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/* This file contains file writing system call handlers.
*
* The entry points into this file are:
* do_write perform the WRITE file system call
* do_trunc perform the TRUNC file system call
*
* Created:
* April 2009 (D.C. van Moolenbroek)
*/
#include "inc.h"
/*===========================================================================*
* write_file *
*===========================================================================*/
static ssize_t write_file(struct inode *ino, off_t pos, size_t count,
struct fsdriver_data *data)
{
/* Write data or zeroes to a file, depending on whether a valid pointer to
* a data grant was provided.
*/
size_t size, off, chunk;
char *ptr;
int r;
if (pos < 0)
return EINVAL;
assert(!IS_DIR(ino));
if ((r = get_handle(ino)) != OK)
return r;
assert(count > 0);
/* Use the buffer from below to eliminate extra copying. */
size = sffs_table->t_writebuf(&ptr);
off = 0;
while (count > 0) {
chunk = MIN(count, size);
if (data != NULL) {
if ((r = fsdriver_copyin(data, off, ptr, chunk)) != OK)
break;
} else {
/* Do this every time. We don't know what happens below. */
memset(ptr, 0, chunk);
}
if ((r = sffs_table->t_write(ino->i_file, ptr, chunk, pos)) <= 0)
break;
count -= r;
off += r;
pos += r;
}
if (r < 0)
return r;
return off;
}
/*===========================================================================*
* do_write *
*===========================================================================*/
ssize_t do_write(ino_t ino_nr, struct fsdriver_data *data, size_t count,
off_t pos, int call)
{
/* Write data to a file.
*/
struct inode *ino;
if (read_only)
return EROFS;
if ((ino = find_inode(ino_nr)) == NULL)
return EINVAL;
if (IS_DIR(ino)) return EISDIR;
if (count == 0) return 0;
return write_file(ino, pos, count, data);
}
/*===========================================================================*
* do_trunc *
*===========================================================================*/
int do_trunc(ino_t ino_nr, off_t start, off_t end)
{
/* Change file size or create file holes.
*/
char path[PATH_MAX];
struct inode *ino;
struct sffs_attr attr;
uint64_t delta;
ssize_t r;
if (read_only)
return EROFS;
if ((ino = find_inode(ino_nr)) == NULL)
return EINVAL;
if (IS_DIR(ino)) return EISDIR;
if (end == 0) {
/* Truncate or expand the file. */
if ((r = verify_inode(ino, path, NULL)) != OK)
return r;
attr.a_mask = SFFS_ATTR_SIZE;
attr.a_size = start;
r = sffs_table->t_setattr(path, &attr);
} else {
/* Write zeroes to the file. We can't create holes. */
if (end <= start) return EINVAL;
delta = (uint64_t)end - (uint64_t)start;
if (delta > SSIZE_MAX) return EINVAL;
if ((r = write_file(ino, start, (size_t)delta, NULL)) >= 0)
r = OK;
}
return r;
}
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