submodules: allow parallel fetching, add tests and documentation
[git/git.git] / run-command.h
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1#ifndef RUN_COMMAND_H
2#define RUN_COMMAND_H
3
f6b60983 4#ifndef NO_PTHREADS
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5#include <pthread.h>
6#endif
7
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8#include "argv-array.h"
9
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10struct child_process {
11 const char **argv;
c460c0ec 12 struct argv_array args;
19a583dc 13 struct argv_array env_array;
ebcb5d16 14 pid_t pid;
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15 /*
16 * Using .in, .out, .err:
17 * - Specify 0 for no redirections (child inherits stdin, stdout,
18 * stderr from parent).
19 * - Specify -1 to have a pipe allocated as follows:
20 * .in: returns the writable pipe end; parent writes to it,
21 * the readable pipe end becomes child's stdin
22 * .out, .err: returns the readable pipe end; parent reads from
23 * it, the writable pipe end becomes child's stdout/stderr
24 * The caller of start_command() must close the returned FDs
25 * after it has completed reading from/writing to it!
26 * - Specify > 0 to set a channel to a particular FD as follows:
27 * .in: a readable FD, becomes child's stdin
28 * .out: a writable FD, becomes child's stdout/stderr
4f41b611 29 * .err: a writable FD, becomes child's stderr
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30 * The specified FD is closed by start_command(), even in case
31 * of errors!
32 */
4919bf03 33 int in;
f4bba25b 34 int out;
f3b33f1d 35 int err;
1568fea0 36 const char *dir;
ee493148 37 const char *const *env;
f1000898 38 unsigned no_stdin:1;
e4507ae8 39 unsigned no_stdout:1;
b73a4397 40 unsigned no_stderr:1;
f1000898 41 unsigned git_cmd:1; /* if this is to be git sub-command */
c024beb5 42 unsigned silent_exec_failure:1;
f1000898 43 unsigned stdout_to_stderr:1;
8dba1e63 44 unsigned use_shell:1;
afe19ff7 45 unsigned clean_on_exit:1;
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46};
47
19a583dc 48#define CHILD_PROCESS_INIT { NULL, ARGV_ARRAY_INIT, ARGV_ARRAY_INIT }
483bbd4e 49void child_process_init(struct child_process *);
2d71608e 50void child_process_clear(struct child_process *);
d3180279 51
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52int start_command(struct child_process *);
53int finish_command(struct child_process *);
507d7804 54int finish_command_in_signal(struct child_process *);
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55int run_command(struct child_process *);
56
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57/*
58 * Returns the path to the hook file, or NULL if the hook is missing
59 * or disabled. Note that this points to static storage that will be
60 * overwritten by further calls to find_hook and run_hook_*.
61 */
dcf69262 62extern const char *find_hook(const char *name);
9fe3edc4 63LAST_ARG_MUST_BE_NULL
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64extern int run_hook_le(const char *const *env, const char *name, ...);
65extern int run_hook_ve(const char *const *env, const char *name, va_list args);
66
95d3c4f5 67#define RUN_COMMAND_NO_STDIN 1
77cb17e9 68#define RUN_GIT_CMD 2 /*If this is to be git sub-command */
cd83c74c 69#define RUN_COMMAND_STDOUT_TO_STDERR 4
c024beb5 70#define RUN_SILENT_EXEC_FAILURE 8
8dba1e63 71#define RUN_USING_SHELL 16
10c6cddd 72#define RUN_CLEAN_ON_EXIT 32
9b0b5093 73int run_command_v_opt(const char **argv, int opt);
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74
75/*
76 * env (the environment) is to be formatted like environ: "VAR=VALUE".
77 * To unset an environment variable use just "VAR".
78 */
ee493148 79int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env);
b1bf95bb 80
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81/**
82 * Execute the given command, capturing its stdout in the given strbuf.
83 * Returns -1 if starting the command fails or reading fails, and otherwise
84 * returns the exit code of the command. The output collected in the
85 * buffer is kept even if the command returns a non-zero exit. The hint field
86 * gives a starting size for the strbuf allocation.
87 *
88 * The fields of "cmd" should be set up as they would for a normal run_command
89 * invocation. But note that there is no need to set cmd->out; the function
90 * sets it up for the caller.
