minix/lib/libsffs/write.c
Ben Gras 2bfeeed885 drop segment from safecopy invocations
. all invocations were S or D, so can safely be dropped
	  to prepare for the segmentless world
	. still assign D to the SCP_SEG field in the message
	  to make previous kernels usable
2012-06-16 16:22:51 +00:00

164 lines
3.4 KiB
C

/* This file contains file writing system call handlers.
*
* The entry points into this file are:
* do_write perform the WRITE file system call
* do_ftrunc perform the FTRUNC file system call
*
* Created:
* April 2009 (D.C. van Moolenbroek)
*/
#include "inc.h"
static int write_file(struct inode *ino, u64_t *posp, size_t *countp,
cp_grant_id_t *grantp);
/*===========================================================================*
* write_file *
*===========================================================================*/
static int write_file(ino, posp, countp, grantp)
struct inode *ino;
u64_t *posp;
size_t *countp;
cp_grant_id_t *grantp;
{
/* Write data or zeroes to a file, depending on whether a valid pointer to
* a data grant was provided.
*/
u64_t pos;
size_t count, size;
vir_bytes off;
char *ptr;
int r, chunk;
assert(!IS_DIR(ino));
if ((r = get_handle(ino)) != OK)
return r;
pos = *posp;
count = *countp;
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 (grantp != NULL) {
r = sys_safecopyfrom(m_in.m_source, *grantp,
off, (vir_bytes) ptr, chunk);
if (r != 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 = add64u(pos, r);
}
if (r < 0)
return r;
*posp = pos;
*countp = off;
return OK;
}
/*===========================================================================*
* do_write *
*===========================================================================*/
int do_write()
{
/* Write data to a file.
*/
struct inode *ino;
u64_t pos;
size_t count;
cp_grant_id_t grant;
int r;
if (state.s_read_only)
return EROFS;
if ((ino = find_inode(m_in.REQ_INODE_NR)) == NULL)
return EINVAL;
if (IS_DIR(ino)) return EISDIR;
pos = make64(m_in.REQ_SEEK_POS_LO, m_in.REQ_SEEK_POS_HI);
count = m_in.REQ_NBYTES;
grant = m_in.REQ_GRANT;
if (count == 0) return EINVAL;
if ((r = write_file(ino, &pos, &count, &grant)) != OK)
return r;
m_out.RES_SEEK_POS_HI = ex64hi(pos);
m_out.RES_SEEK_POS_LO = ex64lo(pos);
m_out.RES_NBYTES = count;
return OK;
}
/*===========================================================================*
* do_ftrunc *
*===========================================================================*/
int do_ftrunc()
{
/* Change file size or create file holes.
*/
char path[PATH_MAX];
struct inode *ino;
struct sffs_attr attr;
u64_t start, end, delta;
size_t count;
int r;
if (state.s_read_only)
return EROFS;
if ((ino = find_inode(m_in.REQ_INODE_NR)) == NULL)
return EINVAL;
if (IS_DIR(ino)) return EISDIR;
start = make64(m_in.REQ_TRC_START_LO, m_in.REQ_TRC_START_HI);
end = make64(m_in.REQ_TRC_END_LO, m_in.REQ_TRC_END_HI);
if (cmp64u(end, 0) == 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 (cmp64(end, start) <= 0) return EINVAL;
delta = sub64(end, start);
if (ex64hi(delta) != 0) return EINVAL;
count = ex64lo(delta);
r = write_file(ino, &start, &count, NULL);
}
return r;
}