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#ifndef NO_LUA
 12#include <dlfcn.h>
 13#include <lua.h>
 14#include <lualib.h>
 15#include <lauxlib.h>
 16#endif
 17
 18static inline void reap_filter(struct cgit_filter *filter)
 19{
 20	if (filter && filter->cleanup)
 21		filter->cleanup(filter);
 22}
 23
 24void cgit_cleanup_filters(void)
 25{
 26	int i;
 27	reap_filter(ctx.cfg.about_filter);
 28	reap_filter(ctx.cfg.commit_filter);
 29	reap_filter(ctx.cfg.source_filter);
 30	reap_filter(ctx.cfg.email_filter);
 31	reap_filter(ctx.cfg.owner_filter);
 32	reap_filter(ctx.cfg.auth_filter);
 33	for (i = 0; i < cgit_repolist.count; ++i) {
 34		reap_filter(cgit_repolist.repos[i].about_filter);
 35		reap_filter(cgit_repolist.repos[i].commit_filter);
 36		reap_filter(cgit_repolist.repos[i].source_filter);
 37		reap_filter(cgit_repolist.repos[i].email_filter);
 38		reap_filter(cgit_repolist.repos[i].owner_filter);
 39	}
 40}
 41
 42static int open_exec_filter(struct cgit_filter *base, va_list ap)
 43{
 44	struct cgit_exec_filter *filter = (struct cgit_exec_filter *)base;
 45	int i;
 46
 47	for (i = 0; i < filter->base.argument_count; i++)
 48		filter->argv[i + 1] = va_arg(ap, char *);
 49
 50	filter->old_stdout = chk_positive(dup(STDOUT_FILENO),
 51		"Unable to duplicate STDOUT");
 52	chk_zero(pipe(filter->pipe_fh), "Unable to create pipe to subprocess");
 53	filter->pid = chk_non_negative(fork(), "Unable to create subprocess");
 54	if (filter->pid == 0) {
 55		close(filter->pipe_fh[1]);
 56		chk_non_negative(dup2(filter->pipe_fh[0], STDIN_FILENO),
 57			"Unable to use pipe as STDIN");
 58		execvp(filter->cmd, filter->argv);
 59		die_errno("Unable to exec subprocess %s", filter->cmd);
 60	}
 61	close(filter->pipe_fh[0]);
 62	chk_non_negative(dup2(filter->pipe_fh[1], STDOUT_FILENO),
 63		"Unable to use pipe as STDOUT");
 64	close(filter->pipe_fh[1]);
 65	return 0;
 66}
 67
 68static int close_exec_filter(struct cgit_filter *base)
 69{
 70	struct cgit_exec_filter *filter = (struct cgit_exec_filter *)base;
 71	int i, exit_status = 0;
 72
 73	chk_non_negative(dup2(filter->old_stdout, STDOUT_FILENO),
 74		"Unable to restore STDOUT");
 75	close(filter->old_stdout);
 76	if (filter->pid < 0)
 77		goto done;
 78	waitpid(filter->pid, &exit_status, 0);
 79	if (WIFEXITED(exit_status))
 80		goto done;
 81	die("Subprocess %s exited abnormally", filter->cmd);
 82
 83done:
 84	for (i = 0; i < filter->base.argument_count; i++)
 85		filter->argv[i + 1] = NULL;
 86	return WEXITSTATUS(exit_status);
 87
 88}
 89
 90static void fprintf_exec_filter(struct cgit_filter *base, FILE *f, const char *prefix)
 91{
 92	struct cgit_exec_filter *filter = (struct cgit_exec_filter *)base;
 93	fprintf(f, "%sexec:%s\n", prefix, filter->cmd);
 94}
 95
 96static void cleanup_exec_filter(struct cgit_filter *base)
 97{
 98	struct cgit_exec_filter *filter = (struct cgit_exec_filter *)base;
 99	if (filter->argv) {
100		free(filter->argv);
101		filter->argv = NULL;
102	}
103	if (filter->cmd) {
104		free(filter->cmd);
105		filter->cmd = NULL;
106	}
107}
108
109static struct cgit_filter *new_exec_filter(const char *cmd, int argument_count)
110{
111	struct cgit_exec_filter *f;
112	int args_size = 0;
113
114	f = xmalloc(sizeof(*f));
115	/* We leave argv for now and assign it below. */
116	cgit_exec_filter_init(f, xstrdup(cmd), NULL);
117	f->base.argument_count = argument_count;
118	args_size = (2 + argument_count) * sizeof(char *);
119	f->argv = xmalloc(args_size);
120	memset(f->argv, 0, args_size);
121	f->argv[0] = f->cmd;
122	return &f->base;
123}
124
125void cgit_exec_filter_init(struct cgit_exec_filter *filter, char *cmd, char **argv)
126{
127	memset(filter, 0, sizeof(*filter));
128	filter->base.open = open_exec_filter;
129	filter->base.close = close_exec_filter;
130	filter->base.fprintf = fprintf_exec_filter;
131	filter->base.cleanup = cleanup_exec_filter;
132	filter->cmd = cmd;
133	filter->argv = argv;
134	/* The argument count for open_filter is zero by default, unless called from new_filter, above. */
135	filter->base.argument_count = 0;
136}
137
138#ifdef NO_LUA
139void cgit_init_filters(void)
140{
141}
142#endif
143
