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lighttpd1.4/src/stat_cache.c

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#include "first.h"
#include "stat_cache.h"
#include "base.h"
#include "log.h"
#include "fdevent.h"
#include "etag.h"
#include "splaytree.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#ifdef HAVE_ATTR_ATTRIBUTES_H
# include <attr/attributes.h>
#endif
#ifdef HAVE_SYS_EXTATTR_H
# include <sys/extattr.h>
#endif
#ifndef HAVE_LSTAT
#define lstat stat
#ifndef S_ISLNK
#define S_ISLNK(mode) (0)
#endif
#endif
/*
* stat-cache
*
* - a splay-tree is used as we can use the caching effect of it
*/
enum {
STAT_CACHE_ENGINE_UNSET,
STAT_CACHE_ENGINE_NONE,
STAT_CACHE_ENGINE_SIMPLE,
STAT_CACHE_ENGINE_FAM
};
struct stat_cache_fam; /* declaration */
typedef struct stat_cache {
splay_tree *files; /* nodes of tree are (stat_cache_entry *) */
struct stat_cache_fam *scf;
} stat_cache;
/* the famous DJB hash function for strings */
__attribute_pure__
static uint32_t djbhash(const char *str, const size_t len)
{
const unsigned char * const s = (const unsigned char *)str;
uint32_t hash = 5381;
for (size_t i = 0; i < len; ++i) hash = ((hash << 5) + hash) ^ s[i];
return hash;
}
__attribute_pure__
static uint32_t hashme(const char *str, const size_t len)
{
/* strip highest bit of hash value for splaytree */
return djbhash(str,len) & ~(((uint32_t)1) << 31);
}
static void * stat_cache_sptree_find(splay_tree ** const sptree,
const char * const name,
size_t len)
{
const int ndx = hashme(name, len);
*sptree = splaytree_splay(*sptree, ndx);
return (*sptree && (*sptree)->key == ndx) ? (*sptree)->data : NULL;
}
#ifdef HAVE_FAM_H
/* monitor changes in directories using FAM
*
* This implementation employing FAM monitors directories as they are used,
* and maintains a reference count for cache use within stat_cache.c.
* A periodic job runs in lighttpd every 32 seconds, expiring entires unused
* in last 64 seconds out of the cache and cancelling FAM monitoring. Items
* within the cache are checked against the filesystem upon use if last stat()
* was greater than or equal to 16 seconds ago.
*
* This implementation does not monitor every directory in a tree, and therefore
* the cache may get out-of-sync with the filesystem. Delays in receiving and
* processing events from FAM might also lead to stale cache entries.
*
* For many websites, a large number of files are seldom, if ever, modified,
* and a common practice with images is to create a new file with a new name
* when a new version is needed, in order for client browsers and CDNs to better
* cache the content. Given this, most use will see little difference in
* performance between server.stat-cache-engine = "fam" and "simple" (default).
* The default server.stat-cache-engine = "simple" calls stat() on a target once
* per second, and reuses that information until the next second. For use where
* changes must be immediately visible, server.stat-cache-engine = "disable"
* should be used.
*
* When considering use of server.stat-cache-engine = "fam", there are a few
* additional limitations for this cache implementation using FAM.
* - symlinks to files located outside of the current directory do not result
* in changes to that file being monitored (unless that file is in a directory
* which is monitored as a result of a different request). symlinks can be
* chained and can be circular. This implementation *does not* readlink() or
* realpath() to resolve the chains to find and monitor the ultimate target
* directory. While symlinks to files located outside the current directory
* are not monitored, symlinks to directories *are* monitored, though chains
* of symlinks to directories do not result in monitoring of the directories
* containing intermediate symlinks to the target directory.
* - directory rename of a directory which is not currently being monitored will
* result in stale information in the cache if there is a subdirectory that is
* being monitored.
* Even though lighttpd will not receive FAM events in the above cases, lighttpd
* does re-validate the information in the cache upon use if the cache entry has
* not been checked in 16 seconds, so that is the upper limit for use of stale
* data.
*
* Use of server.stat-cache-engine = "fam" is discouraged for extremely volatile
* directories such as temporary directories (e.g. /tmp and maybe /var/tmp) due
* to the overhead of processing the additional noise generated from changes.
* Related, server.stat-cache-engine = "fam" is not recommended on trees of
* untrusted files where a malicious user could generate an excess of change
* events.
*
* Internal note: lighttpd walks the caches to prune trees in stat_cache when an
* event is received for a directory (or symlink to a directory) which has been
* deleted or renamed. The splaytree data structure is suboptimal for frequent
* changes of large directories trees where there have been a large number of
* different files recently accessed and part of the stat_cache.
