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#include "first.h"
#include "mod_magnet_cache.h"
#include "stat_cache.h"
#include <errno.h>
#include <stdlib.h>
#include <string.h> /* strstr() */
#include <unistd.h> /* lseek() read() */
#include <lualib.h>
#include <lauxlib.h>
__attribute_cold__
static script *script_init(void)
{
return ck_calloc(1, sizeof(script));
}
__attribute_cold__
static void script_free(script *sc)
{
if (!sc) return;
lua_close(sc->L);
free(sc->name.ptr);
free(sc->etag.ptr);
free(sc);
}
#if 0
script_cache *script_cache_init(void)
{
return ck_calloc(1, sizeof(script_cache));
}
#endif
void script_cache_free_data(script_cache *p)
{
if (!p) return;
for (uint32_t i = 0; i < p->used; ++i)
script_free(p->ptr[i]);
free(p->ptr);
}
__attribute_cold__
__attribute_noinline__
static lua_State *script_cache_load_script(script * const sc, int etag_flags)
{
/* read file and use luaL_loadbuffer()
* eliminate TOC-TOU race w/ independent stat() in stat_cache_get_entry() */
stat_cache_entry * const sce = stat_cache_get_entry_open(&sc->name, 1);
buffer_clear(&sc->etag);
if (NULL == sce || sce->fd < 0 || -1 == lseek(sce->fd, 0, SEEK_SET)) {
/*(sce->fd < 0 might indicate empty file, which is not a valid script)*/
if (NULL != sce) errno = EBADF;
return NULL;
}
const buffer * const etag = stat_cache_etag_get(sce, etag_flags);
if (etag)
buffer_copy_buffer(&sc->etag, etag);
const off_t sz = sce->st.st_size;
char * const buf = ck_malloc(sz+1);
ssize_t rd = 0;
off_t off = 0;
do {
rd = read(sce->fd, buf+off, (size_t)(sz-off));
} while (rd > 0 ? (off += rd) != sz : rd < 0 && errno == EINTR);
if (off != sz) { /*(file truncated?)*/
if (rd >= 0) errno = EIO;
free(buf);
return NULL;
}
/*(coarse heuristic to detect if script needs req_env initialized)*/
buf[sz] = '\0'; /* for strstr() */
sc->req_env_init = (NULL != strstr(buf, "req_env"));
int rc = luaL_loadbuffer(sc->L, buf, (size_t)sz, sc->name.ptr);
free(buf);
if (0 != rc) {
/* oops, an error, return it */
return sc->L;
}
force_assert(lua_isfunction(sc->L, -1));
return sc->L;
}
__attribute_cold__
__attribute_nonnull__()
__attribute_returns_nonnull__
static script *script_cache_new_script(script_cache * const cache, const buffer * const name)
{
script * const sc = script_init();
if (!(cache->used & (16-1)))
ck_realloc_u32((void **)&cache->ptr,cache->used,16,sizeof(*cache->ptr));
cache->ptr[cache->used++] = sc;
buffer_copy_buffer(&sc->name, name);
sc->L = luaL_newstate();
luaL_openlibs(sc->L);
return sc;
}
script *script_cache_get_script(script_cache *cache, const buffer *name)
{
for (uint32_t i = 0; i < cache->used; ++i) {
script * const sc = cache->ptr[i];
if (buffer_is_equal(&sc->name, name))
return sc;
}
return script_cache_new_script(cache, name);
}
lua_State *script_cache_check_script(script * const sc, int etag_flags)
{
if (lua_gettop(sc->L) == 0)
return script_cache_load_script(sc, etag_flags);
/*force_assert(lua_gettop(sc->L) == 4);*/
/*force_assert(lua_isfunction(sc->L, 1));*/
stat_cache_entry * const sce = stat_cache_get_entry(&sc->name);
if (NULL == sce) {
lua_settop(sc->L, 0); /* pop the old function; clear stack */
return script_cache_load_script(sc, etag_flags);
}
const buffer * const etag = stat_cache_etag_get(sce, etag_flags);
if (NULL == etag || !buffer_is_equal(&sc->etag, etag)) {
if (0 == etag_flags)
return sc->L;
/* the etag is outdated, reload the function */
lua_settop(sc->L, 0); /* pop the old function; clear stack */
return script_cache_load_script(sc, etag_flags);
}
return sc->L;
}
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