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1 | #ifndef RUN_COMMAND_H | |
2 | #define RUN_COMMAND_H | |
3 | ||
4 | #include "thread-utils.h" | |
5 | ||
6 | #include "strvec.h" | |
7 | ||
8 | /** | |
9 | * The run-command API offers a versatile tool to run sub-processes with | |
10 | * redirected input and output as well as with a modified environment | |
11 | * and an alternate current directory. | |
12 | * | |
13 | * A similar API offers the capability to run a function asynchronously, | |
14 | * which is primarily used to capture the output that the function | |
15 | * produces in the caller in order to process it. | |
16 | */ | |
17 | ||
18 | ||
19 | /** | |
20 | * This describes the arguments, redirections, and environment of a | |
21 | * command to run in a sub-process. | |
22 | * | |
23 | * The caller: | |
24 | * | |
25 | * 1. allocates and clears (using child_process_init() or | |
26 | * CHILD_PROCESS_INIT) a struct child_process variable; | |
27 | * 2. initializes the members; | |
28 | * 3. calls start_command(); | |
29 | * 4. processes the data; | |
30 | * 5. closes file descriptors (if necessary; see below); | |
31 | * 6. calls finish_command(). | |
32 | * | |
33 | * Special forms of redirection are available by setting these members | |
34 | * to 1: | |
35 | * | |
36 | * .no_stdin, .no_stdout, .no_stderr: The respective channel is | |
37 | * redirected to /dev/null. | |
38 | * | |
39 | * .stdout_to_stderr: stdout of the child is redirected to its | |
40 | * stderr. This happens after stderr is itself redirected. | |
41 | * So stdout will follow stderr to wherever it is | |
42 | * redirected. | |
43 | */ | |
44 | struct child_process { | |
45 | ||
46 | /** | |
47 | * The .argv member is set up as an array of string pointers (NULL | |
48 | * terminated), of which .argv[0] is the program name to run (usually | |
49 | * without a path). If the command to run is a git command, set argv[0] to | |
50 | * the command name without the 'git-' prefix and set .git_cmd = 1. | |
51 | * | |
52 | * Note that the ownership of the memory pointed to by .argv stays with the | |
53 | * caller, but it should survive until `finish_command` completes. If the | |
54 | * .argv member is NULL, `start_command` will point it at the .args | |
55 | * `strvec` (so you may use one or the other, but you must use exactly | |
56 | * one). The memory in .args will be cleaned up automatically during | |
57 | * `finish_command` (or during `start_command` when it is unsuccessful). | |
58 | * | |
59 | */ | |
60 | const char **argv; | |
61 | ||
62 | struct strvec args; | |
63 | struct strvec env_array; | |
64 | pid_t pid; | |
65 | ||
66 | int trace2_child_id; | |
67 | uint64_t trace2_child_us_start; | |
68 | const char *trace2_child_class; | |
69 | const char *trace2_hook_name; | |
70 | ||
71 | /* | |
72 | * Using .in, .out, .err: | |
73 | * - Specify 0 for no redirections. No new file descriptor is allocated. | |
74 | * (child inherits stdin, stdout, stderr from parent). | |
75 | * - Specify -1 to have a pipe allocated as follows: | |
76 | * .in: returns the writable pipe end; parent writes to it, | |
77 | * the readable pipe end becomes child's stdin | |
78 | * .out, .err: returns the readable pipe end; parent reads from | |
79 | * it, the writable pipe end becomes child's stdout/stderr | |
80 | * The caller of start_command() must close the returned FDs | |
81 | * after it has completed reading from/writing to it! | |
82 | * - Specify > 0 to set a channel to a particular FD as follows: | |
83 | * .in: a readable FD, becomes child's stdin | |
84 | * .out: a writable FD, becomes child's stdout/stderr | |
85 | * .err: a writable FD, becomes child's stderr | |
86 | * The specified FD is closed by start_command(), even in case | |
87 | * of errors! | |
88 | */ | |
89 | int in; | |
90 | int out; | |
91 | int err; | |
92 | ||
93 | /** | |
94 | * To specify a new initial working directory for the sub-process, | |
95 | * specify it in the .dir member. | |
96 | */ | |
97 | const char *dir; | |
98 | ||
99 | /** | |
100 | * To modify the environment of the sub-process, specify an array of | |
