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samba-mirror/source3/modules/vfs_preopen.c
Jelmer Vernooij c0288e0612 lib/util: Remove obsolete sys_getpid() and sys_fork().
The performance of these is minimal (these days) and they can return
invalid results when used as part of applications that do not use
sys_fork().

Autobuild-User: Jelmer Vernooij <jelmer@samba.org>
Autobuild-Date: Sat Mar 24 21:55:41 CET 2012 on sn-devel-104
2012-03-24 21:55:40 +01:00

455 lines
9.6 KiB
C

/*
* Force a readahead of files by opening them and reading the first bytes
*
* Copyright (C) Volker Lendecke 2008
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "includes.h"
#include "system/filesys.h"
#include "smbd/smbd.h"
struct preopen_state;
struct preopen_helper {
struct preopen_state *state;
struct fd_event *fde;
pid_t pid;
int fd;
bool busy;
};
struct preopen_state {
int num_helpers;
struct preopen_helper *helpers;
size_t to_read; /* How many bytes to read in children? */
int queue_max;
char *template_fname; /* Filename to be sent to children */
size_t number_start; /* start offset into "template_fname" */
int num_digits; /* How many digits is the number long? */
int fnum_sent; /* last fname sent to children */
int fnum_queue_end; /* last fname to be sent, based on
* last open call + preopen:queuelen
*/
name_compare_entry *preopen_names;
};
static void preopen_helper_destroy(struct preopen_helper *c)
{
int status;
close(c->fd);
c->fd = -1;
kill(c->pid, SIGKILL);
waitpid(c->pid, &status, 0);
c->busy = true;
}
static void preopen_queue_run(struct preopen_state *state)
{
char *pdelimiter;
char delimiter;
pdelimiter = state->template_fname + state->number_start
+ state->num_digits;
delimiter = *pdelimiter;
while (state->fnum_sent < state->fnum_queue_end) {
ssize_t written;
size_t to_write;
int helper;
for (helper=0; helper<state->num_helpers; helper++) {
if (state->helpers[helper].busy) {
continue;
}
break;
}
if (helper == state->num_helpers) {
/* everyone is busy */
return;
}
snprintf(state->template_fname + state->number_start,
state->num_digits + 1,
"%.*lu", state->num_digits,
(long unsigned int)(state->fnum_sent + 1));
*pdelimiter = delimiter;
to_write = talloc_get_size(state->template_fname);
written = write_data(state->helpers[helper].fd,
state->template_fname, to_write);
state->helpers[helper].busy = true;
if (written != to_write) {
preopen_helper_destroy(&state->helpers[helper]);
}
state->fnum_sent += 1;
}
}
static void preopen_helper_readable(struct event_context *ev,
struct fd_event *fde, uint16_t flags,
void *priv)
{
struct preopen_helper *helper = (struct preopen_helper *)priv;
struct preopen_state *state = helper->state;
ssize_t nread;
char c;
if ((flags & EVENT_FD_READ) == 0) {
return;
}
nread = read(helper->fd, &c, 1);
if (nread <= 0) {
preopen_helper_destroy(helper);
return;
}
helper->busy = false;
preopen_queue_run(state);
}
static int preopen_helpers_destructor(struct preopen_state *c)
{
int i;
for (i=0; i<c->num_helpers; i++) {
if (c->helpers[i].fd == -1) {
continue;
}
preopen_helper_destroy(&c->helpers[i]);
}
return 0;
}
static bool preopen_helper_open_one(int sock_fd, char **pnamebuf,
size_t to_read, void *filebuf)
{
char *namebuf = *pnamebuf;
ssize_t nwritten, nread;
char c = 0;
int fd;
nread = 0;
while ((nread == 0) || (namebuf[nread-1] != '\0')) {
ssize_t thistime;
thistime = read(sock_fd, namebuf + nread,
talloc_get_size(namebuf) - nread);
if (thistime <= 0) {
return false;
}
nread += thistime;
if (nread == talloc_get_size(namebuf)) {
namebuf = talloc_realloc(
NULL, namebuf, char,
talloc_get_size(namebuf) * 2);
if (namebuf == NULL) {
return false;
}
*pnamebuf = namebuf;
}
}
fd = open(namebuf, O_RDONLY);
if (fd == -1) {
goto done;
}
nread = read(fd, filebuf, to_read);
close(fd);
done:
nwritten = write(sock_fd, &c, 1);
return true;
}
static bool preopen_helper(int fd, size_t to_read)
{
char *namebuf;
void *readbuf;
namebuf = talloc_array(NULL, char, 1024);
if (namebuf == NULL) {
return false;
}
readbuf = talloc_size(NULL, to_read);
if (readbuf == NULL) {
TALLOC_FREE(namebuf);
return false;
}
while (preopen_helper_open_one(fd, &namebuf, to_read, readbuf)) {
;
}
TALLOC_FREE(readbuf);
TALLOC_FREE(namebuf);
return false;
}
static NTSTATUS preopen_init_helper(struct preopen_helper *h)
{
int fdpair[2];
NTSTATUS status;
if (socketpair(AF_UNIX, SOCK_STREAM, 0, fdpair) == -1) {
status = map_nt_error_from_unix(errno);
DEBUG(10, ("socketpair() failed: %s\n", strerror(errno)));
return status;
}
h->pid = fork();
if (h->pid == -1) {
