;
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int pointersPerBlock = 256 << super->s_log_block_size;
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if (open_inode->block_pointers && // there is a block pointers cache block allocated
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(open_inode->block >= open_inode->block_pointers_start) && // and the block number is in it
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(open_inode->block < (open_inode->block_pointers_start + pointersPerBlock)))
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return open_inode->block_pointers[open_inode->block - open_inode->block_pointers_start];
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u32_t rel_block = open_inode->block - 12;
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if (!open_inode->block_pointers)
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open_inode->block_pointers = kmalloc(pointersPerBlock << 2);
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if (rel_block < pointersPerBlock) // indirect block in i_block[12]
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{
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block_read(mount->major, mount->minor, ext2_FSToDiskBlock(open_inode->inode.i_block[12], super),
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2 << super->s_log_block_size, open_inode->block_pointers);
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open_inode->block_pointers_start = 12;
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return open_inode->block_pointers[rel_block];
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}
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rel_block -= pointersPerBlock;
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if (rel_block < (pointersPerBlock * pointersPerBlock)) // double-indirect block in i_block[13]
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{
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block_read(mount->major, mount->minor, ext2_FSToDiskBlock(open_inode->inode.i_block[13], super),
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2 << super->s_log_block_size, open_inode->block_pointers);
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u32_t real_block = open_inode->block_pointers[rel_block / pointersPerBlock];
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block_read(mount->major, mount->minor, ext2_FSToDiskBlock(real_block, super),
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2 << super->s_log_block_size, open_inode->block_pointers);
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open_inode->block_pointers_start = 12 + pointersPerBlock + rel_block - (rel_block % pointersPerBlock);
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return open_inode->block_pointers[rel_block % pointersPerBlock];
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}
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// this code shouldn't run unless we are dealing with a 65+mb file ...
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rel_block -= pointersPerBlock * pointersPerBlock;
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block_read(mount->major, mount->minor, ext2_FSToDiskBlock(open_inode->inode.i_block[14], super),
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2 << super->s_log_block_size, open_inode->block_pointers);
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u32_t index_1 = rel_block / (pointersPerBlock * pointersPerBlock);
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u32_t leftover_1 = rel_block % (pointersPerBlock * pointersPerBlock);
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u32_t block_1 = open_inode->block_pointers[index_1];
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block_read(mount->major, mount->minor, ext2_FSToDiskBlock(block_1, super),
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2 << super->s_log_block_size, open_inode->block_pointers);
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u32_t index_2 = leftover_1 / pointersPerBlock;
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u32_t leftover_2 = leftover_1 % pointersPerBlock;
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u32_t block_2 = open_inode->block_pointers[index_2];
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block_read(mount->major, mount->minor, ext2_FSToDiskBlock(block_2, super),
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2 << super->s_log_block_size, open_inode->block_pointers);
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open_inode->block_pointers_start = 12 + (pointersPerBlock + 1) * pointersPerBlock + rel_block - (rel_block % pointersPerBlock);
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return open_inode->block_pointers[leftover_2];
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}
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// read the inode structure from the device and return it
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ext2_inode_t ext2_get_inode(vfs_mount_t *mount, u32_t inode)
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{
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ext2_super_block_t *super = mount->super;
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inode--; // turn inode into a 0-based index
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u32_t group = inode / super->s_inodes_per_group;
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u32_t index = inode % super->s_inodes_per_group;
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u32_t inodeAddr = (ext2_get_group_desc(mount, group).bg_inode_table <<
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(10 + super->s_log_block_size)) + (index << 7);
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void *block = kmalloc(512);
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block_read(mount->major, mount->minor, inodeAddr >> 9, 1, block);
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ext2_inode_t in = *(ext2_inode_t *)(block + (inodeAddr & 0x1FF));
