Merge branch 'master' of github.com:alshopov/git-po
[alt-git.git] / run-command.h
blob0e85e5846a568d12472e24958860b11598d93599
1 #ifndef RUN_COMMAND_H
2 #define RUN_COMMAND_H
4 #include "thread-utils.h"
6 #include "strvec.h"
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.
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.
19 /**
20 * This describes the arguments, redirections, and environment of a
21 * command to run in a sub-process.
23 * The caller:
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().
33 * Special forms of redirection are available by setting these members
34 * to 1:
36 * .no_stdin, .no_stdout, .no_stderr: The respective channel is
37 * redirected to /dev/null.
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.
44 struct child_process {
46 /**
47 * The .args is a `struct strvec', use that API to manipulate
48 * it, e.g. strvec_pushv() to add an existing "const char **"
49 * vector.
51 * If the command to run is a git command, set the first
52 * element in the strvec to the command name without the
53 * 'git-' prefix and set .git_cmd = 1.
55 * The memory in .args will be cleaned up automatically during
56 * `finish_command` (or during `start_command` when it is unsuccessful).
58 struct strvec args;
60 /**
61 * Like .args the .env is a `struct strvec'.
63 * To modify the environment of the sub-process, specify an array of
64 * environment settings. Each string in the array manipulates the
65 * environment.
67 * - If the string is of the form "VAR=value", i.e. it contains '='
68 * the variable is added to the child process's environment.
70 * - If the string does not contain '=', it names an environment
71 * variable that will be removed from the child process's environment.
73 * The memory in .env will be cleaned up automatically during
74 * `finish_command` (or during `start_command` when it is unsuccessful).
76 struct strvec env;
77 pid_t pid;
79 int trace2_child_id;
80 uint64_t trace2_child_us_start;
81 const char *trace2_child_class;
82 const char *trace2_hook_name;
85 * Using .in, .out, .err:
86 * - Specify 0 for no redirections. No new file descriptor is allocated.
87 * (child inherits stdin, stdout, stderr from parent).
88 * - Specify -1 to have a pipe allocated as follows:
89 * .in: returns the writable pipe end; parent writes to it,
90 * the readable pipe end becomes child's stdin
91 * .out, .err: returns the readable pipe end; parent reads from
92 * it, the writable pipe end becomes child's stdout/stderr
93 * The caller of start_command() must close the returned FDs
94 * after it has completed reading from/writing to it!
95 * - Specify > 0 to set a channel to a particular FD as follows:
96 * .in: a readable FD, becomes child's stdin
97 * .out: a writable FD, becomes child's stdout/stderr
98 * .err: a writable FD, becomes child's stderr
99 * The specified FD is closed by start_command(), even in case
100 * of errors!
102 int in;
103 int out;
104 int err;
107 * To specify a new initial working directory for the sub-process,
108 * specify it in the .dir member.
110 const char *dir;
112 unsigned no_stdin:1;
113 unsigned no_stdout:1;
114 unsigned no_stderr:1;
115 unsigned git_cmd:1; /* if this is to be git sub-command */
118 * If the program cannot be found, the functions return -1 and set
119 * errno to ENOENT. Normally, an error message is printed, but if
120 * .silent_exec_failure is set to 1, no message is printed for this
121 * special error condition.
123 unsigned silent_exec_failure:1;
126 * Run the command from argv[0] using a shell (but note that we may
127 * still optimize out the shell call if the command contains no
128 * metacharacters). Note that further arguments to the command in
129 * argv[1], etc, do not need to be shell-quoted.
131 unsigned use_shell:1;
134 * Release any open file handles to the object store before running
135 * the command; This is necessary e.g. when the spawned process may
136 * want to repack because that would delete `.pack` files (and on
137 * Windows, you cannot delete files that are still in use).
139 unsigned close_object_store:1;
141 unsigned stdout_to_stderr:1;
142 unsigned clean_on_exit:1;
143 unsigned wait_after_clean:1;
144 void (*clean_on_exit_handler)(struct child_process *process);
147 #define CHILD_PROCESS_INIT { \
148 .args = STRVEC_INIT, \
149 .env = STRVEC_INIT, \
153 * The functions: child_process_init, start_command, finish_command,
154 * run_command, run_command_v_opt, run_command_v_opt_cd_env, child_process_clear
155 * do the following:
157 * - If a system call failed, errno is set and -1 is returned. A diagnostic
158 * is printed.
160 * - If the program was not found, then -1 is returned and errno is set to
161 * ENOENT; a diagnostic is printed only if .silent_exec_failure is 0.