return map_nt_error_from_unix(errno);
}
if (h->pid == 0) {
close(fdpair[0]);
preopen_helper(fdpair[1], h->state->to_read);
exit(0);
}
close(fdpair[1]);
h->fd = fdpair[0];
h->fde = event_add_fd(server_event_context(), h->state, h->fd,
EVENT_FD_READ, preopen_helper_readable, h);
if (h->fde == NULL) {
close(h->fd);
h->fd = -1;
return NT_STATUS_NO_MEMORY;
}
h->busy = false;
return NT_STATUS_OK;
}
static NTSTATUS preopen_init_helpers(TALLOC_CTX *mem_ctx, size_t to_read,
int num_helpers, int queue_max,
struct preopen_state **presult)
{
struct preopen_state *result;
int i;
result = talloc(mem_ctx, struct preopen_state);
if (result == NULL) {
return NT_STATUS_NO_MEMORY;
}
result->num_helpers = num_helpers;
result->helpers = talloc_array(result, struct preopen_helper,
num_helpers);
if (result->helpers == NULL) {
TALLOC_FREE(result);
return NT_STATUS_NO_MEMORY;
}
result->to_read = to_read;
result->queue_max = queue_max;
result->template_fname = NULL;
result->fnum_sent = 0;
for (i=0; i<num_helpers; i++) {
result->helpers[i].state = result;
result->helpers[i].fd = -1;
}
talloc_set_destructor(result, preopen_helpers_destructor);
for (i=0; i<num_helpers; i++) {
preopen_init_helper(&result->helpers[i]);
}
*presult = result;
return NT_STATUS_OK;
}
static void preopen_free_helpers(void **ptr)
{
TALLOC_FREE(*ptr);
}
static struct preopen_state *preopen_state_get(vfs_handle_struct *handle)
{
struct preopen_state *state;
NTSTATUS status;
const char *namelist;
if (SMB_VFS_HANDLE_TEST_DATA(handle)) {
SMB_VFS_HANDLE_GET_DATA(handle, state, struct preopen_state,
return NULL);
return state;
}
namelist = lp_parm_const_string(SNUM(handle->conn), "preopen", "names",
NULL);
if (namelist == NULL) {
return NULL;
}
status = preopen_init_helpers(
NULL,
lp_parm_int(SNUM(handle->conn), "preopen", "num_bytes", 1),
lp_parm_int(SNUM(handle->conn), "preopen", "helpers", 1),
lp_parm_int(SNUM(handle->conn), "preopen", "queuelen", 10),
&state);
if (!NT_STATUS_IS_OK(status)) {
return NULL;
}
set_namearray(&state->preopen_names, namelist);
if (state->preopen_names == NULL) {
TALLOC_FREE(state);
return NULL;
}
if (!SMB_VFS_HANDLE_TEST_DATA(handle)) {
SMB_VFS_HANDLE_SET_DATA(handle, state, preopen_free_helpers,
struct preopen_state, return NULL);
}
return state;
}
static bool preopen_parse_fname(const char *fname, unsigned long *pnum,
size_t *pstart_idx, int *pnum_digits)
{
const char *p, *q;
unsigned long num;
p = strrchr_m(fname, '/');
if (p == NULL) {
p = fname;
}
p += 1;
while (p[0] != '\0') {
if (isdigit(p[0]) && isdigit(p[1]) && isdigit(p[2])) {
break;
}
p += 1;
}
if (*p == '\0') {
/* no digits around */
return false;
}
num = strtoul(p, (char **)&q, 10);
if (num+1 < num) {
/* overflow */
return false;
}
*pnum = num;
*pstart_idx = (p - fname);
*pnum_digits = (q - p);
return true;
}
static int preopen_open(vfs_handle_struct *handle,
struct smb_filename *smb_fname, files_struct *fsp,
int flags, mode_t mode)
{
struct preopen_state *state;
int res;
unsigned long num;
DEBUG(10, ("preopen_open called on %s\n", smb_fname_str_dbg(smb_fname)));
state = preopen_state_get(handle);
if (state == NULL) {
return SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
}
res = SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
if (res == -1) {
return -1;
}
if (flags != O_RDONLY) {
return res;
}
if (!is_in_path(smb_fname->base_name, state->preopen_names, true)) {
DEBUG(10, ("%s does not match the preopen:names list\n",
smb_fname_str_dbg(smb_fname)));
return res;
}
TALLOC_FREE(state->template_fname);
state->template_fname = talloc_asprintf(
state, "%s/%s", fsp->conn->connectpath, smb_fname->base_name);
if (state->template_fname == NULL) {
return res;
}
if (!preopen_parse_fname(state->template_fname, &num,
&state->number_start, &state->num_digits)) {
TALLOC_FREE(state->template_fname);
return res;
}
if (num > state->fnum_sent) {
/*
* Helpers were too slow, there's no point in reading
* files in helpers that we already read in the
* parent.
*/
state->fnum_sent = num;
}
if ((state->fnum_queue_end != 0) /* Something was started earlier */
&& (num < (state->fnum_queue_end - state->queue_max))) {
/*
* "num" is before the queue we announced. This means
* a new run is started.
*/
state->fnum_sent = num;
}
state->fnum_queue_end = num + state->queue_max;
preopen_queue_run(state);
return res;
}
static struct vfs_fn_pointers vfs_preopen_fns = {
.open_fn = preopen_open
};
NTSTATUS vfs_preopen_init(void);
NTSTATUS vfs_preopen_init(void)
{
return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
"preopen", &vfs_preopen_fns);
}