*/
#include <fam.h>
typedef struct fam_dir_entry {
buffer *name;
int refcnt;
FAMRequest req;
time_t stat_ts;
dev_t st_dev;
ino_t st_ino;
struct fam_dir_entry *fam_parent;
} fam_dir_entry;
typedef struct stat_cache_fam {
splay_tree *dirs; /* the nodes of the tree are fam_dir_entry */
FAMConnection fam;
fdnode *fdn;
int fd;
} stat_cache_fam;
static fam_dir_entry * fam_dir_entry_init(const char *name, size_t len)
{
fam_dir_entry * const fam_dir = calloc(1, sizeof(*fam_dir));
force_assert(NULL != fam_dir);
fam_dir->name = buffer_init();
buffer_copy_string_len(fam_dir->name, name, len);
fam_dir->refcnt = 0;
return fam_dir;
}
static void fam_dir_entry_free(fam_dir_entry *fam_dir)
{
if (!fam_dir) return;
/*(fam_dir->parent might be invalid pointer here; ignore)*/
buffer_free(fam_dir->name);
free(fam_dir);
}
static void fam_dir_invalidate_node(fam_dir_entry *fam_dir)
{
fam_dir->stat_ts = 0;
if (fam_dir->fam_parent) {
--fam_dir->fam_parent->refcnt;
fam_dir->fam_parent = NULL;
}
}
/*
* walk though splay_tree and collect contents of dir tree.
* remove tagged entries in a second loop
*/
static void fam_dir_tag_refcnt(splay_tree *t, int *keys, int *ndx)
{
if (*ndx == 8192) return; /*(must match num array entries in keys[])*/
if (t->left) fam_dir_tag_refcnt(t->left, keys, ndx);
if (t->right) fam_dir_tag_refcnt(t->right, keys, ndx);
if (*ndx == 8192) return; /*(must match num array entries in keys[])*/
fam_dir_entry * const fam_dir = t->data;
if (0 == fam_dir->refcnt) {
fam_dir_invalidate_node(fam_dir);
keys[(*ndx)++] = t->key;
}
}
static void fam_dir_periodic_cleanup(server *srv) {
int max_ndx, i;
int keys[8192]; /* 32k size on stack */
stat_cache_fam * const scf = srv->stat_cache->scf;
do {
if (!scf->dirs) return;
max_ndx = 0;
fam_dir_tag_refcnt(scf->dirs, keys, &max_ndx);
for (i = 0; i < max_ndx; ++i) {
const int ndx = keys[i];
splay_tree *node = scf->dirs = splaytree_splay(scf->dirs, ndx);
if (node && node->key == ndx) {
fam_dir_entry *fam_dir = node->data;
scf->dirs = splaytree_delete(scf->dirs, ndx);
FAMCancelMonitor(&scf->fam, &fam_dir->req);
fam_dir_entry_free(fam_dir);
}
}
} while (max_ndx == sizeof(keys)/sizeof(int));
}
static void fam_dir_invalidate_tree(splay_tree *t, const char *name, size_t len)
{
/*force_assert(t);*/
if (t->left) fam_dir_invalidate_tree(t->left, name, len);
if (t->right) fam_dir_invalidate_tree(t->right, name, len);
fam_dir_entry * const fam_dir = t->data;
buffer *b = fam_dir->name;
size_t blen = buffer_string_length(b);
if (blen > len && b->ptr[len] == '/' && 0 == memcmp(b->ptr, name, len))
fam_dir_invalidate_node(fam_dir);
}
/* declarations */
static void stat_cache_delete_tree(server *srv, const char *name, size_t len);
static void stat_cache_invalidate_dir_tree(server *srv, const char *name, size_t len);
static void stat_cache_handle_fdevent_in(server *srv, stat_cache_fam *scf)
{
for (int i = 0, ndx; i || (i = FAMPending(&scf->fam)) > 0; --i) {
FAMEvent fe;
if (FAMNextEvent(&scf->fam, &fe) < 0) break;
/* ignore events which may have been pending for
* paths recently cancelled via FAMCancelMonitor() */
ndx = (int)(intptr_t)fe.userdata;
scf->dirs = splaytree_splay(scf->dirs, ndx);
if (!scf->dirs || scf->dirs->key != ndx) {
continue;
}
fam_dir_entry *fam_dir = scf->dirs->data;
if (FAMREQUEST_GETREQNUM(&fam_dir->req)
!= FAMREQUEST_GETREQNUM(&fe.fr)) {
continue;
}
if (fe.filename[0] != '/') {
buffer * const n = fam_dir->name;
fam_dir_entry *fam_link;
size_t len;
switch(fe.code) {
case FAMCreated:
/* file created in monitored dir modifies dir and
* we should get a separate FAMChanged event for dir.
* Therefore, ignore file FAMCreated event here.
