From d1e063beb43e595680c65e3804d1f8ddff53373b Mon Sep 17 00:00:00 2001 From: Guido Guenther Date: Sat, 18 Nov 2006 23:48:07 +0100 Subject: Imported Debian version 0.3.8.8 --- e2fslib/fileio.c | 336 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 336 insertions(+) create mode 100644 e2fslib/fileio.c (limited to 'e2fslib/fileio.c') diff --git a/e2fslib/fileio.c b/e2fslib/fileio.c new file mode 100644 index 0000000..80e5032 --- /dev/null +++ b/e2fslib/fileio.c @@ -0,0 +1,336 @@ +/* + * fileio.c --- Simple file I/O routines + * + * Copyright (C) 1997 Theodore Ts'o. + * + * %Begin-Header% + * This file may be redistributed under the terms of the GNU Public + * License. + * %End-Header% + */ + +#include +#include +#if HAVE_UNISTD_H +#include +#endif + +#include "ext2_fs.h" +#include "ext2fs.h" + +struct ext2_file { + errcode_t magic; + ext2_filsys fs; + ext2_ino_t ino; + struct ext2_inode inode; + int flags; + ext2_off_t pos; + blk_t blockno; + blk_t physblock; + char *buf; +}; + +#define BMAP_BUFFER (file->buf + fs->blocksize) + +errcode_t ext2fs_file_open(ext2_filsys fs, ext2_ino_t ino, + int flags, ext2_file_t *ret) +{ + ext2_file_t file; + errcode_t retval; + + /* + * Don't let caller create or open a file for writing if the + * filesystem is read-only. + */ + if ((flags & (EXT2_FILE_WRITE | EXT2_FILE_CREATE)) && + !(fs->flags & EXT2_FLAG_RW)) + return EXT2_ET_RO_FILSYS; + + retval = ext2fs_get_mem(sizeof(struct ext2_file), (void **) &file); + if (retval) + return retval; + + memset(file, 0, sizeof(struct ext2_file)); + file->magic = EXT2_ET_MAGIC_EXT2_FILE; + file->fs = fs; + file->ino = ino; + file->flags = flags & EXT2_FILE_MASK; + + retval = ext2fs_read_inode(fs, ino, &file->inode); + if (retval) + goto fail; + + retval = ext2fs_get_mem(fs->blocksize * 3, (void **) &file->buf); + if (retval) + goto fail; + + *ret = file; + return 0; + +fail: + if (file->buf) + ext2fs_free_mem((void **) &file->buf); + ext2fs_free_mem((void **) &file); + return retval; +} + +/* + * This function returns the filesystem handle of a file from the structure + */ +ext2_filsys ext2fs_file_get_fs(ext2_file_t file) +{ + if (file->magic != EXT2_ET_MAGIC_EXT2_FILE) + return 0; + return file->fs; +} + +/* + * This function flushes the dirty block buffer out to disk if + * necessary. + */ +static errcode_t ext2fs_file_flush(ext2_file_t file) +{ + errcode_t retval; + ext2_filsys fs; + + EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE); + fs = file->fs; + + if (!(file->flags & EXT2_FILE_BUF_VALID) || + !(file->flags & EXT2_FILE_BUF_DIRTY)) + return 0; + + /* + * OK, the physical block hasn't been allocated yet. + * Allocate it. + */ + if (!file->physblock) { + retval = ext2fs_bmap(fs, file->ino, &file->inode, + BMAP_BUFFER, BMAP_ALLOC, + file->blockno, &file->physblock); + if (retval) + return retval; + } + + retval = io_channel_write_blk(fs->io, file->physblock, + 1, file->buf); + if (retval) + return retval; + + file->flags &= ~EXT2_FILE_BUF_DIRTY; + + return retval; +} + +/* + * This function synchronizes the file's block buffer and the current + * file position, possibly invalidating block buffer if necessary + */ +static errcode_t sync_buffer_position(ext2_file_t file) +{ + blk_t b; + errcode_t retval; + + b = file->pos / file->fs->blocksize; + if (b != file->blockno) { + retval = ext2fs_file_flush(file); + if (retval) + return retval; + file->flags &= ~EXT2_FILE_BUF_VALID; + } + file->blockno = b; + return 0; +} + +/* + * This function loads the file's block buffer with valid data from + * the disk as necessary. + * + * If dontfill is true, then skip initializing the buffer since we're + * going to be replacing its entire contents anyway. If set, then the + * function basically only sets file->physblock and EXT2_FILE_BUF_VALID + */ +#define DONTFILL 1 +static errcode_t load_buffer(ext2_file_t file, int dontfill) +{ + ext2_filsys fs = file->fs; + errcode_t retval; + + if (!