filter.c

   1 /* filter.c: filter framework functions
   2  *
   3  * Copyright (C) 2006-2014 cgit Development Team <cgit@lists.zx2c4.com>
   4  *
   5  * Licensed under GNU General Public License v2
   6  *   (see COPYING for full license text)
   7  */
   8
   9 #include "cgit.h"
  10 #include "html.h"
  11 #include <sys/types.h>
  12 #include <sys/wait.h>
  13 #include <unistd.h>
  14 #include <string.h>
  15 #include <stdlib.h>
  16 #include <dlfcn.h>
  17 #include <errno.h>
  18 #ifndef NO_LUA
  19 #include <lua.h>
  20 #include <lualib.h>
  21 #include <lauxlib.h>
  22 #endif
  23
  24 static ssize_t (*libc_write)(int fd, const void *buf, size_t count);
  25 static ssize_t (*filter_write)(struct cgit_filter *base, const void *buf, size_t count) = NULL;
  26 static struct cgit_filter *current_write_filter = NULL;
  27
  28 static inline void reap_filter(struct cgit_filter *filter)
  29 {
  30         if (filter && filter->cleanup)
  31                 filter->cleanup(filter);
  32 }
  33
  34 void cgit_cleanup_filters(void)
  35 {
  36         int i;
  37         reap_filter(ctx.cfg.about_filter);
  38         reap_filter(ctx.cfg.commit_filter);
  39         reap_filter(ctx.cfg.source_filter);
  40         reap_filter(ctx.cfg.email_filter);
  41         for (i = 0; i < cgit_repolist.count; ++i) {
  42                 reap_filter(cgit_repolist.repos[i].about_filter);
  43                 reap_filter(cgit_repolist.repos[i].commit_filter);
  44                 reap_filter(cgit_repolist.repos[i].source_filter);
  45                 reap_filter(cgit_repolist.repos[i].email_filter);
  46         }
  47 }
  48
  49 void cgit_init_filters(void)
  50 {
  51         libc_write = dlsym(RTLD_NEXT, "write");
  52         if (!libc_write)
  53                 die("Could not locate libc's write function");
  54 }
  55
  56 ssize_t write(int fd, const void *buf, size_t count)
  57 {
  58         if (fd != STDOUT_FILENO || !filter_write)
  59                 return libc_write(fd, buf, count);
  60         return filter_write(current_write_filter, buf, count);
  61 }
  62
  63 static inline void hook_write(struct cgit_filter *filter, ssize_t (*new_write)(struct cgit_filter *base, const void *buf, size_t count))
  64 {
  65         /* We want to avoid buggy nested patterns. */
  66         assert(filter_write == NULL);
  67         assert(current_write_filter == NULL);
  68         current_write_filter = filter;
  69         filter_write = new_write;
  70 }
  71
  72 static inline void unhook_write()
  73 {
  74         assert(filter_write != NULL);
  75         assert(current_write_filter != NULL);
  76         filter_write = NULL;
  77         current_write_filter = NULL;
  78 }
  79
  80 static int open_exec_filter(struct cgit_filter *base, va_list ap)
  81 {
  82         struct cgit_exec_filter *filter = (struct cgit_exec_filter *)base;
  83         int i;
  84
  85         for (i = 0; i < filter->base.argument_count; i++)
  86                 filter->argv[i + 1] = va_arg(ap, char *);
  87
  88         filter->old_stdout = chk_positive(dup(STDOUT_FILENO),
  89                 "Unable to duplicate STDOUT");
  90         chk_zero(pipe(filter->pipe_fh), "Unable to create pipe to subprocess");
  91         filter->pid = chk_non_negative(fork(), "Unable to create subprocess");
  92         if (filter->pid == 0) {
  93                 close(filter->pipe_fh[1]);
  94                 chk_non_negative(dup2(filter->pipe_fh[0], STDIN_FILENO),
  95                         "Unable to use pipe as STDIN");
  96                 execvp(filter->cmd, filter->argv);
  97                 die_errno("Unable to exec subprocess %s", filter->cmd);
  98         }
  99         close(filter->pipe_fh[0]);
 100         chk_non_negative(dup2(filter->pipe_fh[1], STDOUT_FILENO),
 101                 "Unable to use pipe as STDOUT");
 102         close(filter->pipe_fh[1]);
 103         return 0;