* Also, if FAMNoExists() is used, might get spurious
* FAMCreated events as changes are made e.g. in monitored
* sub-sub-sub dirs and the library discovers new (already
* existing) dir entries */
continue;
case FAMChanged:
/* file changed in monitored dir does not modify dir */
case FAMDeleted:
case FAMMoved:
/* file deleted or moved in monitored dir modifies dir,
* but FAM provides separate notification for that */
/* temporarily append filename to dir in fam_dir->name to
* construct path, then delete stat_cache entry (if any)*/
len = buffer_string_length(n);
buffer_append_string_len(n, CONST_STR_LEN("/"));
buffer_append_string_len(n,fe.filename,strlen(fe.filename));
/* (alternatively, could chose to stat() and update)*/
stat_cache_invalidate_entry(srv, CONST_BUF_LEN(n));
fam_link = /*(check if might be symlink to monitored dir)*/
stat_cache_sptree_find(&scf->dirs, CONST_BUF_LEN(n));
if (fam_link && !buffer_is_equal(fam_link->name, n))
fam_link = NULL;
buffer_string_set_length(n, len);
if (fam_link) {
/* replaced symlink changes containing dir */
stat_cache_invalidate_entry(srv, CONST_BUF_LEN(n));
/* handle symlink to dir as deleted dir below */
fe.code = FAMDeleted;
fam_dir = fam_link;
break;
}
continue;
default:
continue;
}
}
switch(fe.code) {
case FAMChanged:
stat_cache_invalidate_entry(srv, CONST_BUF_LEN(fam_dir->name));
break;
case FAMDeleted:
case FAMMoved:
stat_cache_delete_tree(srv, CONST_BUF_LEN(fam_dir->name));
fam_dir_invalidate_node(fam_dir);
if (scf->dirs)
fam_dir_invalidate_tree(scf->dirs,CONST_BUF_LEN(fam_dir->name));
fam_dir_periodic_cleanup(srv);
break;
default:
break;
}
}
}
static handler_t stat_cache_handle_fdevent(server *srv, void *_fce, int revent)
{
stat_cache_fam *scf = srv->stat_cache->scf;
UNUSED(_fce);
if (revent & FDEVENT_IN) {
stat_cache_handle_fdevent_in(srv, scf);
}
if (revent & (FDEVENT_HUP|FDEVENT_RDHUP)) {
/* fam closed the connection */
fdevent_fdnode_event_del(srv->ev, scf->fdn);
fdevent_unregister(srv->ev, scf->fd);
scf->fdn = NULL;
FAMClose(&scf->fam);
scf->fd = -1;
}
return HANDLER_GO_ON;
}
static stat_cache_fam * stat_cache_init_fam(server *srv) {
stat_cache_fam *scf = calloc(1, sizeof(*scf));
force_assert(scf);
scf->fd = -1;
/* setup FAM */
if (0 != FAMOpen2(&scf->fam, "lighttpd")) {
log_error_write(srv, __FILE__, __LINE__, "s",
"could not open a fam connection, dieing.");
return NULL;
}
#ifdef HAVE_FAMNOEXISTS
FAMNoExists(&scf->fam);
#endif
scf->fd = FAMCONNECTION_GETFD(&scf->fam);
fdevent_setfd_cloexec(scf->fd);
scf->fdn = fdevent_register(srv->ev, scf->fd, stat_cache_handle_fdevent, NULL);
fdevent_fdnode_event_set(srv->ev, scf->fdn, FDEVENT_IN | FDEVENT_RDHUP);
return scf;
}
static void stat_cache_free_fam(stat_cache_fam *scf) {
if (NULL == scf) return;
while (scf->dirs) {
/*(skip entry invalidation and FAMCancelMonitor())*/
splay_tree *node = scf->dirs;
fam_dir_entry_free((fam_dir_entry *)node->data);
scf->dirs = splaytree_delete(scf->dirs, node->key);
}
if (-1 != scf->fd) {
/*scf->fdn already cleaned up in fdevent_free()*/
FAMClose(&scf->fam);
/*scf->fd = -1;*/
}
free(scf);
}
static fam_dir_entry * fam_dir_monitor(server *srv, stat_cache_fam *scf, char *fn, size_t dirlen, struct stat *st)
{
const int fn_is_dir = S_ISDIR(st->st_mode);
/*force_assert(0 != dirlen);*/
/*force_assert(fn[0] == '/');*/
/* consistency: ensure fn does not end in '/' unless root "/"
* FAM events will not end in '/', so easier to match this way */
if (fn[dirlen-1] == '/') --dirlen;
if (0 == dirlen) dirlen = 1; /* root dir ("/") */
/* Note: paths are expected to be normalized before calling stat_cache,