101 | * string pointers (NULL terminated) in .env: | |
102 | * | |
103 | * - If the string is of the form "VAR=value", i.e. it contains '=' | |
104 | * the variable is added to the child process's environment. | |
105 | * | |
106 | * - If the string does not contain '=', it names an environment | |
107 | * variable that will be removed from the child process's environment. | |
108 | * | |
109 | * If the .env member is NULL, `start_command` will point it at the | |
110 | * .env_array `strvec` (so you may use one or the other, but not both). | |
111 | * The memory in .env_array will be cleaned up automatically during | |
112 | * `finish_command` (or during `start_command` when it is unsuccessful). | |
113 | */ | |
114 | const char *const *env; | |
115 | ||
116 | unsigned no_stdin:1; | |
117 | unsigned no_stdout:1; | |
118 | unsigned no_stderr:1; | |
119 | unsigned git_cmd:1; /* if this is to be git sub-command */ | |
120 | ||
121 | /** | |
122 | * If the program cannot be found, the functions return -1 and set | |
123 | * errno to ENOENT. Normally, an error message is printed, but if | |
124 | * .silent_exec_failure is set to 1, no message is printed for this | |
125 | * special error condition. | |
126 | */ | |
127 | unsigned silent_exec_failure:1; | |
128 | ||
129 | unsigned stdout_to_stderr:1; | |
130 | unsigned use_shell:1; | |
131 | unsigned clean_on_exit:1; | |
132 | unsigned wait_after_clean:1; | |
133 | void (*clean_on_exit_handler)(struct child_process *process); | |
134 | void *clean_on_exit_handler_cbdata; | |
135 | }; | |
136 | ||
137 | #define CHILD_PROCESS_INIT { NULL, STRVEC_INIT, STRVEC_INIT } | |
138 | ||
139 | /** | |
140 | * The functions: child_process_init, start_command, finish_command, | |
141 | * run_command, run_command_v_opt, run_command_v_opt_cd_env, child_process_clear | |
142 | * do the following: | |
143 | * | |
144 | * - If a system call failed, errno is set and -1 is returned. A diagnostic | |
145 | * is printed. | |
146 | * | |
147 | * - If the program was not found, then -1 is returned and errno is set to | |
148 | * ENOENT; a diagnostic is printed only if .silent_exec_failure is 0. | |
149 | * | |
150 | * - Otherwise, the program is run. If it terminates regularly, its exit | |
151 | * code is returned. No diagnostic is printed, even if the exit code is | |
152 | * non-zero. | |
153 | * | |
154 | * - If the program terminated due to a signal, then the return value is the | |
155 | * signal number + 128, ie. the same value that a POSIX shell's $? would | |
156 | * report. A diagnostic is printed. | |
157 | * | |
158 | */ | |
159 | ||
160 | /** | |
161 | * Initialize a struct child_process variable. | |
162 | */ | |
163 | void child_process_init(struct child_process *); | |
164 | ||
165 | /** | |
166 | * Release the memory associated with the struct child_process. | |
167 | * Most users of the run-command API don't need to call this | |
168 | * function explicitly because `start_command` invokes it on | |
169 | * failure and `finish_command` calls it automatically already. | |
170 | */ | |
171 | void child_process_clear(struct child_process *); | |
172 | ||
173 | int is_executable(const char *name); | |
174 | ||
175 | /** | |
176 | * Start a sub-process. Takes a pointer to a `struct child_process` | |
177 | * that specifies the details and returns pipe FDs (if requested). | |
178 | * See below for details. | |
179 | */ | |
180 | int start_command(struct child_process *); | |
181 | ||
182 | /** | |
183 | * Wait for the completion of a sub-process that was started with | |
184 | * start_command(). | |
185 | */ | |
186 | int finish_command(struct child_process *); | |
187 | ||
188 | int finish_command_in_signal(struct child_process *); | |
189 | ||
190 | /** | |
191 | * A convenience function that encapsulates a sequence of | |
192 | * start_command() followed by finish_command(). Takes a pointer | |
193 | * to a `struct child_process` that specifies the details. | |
194 | */ | |
195 | int run_command(struct child_process *); | |
196 | ||
197 | /* | |
198 | * Returns the path to the hook file, or NULL if the hook is missing | |
199 | * or disabled. Note that this points to static storage that will be | |
