Handling of child processes in GNUnet. More...

#include "platform.h"
#include "gnunet_util_lib.h"

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Data Structures
struct	GNUNET_ChildWaitHandle
	Struct which defines a Child Wait handle. More...

Macros
#define	LOG(kind, ...) GNUNET_log (kind, __VA_ARGS__)
	Generic logging shortcut. More...

Functions
static void	maint_child_death (void *cls)
	Task triggered whenever we receive a SIGCHLD (child process died) or when user presses CTRL-C. More...

static void	sighandler_child_death (void)
	Signal handler called for SIGCHLD. More...

static void	child_management_start (void)
	Initializing the signal pipe for child handling. More...

static void	child_management_done (void)
	Clean up. More...

struct GNUNET_ChildWaitHandle *	GNUNET_wait_child (struct GNUNET_OS_Process proc, GNUNET_ChildCompletedCallback cb, void cb_cls)
	Starts the handling of the child processes. More...

void	GNUNET_wait_child_cancel (struct GNUNET_ChildWaitHandle *cwh)
	Stop waiting on this child. More...

Variables
static struct GNUNET_DISK_PipeHandle *	sigpipe
	Pipe used to communicate shutdown via signal. More...

static struct GNUNET_SIGNAL_Context *	shc_chld

static struct GNUNET_SCHEDULER_Task *	sig_task

static struct GNUNET_ChildWaitHandle *	cwh_head

static struct GNUNET_ChildWaitHandle *	cwh_tail

Detailed Description

Handling of child processes in GNUnet.

Author: Christian Grothoff (ANASTASIS); Dominik Meister (ANASTASIS); t3sserakt

Definition in file child_management.c.

Macro Definition Documentation

◆ LOG

#define LOG	(	kind,
		...
	)	GNUNET_log (kind, __VA_ARGS__)

Generic logging shortcut.

Definition at line 35 of file child_management.c.

Function Documentation

◆ maint_child_death()

static void maint_child_death ( void * cls )

static

Task triggered whenever we receive a SIGCHLD (child process died) or when user presses CTRL-C.

Parameters

cls	closure, NULL

Definition at line 86 of file child_management.c.

{
  char buf[16];
  const struct GNUNET_DISK_FileHandle *pr;
  struct GNUNET_ChildWaitHandle *nxt;
 
  (void) cls;
  sig_task = NULL;
  /* drain pipe */
  pr = GNUNET_DISK_pipe_handle (sigpipe,
                                GNUNET_DISK_PIPE_END_READ);
  GNUNET_assert (! GNUNET_DISK_handle_invalid (pr));
  (void) GNUNET_DISK_file_read (pr,
                                buf,
                                sizeof(buf));
 
  /* find applicable processes that exited */
  for (struct GNUNET_ChildWaitHandle *cwh = cwh_head;
       NULL != cwh;
       cwh = nxt)
  {
    enum GNUNET_OS_ProcessStatusType type;
    long unsigned int exit_code = 0;
 
    nxt = cwh->next;
    if (GNUNET_OK ==
        GNUNET_OS_process_status (cwh->proc,
                                  &type,
                                  &exit_code))
    {
      GNUNET_CONTAINER_DLL_remove (cwh_head,
                                   cwh_tail,
                                   cwh);
      cwh->cb (cwh->cb_cls,
               type,
               exit_code);
      GNUNET_free (cwh);
    }
  }
  if (NULL == cwh_head)
    return;
  /* wait for more */
  sig_task = GNUNET_SCHEDULER_add_read_file (
    GNUNET_TIME_UNIT_FOREVER_REL,
    GNUNET_DISK_pipe_handle (sigpipe,
                             GNUNET_DISK_PIPE_END_READ),
    &maint_child_death,
    NULL);
}

References cwh_head, cwh_tail, exit_code, GNUNET_assert, GNUNET_CONTAINER_DLL_remove, GNUNET_DISK_file_read(), GNUNET_DISK_handle_invalid(), GNUNET_DISK_PIPE_END_READ, GNUNET_DISK_pipe_handle(), GNUNET_free, GNUNET_OK, GNUNET_OS_process_status(), GNUNET_SCHEDULER_add_read_file(), GNUNET_TIME_UNIT_FOREVER_REL, maint_child_death(), GNUNET_ChildWaitHandle::next, sig_task, sigpipe, and type.

Referenced by GNUNET_wait_child(), and maint_child_death().

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◆ sighandler_child_death()

static void sighandler_child_death ( void )

static

Signal handler called for SIGCHLD.

Triggers the respective handler by writing to the trigger pipe.

Definition at line 142 of file child_management.c.

{
  static char c;
  int old_errno = errno; /* back-up errno */
 
  GNUNET_break (
    1 ==
    GNUNET_DISK_file_write (GNUNET_DISK_pipe_handle (sigpipe,
                                                     GNUNET_DISK_PIPE_END_WRITE),
                            &c,
                            sizeof(c)));
  errno = old_errno; /* restore errno */
}

References GNUNET_break, GNUNET_DISK_file_write(), GNUNET_DISK_PIPE_END_WRITE, GNUNET_DISK_pipe_handle(), and sigpipe.

Referenced by child_management_start(), and GNUNET_wait_child().

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◆ child_management_start()

static void child_management_start ( void )

static

Initializing the signal pipe for child handling.

Definition at line 161 of file child_management.c.

{
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Trying to start child management.\n");
  if (NULL != sigpipe)
    return; /* already initialized */
  sigpipe = GNUNET_DISK_pipe (GNUNET_DISK_PF_NONE);
  GNUNET_assert (sigpipe != NULL);
  shc_chld =
    GNUNET_SIGNAL_handler_install (GNUNET_SIGCHLD,
                                   &sighandler_child_death);
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Child management started.\n");
}

References GNUNET_assert, GNUNET_DISK_PF_NONE, GNUNET_DISK_pipe(), GNUNET_ERROR_TYPE_INFO, GNUNET_log, GNUNET_SIGCHLD, GNUNET_SIGNAL_handler_install(), shc_chld, sighandler_child_death(), and sigpipe.

Referenced by GNUNET_wait_child().

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◆ child_management_done()

static void child_management_done ( void )

static

Clean up.

Definition at line 181 of file child_management.c.

{
  if (NULL != sig_task)
  {
    GNUNET_SCHEDULER_cancel (sig_task);
    sig_task = NULL;
  }
  GNUNET_SIGNAL_handler_uninstall (shc_chld);
  shc_chld = NULL;
  GNUNET_DISK_pipe_close (sigpipe);
  sigpipe = NULL;
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Child management stopped.\n");
}