* e.g. without repeated '/' */
if (!fn_is_dir) {
while (fn[--dirlen] != '/') ;
if (0 == dirlen) dirlen = 1; /*(should not happen for file)*/
}
int dir_ndx = hashme(fn, dirlen);
fam_dir_entry *fam_dir = NULL;
scf->dirs = splaytree_splay(scf->dirs, dir_ndx);
if (NULL != scf->dirs && scf->dirs->key == dir_ndx) {
fam_dir = scf->dirs->data;
if (!buffer_is_equal_string(fam_dir->name, fn, dirlen)) {
/* hash collision; preserve existing
* do not monitor new to avoid cache thrashing */
return NULL;
}
/* directory already registered */
}
struct stat lst;
int ck_dir = fn_is_dir;
if (!fn_is_dir && (NULL==fam_dir || srv->cur_ts - fam_dir->stat_ts >= 16)) {
ck_dir = 1;
/*(temporarily modify fn)*/
fn[dirlen] = '\0';
if (0 != lstat(fn, &lst)) {
fn[dirlen] = '/';
return NULL;
}
if (!S_ISLNK(lst.st_mode)) {
st = &lst;
}
else if (0 != stat(fn, st)) { /*st passed in now is stat() of dir*/
fn[dirlen] = '/';
return NULL;
}
fn[dirlen] = '/';
}
int ck_lnk = (NULL == fam_dir);
if (ck_dir && NULL != fam_dir) {
/* check stat() matches device and inode, just in case an external event
* not being monitored occurs (e.g. rename of unmonitored parent dir)*/
if (st->st_dev != fam_dir->st_dev || st->st_ino != fam_dir->st_ino) {
ck_lnk = 1;
/*(modifies scf->dirs but no need to re-splay for dir_ndx since
* fam_dir is not NULL and so splaytree_insert not called below)*/
if (scf->dirs) fam_dir_invalidate_tree(scf->dirs, fn, dirlen);
if (!fn_is_dir) /*(if dir, caller is updating stat_cache_entry)*/
stat_cache_update_entry(srv, fn, dirlen, st, NULL);
/*(must not delete tree since caller is holding a valid node)*/
stat_cache_invalidate_dir_tree(srv, fn, dirlen);
if (0 != FAMCancelMonitor(&scf->fam, &fam_dir->req)
|| 0 != FAMMonitorDirectory(&scf->fam, fam_dir->name->ptr,
&fam_dir->req,
(void *)(intptr_t)dir_ndx)) {
fam_dir->stat_ts = 0; /* invalidate */
return NULL;
}
fam_dir->st_dev = st->st_dev;
fam_dir->st_ino = st->st_ino;
}
fam_dir->stat_ts = srv->cur_ts;
}
if (NULL == fam_dir) {
fam_dir = fam_dir_entry_init(fn, dirlen);
if (0 != FAMMonitorDirectory(&scf->fam,fam_dir->name->ptr,&fam_dir->req,
(void *)(intptr_t)dir_ndx)) {
log_error_write(srv, __FILE__, __LINE__, "sbsss",
"monitoring dir failed:",
fam_dir->name,
"file:", fn,
FamErrlist[FAMErrno]);
fam_dir_entry_free(fam_dir);
return NULL;
}
scf->dirs = splaytree_insert(scf->dirs, dir_ndx, fam_dir);
fam_dir->stat_ts= srv->cur_ts;
fam_dir->st_dev = st->st_dev;
fam_dir->st_ino = st->st_ino;
}
if (ck_lnk) {
if (fn_is_dir) {
/*(temporarily modify fn)*/
char e = fn[dirlen];
fn[dirlen] = '\0';
if (0 != lstat(fn, &lst)) {
fn[dirlen] = e;
return NULL;
}
fn[dirlen] = e;
}
if (fam_dir->fam_parent) {
--fam_dir->fam_parent->refcnt;
fam_dir->fam_parent = NULL;
}
if (S_ISLNK(lst.st_mode)) {
fam_dir->fam_parent = fam_dir_monitor(srv, scf, fn, dirlen, &lst);
}
}
++fam_dir->refcnt;
return fam_dir;
}
#endif
stat_cache *stat_cache_init(server *srv) {
stat_cache *sc = NULL;
UNUSED(srv);
sc = calloc(1, sizeof(*sc));
force_assert(NULL != sc);
#ifdef HAVE_FAM_H
if (STAT_CACHE_ENGINE_FAM == srv->srvconf.stat_cache_engine) {
sc->scf = stat_cache_init_fam(srv);
if (NULL == sc->scf) {
free(sc);
return NULL;
}
}
#endif
return sc;
}
static stat_cache_entry * stat_cache_entry_init(void) {
stat_cache_entry *sce = NULL;
sce = calloc(1, sizeof(*sce));
force_assert(NULL != sce);
sce->name = buffer_init();
sce->etag = buffer_init();
sce->content_type = buffer_init();
return sce;
}
static void stat_cache_entry_free(void *data) {
stat_cache_entry *sce = data;
if (!sce) return;
#ifdef HAVE_FAM_H
/*(decrement refcnt only;