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kfree(block);
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return in;
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}
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// read the group descriptor structure from the device and return it
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ext2_group_desc_t ext2_get_group_desc(vfs_mount_t *mount, u32_t group)
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{
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ext2_super_block_t *super = mount->super;
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u32_t groupDescAddr = ((1 + super->s_first_data_block) << (10 + super->s_log_block_size)) + (group << 5);
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void *block = kmalloc(512);
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block_read(mount->major, mount->minor, groupDescAddr >> 9, 1, block);
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ext2_group_desc_t gd = *(ext2_group_desc_t *)(block + (groupDescAddr & 0x1FF));
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kfree(block);
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return gd;
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}
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int ext2__open_dir(vfs_mount_t *mount, char *file, vfs_open_file_t *dir)
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{
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u32_t dir_inode = ext2_get_inode_number(mount, file);
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if (!dir_inode)
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return -1;
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ext2_open_dir_t *open_dir = ext2_open_dir(mount, dir_inode);
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if (!open_dir)
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return -2;
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dir->fs_data = open_dir;
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return 0;
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}
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int ext2__read_dir(vfs_mount_t *mount, vfs_open_file_t *dir, vfs_dir_entry_t *dentry)
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{
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ext2_dir_entry_t t_dentry;
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int status = ext2_dir_read_entry(mount, dir->fs_data, &t_dentry);
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if (status)
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return status;
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memcpy(dentry->name, t_dentry.name, t_dentry.name_length);
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dentry->name[t_dentry.name_length] = 0;
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return 0;
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}
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int ext2__close_dir(vfs_mount_t *mount, vfs_open_file_t *dir)
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{
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return ext2_close_dir(mount, dir->fs_data);
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}
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int ext2__open_file(vfs_mount_t *mount, char *file, vfs_open_file_t *open_file)
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{
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}
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int ext2__read_file(vfs_mount_t *mount, vfs_open_file_t *open_file)
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{
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}
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int ext2__close_file(vfs_mount_t *mount, vfs_open_file_t *open_file)
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{
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}
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int ext2__open_block_file(vfs_mount_t *mount, char *file, vfs_open_file_t *open_file)
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{
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u32_t file_inode = ext2_get_inode_number(mount, file);
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if (!file_inode)
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return -1;
|
|
ext2_open_inode_t *open_inode = ext2_open_inode(mount, file_inode);
|
|
if (!open_inode)
|
|
return -2;
|
|
ext2__open_block_file_t *open_block_file = New(ext2__open_block_file_t);
|
|
open_block_file->open_inode = open_inode;
|
|
open_block_file->block = 0;
|
|
open_file->fs_data = open_block_file;
|
|
return 0;
|
|
}
|
|
|
|
// returns the number of bytes read
|
|
int ext2__read_block_file(vfs_mount_t *mount, vfs_open_file_t *open_file, void *buffer)
|
|
{
|
|
ext2_super_block_t *super = mount->super;
|
|
ext2__open_block_file_t *open_block_file = open_file->fs_data;
|
|
if (ext2_inode_seek(mount, open_block_file->open_inode, ext2_diskToFSBlock(open_block_file->block, super)))
|
|
return 0; // EOF
|
|
u8_t *block = kmalloc(1024 << super->s_log_block_size);
|
|
u32_t file_position_read = (1024 << super->s_log_block_size) * open_block_file->open_inode->block;
|
|
u32_t file_position_want = open_block_file->block << 9;
|
|
u32_t data_offset = file_position_want - file_position_read;
|
|
int bytes_read = ext2_read_inode_block(mount, open_block_file->open_inode, block);
|
|
if (bytes_read <= data_offset)
|
|
{
|
|
kfree(block);
|
|
return 0; // EOF
|
|
}
|
|
memcpy(buffer, block + data_offset, 512);
|
|
kfree(block);
|
|
return min(512, bytes_read - data_offset);
|
|
}
|
|
|
|
int ext2__close_block_file(vfs_mount_t *mount, vfs_open_file_t *open_file)
|
|
{
|
|
ext2__open_block_file_t *open_block_file = open_file->fs_data;
|
|
ext2_close_inode(mount, open_block_file->open_inode);
|
|
kfree(open_block_file);
|
|
return 0;
|
|
}
|
|
|
|
|
|
|
|
|