(file->flags & EXT2_FILE_BUF_VALID)) { + retval = ext2fs_bmap(fs, file->ino, &file->inode, + BMAP_BUFFER, 0, file->blockno, + &file->physblock); + if (retval) + return retval; + if (!dontfill) { + if (file->physblock) { + retval = io_channel_read_blk(fs->io, + file->physblock, + 1, file->buf); + if (retval) + return retval; + } else + memset(file->buf, 0, fs->blocksize); + } + file->flags |= EXT2_FILE_BUF_VALID; + } + return 0; +} + + +errcode_t ext2fs_file_close(ext2_file_t file) +{ + errcode_t retval; + + EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE); + + retval = ext2fs_file_flush(file); + + if (file->buf) + ext2fs_free_mem((void **) &file->buf); + ext2fs_free_mem((void **) &file); + + return retval; +} + + +errcode_t ext2fs_file_read(ext2_file_t file, void *buf, + unsigned int wanted, unsigned int *got) +{ + ext2_filsys fs; + errcode_t retval = 0; + unsigned int start, left, c, count = 0; + char *ptr = (char *) buf; + + EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE); + fs = file->fs; + + while ((file->pos < file->inode.i_size) && (wanted > 0)) { + retval = sync_buffer_position(file); + if (retval) + goto fail; + retval = load_buffer(file, 0); + if (retval) + goto fail; + + start = file->pos % fs->blocksize; + c = fs->blocksize - start; + if (c > wanted) + c = wanted; + left = file->inode.i_size - file->pos ; + if (c > left) + c = left; + + memcpy(ptr, file->buf+start, c); + file->pos += c; + ptr += c; + count += c; + wanted -= c; + } + +fail: + if (got) + *got = count; + return retval; +} + + +errcode_t ext2fs_file_write(ext2_file_t file, void *buf, + unsigned int nbytes, unsigned int *written) +{ + ext2_filsys fs; + blk_t pb; + errcode_t retval = 0; + unsigned int start, c, count = 0; + char *ptr = (char *) buf; + int dontfill; + + EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE); + fs = file->fs; + + if (!(file->flags & EXT2_FILE_WRITE)) + return EXT2_ET_FILE_RO; + + while (nbytes > 0) { + retval = sync_buffer_position(file); + if (retval) + goto fail; + + start = file->pos % fs->blocksize; + c = fs->blocksize - start; + if (c > nbytes) + c = nbytes; + + /* + * We only need to do a read-modify-update cycle if + * we're doing a partial write. + */ + retval = load_buffer(file, (c == fs->blocksize)); + if (retval) + goto fail; + + file->flags |= EXT2_FILE_BUF_DIRTY; + memcpy(file->buf+start, ptr, c); + file->pos += c; + ptr += c; + count += c; + nbytes -= c; + } + +fail: + if (written) + *written = count; + return retval; +} + +errcode_t ext2fs_file_lseek(ext2_file_t file, ext2_off_t offset, + int whence, ext2_off_t *ret_pos) +{ + EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE); + + if (whence == EXT2_SEEK_SET) + file->pos = offset; + else if (whence == EXT2_SEEK_CUR) + file->pos += offset; + else if (whence == EXT2_SEEK_END) + file->pos = file->inode.i_size + offset; + else + return EXT2_ET_INVALID_ARGUMENT; + + if (ret_pos) + *ret_pos = file->pos; + + return 0; +} + +/* + * This function returns the size of the file, according to the inode + */ +ext2_off_t ext2fs_file_get_size(ext2_file_t file) +{ + if (file->magic != EXT2_ET_MAGIC_EXT2_FILE) + return 0; + return file->inode.i_size; +} + +/* + * This function sets the size of the file, truncating it if necessary + * + * XXX still need to call truncate + */ +errcode_t ext2fs_file_set_size(ext2_file_t file, ext2_off_t size) +{ + errcode_t retval; + EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE); + + file->inode.i_size = size; + retval = ext2fs_write_inode(file->fs, file->ino, &file->inode); + if (retval) + return retval; + + /* + * XXX truncate inode if necessary + */ + + return 0; +} -- cgit v1.2.3