144#ifndef NO_LUA
145static ssize_t (*libc_write)(int fd, const void *buf, size_t count);
146static ssize_t (*filter_write)(struct cgit_filter *base, const void *buf, size_t count) = NULL;
147static struct cgit_filter *current_write_filter = NULL;
148
149void cgit_init_filters(void)
150{
151	libc_write = dlsym(RTLD_NEXT, "write");
152	if (!libc_write)
153		die("Could not locate libc's write function");
154}
155
156ssize_t write(int fd, const void *buf, size_t count)
157{
158	if (fd != STDOUT_FILENO || !filter_write)
159		return libc_write(fd, buf, count);
160	return filter_write(current_write_filter, buf, count);
161}
162
163static inline void hook_write(struct cgit_filter *filter, ssize_t (*new_write)(struct cgit_filter *base, const void *buf, size_t count))
164{
165	/* We want to avoid buggy nested patterns. */
166	assert(filter_write == NULL);
167	assert(current_write_filter == NULL);
168	current_write_filter = filter;
169	filter_write = new_write;
170}
171
172static inline void unhook_write(void)
173{
174	assert(filter_write != NULL);
175	assert(current_write_filter != NULL);
176	filter_write = NULL;
177	current_write_filter = NULL;
178}
179
180struct lua_filter {
181	struct cgit_filter base;
182	char *script_file;
183	lua_State *lua_state;
184};
185
186static void error_lua_filter(struct lua_filter *filter)
187{
188	die("Lua error in %s: %s", filter->script_file, lua_tostring(filter->lua_state, -1));
189	lua_pop(filter->lua_state, 1);
190}
191
192static ssize_t write_lua_filter(struct cgit_filter *base, const void *buf, size_t count)
193{
194	struct lua_filter *filter = (struct lua_filter *)base;
195
196	lua_getglobal(filter->lua_state, "filter_write");
197	lua_pushlstring(filter->lua_state, buf, count);
198	if (lua_pcall(filter->lua_state, 1, 0, 0)) {
199		error_lua_filter(filter);
200		errno = EIO;
201		return -1;
202	}
203	return count;
204}
205
206static inline int hook_lua_filter(lua_State *lua_state, void (*fn)(const char *txt))
207{
208	const char *str;
209	ssize_t (*save_filter_write)(struct cgit_filter *base, const void *buf, size_t count);
210	struct cgit_filter *save_filter;
211
212	str = lua_tostring(lua_state, 1);
213	if (!str)
214		return 0;
215
216	save_filter_write = filter_write;
217	save_filter = current_write_filter;
218	unhook_write();
219	fn(str);
220	hook_write(save_filter, save_filter_write);
221
222	return 0;
223}
224
225static int html_lua_filter(lua_State *lua_state)
226{
227	return hook_lua_filter(lua_state, html);
228}
229
230static int html_txt_lua_filter(lua_State *lua_state)
231{
232	return hook_lua_filter(lua_state, html_txt);
233}
234
235static int html_attr_lua_filter(lua_State *lua_state)
236{
237	return hook_lua_filter(lua_state, html_attr);
238}
239
240static int html_url_path_lua_filter(lua_State *lua_state)
241{
242	return hook_lua_filter(lua_state, html_url_path);
243}
244
245static int html_url_arg_lua_filter(lua_State *lua_state)
246{
247	return hook_lua_filter(lua_state, html_url_arg);
248}
249
250static int html_include_lua_filter(lua_State *lua_state)
251{
252	return hook_lua_filter(lua_state, (void (*)(const char *))html_include);
253}
254
255static void cleanup_lua_filter(struct cgit_filter *base)
256{
257	struct lua_filter *filter = (struct lua_filter *)base;
258
259	if (!filter->lua_state)
260		return;
261
262	lua_close(filter->lua_state);
263	filter->lua_state = NULL;
264	if (filter->script_file) {
265		free(filter->script_file);
266		filter->script_file = NULL;
267	}
268}
269
270static int init_lua_filter(struct lua_filter *filter)
271{
272	if (filter->lua_state)
273		return 0;
274
275	if (!(filter->lua_state = luaL_newstate()))
276		return 1;
277
278	luaL_openlibs(filter->lua_state);
279
280	lua_pushcfunction(filter->lua_state, html_lua_filter);
281	lua_setglobal(filter->lua_state, "html");
282	lua_pushcfunction(filter->lua_state, html_txt_lua_filter);
283	lua_setglobal(filter->lua_state, "html_txt");
284	lua_pushcfunction(filter->lua_state, html_attr_lua_filter);
285	lua_setglobal(filter->lua_state, "html_attr");
286	lua_pushcfunction(filter->lua_state, html_url_path_lua_filter);
287	lua_setglobal(filter->lua_state, "html_url_path");