200 | * overwritten by further calls to find_hook and run_hook_*. | |
201 | */ | |
202 | const char *find_hook(const char *name); | |
203 | ||
204 | /** | |
205 | * Run a hook. | |
206 | * The first argument is a pathname to an index file, or NULL | |
207 | * if the hook uses the default index file or no index is needed. | |
208 | * The second argument is the name of the hook. | |
209 | * The further arguments correspond to the hook arguments. | |
210 | * The last argument has to be NULL to terminate the arguments list. | |
211 | * If the hook does not exist or is not executable, the return | |
212 | * value will be zero. | |
213 | * If it is executable, the hook will be executed and the exit | |
214 | * status of the hook is returned. | |
215 | * On execution, .stdout_to_stderr and .no_stdin will be set. | |
216 | */ | |
217 | LAST_ARG_MUST_BE_NULL | |
218 | int run_hook_le(const char *const *env, const char *name, ...); | |
219 | int run_hook_ve(const char *const *env, const char *name, va_list args); | |
220 | ||
221 | /* | |
222 | * Trigger an auto-gc | |
223 | */ | |
224 | int run_auto_maintenance(int quiet); | |
225 | ||
226 | #define RUN_COMMAND_NO_STDIN 1 | |
227 | #define RUN_GIT_CMD 2 /*If this is to be git sub-command */ | |
228 | #define RUN_COMMAND_STDOUT_TO_STDERR 4 | |
229 | #define RUN_SILENT_EXEC_FAILURE 8 | |
230 | #define RUN_USING_SHELL 16 | |
231 | #define RUN_CLEAN_ON_EXIT 32 | |
232 | #define RUN_WAIT_AFTER_CLEAN 64 | |
233 | ||
234 | /** | |
235 | * Convenience functions that encapsulate a sequence of | |
236 | * start_command() followed by finish_command(). The argument argv | |
237 | * specifies the program and its arguments. The argument opt is zero | |
238 | * or more of the flags `RUN_COMMAND_NO_STDIN`, `RUN_GIT_CMD`, | |
239 | * `RUN_COMMAND_STDOUT_TO_STDERR`, or `RUN_SILENT_EXEC_FAILURE` | |
240 | * that correspond to the members .no_stdin, .git_cmd, | |
241 | * .stdout_to_stderr, .silent_exec_failure of `struct child_process`. | |
242 | * The argument dir corresponds the member .dir. The argument env | |
243 | * corresponds to the member .env. | |
244 | */ | |
245 | int run_command_v_opt(const char **argv, int opt); | |
246 | int run_command_v_opt_tr2(const char **argv, int opt, const char *tr2_class); | |
247 | /* | |
248 | * env (the environment) is to be formatted like environ: "VAR=VALUE". | |
249 | * To unset an environment variable use just "VAR". | |
250 | */ | |
251 | int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env); | |
252 | int run_command_v_opt_cd_env_tr2(const char **argv, int opt, const char *dir, | |
253 | const char *const *env, const char *tr2_class); | |
254 | ||
255 | /** | |
256 | * Execute the given command, sending "in" to its stdin, and capturing its | |
257 | * stdout and stderr in the "out" and "err" strbufs. Any of the three may | |
258 | * be NULL to skip processing. | |
259 | * | |
260 | * Returns -1 if starting the command fails or reading fails, and otherwise | |
261 | * returns the exit code of the command. Any output collected in the | |
262 | * buffers is kept even if the command returns a non-zero exit. The hint fields | |
263 | * gives starting sizes for the strbuf allocations. | |
264 | * | |
265 | * The fields of "cmd" should be set up as they would for a normal run_command | |
266 | * invocation. But note that there is no need to set the in, out, or err | |
267 | * fields; pipe_command handles that automatically. | |
268 | */ | |
269 | int pipe_command(struct child_process *cmd, | |
270 | const char *in, size_t in_len, | |
271 | struct strbuf *out, size_t out_hint, | |
272 | struct strbuf *err, size_t err_hint); | |
273 | ||
274 | /** | |
275 | * Convenience wrapper around pipe_command for the common case | |
276 | * of capturing only stdout. | |
277 | */ | |
278 | static inline int capture_command(struct child_process *cmd, | |
279 | struct strbuf *out, | |
280 | size_t hint) | |
281 | { | |
282 | return pipe_command(cmd, NULL, 0, out, hint, NULL, 0); | |
283 | } | |
284 | ||
285 | /* | |
286 | * The purpose of the following functions is to feed a pipe by running | |