 104 }
 105
 106 static int close_exec_filter(struct cgit_filter *base)
 107 {
 108         struct cgit_exec_filter *filter = (struct cgit_exec_filter *)base;
 109         int i, exit_status = 0;
 110
 111         chk_non_negative(dup2(filter->old_stdout, STDOUT_FILENO),
 112                 "Unable to restore STDOUT");
 113         close(filter->old_stdout);
 114         if (filter->pid < 0)
 115                 goto done;
 116         waitpid(filter->pid, &exit_status, 0);
 117         if (WIFEXITED(exit_status))
 118                 goto done;
 119         die("Subprocess %s exited abnormally", filter->cmd);
 120
 121 done:
 122         for (i = 0; i < filter->base.argument_count; i++)
 123                 filter->argv[i + 1] = NULL;
 124         return WEXITSTATUS(exit_status);
 125
 126 }
 127
 128 static void fprintf_exec_filter(struct cgit_filter *base, FILE *f, const char *prefix)
 129 {
 130         struct cgit_exec_filter *filter = (struct cgit_exec_filter *)base;
 131         fprintf(f, "%sexec:%s\n", prefix, filter->cmd);
 132 }
 133
 134 static void cleanup_exec_filter(struct cgit_filter *base)
 135 {
 136         struct cgit_exec_filter *filter = (struct cgit_exec_filter *)base;
 137         if (filter->argv) {
 138                 free(filter->argv);
 139                 filter->argv = NULL;
 140         }
 141         if (filter->cmd) {
 142                 free(filter->cmd);
 143                 filter->cmd = NULL;
 144         }
 145 }
 146
 147 static struct cgit_filter *new_exec_filter(const char *cmd, int argument_count)
 148 {
 149         struct cgit_exec_filter *f;
 150         int args_size = 0;
 151
 152         f = xmalloc(sizeof(*f));
 153         /* We leave argv for now and assign it below. */
 154         cgit_exec_filter_init(f, xstrdup(cmd), NULL);
 155         f->base.argument_count = argument_count;
 156         args_size = (2 + argument_count) * sizeof(char *);
 157         f->argv = xmalloc(args_size);
 158         memset(f->argv, 0, args_size);
 159         f->argv[0] = f->cmd;
 160         return &f->base;
 161 }
 162
 163 void cgit_exec_filter_init(struct cgit_exec_filter *filter, char *cmd, char **argv)
 164 {
 165         memset(filter, 0, sizeof(*filter));
 166         filter->base.open = open_exec_filter;
 167         filter->base.close = close_exec_filter;
 168         filter->base.fprintf = fprintf_exec_filter;
 169         filter->base.cleanup = cleanup_exec_filter;
 170         filter->cmd = cmd;
 171         filter->argv = argv;
 172         /* The argument count for open_filter is zero by default, unless called from new_filter, above. */
 173         filter->base.argument_count = 0;
 174 }
 175
 176 #ifndef NO_LUA
 177 struct lua_filter {
 178         struct cgit_filter base;
 179         char *script_file;
 180         lua_State *lua_state;
 181 };
 182
 183 static void error_lua_filter(struct lua_filter *filter)
 184 {
 185         die("Lua error in %s: %s", filter->script_file, lua_tostring(filter->lua_state, -1));
 186         lua_pop(filter->lua_state, 1);
 187 }
 188
 189 static ssize_t write_lua_filter(struct cgit_filter *base, const void *buf, size_t count)
 190 {
 191         struct lua_filter *filter = (struct lua_filter *)base;
 192
 193         lua_getglobal(filter->lua_state, "filter_write");
 194         lua_pushlstring(filter->lua_state, buf, count);
 195         if (lua_pcall(filter->lua_state, 1, 0, 0)) {
 196                 error_lua_filter(filter);
 197                 errno = EIO;
 198                 return -1;
 199         }
 200         return count;
 201 }
 202
 203 static inline int hook_lua_filter(lua_State *lua_state, void (*fn)(const char *txt))
 204 {
 205         const char *str;
 206         ssize_t (*save_filter_write)(struct cgit_filter *base, const void *buf, size_t count);
 207         struct cgit_filter *save_filter;
 208
 209         str = lua_tostring(lua_state, 1);