163 * - Otherwise, the program is run. If it terminates regularly, its exit
164 * code is returned. No diagnostic is printed, even if the exit code is
165 * non-zero.
167 * - If the program terminated due to a signal, then the return value is the
168 * signal number + 128, ie. the same value that a POSIX shell's $? would
169 * report. A diagnostic is printed.
174 * Initialize a struct child_process variable.
176 void child_process_init(struct child_process *);
179 * Release the memory associated with the struct child_process.
180 * Most users of the run-command API don't need to call this
181 * function explicitly because `start_command` invokes it on
182 * failure and `finish_command` calls it automatically already.
184 void child_process_clear(struct child_process *);
186 int is_executable(const char *name);
189 * Check if the command exists on $PATH. This emulates the path search that
190 * execvp would perform, without actually executing the command so it
191 * can be used before fork() to prepare to run a command using
192 * execve() or after execvp() to diagnose why it failed.
194 * The caller should ensure that command contains no directory separators.
196 * Returns 1 if it is found in $PATH or 0 if the command could not be found.
198 int exists_in_PATH(const char *command);
201 * Start a sub-process. Takes a pointer to a `struct child_process`
202 * that specifies the details and returns pipe FDs (if requested).
203 * See below for details.
205 int start_command(struct child_process *);
208 * Wait for the completion of a sub-process that was started with
209 * start_command().
211 int finish_command(struct child_process *);
213 int finish_command_in_signal(struct child_process *);
216 * A convenience function that encapsulates a sequence of
217 * start_command() followed by finish_command(). Takes a pointer
218 * to a `struct child_process` that specifies the details.
220 int run_command(struct child_process *);
223 * Trigger an auto-gc
225 int run_auto_maintenance(int quiet);
227 #define RUN_COMMAND_NO_STDIN (1<<0)
228 #define RUN_GIT_CMD (1<<1)
229 #define RUN_COMMAND_STDOUT_TO_STDERR (1<<2)
230 #define RUN_SILENT_EXEC_FAILURE (1<<3)
231 #define RUN_USING_SHELL (1<<4)
232 #define RUN_CLEAN_ON_EXIT (1<<5)
233 #define RUN_WAIT_AFTER_CLEAN (1<<6)
234 #define RUN_CLOSE_OBJECT_STORE (1<<7)
237 * Convenience functions that encapsulate a sequence of
238 * start_command() followed by finish_command(). The argument argv
239 * specifies the program and its arguments. The argument opt is zero
240 * or more of the flags `RUN_COMMAND_NO_STDIN`, `RUN_GIT_CMD`,
241 * `RUN_COMMAND_STDOUT_TO_STDERR`, or `RUN_SILENT_EXEC_FAILURE`
242 * that correspond to the members .no_stdin, .git_cmd,
243 * .stdout_to_stderr, .silent_exec_failure of `struct child_process`.
244 * The argument dir corresponds the member .dir. The argument env
245 * corresponds to the member .env.
247 int run_command_v_opt(const char **argv, int opt);
248 int run_command_v_opt_tr2(const char **argv, int opt, const char *tr2_class);
250 * env (the environment) is to be formatted like environ: "VAR=VALUE".
251 * To unset an environment variable use just "VAR".
253 int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env);
254 int run_command_v_opt_cd_env_tr2(const char **argv, int opt, const char *dir,
255 const char *const *env, const char *tr2_class);
258 * Execute the given command, sending "in" to its stdin, and capturing its
259 * stdout and stderr in the "out" and "err" strbufs. Any of the three may
260 * be NULL to skip processing.
262 * Returns -1 if starting the command fails or reading fails, and otherwise
263 * returns the exit code of the command. Any output collected in the
264 * buffers is kept even if the command returns a non-zero exit. The hint fields
265 * gives starting sizes for the strbuf allocations.
267 * The fields of "cmd" should be set up as they would for a normal run_command
268 * invocation. But note that there is no need to set the in, out, or err
269 * fields; pipe_command handles that automatically.
271 int pipe_command(struct child_process *cmd,
272 const char *in, size_t in_len,
273 struct strbuf *out, size_t out_hint,
274 struct strbuf *err, size_t err_hint);
277 * Convenience wrapper around pipe_command for the common case
278 * of capturing only stdout.
280 static inline int capture_command(struct child_process *cmd,
281 struct strbuf *out,
282 size_t hint)
284 return pipe_command(cmd, NULL, 0, out, hint, NULL, 0);
288 * The purpose of the following functions is to feed a pipe by running
289 * a function asynchronously and providing output that the caller reads.
