1 files changed, 378 insertions, 0 deletions

diff --git a/e2fsprogs/ext2fs/fileio.c b/e2fsprogs/ext2fs/fileio.c
new file mode 100644
index 000000000..3e42cbc32
--- /dev/null
+++ b/e2fsprogs/ext2fs/fileio.c
@@ -0,0 +1,378 @@
+/*
+ * 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 <stdio.h>
+#include <string.h>
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#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;
+        __u64                   pos;
+        blk_t                   blockno;
+        blk_t                   physblock;
+        char                    *buf;
+};
+
+#define BMAP_BUFFER (file->buf + fs->blocksize)
+
+errcode_t ext2fs_file_open2(ext2_filsys fs, ext2_ino_t ino,
+                            struct ext2_inode *inode,
+                            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), &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;
+
+        if (inode) {
+                memcpy(&file->inode, inode, sizeof(struct ext2_inode));
+        } else {
+                retval = ext2fs_read_inode(fs, ino, &file->inode);
+                if (retval)
+                        goto fail;
+        }
+        
+        retval = ext2fs_get_mem(fs->blocksize * 3, &file->buf);
+        if (retval)
+                goto fail;
+
+        *ret = file;
+        return 0;
+        
+fail:
+        if (file->buf)
+                ext2fs_free_mem(&file->buf);
+        ext2fs_free_mem(&file);
+        return retval;
+}
+
+errcode_t ext2fs_file_open(ext2_filsys fs, ext2_ino_t ino,
+                           int flags, ext2_file_t *ret)
+{
+        return ext2fs_file_open2(fs, ino, NULL, flags, ret);
+}
+
+/*
+ * 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.
+ */
+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, file->ino ? BMAP_ALLOC : 0,
+                                     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(&file->buf);
+        ext2fs_free_mem(&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, c, count = 0;
+        __u64           left;
+        char            *ptr = (char *) buf;
+
+        EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
+        fs = file->fs;
+
+        while ((file->pos < EXT2_I_SIZE(&file->inode)) && (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 = EXT2_I_SIZE(&file->inode) - 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, const void *buf,
+                            unsigned int nbytes, unsigned int *written)
+{
+        ext2_filsys     fs;
+        errcode_t       retval = 0;
+        unsigned int    start, c, count = 0;
+        const char      *ptr = (const char *) buf;
+
+        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_llseek(ext2_file_t file, __u64 offset,
+                            int whence, __u64 *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 = EXT2_I_SIZE(&file->inode) + offset;
+        else
+                return EXT2_ET_INVALID_ARGUMENT;
+
+        if (ret_pos)
+                *ret_pos = file->pos;
+
+        return 0;
+}
+
+errcode_t ext2fs_file_lseek(ext2_file_t file, ext2_off_t offset,
+                            int whence, ext2_off_t *ret_pos)
+{
+        __u64           loffset, ret_loffset;
+        errcode_t       retval;
+        
+        loffset = offset;
+        retval = ext2fs_file_llseek(file, loffset, whence, &ret_loffset);
+        if (ret_pos)
+                *ret_pos = (ext2_off_t) ret_loffset;
+        return retval;
+}
+
+
+/*
+ * This function returns the size of the file, according to the inode
+ */
+errcode_t ext2fs_file_get_lsize(ext2_file_t file, __u64 *ret_size)
+{
+        if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
+                return EXT2_ET_MAGIC_EXT2_FILE;
+        *ret_size = EXT2_I_SIZE(&file->inode);
+        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)
+{
+        __u64   size;
+
+        if (ext2fs_file_get_lsize(file, &size))
+                return 0;
+        if ((size >> 32) != 0)
+                return 0;
+        return 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;
+        file->inode.i_size_high = 0;
+        if (file->ino) {
+                retval = ext2fs_write_inode(file->fs, file->ino, &file->inode);
+                if (retval)
+                        return retval;
+        }
+
+        /* 
+         * XXX truncate inode if necessary
+         */
+
+        return 0;
+}