mirror of
https://github.com/git/git
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539052f42f
An accidental conversion of a tab to 4 spaces snuck into 4c4066d95d
(run-command: move doc to run-command.h, 2019-11-17), messing up the
alignment when you have the project-recommended 8-width tabstops. Let's
revert that line.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
473 lines
16 KiB
C
473 lines
16 KiB
C
#ifndef RUN_COMMAND_H
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#define RUN_COMMAND_H
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#include "thread-utils.h"
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#include "argv-array.h"
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/**
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* The run-command API offers a versatile tool to run sub-processes with
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* redirected input and output as well as with a modified environment
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* and an alternate current directory.
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*
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* A similar API offers the capability to run a function asynchronously,
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* which is primarily used to capture the output that the function
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* produces in the caller in order to process it.
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*/
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/**
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* This describes the arguments, redirections, and environment of a
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* command to run in a sub-process.
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*
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* The caller:
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*
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* 1. allocates and clears (using child_process_init() or
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* CHILD_PROCESS_INIT) a struct child_process variable;
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* 2. initializes the members;
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* 3. calls start_command();
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* 4. processes the data;
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* 5. closes file descriptors (if necessary; see below);
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* 6. calls finish_command().
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*
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* Special forms of redirection are available by setting these members
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* to 1:
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*
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* .no_stdin, .no_stdout, .no_stderr: The respective channel is
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* redirected to /dev/null.
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*
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* .stdout_to_stderr: stdout of the child is redirected to its
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* stderr. This happens after stderr is itself redirected.
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* So stdout will follow stderr to wherever it is
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* redirected.
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*/
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struct child_process {
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/**
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* The .argv member is set up as an array of string pointers (NULL
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* terminated), of which .argv[0] is the program name to run (usually
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* without a path). If the command to run is a git command, set argv[0] to
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* the command name without the 'git-' prefix and set .git_cmd = 1.
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*
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* Note that the ownership of the memory pointed to by .argv stays with the
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* caller, but it should survive until `finish_command` completes. If the
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* .argv member is NULL, `start_command` will point it at the .args
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* `argv_array` (so you may use one or the other, but you must use exactly
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* one). The memory in .args will be cleaned up automatically during
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* `finish_command` (or during `start_command` when it is unsuccessful).
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*
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*/
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const char **argv;
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struct argv_array args;
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struct argv_array env_array;
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pid_t pid;
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int trace2_child_id;
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uint64_t trace2_child_us_start;
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const char *trace2_child_class;
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const char *trace2_hook_name;
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/*
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* Using .in, .out, .err:
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* - Specify 0 for no redirections. No new file descriptor is allocated.
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* (child inherits stdin, stdout, stderr from parent).
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* - Specify -1 to have a pipe allocated as follows:
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* .in: returns the writable pipe end; parent writes to it,
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* the readable pipe end becomes child's stdin
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* .out, .err: returns the readable pipe end; parent reads from
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* it, the writable pipe end becomes child's stdout/stderr
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* The caller of start_command() must close the returned FDs
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* after it has completed reading from/writing to it!
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* - Specify > 0 to set a channel to a particular FD as follows:
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* .in: a readable FD, becomes child's stdin
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* .out: a writable FD, becomes child's stdout/stderr
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* .err: a writable FD, becomes child's stderr
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* The specified FD is closed by start_command(), even in case
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* of errors!
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*/
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int in;
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int out;
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int err;
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/**
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* To specify a new initial working directory for the sub-process,
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* specify it in the .dir member.
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*/
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const char *dir;
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/**
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* To modify the environment of the sub-process, specify an array of
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* string pointers (NULL terminated) in .env:
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*
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* - If the string is of the form "VAR=value", i.e. it contains '='
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* the variable is added to the child process's environment.
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*
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* - If the string does not contain '=', it names an environment
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* variable that will be removed from the child process's environment.
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*
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* If the .env member is NULL, `start_command` will point it at the
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* .env_array `argv_array` (so you may use one or the other, but not both).
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* The memory in .env_array will be cleaned up automatically during
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* `finish_command` (or during `start_command` when it is unsuccessful).