291 * It is expected that no synchronization and mutual exclusion between
292 * the caller and the feed function is necessary so that the function
293 * can run in a thread without interfering with the caller.
295 * The caller:
297 * 1. allocates and clears (memset(&asy, 0, sizeof(asy));) a
298 * struct async variable;
299 * 2. initializes .proc and .data;
300 * 3. calls start_async();
301 * 4. processes communicates with proc through .in and .out;
302 * 5. closes .in and .out;
303 * 6. calls finish_async().
305 * There are serious restrictions on what the asynchronous function can do
306 * because this facility is implemented by a thread in the same address
307 * space on most platforms (when pthreads is available), but by a pipe to
308 * a forked process otherwise:
310 * - It cannot change the program's state (global variables, environment,
311 * etc.) in a way that the caller notices; in other words, .in and .out
312 * are the only communication channels to the caller.
314 * - It must not change the program's state that the caller of the
315 * facility also uses.
318 struct async {
321 * The function pointer in .proc has the following signature:
323 * int proc(int in, int out, void *data);
325 * - in, out specifies a set of file descriptors to which the function
326 * must read/write the data that it needs/produces. The function
327 * *must* close these descriptors before it returns. A descriptor
328 * may be -1 if the caller did not configure a descriptor for that
329 * direction.
331 * - data is the value that the caller has specified in the .data member
332 * of struct async.
334 * - The return value of the function is 0 on success and non-zero
335 * on failure. If the function indicates failure, finish_async() will
336 * report failure as well.
339 int (*proc)(int in, int out, void *data);
341 void *data;
344 * The members .in, .out are used to provide a set of fd's for
345 * communication between the caller and the callee as follows:
347 * - Specify 0 to have no file descriptor passed. The callee will
348 * receive -1 in the corresponding argument.
350 * - Specify < 0 to have a pipe allocated; start_async() replaces
351 * with the pipe FD in the following way:
353 * .in: Returns the writable pipe end into which the caller
354 * writes; the readable end of the pipe becomes the function's
355 * in argument.
357 * .out: Returns the readable pipe end from which the caller
358 * reads; the writable end of the pipe becomes the function's
359 * out argument.
361 * The caller of start_async() must close the returned FDs after it
362 * has completed reading from/writing from them.
364 * - Specify a file descriptor > 0 to be used by the function:
366 * .in: The FD must be readable; it becomes the function's in.
367 * .out: The FD must be writable; it becomes the function's out.
369 * The specified FD is closed by start_async(), even if it fails to
370 * run the function.
372 int in; /* caller writes here and closes it */
373 int out; /* caller reads from here and closes it */
374 #ifdef NO_PTHREADS
375 pid_t pid;
376 #else
377 pthread_t tid;
378 int proc_in;
379 int proc_out;
380 #endif
381 int isolate_sigpipe;
385 * Run a function asynchronously. Takes a pointer to a `struct
386 * async` that specifies the details and returns a set of pipe FDs
387 * for communication with the function. See below for details.
389 int start_async(struct async *async);
392 * Wait for the completion of an asynchronous function that was
393 * started with start_async().
395 int finish_async(struct async *async);
397 int in_async(void);
398 int async_with_fork(void);
399 void check_pipe(int err);
402 * This callback should initialize the child process and preload the
403 * error channel if desired. The preloading of is useful if you want to
404 * have a message printed directly before the output of the child process.
405 * pp_cb is the callback cookie as passed to run_processes_parallel.
406 * You can store a child process specific callback cookie in pp_task_cb.
408 * See run_processes_parallel() below for a discussion of the "struct
409 * strbuf *out" parameter.
411 * Even after returning 0 to indicate that there are no more processes,
412 * this function will be called again until there are no more running
413 * child processes.
415 * Return 1 if the next child is ready to run.
416 * Return 0 if there are currently no more tasks to be processed.
417 * To send a signal to other child processes for abortion,
418 * return the negative signal number.
420 typedef int (*get_next_task_fn)(struct child_process *cp,
421 struct strbuf *out,
422 void *pp_cb,
423 void **pp_task_cb);
426 * This callback is called whenever there are problems starting
427 * a new process.
429 * See run_processes_parallel() below for a discussion of the "struct
430 * strbuf *out" parameter.
432 * pp_cb is the callback cookie as passed into run_processes_parallel,
433 * pp_task_cb is the callback cookie as passed into get_next_task_fn.
435 * Return 0 to continue the parallel processing. To abort return non zero.
436 * To send a signal to other child processes for abortion, return
437 * the negative signal number.
