path: root/linuxthreads/pthread.c

/* Linuxthreads - a simple clone()-based implementation of Posix        */
/* threads for Linux.                                                   */
/* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr)              */
/*                                                                      */
/* This program is free software; you can redistribute it and/or        */
/* modify it under the terms of the GNU Library General Public License  */
/* as published by the Free Software Foundation; either version 2       */
/* of the License, or (at your option) any later version.               */
/*                                                                      */
/* This program is distributed in the hope that it will be useful,      */
/* but WITHOUT ANY WARRANTY; without even the implied warranty of       */
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the        */
/* GNU Library General Public License for more details.                 */

/* Thread creation, initialization, and basic low-level routines */

#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/wait.h>
#include "pthread.h"
#include "internals.h"
#include "spinlock.h"
#include "restart.h"

/* Descriptor of the initial thread */

struct _pthread_descr_struct __pthread_initial_thread = {
  &__pthread_initial_thread,  /* pthread_descr p_nextlive */
  &__pthread_initial_thread,  /* pthread_descr p_prevlive */
  NULL,                       /* pthread_descr p_nextwaiting */
  PTHREAD_THREADS_MAX,        /* pthread_t p_tid */
  0,                          /* int p_pid */
  0,                          /* int p_priority */
  &__pthread_handles[0].h_spinlock, /* int * p_spinlock */
  0,                          /* int p_signal */
  NULL,                       /* sigjmp_buf * p_signal_buf */
  NULL,                       /* sigjmp_buf * p_cancel_buf */
  0,                          /* char p_terminated */
  0,                          /* char p_detached */
  0,                          /* char p_exited */
  NULL,                       /* void * p_retval */
  0,                          /* int p_retval */
  NULL,                       /* pthread_descr p_joining */
  NULL,                       /* struct _pthread_cleanup_buffer * p_cleanup */
  0,                          /* char p_cancelstate */
  0,                          /* char p_canceltype */
  0,                          /* char p_canceled */
  NULL,                       /* int *p_errnop */
  0,                          /* int p_errno */
  NULL,                       /* int *p_h_errnop */
  0,                          /* int p_h_errno */
  PTHREAD_START_ARGS_INITIALIZER, /* struct pthread_start_args p_start_args */
  {NULL}                      /* void * p_specific[PTHREAD_KEYS_MAX] */
};

/* Descriptor of the manager thread; none of this is used but the error
   variables and the address for identification.  */

struct _pthread_descr_struct __pthread_manager_thread = {
  NULL,                       /* pthread_descr p_nextlive */
  NULL,                       /* pthread_descr p_prevlive */
  NULL,                       /* pthread_descr p_nextwaiting */
  0,                          /* int p_tid */
  0,                          /* int p_pid */
  0,                          /* int p_priority */
  NULL,                       /* int * p_spinlock */
  0,                          /* int p_signal */
  NULL,                       /* sigjmp_buf * p_signal_buf */
  NULL,                       /* sigjmp_buf * p_cancel_buf */
  0,                          /* char p_terminated */
  0,                          /* char p_detached */
  0,                          /* char p_exited */
  NULL,                       /* void * p_retval */
  0,                          /* int p_retval */
  NULL,                       /* pthread_descr p_joining */
  NULL,                       /* struct _pthread_cleanup_buffer * p_cleanup */
  0,                          /* char p_cancelstate */
  0,                          /* char p_canceltype */
  0,                          /* char p_canceled */
  NULL,                       /* int *p_errnop */
  0,                          /* int p_errno */
  NULL,                       /* int *p_h_errnop */
  0,                          /* int p_h_errno */
  PTHREAD_START_ARGS_INITIALIZER, /* struct pthread_start_args p_start_args */
  {NULL}                      /* void * p_specific[PTHREAD_KEYS_MAX] */
};

/* Pointer to the main thread (the father of the thread manager thread) */
/* Originally, this is the initial thread, but this changes after fork() */

pthread_descr __pthread_main_thread = &__pthread_initial_thread;

/* Limit between the stack of the initial thread (above) and the
   stacks of other threads (below). Aligned on a STACK_SIZE boundary. */

char *__pthread_initial_thread_bos = NULL;

/* File descriptor for sending requests to the thread manager. */
/* Initially -1, meaning that the thread manager is not running. */

int __pthread_manager_request = -1;

/* Other end of the pipe for sending requests to the thread manager. */

int __pthread_manager_reader;

/* PID of thread manager */

static int __pthread_manager_pid;

/* Limits of the thread manager stack */

char *__pthread_manager_thread_bos = NULL;
char *__pthread_manager_thread_tos = NULL;

/* For process-wide exit() */

int __pthread_exit_requested = 0;
int __pthread_exit_code = 0;

/* Signal numbers used for the communication.  */
int __pthread_sig_restart;
int __pthread_sig_cancel;

/* These variables are used by the setup code.  */
extern int _errno;
extern int _h_errno;

/* Forward declarations */

static void pthread_exit_process(int retcode, void *arg);
static void pthread_handle_sigcancel(int sig);

/* Initialize the pthread library.
   Initialization is split in two functions:
   - a constructor function that blocks the PTHREAD_SIG_RESTART signal
     (must do this very early, since the program could capture the signal
      mask with e.g. sigsetjmp before creating the first thread);
   - a regular function called from pthread_create when needed. */

static void pthread_initialize(void) __attribute__((constructor));

static void pthread_initialize(void)
{
  struct sigaction sa;
  sigset_t mask;

  /* If already done (e.g. by a constructor called earlier!), bail out */
  if (__pthread_initial_thread_bos != NULL) return;
  /* For the initial stack, reserve at least STACK_SIZE bytes of stack
     below the current stack address, and align that on a
     STACK_SIZE boundary. */
  __pthread_initial_thread_bos =
    (char *)(((long)CURRENT_STACK_FRAME - 2 * STACK_SIZE) & ~(STACK_SIZE - 1));
  /* Update the descriptor for the initial thread. */
  __pthread_initial_thread.p_pid = __getpid();
  /* If we have special thread_self processing, initialize that for the
     main thread now.  */
#ifdef INIT_THREAD_SELF
  INIT_THREAD_SELF(&