Merge branch 'cb/test-use-ere-for-alternation'
[git.git] / run-command.h
blob191dfcdafe3dfcf6aff4b1c15e1be0924fbdb2d1
1 #ifndef RUN_COMMAND_H
2 #define RUN_COMMAND_H
4 #include "thread-utils.h"
6 #include "argv-array.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 .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.
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 * `argv_array` (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).
60 const char **argv;
62 struct argv_array args;
63 struct argv_array env_array;
64 pid_t pid;
66 int trace2_child_id;
67 uint64_t trace2_child_us_start;
68 const char *trace2_child_class;
69 const char *trace2_hook_name;
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!
89 int in;
90 int out;
91 int err;
93 /**
94 * To specify a new initial working directory for the sub-process,
95 * specify it in the .dir member.
97 const char *dir;
99 /**
100 * To modify the environment of the sub-process, specify an array of
101 * string pointers (NULL terminated) in .env:
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.
106 * - If the string does not contain '=', it names an environment
107 * variable that will be removed from the child process's environment.
109 * If the .env member is NULL, `start_command` will point it at the
110 * .env_array `argv_array` (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).
114 const char *const *env;
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 */
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.
127 unsigned silent_exec_failure:1;
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;
137 #define CHILD_PROCESS_INIT { NULL, ARGV_ARRAY_INIT, ARGV_ARRAY_INIT }
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:
144 * - If a system call failed, errno is set and -1 is returned. A diagnostic
145 * is printed.
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.
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.
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.
161 * Initialize a struct child_process variable.
163 void child_process_init(struct child_process *);
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.
171 void child_process_clear(struct child_process *);
173 int is_executable(const char *name);
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.
180 int start_command(struct child_process *);
183 * Wait for the completion of a sub-process that was started with
184 * start_command().
186 int finish_command(struct child_process *);
188 int finish_command_in_signal(struct child_process *);
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.
195 int run_command(struct child_process *);
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_*.
202 const char *find_hook(const char *name);
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.
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);
222 * Trigger an auto-gc
224 int run_auto_gc(int quiet);
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
234 * Convenience functions that encapsulate a sequence of
235 * start_command() followed by finish_command(). The argument argv
236 * specifies the program and its arguments. The argument opt is zero
237 * or more of the flags `RUN_COMMAND_NO_STDIN`, `RUN_GIT_CMD`,
238 * `RUN_COMMAND_STDOUT_TO_STDERR`, or `RUN_SILENT_EXEC_FAILURE`
239 * that correspond to the members .no_stdin, .git_cmd,
240 * .stdout_to_stderr, .silent_exec_failure of `struct child_process`.
241 * The argument dir corresponds the member .dir. The argument env
242 * corresponds to the member .env.
244 int run_command_v_opt(const char **argv, int opt);
245 int run_command_v_opt_tr2(const char **argv, int opt, const char *tr2_class);
247 * env (the environment) is to be formatted like environ: "VAR=VALUE".
248 * To unset an environment variable use just "VAR".
250 int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env);
251 int run_command_v_opt_cd_env_tr2(const char **argv, int opt, const char *dir,
252 const char *const *env, const char *tr2_class);
255 * Execute the given command, sending "in" to its stdin, and capturing its
256 * stdout and stderr in the "out" and "err" strbufs. Any of the three may
257 * be NULL to skip processing.
259 * Returns -1 if starting the command fails or reading fails, and otherwise
260 * returns the exit code of the command. Any output collected in the
261 * buffers is kept even if the command returns a non-zero exit. The hint fields
262 * gives starting sizes for the strbuf allocations.
264 * The fields of "cmd" should be set up as they would for a normal run_command
265 * invocation. But note that there is no need to set the in, out, or err
266 * fields; pipe_command handles that automatically.
268 int pipe_command(struct child_process *cmd,
269 const char *in, size_t in_len,
270 struct strbuf *out, size_t out_hint,
271 struct strbuf *err, size_t err_hint);
274 * Convenience wrapper around pipe_command for the common case
275 * of capturing only stdout.
277 static inline int capture_command(struct child_process *cmd,
278 struct strbuf *out,
279 size_t hint)
281 return pipe_command(cmd, NULL, 0, out, hint, NULL, 0);
285 * The purpose of the following functions is to feed a pipe by running
286 * a function asynchronously and providing output that the caller reads.
288 * It is expected that no synchronization and mutual exclusion between
289 * the caller and the feed function is necessary so that the function
290 * can run in a thread without interfering with the caller.
292 * The caller:
294 * 1. allocates and clears (memset(&asy, 0, sizeof(asy));) a
295 * struct async variable;
296 * 2. initializes .proc and .data;
297 * 3. calls start_async();
298 * 4. processes communicates with proc through .in and .out;
299 * 5. closes .in and .out;
300 * 6. calls finish_async().
302 * There are serious restrictions on what the asynchronous function can do
303 * because this facility is implemented by a thread in the same address
304 * space on most platforms (when pthreads is available), but by a pipe to
305 * a forked process otherwise:
307 * - It cannot change the program's state (global variables, environment,
308 * etc.) in a way that the caller notices; in other words, .in and .out
309 * are the only communication channels to the caller.