 210         if (!str)
 211                 return 0;
 212
 213         save_filter_write = filter_write;
 214         save_filter = current_write_filter;
 215         unhook_write();
 216         fn(str);
 217         hook_write(save_filter, save_filter_write);
 218
 219         return 0;
 220 }
 221
 222 static int html_lua_filter(lua_State *lua_state)
 223 {
 224         return hook_lua_filter(lua_state, html);
 225 }
 226
 227 static int html_txt_lua_filter(lua_State *lua_state)
 228 {
 229         return hook_lua_filter(lua_state, html_txt);
 230 }
 231
 232 static int html_attr_lua_filter(lua_State *lua_state)
 233 {
 234         return hook_lua_filter(lua_state, html_attr);
 235 }
 236
 237 static int html_url_path_lua_filter(lua_State *lua_state)
 238 {
 239         return hook_lua_filter(lua_state, html_url_path);
 240 }
 241
 242 static int html_url_arg_lua_filter(lua_State *lua_state)
 243 {
 244         return hook_lua_filter(lua_state, html_url_arg);
 245 }
 246
 247 static int html_include_lua_filter(lua_State *lua_state)
 248 {
 249         return hook_lua_filter(lua_state, (void (*)(const char *))html_include);
 250 }
 251
 252 static void cleanup_lua_filter(struct cgit_filter *base)
 253 {
 254         struct lua_filter *filter = (struct lua_filter *)base;
 255
 256         if (!filter->lua_state)
 257                 return;
 258
 259         lua_close(filter->lua_state);
 260         filter->lua_state = NULL;
 261         if (filter->script_file) {
 262                 free(filter->script_file);
 263                 filter->script_file = NULL;
 264         }
 265 }
 266
 267 static int init_lua_filter(struct lua_filter *filter)
 268 {
 269         if (filter->lua_state)
 270                 return 0;
 271
 272         if (!(filter->lua_state = luaL_newstate()))
 273                 return 1;
 274
 275         luaL_openlibs(filter->lua_state);
 276
 277         lua_pushcfunction(filter->lua_state, html_lua_filter);
 278         lua_setglobal(filter->lua_state, "html");
 279         lua_pushcfunction(filter->lua_state, html_txt_lua_filter);
 280         lua_setglobal(filter->lua_state, "html_txt");
 281         lua_pushcfunction(filter->lua_state, html_attr_lua_filter);
 282         lua_setglobal(filter->lua_state, "html_attr");
 283         lua_pushcfunction(filter->lua_state, html_url_path_lua_filter);
 284         lua_setglobal(filter->lua_state, "html_url_path");
 285         lua_pushcfunction(filter->lua_state, html_url_arg_lua_filter);
 286         lua_setglobal(filter->lua_state, "html_url_arg");
 287         lua_pushcfunction(filter->lua_state, html_include_lua_filter);
 288         lua_setglobal(filter->lua_state, "html_include");
 289
 290         if (luaL_dofile(filter->lua_state, filter->script_file)) {
 291                 error_lua_filter(filter);
 292                 lua_close(filter->lua_state);
 293                 filter->lua_state = NULL;
 294                 return 1;
 295         }
 296         return 0;
 297 }
 298
 299 static int open_lua_filter(struct cgit_filter *base, va_list ap)
 300 {
 301         struct lua_filter *filter = (struct lua_filter *)base;
 302         int i;
 303
 304         if (init_lua_filter(filter))
 305                 return 1;
 306
 307         hook_write(base, write_lua_filter);
 308
 309         lua_getglobal(filter->lua_state, "filter_open");
 310         for (i = 0; i < filter->base.argument_count; ++i)
 311                 lua_pushstring(filter->lua_state, va_arg(ap, char *));
 312         if (lua_pcall(filter->lua_state, filter->base.argument_count, 0, 0)) {
 313                 error_lua_filter(filter);
 314                 return 1;
 315         }
 316         return 0;
 317 }
 318
 319 static int close_lua_filter(struct cgit_filter *base)
 320 {
 321         struct lua_filter *filter = (struct lua_filter *)base;
 322         int ret = 0;
 323