* defer cancelling FAM monitor on dir even if refcnt reaches zero)*/
if (sce->fam_dir) --((fam_dir_entry *)sce->fam_dir)->refcnt;
#endif
buffer_free(sce->etag);
buffer_free(sce->name);
buffer_free(sce->content_type);
free(sce);
}
void stat_cache_free(stat_cache *sc) {
while (sc->files) {
splay_tree *node = sc->files;
stat_cache_entry_free(node->data);
sc->files = splaytree_delete(sc->files, node->key);
}
#ifdef HAVE_FAM_H
stat_cache_free_fam(sc->scf);
#endif
free(sc);
}
int stat_cache_choose_engine (server *srv, const buffer *stat_cache_string) {
if (buffer_string_is_empty(stat_cache_string)) {
srv->srvconf.stat_cache_engine = STAT_CACHE_ENGINE_SIMPLE;
} else if (buffer_is_equal_string(stat_cache_string, CONST_STR_LEN("simple"))) {
srv->srvconf.stat_cache_engine = STAT_CACHE_ENGINE_SIMPLE;
#ifdef HAVE_FAM_H
} else if (buffer_is_equal_string(stat_cache_string, CONST_STR_LEN("fam"))) {
srv->srvconf.stat_cache_engine = STAT_CACHE_ENGINE_FAM;
#endif
} else if (buffer_is_equal_string(stat_cache_string, CONST_STR_LEN("disable"))) {
srv->srvconf.stat_cache_engine = STAT_CACHE_ENGINE_NONE;
} else {
log_error_write(srv, __FILE__, __LINE__, "sb",
"server.stat-cache-engine can be one of \"disable\", \"simple\","
#ifdef HAVE_FAM_H
" \"fam\","
#endif
" but not:", stat_cache_string);
return -1;
}
return 0;
}
#if defined(HAVE_XATTR)
static int stat_cache_attr_get(buffer *buf, char *name, char *xattrname) {
int attrlen;
int ret;
buffer_string_prepare_copy(buf, 1023);
attrlen = buf->size - 1;
if(0 == (ret = attr_get(name, xattrname, buf->ptr, &attrlen, 0))) {
buffer_commit(buf, attrlen);
}
return ret;
}
#elif defined(HAVE_EXTATTR)
static int stat_cache_attr_get(buffer *buf, char *name, char *xattrname) {
ssize_t attrlen;
buffer_string_prepare_copy(buf, 1023);
if (-1 != (attrlen = extattr_get_file(name, EXTATTR_NAMESPACE_USER, xattrname, buf->ptr, buf->size - 1))) {
buf->used = attrlen + 1;
buf->ptr[attrlen] = '\0';
return 0;
}
return -1;
}
#endif
const buffer * stat_cache_mimetype_by_ext(const connection *con, const char *name, size_t nlen)
{
const char *end = name + nlen; /*(end of string)*/
const size_t used = con->conf.mimetypes->used;
if (used < 16) {
for (size_t i = 0; i < used; ++i) {
/* suffix match */
const data_string *ds = (data_string *)con->conf.mimetypes->data[i];
const size_t klen = buffer_string_length(ds->key);
if (klen <= nlen && 0 == strncasecmp(end-klen, ds->key->ptr, klen))
return ds->value;
}
}
else {
const char *s;
const data_string *ds;
if (nlen) {
for (s = end-1; s != name && *s != '/'; --s) ; /*(like memrchr())*/
if (*s == '/') ++s;
}
else {
s = name;
}
/* search for basename, then longest .ext2.ext1, then .ext1, then "" */
ds = (data_string *)array_get_element_klen(con->conf.mimetypes, s, end - s);
if (NULL != ds) return ds->value;
while (++s < end) {
while (*s != '.' && ++s != end) ;
if (s == end) break;
/* search ".ext" then "ext" */
ds = (data_string *)array_get_element_klen(con->conf.mimetypes, s, end - s);
if (NULL != ds) return ds->value;
/* repeat search without leading '.' to handle situation where
* admin configured mimetype.assign keys without leading '.' */
if (++s < end) {
if (*s == '.') { --s; continue; }
ds = (data_string *)array_get_element_klen(con->conf.mimetypes, s, end - s);
if (NULL != ds) return ds->value;
}
}
/* search for ""; catchall */
ds = (data_string *)array_get_element(con->conf.mimetypes, "");
if (NULL != ds) return ds->value;
}
return NULL;
}
const buffer * stat_cache_content_type_get(server *srv, connection *con, const buffer *name, stat_cache_entry *sce)
{