311 * - It must not change the program's state that the caller of the
312 * facility also uses.
315 struct async {
318 * The function pointer in .proc has the following signature:
320 * int proc(int in, int out, void *data);
322 * - in, out specifies a set of file descriptors to which the function
323 * must read/write the data that it needs/produces. The function
324 * *must* close these descriptors before it returns. A descriptor
325 * may be -1 if the caller did not configure a descriptor for that
326 * direction.
328 * - data is the value that the caller has specified in the .data member
329 * of struct async.
331 * - The return value of the function is 0 on success and non-zero
332 * on failure. If the function indicates failure, finish_async() will
333 * report failure as well.
336 int (*proc)(int in, int out, void *data);
338 void *data;
341 * The members .in, .out are used to provide a set of fd's for
342 * communication between the caller and the callee as follows:
344 * - Specify 0 to have no file descriptor passed. The callee will
345 * receive -1 in the corresponding argument.
347 * - Specify < 0 to have a pipe allocated; start_async() replaces
348 * with the pipe FD in the following way:
350 * .in: Returns the writable pipe end into which the caller
351 * writes; the readable end of the pipe becomes the function's
352 * in argument.
354 * .out: Returns the readable pipe end from which the caller
355 * reads; the writable end of the pipe becomes the function's
356 * out argument.
358 * The caller of start_async() must close the returned FDs after it
359 * has completed reading from/writing from them.
361 * - Specify a file descriptor > 0 to be used by the function:
363 * .in: The FD must be readable; it becomes the function's in.
364 * .out: The FD must be writable; it becomes the function's out.
366 * The specified FD is closed by start_async(), even if it fails to
367 * run the function.
369 int in; /* caller writes here and closes it */
370 int out; /* caller reads from here and closes it */
371 #ifdef NO_PTHREADS
372 pid_t pid;
373 #else
374 pthread_t tid;
375 int proc_in;
376 int proc_out;
377 #endif
378 int isolate_sigpipe;
382 * Run a function asynchronously. Takes a pointer to a `struct
383 * async` that specifies the details and returns a set of pipe FDs
384 * for communication with the function. See below for details.
386 int start_async(struct async *async);
389 * Wait for the completion of an asynchronous function that was
390 * started with start_async().
392 int finish_async(struct async *async);
394 int in_async(void);
395 int async_with_fork(void);
396 void check_pipe(int err);
399 * This callback should initialize the child process and preload the
400 * error channel if desired. The preloading of is useful if you want to
401 * have a message printed directly before the output of the child process.
402 * pp_cb is the callback cookie as passed to run_processes_parallel.
403 * You can store a child process specific callback cookie in pp_task_cb.
405 * Even after returning 0 to indicate that there are no more processes,
406 * this function will be called again until there are no more running
407 * child processes.
409 * Return 1 if the next child is ready to run.
410 * Return 0 if there are currently no more tasks to be processed.
411 * To send a signal to other child processes for abortion,
412 * return the negative signal number.
414 typedef int (*get_next_task_fn)(struct child_process *cp,
415 struct strbuf *out,
416 void *pp_cb,
417 void **pp_task_cb);
420 * This callback is called whenever there are problems starting
421 * a new process.
423 * You must not write to stdout or stderr in this function. Add your
424 * message to the strbuf out instead, which will be printed without
425 * messing up the output of the other parallel processes.
427 * pp_cb is the callback cookie as passed into run_processes_parallel,
428 * pp_task_cb is the callback cookie as passed into get_next_task_fn.
430 * Return 0 to continue the parallel processing. To abort return non zero.
431 * To send a signal to other child processes for abortion, return
432 * the negative signal number.
434 typedef int (*start_failure_fn)(struct strbuf *out,
435 void *pp_cb,
436 void *pp_task_cb);
439 * This callback is called on every child process that finished processing.
441 * You must not write to stdout or stderr in this function. Add your
442 * message to the strbuf out instead, which will be printed without
443 * messing up the output of the other parallel processes.
445 * pp_cb is the callback cookie as passed into run_processes_parallel,
446 * pp_task_cb is the callback cookie as passed into get_next_task_fn.
448 * Return 0 to continue the parallel processing. To abort return non zero.
449 * To send a signal to other child processes for abortion, return
450 * the negative signal number.
452 typedef int (*task_finished_fn)(int result,
453 struct strbuf *out,
454 void *pp_cb,
455 void *pp_task_cb);
458 * Runs up to n processes at the same time. Whenever a process can be
459 * started, the callback get_next_task_fn is called to obtain the data
460 * required to start another child process.
462 * The children started via this function run in parallel. Their output
463 * (both stdout and stderr) is routed to stderr in a manner that output
464 * from different tasks does not interleave.
466 * start_failure_fn and task_finished_fn can be NULL to omit any
467 * special handling.
469 int run_processes_parallel(int n,
470 get_next_task_fn,
471 start_failure_fn,
472 task_finished_fn,
473 void *pp_cb);
474 int run_processes_parallel_tr2(int n, get_next_task_fn, start_failure_fn,
475 task_finished_fn, void *pp_cb,
476 const char *tr2_category, const char *tr2_label);
478 #endif