/**
* Set the location of the next direntry to be read via onefs_readdir().
*
* This function should only pass in locations retrieved from onefs_telldir().
*
* Ideally the seek point will still be in the readdirplus cache, and we'll
* just update our cursors. If the seek location is outside of the current
* cache we must do an expensive re-enumeration of the entire directory up
* to the offset.
*
* @param[in] handle vfs handle given in most VFS calls
* @param[in] dirp system DIR handle to set offset on
* @param[in] offset from the start of the directory where the next read
* will take place
*
* @return no return value
*/
void
onefs_seekdir(vfs_handle_struct *handle, SMB_STRUCT_DIR *dirp, long offset)
{
struct rdp_dir_state *dsp = NULL;
bool same_as_last;
bool outside_cache = false;
int ret = -1, i;
/* Fallback to default system routines if readdirplus is disabled */
if (!lp_parm_bool(SNUM(handle->conn), PARM_ONEFS_TYPE,
PARM_USE_READDIRPLUS, PARM_USE_READDIRPLUS_DEFAULT))
{
return sys_seekdir(dirp, offset);
}
/* Validate inputs */
if (offset < 0) {
DEBUG(1, ("Invalid offset %ld passed.\n", offset));
return;
}
/* Retrieve state based off DIR handle */
ret = rdp_retrieve_dir_state(dirp, &dsp, &same_as_last);
if (ret) {
DEBUG(1, ("Could not retrieve dir_state struct for "
"SMB_STRUCT_DIR pointer.\n"));
/* XXX: we can't return an error, should we ABORT rather than
* return without actually seeking? */
return;
}
/* Short cut if no work needs to be done */
if (offset == dsp->location)
return;
/* If DIR is different from last call, reset all buffers and cursors,
* and refill the global cache from the new DIR */
if (!same_as_last) {
ret = rdp_fill_cache(dsp);
if (ret <= 0)
goto out;
DEBUG(8, ("Switched global rdp cache to new DIR entry.\n"));
}
/* Check if location is outside the currently cached entries */
if (offset < dsp->location - dsp->stat_cursor) {
/* offset is before the current cache */
/* reset to the beginning of the directory */
ret = rdp_init(dsp);
if (ret) {
DEBUG(0, ("Error initializing readdirplus() buffers: "
"%s\n", strerror(ret)));
goto out;
}
outside_cache = true;
} else if (offset >
dsp->location + (dsp->stat_count - 1 - dsp->stat_cursor))
{
/* offset is after the current cache
* advance the cookie to the end of the cache */
dsp->resume_cookie = rdp_cookies[dsp->stat_count - 1];
outside_cache = true;
}
if (outside_cache) {
/* start reading from the directory, until we have the
* specified offset in our cache */
do {
dsp->location += dsp->stat_count - dsp->stat_cursor;
ret = rdp_fill_cache(dsp);
if (ret <= 0) {
DEBUG(1, ("Error seeking to offset outside the "
"cached directory entries. Offset "
"%ld \n", dsp->location));
goto out;
}
dsp->resume_cookie = rdp_cookies[dsp->stat_count - 1];
} while (offset >= dsp->location + dsp->stat_count);
}
/* Location should be within the currently cached entries */
if (offset < dsp->location &&
offset >= dsp->location - dsp->stat_cursor)
{
/* offset is within the current cache, before the cursor.
* update cursors to the new location */
int new_cursor = dsp->stat_cursor - (dsp->location - offset);
dsp->direntries_cursor = rdp_direntries;
for (i=0; i < new_cursor; i++) {
dsp->direntries_cursor +=
((SMB_STRUCT_DIRENT *)
dsp->direntries_cursor)->d_reclen;
}
dsp->stat_cursor = new_cursor;
dsp->resume_cookie = rdp_cookies[dsp->stat_cursor];
dsp->location = offset;
} else if (offset >= dsp->location &&
offset <= dsp->location + (dsp->stat_count - 1 - dsp->stat_cursor))
{
/* offset is within the current cache, at or after the cursor.
* update cursors to the new location */
int add_to_cursor = offset - dsp->location - 1;
for (i=0; i < add_to_cursor; i++) {
dsp->direntries_cursor +=
((SMB_STRUCT_DIRENT *)
dsp->direntries_cursor)->d_reclen;
}
dsp->stat_cursor += add_to_cursor;
dsp->resume_cookie = rdp_cookies[dsp->stat_cursor];
dsp->location = offset;
}
DEBUG(9, ("Seek DIR %p, location: %ld, cache cursor: %zu\n",
dsp->dirp, dsp->location, dsp->stat_cursor));
/* FALLTHROUGH */
out:
/* Set rdp_last_dirp at the end of every VFS call where the cache was
* reloaded */
rdp_last_dirp = dirp;
return;
}
void vfswrap_seekdir(vfs_handle_struct *handle, connection_struct *conn, SMB_STRUCT_DIR *dirp, long offset)
{
START_PROFILE(syscall_seekdir);
sys_seekdir(dirp, offset);
END_PROFILE(syscall_seekdir);
}
int sys_rewinddir(DIR* d) {
sys_seekdir(d, 0);
}