/*(invalid caching if user config has multiple, different
* con->conf.mimetypes for same extension (not expected))*/
if (!buffer_string_is_empty(sce->content_type)) return sce->content_type;
if (S_ISREG(sce->st.st_mode)) {
/* determine mimetype */
buffer_clear(sce->content_type);
#if defined(HAVE_XATTR) || defined(HAVE_EXTATTR)
if (con->conf.use_xattr) {
stat_cache_attr_get(sce->content_type, name->ptr, srv->srvconf.xattr_name->ptr);
}
#else
UNUSED(srv);
#endif
/* xattr did not set a content-type. ask the config */
if (buffer_string_is_empty(sce->content_type)) {
const buffer *type = stat_cache_mimetype_by_ext(con, CONST_BUF_LEN(name));
if (NULL != type) {
buffer_copy_buffer(sce->content_type, type);
}
}
return sce->content_type;
}
return NULL;
}
const buffer * stat_cache_etag_get(stat_cache_entry *sce, etag_flags_t flags) {
/*(invalid caching if user config has multiple, different con->etag_flags
* for same path (not expected, since etag flags should be by filesystem))*/
if (!buffer_string_is_empty(sce->etag)) return sce->etag;
if (S_ISREG(sce->st.st_mode) || S_ISDIR(sce->st.st_mode)) {
etag_create(sce->etag, &sce->st, flags);
return sce->etag;
}
return NULL;
}
void stat_cache_update_entry(server *srv, const char *name, size_t len,
struct stat *st, buffer *etagb)
{
if (srv->srvconf.stat_cache_engine == STAT_CACHE_ENGINE_NONE) return;
force_assert(0 != len);
if (name[len-1] == '/') { if (0 == --len) len = 1; }
splay_tree **sptree = &srv->stat_cache->files;
stat_cache_entry *sce =
stat_cache_sptree_find(sptree, name, len);
if (sce && buffer_is_equal_string(sce->name, name, len)) {
sce->stat_ts = srv->cur_ts;
sce->st = *st; /* etagb might be NULL to clear etag (invalidate) */
buffer_copy_string_len(sce->etag, CONST_BUF_LEN(etagb));
#if defined(HAVE_XATTR) || defined(HAVE_EXTATTR)
buffer_clear(sce->content_type);
#endif
}
}
void stat_cache_delete_entry(server *srv, const char *name, size_t len)
{
if (srv->srvconf.stat_cache_engine == STAT_CACHE_ENGINE_NONE) return;
force_assert(0 != len);
if (name[len-1] == '/') { if (0 == --len) len = 1; }
splay_tree **sptree = &srv->stat_cache->files;
stat_cache_entry *sce = stat_cache_sptree_find(sptree, name, len);
if (sce && buffer_is_equal_string(sce->name, name, len)) {
stat_cache_entry_free(sce);
*sptree = splaytree_delete(*sptree, (*sptree)->key);
}
}
void stat_cache_invalidate_entry(server *srv, const char *name, size_t len)
{
splay_tree **sptree = &srv->stat_cache->files;
stat_cache_entry *sce = stat_cache_sptree_find(sptree, name, len);
if (sce && buffer_is_equal_string(sce->name, name, len)) {
sce->stat_ts = 0;
#ifdef HAVE_FAM_H
if (sce->fam_dir != NULL) {
--((fam_dir_entry *)sce->fam_dir)->refcnt;
sce->fam_dir = NULL;
}
#endif
}
}
#ifdef HAVE_FAM_H
static void stat_cache_invalidate_dir_tree_walk(splay_tree *t,
const char *name, size_t len)
{
if (t->left) stat_cache_invalidate_dir_tree_walk(t->left, name, len);
if (t->right) stat_cache_invalidate_dir_tree_walk(t->right, name, len);
buffer *b = ((stat_cache_entry *)t->data)->name;
size_t blen = buffer_string_length(b);
if (blen > len && b->ptr[len] == '/' && 0 == memcmp(b->ptr, name, len)) {
stat_cache_entry *sce = t->data;
sce->stat_ts = 0;
#ifdef HAVE_FAM_H
if (sce->fam_dir != NULL) {
--((fam_dir_entry *)sce->fam_dir)->refcnt;
sce->fam_dir = NULL;
}
#endif
}
}
static void stat_cache_invalidate_dir_tree(server *srv,
const char *name, size_t len)
{
splay_tree *sptree = srv->stat_cache->files;
if (sptree) stat_cache_invalidate_dir_tree_walk(sptree, name, len);
}
#endif
/*
* walk though splay_tree and collect contents of dir tree.
