fish-shell/src/postfork.h

/** \file postfork.h

  Functions that we may safely call after fork(), of which there are very few. In particular we cannot allocate memory, since we're insane enough to call fork from a multithreaded process.
*/
#ifndef FISH_POSTFORK_H
#define FISH_POSTFORK_H

#include "config.h"

#include <unistd.h>
#if HAVE_SPAWN_H
#include <spawn.h>
#endif
#ifndef FISH_USE_POSIX_SPAWN
#define FISH_USE_POSIX_SPAWN HAVE_SPAWN_H
#endif
#include <stdbool.h>

class io_chain_t;
class job_t;
class process_t;

/**
   This function should be called by both the parent process and the
   child right after fork() has been called. If job control is
   enabled, the child is put in the jobs group, and if the child is
   also in the foreground, it is also given control of the
   terminal. When called in the parent process, this function may
   fail, since the child might have already finished and called
   exit. The parent process may safely ignore the exit status of this
   call.

   Returns 0 on sucess, -1 on failiure.
*/
int set_child_group(job_t *j, process_t *p, int print_errors);

/**
   Initialize a new child process. This should be called right away
   after forking in the child process. If job control is enabled for
   this job, the process is put in the process group of the job, all
   signal handlers are reset, signals are unblocked (this function may
   only be called inside the exec function, which blocks all signals),
   and all IO redirections and other file descriptor actions are
   performed.

   \param j the job to set up the IO for
   \param p the child process to set up
   \param io_chain the IO chain to use

   \return 0 on sucess, -1 on failiure. When this function returns,
   signals are always unblocked. On failiure, signal handlers, io
   redirections and process group of the process is undefined.
*/
int setup_child_process(job_t *j, process_t *p, const io_chain_t &io_chain);

/* Call fork(), optionally waiting until we are no longer multithreaded. If the forked child doesn't do anything that could allocate memory, take a lock, etc. (like call exec), then it's not necessary to wait for threads to die. If the forked child may do those things, it should wait for threads to die.
*/
pid_t execute_fork(bool wait_for_threads_to_die);

/* Perform output from builtins. Returns true on success. */
bool do_builtin_io(const char *out, size_t outlen, const char *err, size_t errlen);

/** Report an error from failing to exec or posix_spawn a command */
void safe_report_exec_error(int err, const char *actual_cmd, const char * const *argv, const char * const *envv);

#if FISH_USE_POSIX_SPAWN
/* Initializes and fills in a posix_spawnattr_t; on success, the caller should destroy it via posix_spawnattr_destroy */
bool fork_actions_make_spawn_properties(posix_spawnattr_t *attr, posix_spawn_file_actions_t *actions, job_t *j, process_t *p, const io_chain_t &io_chain);
#endif

#endif