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*/
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const char *const *env;
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unsigned no_stdin:1;
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unsigned no_stdout:1;
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unsigned no_stderr:1;
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unsigned git_cmd:1; /* if this is to be git sub-command */
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/**
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* If the program cannot be found, the functions return -1 and set
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* errno to ENOENT. Normally, an error message is printed, but if
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* .silent_exec_failure is set to 1, no message is printed for this
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* special error condition.
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*/
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unsigned silent_exec_failure:1;
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unsigned stdout_to_stderr:1;
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unsigned use_shell:1;
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unsigned clean_on_exit:1;
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unsigned wait_after_clean:1;
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void (*clean_on_exit_handler)(struct child_process *process);
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void *clean_on_exit_handler_cbdata;
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};
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#define CHILD_PROCESS_INIT { NULL, ARGV_ARRAY_INIT, ARGV_ARRAY_INIT }
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/**
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* The functions: child_process_init, start_command, finish_command,
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* run_command, run_command_v_opt, run_command_v_opt_cd_env, child_process_clear
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* do the following:
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*
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* - If a system call failed, errno is set and -1 is returned. A diagnostic
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* is printed.
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*
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* - If the program was not found, then -1 is returned and errno is set to
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* ENOENT; a diagnostic is printed only if .silent_exec_failure is 0.
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*
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* - Otherwise, the program is run. If it terminates regularly, its exit
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* code is returned. No diagnostic is printed, even if the exit code is
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* non-zero.
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*
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* - If the program terminated due to a signal, then the return value is the
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* signal number + 128, ie. the same value that a POSIX shell's $? would
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* report. A diagnostic is printed.
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*
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*/
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/**
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* Initialize a struct child_process variable.
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*/
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void child_process_init(struct child_process *);
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/**
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* Release the memory associated with the struct child_process.
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* Most users of the run-command API don't need to call this
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* function explicitly because `start_command` invokes it on
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* failure and `finish_command` calls it automatically already.
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*/
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void child_process_clear(struct child_process *);
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int is_executable(const char *name);
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/**
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* Start a sub-process. Takes a pointer to a `struct child_process`
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* that specifies the details and returns pipe FDs (if requested).
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* See below for details.
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*/
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int start_command(struct child_process *);
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/**
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* Wait for the completion of a sub-process that was started with
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* start_command().
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*/
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int finish_command(struct child_process *);
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int finish_command_in_signal(struct child_process *);
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/**
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* A convenience function that encapsulates a sequence of
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* start_command() followed by finish_command(). Takes a pointer
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* to a `struct child_process` that specifies the details.
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*/
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int run_command(struct child_process *);
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/*
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* Returns the path to the hook file, or NULL if the hook is missing
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* or disabled. Note that this points to static storage that will be
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* overwritten by further calls to find_hook and run_hook_*.
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*/
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const char *find_hook(const char *name);
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/**
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* Run a hook.
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* The first argument is a pathname to an index file, or NULL
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* if the hook uses the default index file or no index is needed.
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* The second argument is the name of the hook.
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* The further arguments correspond to the hook arguments.
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* The last argument has to be NULL to terminate the arguments list.
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* If the hook does not exist or is not executable, the return
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* value will be zero.
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* If it is executable, the hook will be executed and the exit
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* status of the hook is returned.
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* On execution, .stdout_to_stderr and .no_stdin will be set.
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*/
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LAST_ARG_MUST_BE_NULL
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int run_hook_le(const char *const *env, const char *name, ...);
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int run_hook_ve(const char *const *env, const char *name, va_list args);
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#define RUN_COMMAND_NO_STDIN 1
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#define RUN_GIT_CMD 2 /*If this is to be git sub-command */
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#define RUN_COMMAND_STDOUT_TO_STDERR 4
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#define RUN_SILENT_EXEC_FAILURE 8
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#define RUN_USING_SHELL 16
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#define RUN_CLEAN_ON_EXIT 32
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/**
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* Convenience functions that encapsulate a sequence of
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* start_command() followed by finish_command(). The argument argv
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* specifies the program and its arguments. The argument opt is zero
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* or more of the flags `RUN_COMMAND_NO_STDIN`, `RUN_GIT_CMD`,
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* `RUN_COMMAND_STDOUT_TO_STDERR`, or `RUN_SILENT_EXEC_FAILURE`
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* that correspond to the members .no_stdin, .git_cmd,
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* .stdout_to_stderr, .silent_exec_failure of `struct child_process`.