 324         lua_getglobal(filter->lua_state, "filter_close");
 325         if (lua_pcall(filter->lua_state, 0, 1, 0)) {
 326                 error_lua_filter(filter);
 327                 ret = -1;
 328         } else {
 329                 ret = lua_tonumber(filter->lua_state, -1);
 330                 lua_pop(filter->lua_state, 1);
 331         }
 332
 333         unhook_write();
 334         return ret;
 335 }
 336
 337 static void fprintf_lua_filter(struct cgit_filter *base, FILE *f, const char *prefix)
 338 {
 339         struct lua_filter *filter = (struct lua_filter *)base;
 340         fprintf(f, "%slua:%s\n", prefix, filter->script_file);
 341 }
 342
 343
 344 static struct cgit_filter *new_lua_filter(const char *cmd, int argument_count)
 345 {
 346         struct lua_filter *filter;
 347
 348         filter = xmalloc(sizeof(*filter));
 349         memset(filter, 0, sizeof(*filter));
 350         filter->base.open = open_lua_filter;
 351         filter->base.close = close_lua_filter;
 352         filter->base.fprintf = fprintf_lua_filter;
 353         filter->base.cleanup = cleanup_lua_filter;
 354         filter->base.argument_count = argument_count;
 355         filter->script_file = xstrdup(cmd);
 356
 357         return &filter->base;
 358 }
 359
 360 #endif
 361
 362
 363 int cgit_open_filter(struct cgit_filter *filter, ...)
 364 {
 365         int result;
 366         va_list ap;
 367         if (!filter)
 368                 return 0;
 369         va_start(ap, filter);
 370         result = filter->open(filter, ap);
 371         va_end(ap);
 372         return result;
 373 }
 374
 375 int cgit_close_filter(struct cgit_filter *filter)
 376 {
 377         if (!filter)
 378                 return 0;
 379         return filter->close(filter);
 380 }
 381
 382 void cgit_fprintf_filter(struct cgit_filter *filter, FILE *f, const char *prefix)
 383 {
 384         filter->fprintf(filter, f, prefix);
 385 }
 386
 387
 388
 389 static const struct {
 390         const char *prefix;
 391         struct cgit_filter *(*ctor)(const char *cmd, int argument_count);
 392 } filter_specs[] = {
 393         { "exec", new_exec_filter },
 394 #ifndef NO_LUA
 395         { "lua", new_lua_filter },
 396 #endif
 397 };
 398
 399 struct cgit_filter *cgit_new_filter(const char *cmd, filter_type filtertype)
 400 {
 401         char *colon;
 402         int i;
 403         size_t len;
 404         int argument_count;
 405
 406         if (!cmd || !cmd[0])
 407                 return NULL;
 408
 409         colon = strchr(cmd, ':');
 410         len = colon - cmd;
 411         /*
 412          * In case we're running on Windows, don't allow a single letter before
 413          * the colon.
 414          */
 415         if (len == 1)
 416                 colon = NULL;
 417
 418         switch (filtertype) {
 419                 case AUTH:
 420                         argument_count = 12;
 421                         break;
 422
 423                 case EMAIL:
 424                         argument_count = 2;
 425                         break;
 426
 427                 case SOURCE:
 428                 case ABOUT:
 429                         argument_count = 1;
 430                         break;
 431
 432                 case COMMIT:
 433                 default:
 434                         argument_count = 0;
 435                         break;
 436         }
 437
 438         /* If no prefix is given, exec filter is the default. */
 439         if (!colon)
 440                 return new_exec_filter(cmd, argument_count);
 441
 442         for (i = 0; i < ARRAY_SIZE(filter_specs); i++) {
 443                 if (len == strlen(filter_specs[i].prefix) &&
 444                     !strncmp(filter_specs[i].prefix, cmd, len))
 445                         return filter_specs[i].ctor(colon + 1, argument_count);
 446         }
 447
 448         die("Invalid filter type: %.*s", (int) len, cmd);
 449 }