* remove tagged entries in a second loop
*/
static void stat_cache_tag_dir_tree(splay_tree *t, const char *name, size_t len,
int *keys, int *ndx)
{
if (*ndx == 8192) return; /*(must match num array entries in keys[])*/
if (t->left) stat_cache_tag_dir_tree(t->left, name, len, keys, ndx);
if (t->right) stat_cache_tag_dir_tree(t->right, name, len, keys, ndx);
if (*ndx == 8192) return; /*(must match num array entries in keys[])*/
buffer *b = ((stat_cache_entry *)t->data)->name;
size_t blen = buffer_string_length(b);
if (blen > len && b->ptr[len] == '/' && 0 == memcmp(b->ptr, name, len))
keys[(*ndx)++] = t->key;
}
static void stat_cache_prune_dir_tree(stat_cache * const sc,
const char *name, size_t len)
{
int max_ndx, i;
int keys[8192]; /* 32k size on stack */
do {
if (!sc->files) return;
max_ndx = 0;
stat_cache_tag_dir_tree(sc->files, name, len, keys, &max_ndx);
for (i = 0; i < max_ndx; ++i) {
const int ndx = keys[i];
splay_tree *node = sc->files = splaytree_splay(sc->files, ndx);
if (node && node->key == ndx) {
stat_cache_entry_free(node->data);
sc->files = splaytree_delete(sc->files, ndx);
}
}
} while (max_ndx == sizeof(keys)/sizeof(int));
}
static void stat_cache_delete_tree(server *srv, const char *name, size_t len)
{
stat_cache_delete_entry(srv, name, len);
stat_cache_prune_dir_tree(srv->stat_cache, name, len);
}
void stat_cache_delete_dir(server *srv, const char *name, size_t len)
{
force_assert(0 != len);
if (name[len-1] == '/') { if (0 == --len) len = 1; }
stat_cache_delete_tree(srv, name, len);
#ifdef HAVE_FAM_H
if (srv->srvconf.stat_cache_engine == STAT_CACHE_ENGINE_FAM) {
splay_tree **sptree = &srv->stat_cache->scf->dirs;
fam_dir_entry *fam_dir = stat_cache_sptree_find(sptree, name, len);
if (fam_dir && buffer_is_equal_string(fam_dir->name, name, len))
fam_dir_invalidate_node(fam_dir);
if (*sptree) fam_dir_invalidate_tree(*sptree, name, len);
fam_dir_periodic_cleanup(srv);
}
#endif
}
/***
*
*
*
* returns:
* - HANDLER_FINISHED on cache-miss (don't forget to reopen the file)
* - HANDLER_ERROR on stat() failed -> see errno for problem
*/
handler_t stat_cache_get_entry(server *srv, connection *con, buffer *name, stat_cache_entry **ret_sce) {
stat_cache_entry *sce = NULL;
stat_cache *sc;
struct stat st;
int file_ndx;
UNUSED(con);
*ret_sce = NULL;
/* consistency: ensure lookup name does not end in '/' unless root "/"
* (but use full path given with stat(), even with trailing '/') */
int final_slash = 0;
size_t len = buffer_string_length(name);
force_assert(0 != len);
if (name->ptr[len-1] == '/') { final_slash = 1; if (0 == --len) len = 1; }
/* Note: paths are expected to be normalized before calling stat_cache,
* e.g. without repeated '/' */
if (name->ptr[0] != '/') return HANDLER_ERROR;
/*
* check if the directory for this file has changed
*/
sc = srv->stat_cache;
file_ndx = hashme(name->ptr, len);
sc->files = splaytree_splay(sc->files, file_ndx);
if (sc->files && (sc->files->key == file_ndx)) {
/* we have seen this file already and
* don't stat() it again in the same second */
sce = sc->files->data;
/* check if the name is the same, we might have a collision */
if (buffer_is_equal_string(sce->name, name->ptr, len)) {
if (srv->srvconf.stat_cache_engine == STAT_CACHE_ENGINE_SIMPLE) {
if (sce->stat_ts == srv->cur_ts) {
if (final_slash && !S_ISDIR(sce->st.st_mode)) {
errno = ENOTDIR;
return HANDLER_ERROR;
}
*ret_sce = sce;
return HANDLER_GO_ON;
}
}
#ifdef HAVE_FAM_H
else if (srv->srvconf.stat_cache_engine == STAT_CACHE_ENGINE_FAM
&& sce->fam_dir) { /* entry is in monitored dir */
/* re-stat() periodically, even if monitoring for changes
* (due to limitations in stat_cache.c use of FAM)
* (gaps due to not continually monitoring an entire tree) */
if (srv->cur_ts - sce->stat_ts < 16) {
if (final_slash && !S_ISDIR(sce->st.st_mode)) {
errno = ENOTDIR;
return HANDLER_ERROR;
}
*ret_sce = sce;
return HANDLER_GO_ON;
}
}
#endif
} else {
/* collision, forget about the entry */
sce = NULL;
}
}
if (-1 == stat(name->ptr, &st)) {
return HANDLER_ERROR;
}
if (S_ISREG(st.st_mode)) {
/* fix broken stat/open for symlinks to reg files with appended slash on freebsd,osx */
if (name->ptr[buffer_string_length(name) - 1] == '/') {
errno = ENOTDIR;
return HANDLER_ERROR;
}
}
if (NULL == sce) {
sce = stat_cache_entry_init();
buffer_copy_string_len(sce->name, name->ptr, len);
/* already splayed file_ndx */
if ((NULL != sc->files) && (sc->files->key == file_ndx)) {
/* hash collision: replace old entry */
stat_cache_entry_free(sc->files->data);
sc->files->data = sce;
} else {
sc->files = splaytree_insert(sc->files, file_ndx, sce);
}
} else {
buffer_clear(sce->etag);
#if defined(HAVE_XATTR) || defined(HAVE_EXTATTR)
buffer_clear(sce->content_type);
#endif
}
sce->st = st; /*(copy prior to calling fam_dir_monitor())*/
#ifdef HAVE_FAM_H
if (srv->srvconf.stat_cache_engine == STAT_CACHE_ENGINE_FAM) {
if (sce->fam_dir) --((fam_dir_entry *)sce->fam_dir)->refcnt;
sce->fam_dir =
fam_dir_monitor(srv, sc->scf, CONST_BUF_LEN(name), &st);
#if 0 /*(performed below)*/
if (NULL != sce->fam_dir) {
/*(may have been invalidated by dir change)*/
sce->stat_ts = srv->cur_ts;
}
#endif
}
#endif
sce->stat_ts = srv->cur_ts;
*ret_sce = sce;
return HANDLER_GO_ON;
}
int stat_cache_path_contains_symlink(server *srv, buffer *name) {
/* caller should check for symlinks only if we should block symlinks. */
/* catch the obvious symlinks
*
* this is not a secure check as we still have a race-condition between
* the stat() and the open. We can only solve this by
* 1. open() the file
* 2. fstat() the fd
*
* and keeping the file open for the rest of the time. But this can
* only be done at network level.