91 */
92int capture_command(struct child_process *cmd, struct strbuf *buf, size_t hint);
93
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94/*
95 * The purpose of the following functions is to feed a pipe by running
96 * a function asynchronously and providing output that the caller reads.
97 *
98 * It is expected that no synchronization and mutual exclusion between
99 * the caller and the feed function is necessary so that the function
100 * can run in a thread without interfering with the caller.
101 */
102struct async {
103 /*
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104 * proc reads from in; closes it before return
105 * proc writes to out; closes it before return
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106 * returns 0 on success, non-zero on failure
107 */
ae6a5609 108 int (*proc)(int in, int out, void *data);
2d22c208 109 void *data;
ae6a5609 110 int in; /* caller writes here and closes it */
2d22c208 111 int out; /* caller reads from here and closes it */
f6b60983 112#ifdef NO_PTHREADS
2d22c208 113 pid_t pid;
618ebe9f 114#else
200a76b7 115 pthread_t tid;
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116 int proc_in;
117 int proc_out;
618ebe9f 118#endif
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119};
120
121int start_async(struct async *async);
122int finish_async(struct async *async);
661a8cf4 123int in_async(void);
2d22c208 124
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125/**
126 * This callback should initialize the child process and preload the
127 * error channel if desired. The preloading of is useful if you want to
128 * have a message printed directly before the output of the child process.
129 * pp_cb is the callback cookie as passed to run_processes_parallel.
130 * You can store a child process specific callback cookie in pp_task_cb.
131 *
132 * Even after returning 0 to indicate that there are no more processes,
133 * this function will be called again until there are no more running
134 * child processes.
135 *
136 * Return 1 if the next child is ready to run.
137 * Return 0 if there are currently no more tasks to be processed.
138 * To send a signal to other child processes for abortion,
139 * return the negative signal number.
140 */
141typedef int (*get_next_task_fn)(struct child_process *cp,
142 struct strbuf *err,
143 void *pp_cb,
144 void **pp_task_cb);
145
146/**
147 * This callback is called whenever there are problems starting
148 * a new process.
149 *
150 * You must not write to stdout or stderr in this function. Add your
151 * message to the strbuf err instead, which will be printed without
152 * messing up the output of the other parallel processes.
153 *
154 * pp_cb is the callback cookie as passed into run_processes_parallel,
155 * pp_task_cb is the callback cookie as passed into get_next_task_fn.
156 *
157 * Return 0 to continue the parallel processing. To abort return non zero.
158 * To send a signal to other child processes for abortion, return
159 * the negative signal number.
160 */
161typedef int (*start_failure_fn)(struct child_process *cp,
162 struct strbuf *err,
163 void *pp_cb,
164 void *pp_task_cb);
165
166/**
167 * This callback is called on every child process that finished processing.
168 *
169 * You must not write to stdout or stderr in this function. Add your
170 * message to the strbuf err instead, which will be printed without
171 * messing up the output of the other parallel processes.
172 *
173 * pp_cb is the callback cookie as passed into run_processes_parallel,
174 * pp_task_cb is the callback cookie as passed into get_next_task_fn.
175 *
176 * Return 0 to continue the parallel processing. To abort return non zero.
177 * To send a signal to other child processes for abortion, return
178 * the negative signal number.
179 */
180typedef int (*task_finished_fn)(int result,
181 struct child_process *cp,
182 struct strbuf *err,
183 void *pp_cb,
184 void *pp_task_cb);
185
186/**
187 * Runs up to n processes at the same time. Whenever a process can be
188 * started, the callback get_next_task_fn is called to obtain the data
189 * required to start another child process.
190 *
191 * The children started via this function run in parallel. Their output
192 * (both stdout and stderr) is routed to stderr in a manner that output
193 * from different tasks does not interleave.
194 *
195 * If start_failure_fn or task_finished_fn are NULL, default handlers
196 * will be used. The default handlers will print an error message on
197 * error without issuing an emergency stop.
198 */
199int run_processes_parallel(int n,
200 get_next_task_fn,
201 start_failure_fn,
202 task_finished_fn,
203 void *pp_cb);
204
b1bf95bb 205#endif