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* The argument dir corresponds the member .dir. The argument env
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* corresponds to the member .env.
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*/
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int run_command_v_opt(const char **argv, int opt);
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int run_command_v_opt_tr2(const char **argv, int opt, const char *tr2_class);
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/*
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* env (the environment) is to be formatted like environ: "VAR=VALUE".
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* To unset an environment variable use just "VAR".
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*/
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int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env);
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int run_command_v_opt_cd_env_tr2(const char **argv, int opt, const char *dir,
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const char *const *env, const char *tr2_class);
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/**
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* Execute the given command, sending "in" to its stdin, and capturing its
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* stdout and stderr in the "out" and "err" strbufs. Any of the three may
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* be NULL to skip processing.
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*
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* Returns -1 if starting the command fails or reading fails, and otherwise
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* returns the exit code of the command. Any output collected in the
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* buffers is kept even if the command returns a non-zero exit. The hint fields
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* gives starting sizes for the strbuf allocations.
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*
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* The fields of "cmd" should be set up as they would for a normal run_command
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* invocation. But note that there is no need to set the in, out, or err
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* fields; pipe_command handles that automatically.
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*/
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int pipe_command(struct child_process *cmd,
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const char *in, size_t in_len,
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struct strbuf *out, size_t out_hint,
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struct strbuf *err, size_t err_hint);
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/**
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* Convenience wrapper around pipe_command for the common case
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* of capturing only stdout.
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*/
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static inline int capture_command(struct child_process *cmd,
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struct strbuf *out,
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size_t hint)
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{
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return pipe_command(cmd, NULL, 0, out, hint, NULL, 0);
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}
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/*
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* The purpose of the following functions is to feed a pipe by running
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* a function asynchronously and providing output that the caller reads.
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*
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* It is expected that no synchronization and mutual exclusion between
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* the caller and the feed function is necessary so that the function
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* can run in a thread without interfering with the caller.
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*
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* The caller:
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*
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* 1. allocates and clears (memset(&asy, 0, sizeof(asy));) a
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* struct async variable;
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* 2. initializes .proc and .data;
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* 3. calls start_async();
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* 4. processes communicates with proc through .in and .out;
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* 5. closes .in and .out;
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* 6. calls finish_async().
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*
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* There are serious restrictions on what the asynchronous function can do
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* because this facility is implemented by a thread in the same address
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* space on most platforms (when pthreads is available), but by a pipe to
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* a forked process otherwise:
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*
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* - It cannot change the program's state (global variables, environment,
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* etc.) in a way that the caller notices; in other words, .in and .out
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* are the only communication channels to the caller.
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*
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* - It must not change the program's state that the caller of the
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* facility also uses.
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*
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*/
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struct async {
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/**
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* The function pointer in .proc has the following signature:
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*
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* int proc(int in, int out, void *data);
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*
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* - in, out specifies a set of file descriptors to which the function
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* must read/write the data that it needs/produces. The function
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* *must* close these descriptors before it returns. A descriptor
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* may be -1 if the caller did not configure a descriptor for that
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* direction.
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*
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* - data is the value that the caller has specified in the .data member
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* of struct async.
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*
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* - The return value of the function is 0 on success and non-zero
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* on failure. If the function indicates failure, finish_async() will
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* report failure as well.
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*
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*/
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int (*proc)(int in, int out, void *data);
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void *data;
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/**
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* The members .in, .out are used to provide a set of fd's for
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* communication between the caller and the callee as follows:
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*
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* - Specify 0 to have no file descriptor passed. The callee will
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* receive -1 in the corresponding argument.
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*
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* - Specify < 0 to have a pipe allocated; start_async() replaces
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* with the pipe FD in the following way:
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*
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* .in: Returns the writable pipe end into which the caller
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* writes; the readable end of the pipe becomes the function's
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* in argument.