287 | * a function asynchronously and providing output that the caller reads. | |
288 | * | |
289 | * It is expected that no synchronization and mutual exclusion between | |
290 | * the caller and the feed function is necessary so that the function | |
291 | * can run in a thread without interfering with the caller. | |
292 | * | |
293 | * The caller: | |
294 | * | |
295 | * 1. allocates and clears (memset(&asy, 0, sizeof(asy));) a | |
296 | * struct async variable; | |
297 | * 2. initializes .proc and .data; | |
298 | * 3. calls start_async(); | |
299 | * 4. processes communicates with proc through .in and .out; | |
300 | * 5. closes .in and .out; | |
301 | * 6. calls finish_async(). | |
302 | * | |
303 | * There are serious restrictions on what the asynchronous function can do | |
304 | * because this facility is implemented by a thread in the same address | |
305 | * space on most platforms (when pthreads is available), but by a pipe to | |
306 | * a forked process otherwise: | |
307 | * | |
308 | * - It cannot change the program's state (global variables, environment, | |
309 | * etc.) in a way that the caller notices; in other words, .in and .out | |
310 | * are the only communication channels to the caller. | |
311 | * | |
312 | * - It must not change the program's state that the caller of the | |
313 | * facility also uses. | |
314 | * | |
315 | */ | |
316 | struct async { | |
317 | ||
318 | /** | |
319 | * The function pointer in .proc has the following signature: | |
320 | * | |
321 | * int proc(int in, int out, void *data); | |
322 | * | |
323 | * - in, out specifies a set of file descriptors to which the function | |
324 | * must read/write the data that it needs/produces. The function | |
325 | * *must* close these descriptors before it returns. A descriptor | |
326 | * may be -1 if the caller did not configure a descriptor for that | |
327 | * direction. | |
328 | * | |
329 | * - data is the value that the caller has specified in the .data member | |
330 | * of struct async. | |
331 | * | |
332 | * - The return value of the function is 0 on success and non-zero | |
333 | * on failure. If the function indicates failure, finish_async() will | |
334 | * report failure as well. | |
335 | * | |
336 | */ | |
337 | int (*proc)(int in, int out, void *data); | |
338 | ||
339 | void *data; | |
340 | ||
341 | /** | |
342 | * The members .in, .out are used to provide a set of fd's for | |
343 | * communication between the caller and the callee as follows: | |
344 | * | |
345 | * - Specify 0 to have no file descriptor passed. The callee will | |
346 | * receive -1 in the corresponding argument. | |
347 | * | |
348 | * - Specify < 0 to have a pipe allocated; start_async() replaces | |
349 | * with the pipe FD in the following way: | |
350 | * | |
351 | * .in: Returns the writable pipe end into which the caller | |
352 | * writes; the readable end of the pipe becomes the function's | |
353 | * in argument. | |
354 | * | |
355 | * .out: Returns the readable pipe end from which the caller | |
356 | * reads; the writable end of the pipe becomes the function's | |
357 | * out argument. | |
358 | * | |
359 | * The caller of start_async() must close the returned FDs after it | |
360 | * has completed reading from/writing from them. | |
361 | * | |
362 | * - Specify a file descriptor > 0 to be used by the function: | |
363 | * | |
364 | * .in: The FD must be readable; it becomes the function's in. | |
365 | * .out: The FD must be writable; it becomes the function's out. | |
366 | * | |
367 | * The specified FD is closed by start_async(), even if it fails to | |
368 | * run the function. | |
369 | */ | |
370 | int in; /* caller writes here and closes it */ | |
371 | int out; /* caller reads from here and closes it */ | |
372 | #ifdef NO_PTHREADS | |
373 | pid_t pid; | |
374 | #else | |
375 | pthread_t tid; | |
376 | int proc_in; | |
377 | int proc_out; | |
378 | #endif | |
379 | int isolate_sigpipe; | |
380 | }; | |
381 | ||
382 | /** | |
383 | * Run a function asynchronously. Takes a pointer to a `struct | |
384 | * async` that specifies the details and returns a set of pipe FDs | |