288	lua_pushcfunction(filter->lua_state, html_url_arg_lua_filter);
289	lua_setglobal(filter->lua_state, "html_url_arg");
290	lua_pushcfunction(filter->lua_state, html_include_lua_filter);
291	lua_setglobal(filter->lua_state, "html_include");
292
293	if (luaL_dofile(filter->lua_state, filter->script_file)) {
294		error_lua_filter(filter);
295		lua_close(filter->lua_state);
296		filter->lua_state = NULL;
297		return 1;
298	}
299	return 0;
300}
301
302static int open_lua_filter(struct cgit_filter *base, va_list ap)
303{
304	struct lua_filter *filter = (struct lua_filter *)base;
305	int i;
306
307	if (init_lua_filter(filter))
308		return 1;
309
310	hook_write(base, write_lua_filter);
311
312	lua_getglobal(filter->lua_state, "filter_open");
313	for (i = 0; i < filter->base.argument_count; ++i)
314		lua_pushstring(filter->lua_state, va_arg(ap, char *));
315	if (lua_pcall(filter->lua_state, filter->base.argument_count, 0, 0)) {
316		error_lua_filter(filter);
317		return 1;
318	}
319	return 0;
320}
321
322static int close_lua_filter(struct cgit_filter *base)
323{
324	struct lua_filter *filter = (struct lua_filter *)base;
325	int ret = 0;
326
327	lua_getglobal(filter->lua_state, "filter_close");
328	if (lua_pcall(filter->lua_state, 0, 1, 0)) {
329		error_lua_filter(filter);
330		ret = -1;
331	} else {
332		ret = lua_tonumber(filter->lua_state, -1);
333		lua_pop(filter->lua_state, 1);
334	}
335
336	unhook_write();
337	return ret;
338}
339
340static void fprintf_lua_filter(struct cgit_filter *base, FILE *f, const char *prefix)
341{
342	struct lua_filter *filter = (struct lua_filter *)base;
343	fprintf(f, "%slua:%s\n", prefix, filter->script_file);
344}
345
346
347static struct cgit_filter *new_lua_filter(const char *cmd, int argument_count)
348{
349	struct lua_filter *filter;
350
351	filter = xmalloc(sizeof(*filter));
352	memset(filter, 0, sizeof(*filter));
353	filter->base.open = open_lua_filter;
354	filter->base.close = close_lua_filter;
355	filter->base.fprintf = fprintf_lua_filter;
356	filter->base.cleanup = cleanup_lua_filter;
357	filter->base.argument_count = argument_count;
358	filter->script_file = xstrdup(cmd);
359
360	return &filter->base;
361}
362
363#endif
364
365
366int cgit_open_filter(struct cgit_filter *filter, ...)
367{
368	int result;
369	va_list ap;
370	if (!filter)
371		return 0;
372	va_start(ap, filter);
373	result = filter->open(filter, ap);
374	va_end(ap);
375	return result;
376}
377
378int cgit_close_filter(struct cgit_filter *filter)
379{
380	if (!filter)
381		return 0;
382	return filter->close(filter);
383}
384
385void cgit_fprintf_filter(struct cgit_filter *filter, FILE *f, const char *prefix)
386{
387	filter->fprintf(filter, f, prefix);
388}
389
390
391
392static const struct {
393	const char *prefix;
394	struct cgit_filter *(*ctor)(const char *cmd, int argument_count);
395} filter_specs[] = {
396	{ "exec", new_exec_filter },
397#ifndef NO_LUA
398	{ "lua", new_lua_filter },
399#endif
400};
401
402struct cgit_filter *cgit_new_filter(const char *cmd, filter_type filtertype)
403{
404	char *colon;
405	int i;
406	size_t len;
407	int argument_count;
408
409	if (!cmd || !cmd[0])
410		return NULL;
411
412	colon = strchr(cmd, ':');
413	len = colon - cmd;
414	/*
415	 * In case we're running on Windows, don't allow a single letter before
416	 * the colon.
417	 */
418	if (len == 1)
419		colon = NULL;
420
421	switch (filtertype) {
422		case AUTH:
423			argument_count = 12;
424			break;
425
426		case EMAIL:
427			argument_count = 2;
428			break;
429
430		case OWNER:
431			argument_count = 0;
432			break;
433
434		case SOURCE:
435		case ABOUT:
436			argument_count = 1;
437			break;
438
439		case COMMIT:
440		default:
441			argument_count = 0;
442			break;
443	}
444
445	/* If no prefix is given, exec filter is the default. */
446	if (!colon)
447		return new_exec_filter(cmd, argument_count);
448
449	for (i = 0; i < ARRAY_SIZE(filter_specs); i++) {
450		if (len == strlen(filter_specs[i].prefix) &&
451		    !strncmp(filter_specs[i].prefix, cmd, len))
452			return filter_specs[i].ctor(colon + 1, argument_count);
453	}
454
455	die("Invalid filter type: %.*s", (int) len, cmd);
456}