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*
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* .out: Returns the readable pipe end from which the caller
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* reads; the writable end of the pipe becomes the function's
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* out argument.
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*
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* The caller of start_async() must close the returned FDs after it
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* has completed reading from/writing from them.
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*
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* - Specify a file descriptor > 0 to be used by the function:
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*
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* .in: The FD must be readable; it becomes the function's in.
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* .out: The FD must be writable; it becomes the function's out.
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*
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* The specified FD is closed by start_async(), even if it fails to
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* run the function.
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*/
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int in; /* caller writes here and closes it */
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int out; /* caller reads from here and closes it */
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#ifdef NO_PTHREADS
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pid_t pid;
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#else
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pthread_t tid;
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int proc_in;
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int proc_out;
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#endif
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int isolate_sigpipe;
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};
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/**
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* Run a function asynchronously. Takes a pointer to a `struct
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* async` that specifies the details and returns a set of pipe FDs
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* for communication with the function. See below for details.
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*/
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int start_async(struct async *async);
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/**
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* Wait for the completion of an asynchronous function that was
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* started with start_async().
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*/
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int finish_async(struct async *async);
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int in_async(void);
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int async_with_fork(void);
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void check_pipe(int err);
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/**
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* This callback should initialize the child process and preload the
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* error channel if desired. The preloading of is useful if you want to
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* have a message printed directly before the output of the child process.
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* pp_cb is the callback cookie as passed to run_processes_parallel.
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* You can store a child process specific callback cookie in pp_task_cb.
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*
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* Even after returning 0 to indicate that there are no more processes,
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* this function will be called again until there are no more running
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* child processes.
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*
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* Return 1 if the next child is ready to run.
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* Return 0 if there are currently no more tasks to be processed.
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* To send a signal to other child processes for abortion,
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* return the negative signal number.
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*/
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typedef int (*get_next_task_fn)(struct child_process *cp,
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struct strbuf *out,
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void *pp_cb,
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void **pp_task_cb);
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/**
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* This callback is called whenever there are problems starting
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* a new process.
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*
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* You must not write to stdout or stderr in this function. Add your
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* message to the strbuf out instead, which will be printed without
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* messing up the output of the other parallel processes.
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*
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* pp_cb is the callback cookie as passed into run_processes_parallel,
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* pp_task_cb is the callback cookie as passed into get_next_task_fn.
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*
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* Return 0 to continue the parallel processing. To abort return non zero.
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* To send a signal to other child processes for abortion, return
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* the negative signal number.
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*/
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typedef int (*start_failure_fn)(struct strbuf *out,
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void *pp_cb,
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void *pp_task_cb);
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/**
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* This callback is called on every child process that finished processing.
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*
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* You must not write to stdout or stderr in this function. Add your
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* message to the strbuf out instead, which will be printed without
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* messing up the output of the other parallel processes.
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*
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* pp_cb is the callback cookie as passed into run_processes_parallel,
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* pp_task_cb is the callback cookie as passed into get_next_task_fn.
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*
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* Return 0 to continue the parallel processing. To abort return non zero.
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* To send a signal to other child processes for abortion, return
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* the negative signal number.
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*/
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typedef int (*task_finished_fn)(int result,
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struct strbuf *out,
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void *pp_cb,
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void *pp_task_cb);
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/**
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* Runs up to n processes at the same time. Whenever a process can be
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* started, the callback get_next_task_fn is called to obtain the data
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* required to start another child process.
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*
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* The children started via this function run in parallel. Their output
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* (both stdout and stderr) is routed to stderr in a manner that output
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* from different tasks does not interleave.
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*
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* start_failure_fn and task_finished_fn can be NULL to omit any
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* special handling.
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*/
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int run_processes_parallel(int n,
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get_next_task_fn,
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start_failure_fn,
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task_finished_fn,
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void *pp_cb);
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int run_processes_parallel_tr2(int n, get_next_task_fn, start_failure_fn,
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task_finished_fn, void *pp_cb,
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const char *tr2_category, const char *tr2_label);
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#endif
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