1 #include "first.h"
2
3 #include "mod_magnet_cache.h"
4 #include "stat_cache.h"
5
6 #include <errno.h>
7 #include <stdlib.h>
8 #include <string.h> /* strstr() */
9 #include <unistd.h> /* lseek() read() */
10
11 #include <lualib.h>
12 #include <lauxlib.h>
13
14 __attribute_cold__
script_init(void)15 static script *script_init(void)
16 {
17 return ck_calloc(1, sizeof(script));
18 }
19
20 __attribute_cold__
script_free(script * sc)21 static void script_free(script *sc)
22 {
23 if (!sc) return;
24 lua_close(sc->L);
25 free(sc->name.ptr);
26 free(sc->etag.ptr);
27 free(sc);
28 }
29
30 #if 0
31 script_cache *script_cache_init(void)
32 {
33 return ck_calloc(1, sizeof(script_cache));
34 }
35 #endif
36
script_cache_free_data(script_cache * p)37 void script_cache_free_data(script_cache *p)
38 {
39 if (!p) return;
40 for (uint32_t i = 0; i < p->used; ++i)
41 script_free(p->ptr[i]);
42 free(p->ptr);
43 }
44
45 __attribute_cold__
46 __attribute_noinline__
script_cache_load_script(script * const sc,int etag_flags)47 static lua_State *script_cache_load_script(script * const sc, int etag_flags)
48 {
49 /* read file and use luaL_loadbuffer()
50 * eliminate TOC-TOU race w/ independent stat() in stat_cache_get_entry() */
51
52 stat_cache_entry * const sce = stat_cache_get_entry_open(&sc->name, 1);
53 buffer_clear(&sc->etag);
54 if (NULL == sce || sce->fd < 0 || -1 == lseek(sce->fd, 0, SEEK_SET)) {
55 /*(sce->fd < 0 might indicate empty file, which is not a valid script)*/
56 if (NULL != sce) errno = EBADF;
57 return NULL;
58 }
59 const buffer * const etag = stat_cache_etag_get(sce, etag_flags);
60 if (etag)
61 buffer_copy_buffer(&sc->etag, etag);
62
63 const off_t sz = sce->st.st_size;
64 char * const buf = ck_malloc(sz+1);
65
66 ssize_t rd = 0;
67 off_t off = 0;
68 do {
69 rd = read(sce->fd, buf+off, (size_t)(sz-off));
70 } while (rd > 0 ? (off += rd) != sz : rd < 0 && errno == EINTR);
71 if (off != sz) { /*(file truncated?)*/
72 if (rd >= 0) errno = EIO;
73 free(buf);
74 return NULL;
75 }
76
77 /*(coarse heuristic to detect if script needs req_env initialized)*/
78 buf[sz] = '\0'; /* for strstr() */
79 sc->req_env_init = (NULL != strstr(buf, "req_env"));
80
81 int rc = luaL_loadbuffer(sc->L, buf, (size_t)sz, sc->name.ptr);
82 free(buf);
83
84 if (0 != rc) {
85 /* oops, an error, return it */
86 return sc->L;
87 }
88
89 force_assert(lua_isfunction(sc->L, -1));
90 return sc->L;
91 }
92
93 __attribute_cold__
__attribute_nonnull__()94 __attribute_nonnull__()
95 __attribute_returns_nonnull__
96 static script *script_cache_new_script(script_cache * const cache, const buffer * const name)
97 {
98 script * const sc = script_init();
99
100 if (!(cache->used & (16-1)))
101 ck_realloc_u32((void **)&cache->ptr,cache->used,16,sizeof(*cache->ptr));
102 cache->ptr[cache->used++] = sc;
103
104 buffer_copy_buffer(&sc->name, name);
105 sc->L = luaL_newstate();
106 luaL_openlibs(sc->L);
107 return sc;
108 }
109
script_cache_get_script(script_cache * cache,const buffer * name)110 script *script_cache_get_script(script_cache *cache, const buffer *name)
111 {
112 for (uint32_t i = 0; i < cache->used; ++i) {
113 script * const sc = cache->ptr[i];
114 if (buffer_is_equal(&sc->name, name))
115 return sc;
116 }
117 return script_cache_new_script(cache, name);
118 }
119
script_cache_check_script(script * const sc,int etag_flags)120 lua_State *script_cache_check_script(script * const sc, int etag_flags)
121 {
122 if (lua_gettop(sc->L) == 0)
123 return script_cache_load_script(sc, etag_flags);
124
125 /*force_assert(lua_gettop(sc->L) == 4);*/
126 /*force_assert(lua_isfunction(sc->L, 1));*/
127
128 stat_cache_entry * const sce = stat_cache_get_entry(&sc->name);
129 if (NULL == sce) {
130 lua_settop(sc->L, 0); /* pop the old function; clear stack */
131 return script_cache_load_script(sc, etag_flags);
132 }
133
134 const buffer * const etag = stat_cache_etag_get(sce, etag_flags);
135 if (NULL == etag || !buffer_is_equal(&sc->etag, etag)) {
136 if (0 == etag_flags)
137 return sc->L;
138 /* the etag is outdated, reload the function */
139 lua_settop(sc->L, 0); /* pop the old function; clear stack */
140 return script_cache_load_script(sc, etag_flags);
141 }
142
143 return sc->L;
144 }
145