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