385 | * for communication with the function. See below for details. | |
386 | */ | |
387 | int start_async(struct async *async); | |
388 | ||
389 | /** | |
390 | * Wait for the completion of an asynchronous function that was | |
391 | * started with start_async(). | |
392 | */ | |
393 | int finish_async(struct async *async); | |
394 | ||
395 | int in_async(void); | |
396 | int async_with_fork(void); | |
397 | void check_pipe(int err); | |
398 | ||
399 | /** | |
400 | * This callback should initialize the child process and preload the | |
401 | * error channel if desired. The preloading of is useful if you want to | |
402 | * have a message printed directly before the output of the child process. | |
403 | * pp_cb is the callback cookie as passed to run_processes_parallel. | |
404 | * You can store a child process specific callback cookie in pp_task_cb. | |
405 | * | |
406 | * Even after returning 0 to indicate that there are no more processes, | |
407 | * this function will be called again until there are no more running | |
408 | * child processes. | |
409 | * | |
410 | * Return 1 if the next child is ready to run. | |
411 | * Return 0 if there are currently no more tasks to be processed. | |
412 | * To send a signal to other child processes for abortion, | |
413 | * return the negative signal number. | |
414 | */ | |
415 | typedef int (*get_next_task_fn)(struct child_process *cp, | |
416 | struct strbuf *out, | |
417 | void *pp_cb, | |
418 | void **pp_task_cb); | |
419 | ||
420 | /** | |
421 | * This callback is called whenever there are problems starting | |
422 | * a new process. | |
423 | * | |
424 | * You must not write to stdout or stderr in this function. Add your | |
425 | * message to the strbuf out instead, which will be printed without | |
426 | * messing up the output of the other parallel processes. | |
427 | * | |
428 | * pp_cb is the callback cookie as passed into run_processes_parallel, | |
429 | * pp_task_cb is the callback cookie as passed into get_next_task_fn. | |
430 | * | |
431 | * Return 0 to continue the parallel processing. To abort return non zero. | |
432 | * To send a signal to other child processes for abortion, return | |
433 | * the negative signal number. | |
434 | */ | |
435 | typedef int (*start_failure_fn)(struct strbuf *out, | |
436 | void *pp_cb, | |
437 | void *pp_task_cb); | |
438 | ||
439 | /** | |
440 | * This callback is called on every child process that finished processing. | |
441 | * | |
442 | * You must not write to stdout or stderr in this function. Add your | |
443 | * message to the strbuf out instead, which will be printed without | |
444 | * messing up the output of the other parallel processes. | |
445 | * | |
446 | * pp_cb is the callback cookie as passed into run_processes_parallel, | |
447 | * pp_task_cb is the callback cookie as passed into get_next_task_fn. | |
448 | * | |
449 | * Return 0 to continue the parallel processing. To abort return non zero. | |
450 | * To send a signal to other child processes for abortion, return | |
451 | * the negative signal number. | |
452 | */ | |
453 | typedef int (*task_finished_fn)(int result, | |
454 | struct strbuf *out, | |
455 | void *pp_cb, | |
456 | void *pp_task_cb); | |
457 | ||
458 | /** | |
459 | * Runs up to n processes at the same time. Whenever a process can be | |
460 | * started, the callback get_next_task_fn is called to obtain the data | |
461 | * required to start another child process. | |
462 | * | |
463 | * The children started via this function run in parallel. Their output | |
464 | * (both stdout and stderr) is routed to stderr in a manner that output | |
465 | * from different tasks does not interleave. | |
466 | * | |
467 | * start_failure_fn and task_finished_fn can be NULL to omit any | |
468 | * special handling. | |
469 | */ | |
470 | int run_processes_parallel(int n, | |
471 | get_next_task_fn, | |
472 | start_failure_fn, | |
473 | task_finished_fn, | |
474 | void *pp_cb); | |
475 | int run_processes_parallel_tr2(int n, get_next_task_fn, start_failure_fn, | |
476 | task_finished_fn, void *pp_cb, | |
477 | const char *tr2_category, const char *tr2_label); | |
478 | ||
479 | #endif |