* */
#ifdef HAVE_LSTAT
/* we assume "/" can not be symlink,
* so skip the symlink stuff if path is "/" */
size_t len = buffer_string_length(name);
force_assert(0 != len);
force_assert(name->ptr[0] == '/');
if (1 == len) return 0;
#ifndef PATH_MAX
#define PATH_MAX 4096
#endif
if (len >= PATH_MAX) return -1;
char buf[PATH_MAX];
memcpy(buf, name->ptr, len);
char *s_cur = buf+len;
do {
*s_cur = '\0';
struct stat st;
if (0 == lstat(buf, &st)) {
if (S_ISLNK(st.st_mode)) return 1;
}
else {
log_error_write(srv, __FILE__, __LINE__, "sss",
"lstat failed for:", buf, strerror(errno));
return -1;
}
} while ((s_cur = strrchr(buf, '/')) != buf);
#endif
return 0;
}
int stat_cache_open_rdonly_fstat (buffer *name, struct stat *st, int symlinks) {
/*(Note: O_NOFOLLOW affects only the final path segment, the target file,
* not any intermediate symlinks along the path)*/
const int fd = fdevent_open_cloexec(name->ptr, symlinks, O_RDONLY, 0);
if (fd >= 0) {
if (0 == fstat(fd, st)) {
return fd;
} else {
close(fd);
}
}
return -1;
}
/**
* remove stat() from cache which haven't been stat()ed for
* more than 2 seconds
*
*
* walk though the stat-cache, collect the ids which are too old
* and remove them in a second loop
*/
static int stat_cache_tag_old_entries(server *srv, splay_tree *t, int *keys, size_t *ndx, time_t max_age) {
stat_cache_entry *sce;
if (!t) return 0;
stat_cache_tag_old_entries(srv, t->left, keys, ndx, max_age);
stat_cache_tag_old_entries(srv, t->right, keys, ndx, max_age);
sce = t->data;
if (srv->cur_ts - sce->stat_ts > max_age) {
keys[(*ndx)++] = t->key;
}
return 0;
}
static int stat_cache_periodic_cleanup(server *srv, time_t max_age) {
stat_cache *sc;
size_t max_ndx = 0, i;
int *keys;
sc = srv->stat_cache;
if (!sc->files) return 0;
keys = calloc(1, sizeof(int) * sc->files->size);
force_assert(NULL != keys);
stat_cache_tag_old_entries(srv, sc->files, keys, &max_ndx, max_age);
for (i = 0; i < max_ndx; i++) {
int ndx = keys[i];
splay_tree *node;
sc->files = splaytree_splay(sc->files, ndx);
node = sc->files;
if (node && (node->key == ndx)) {
stat_cache_entry_free(node->data);
sc->files = splaytree_delete(sc->files, ndx);
}
}
free(keys);
return 0;
}
int stat_cache_trigger_cleanup(server *srv) {
time_t max_age = 2;
#ifdef HAVE_FAM_H
if (srv->srvconf.stat_cache_engine == STAT_CACHE_ENGINE_FAM) {
if (srv->cur_ts & 0x1F) return 0;
/* once every 32 seconds (0x1F == 31) */
max_age = 32;
fam_dir_periodic_cleanup(srv);
/* By doing this before stat_cache_periodic_cleanup(),
* entries used within the next max_age secs will remain
* monitored, instead of effectively flushing and
* rebuilding the FAM monitoring every max_age seconds */
}
#endif
stat_cache_periodic_cleanup(srv, max_age);
return 0;
}