439 typedef int (*start_failure_fn)(struct strbuf *out,
440 void *pp_cb,
441 void *pp_task_cb);
444 * This callback is called on every child process that finished processing.
446 * See run_processes_parallel() below for a discussion of the "struct
447 * strbuf *out" parameter.
449 * pp_cb is the callback cookie as passed into run_processes_parallel,
450 * pp_task_cb is the callback cookie as passed into get_next_task_fn.
452 * Return 0 to continue the parallel processing. To abort return non zero.
453 * To send a signal to other child processes for abortion, return
454 * the negative signal number.
456 typedef int (*task_finished_fn)(int result,
457 struct strbuf *out,
458 void *pp_cb,
459 void *pp_task_cb);
462 * Runs up to n processes at the same time. Whenever a process can be
463 * started, the callback get_next_task_fn is called to obtain the data
464 * required to start another child process.
466 * The children started via this function run in parallel. Their output
467 * (both stdout and stderr) is routed to stderr in a manner that output
468 * from different tasks does not interleave (but see "ungroup" below).
470 * start_failure_fn and task_finished_fn can be NULL to omit any
471 * special handling.
473 * If the "ungroup" option isn't specified, the API will set the
474 * "stdout_to_stderr" parameter in "struct child_process" and provide
475 * the callbacks with a "struct strbuf *out" parameter to write output
476 * to. In this case the callbacks must not write to stdout or
477 * stderr as such output will mess up the output of the other parallel
478 * processes. If "ungroup" option is specified callbacks will get a
479 * NULL "struct strbuf *out" parameter, and are responsible for
480 * emitting their own output, including dealing with any race
481 * conditions due to writing in parallel to stdout and stderr.
482 * The "ungroup" option can be enabled by setting the global
483 * "run_processes_parallel_ungroup" to "1" before invoking
484 * run_processes_parallel(), it will be set back to "0" as soon as the
485 * API reads that setting.
487 extern int run_processes_parallel_ungroup;
488 int run_processes_parallel(int n,
489 get_next_task_fn,
490 start_failure_fn,
491 task_finished_fn,
492 void *pp_cb);
493 int run_processes_parallel_tr2(int n, get_next_task_fn, start_failure_fn,
494 task_finished_fn, void *pp_cb,
495 const char *tr2_category, const char *tr2_label);
498 * Convenience function which prepares env for a command to be run in a
499 * new repo. This adds all GIT_* environment variables to env with the
500 * exception of GIT_CONFIG_PARAMETERS and GIT_CONFIG_COUNT (which cause the
501 * corresponding environment variables to be unset in the subprocess) and adds
502 * an environment variable pointing to new_git_dir. See local_repo_env in
503 * cache.h for more information.
505 void prepare_other_repo_env(struct strvec *env, const char *new_git_dir);
508 * Possible return values for start_bg_command().
510 enum start_bg_result {
511 /* child process is "ready" */
512 SBGR_READY = 0,
514 /* child process could not be started */
515 SBGR_ERROR,
517 /* callback error when testing for "ready" */
518 SBGR_CB_ERROR,
520 /* timeout expired waiting for child to become "ready" */
521 SBGR_TIMEOUT,
523 /* child process exited or was signalled before becomming "ready" */
524 SBGR_DIED,
528 * Callback used by start_bg_command() to ask whether the
529 * child process is ready or needs more time to become "ready".
531 * The callback will receive the cmd and cb_data arguments given to
532 * start_bg_command().
534 * Returns 1 is child needs more time (subject to the requested timeout).
535 * Returns 0 if child is "ready".
536 * Returns -1 on any error and cause start_bg_command() to also error out.
538 typedef int(start_bg_wait_cb)(const struct child_process *cmd, void *cb_data);
541 * Start a command in the background. Wait long enough for the child
542 * to become "ready" (as defined by the provided callback). Capture
543 * immediate errors (like failure to start) and any immediate exit
544 * status (such as a shutdown/signal before the child became "ready")
545 * and return this like start_command().
547 * We run a custom wait loop using the provided callback to wait for
548 * the child to start and become "ready". This is limited by the given
549 * timeout value.
551 * If the child does successfully start and become "ready", we orphan
552 * it into the background.
554 * The caller must not call finish_command().
556 * The opaque cb_data argument will be forwarded to the callback for
557 * any instance data that it might require. This may be NULL.
559 enum start_bg_result start_bg_command(struct child_process *cmd,
560 start_bg_wait_cb *wait_cb,
561 void *cb_data,
562 unsigned int timeout_sec);
564 #endif