/process.c

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/**********************************************************************

  process.c -

  $Author$
  created at: Tue Aug 10 14:30:50 JST 1993

  Copyright (C) 1993-2007 Yukihiro Matsumoto
  Copyright (C) 2000  Network Applied Communication Laboratory, Inc.
  Copyright (C) 2000  Information-technology Promotion Agency, Japan

**********************************************************************/

#include "ruby/ruby.h"
#include "ruby/io.h"
#include "ruby/thread.h"
#include "ruby/util.h"
#include "internal.h"
#include "vm_core.h"

#include <stdio.h>
#include <errno.h>
#include <signal.h>
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef HAVE_PROCESS_H
#include <process.h>
#endif

#include <time.h>
#include <ctype.h>

#ifndef EXIT_SUCCESS
#define EXIT_SUCCESS 0
#endif
#ifndef EXIT_FAILURE
#define EXIT_FAILURE 1
#endif

#ifdef HAVE_SYS_WAIT_H
# include <sys/wait.h>
#endif
#ifdef HAVE_SYS_RESOURCE_H
# include <sys/resource.h>
#endif
#ifdef HAVE_SYS_PARAM_H
# include <sys/param.h>
#endif
#ifndef MAXPATHLEN
# define MAXPATHLEN 1024
#endif
#include "ruby/st.h"

#ifdef __EMX__
#undef HAVE_GETPGRP
#endif

#include <sys/stat.h>
#if defined(__native_client__) && defined(NACL_NEWLIB)
# include "nacl/stat.h"
# include "nacl/unistd.h"
#endif


#ifdef HAVE_SYS_TIMES_H
#include <sys/times.h>
#endif

#ifdef HAVE_PWD_H
#include <pwd.h>
#endif
#ifdef HAVE_GRP_H
#include <grp.h>
#endif

#define numberof(array) (int)(sizeof(array)/sizeof((array)[0]))

#if defined(HAVE_TIMES) || defined(_WIN32)
static VALUE rb_cProcessTms;
#endif

#ifndef WIFEXITED
#define WIFEXITED(w)    (((w) & 0xff) == 0)
#endif
#ifndef WIFSIGNALED
#define WIFSIGNALED(w)  (((w) & 0x7f) > 0 && (((w) & 0x7f) < 0x7f))
#endif
#ifndef WIFSTOPPED
#define WIFSTOPPED(w)   (((w) & 0xff) == 0x7f)
#endif
#ifndef WEXITSTATUS
#define WEXITSTATUS(w)  (((w) >> 8) & 0xff)
#endif
#ifndef WTERMSIG
#define WTERMSIG(w)     ((w) & 0x7f)
#endif
#ifndef WSTOPSIG
#define WSTOPSIG        WEXITSTATUS
#endif

#if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__bsdi__)
#define HAVE_44BSD_SETUID 1
#define HAVE_44BSD_SETGID 1
#endif

#ifdef __NetBSD__
#undef HAVE_SETRUID
#undef HAVE_SETRGID
#endif

#ifdef BROKEN_SETREUID
#define setreuid ruby_setreuid
int setreuid(rb_uid_t ruid, rb_uid_t euid);
#endif
#ifdef BROKEN_SETREGID
#define setregid ruby_setregid
int setregid(rb_gid_t rgid, rb_gid_t egid);
#endif

#if defined(HAVE_44BSD_SETUID) || defined(__APPLE__)
#if !defined(USE_SETREUID) && !defined(BROKEN_SETREUID)
#define OBSOLETE_SETREUID 1
#endif
#if !defined(USE_SETREGID) && !defined(BROKEN_SETREGID)
#define OBSOLETE_SETREGID 1
#endif
#endif

#define preserving_errno(stmts) \
	do {int saved_errno = errno; stmts; errno = saved_errno;} while (0)

static void check_uid_switch(void);
static void check_gid_switch(void);

#if 1
#define p_uid_from_name p_uid_from_name
#define p_gid_from_name p_gid_from_name
#endif

#if defined(HAVE_PWD_H)
# ifdef HAVE_GETPWNAM_R
#   define PREPARE_GETPWNAM \
    long getpw_buf_len = sysconf(_SC_GETPW_R_SIZE_MAX); \
    char *getpw_buf = ALLOCA_N(char, (getpw_buf_len < 0 ? (getpw_buf_len = 4096) : getpw_buf_len));
#   define OBJ2UID(id) obj2uid((id), getpw_buf, getpw_buf_len)
static rb_uid_t obj2uid(VALUE id, char *getpw_buf, size_t getpw_buf_len);
# else
#   define PREPARE_GETPWNAM	/* do nothing */
#   define OBJ2UID(id) obj2uid((id))
static rb_uid_t obj2uid(VALUE id);
# endif
#else
# define PREPARE_GETPWNAM	/* do nothing */
# define OBJ2UID(id) NUM2UIDT(id)
# ifdef p_uid_from_name
#   undef p_uid_from_name
#   define p_uid_from_name rb_f_notimplement
# endif
#endif

#if defined(HAVE_GRP_H)
# ifdef HAVE_GETGRNAM_R
#   define PREPARE_GETGRNAM \
    long getgr_buf_len = sysconf(_SC_GETGR_R_SIZE_MAX); \
    char *getgr_buf = ALLOCA_N(char, (getgr_buf_len < 0 ? (getgr_buf_len = 4096) : getgr_buf_len));
#   define OBJ2GID(id) obj2gid((id), getgr_buf, getgr_buf_len)
static rb_gid_t obj2gid(VALUE id, char *getgr_buf, size_t getgr_buf_len);
# else
#   define PREPARE_GETGRNAM	/* do nothing */
#   define OBJ2GID(id) obj2gid((id))
static rb_gid_t obj2gid(VALUE id);
# endif
#else
# define PREPARE_GETGRNAM	/* do nothing */
# define OBJ2GID(id) NUM2GIDT(id)
# ifdef p_gid_from_name
#   undef p_gid_from_name
#   define p_gid_from_name rb_f_notimplement
# endif
#endif

/*
 *  call-seq:
 *     Process.pid   -> fixnum
 *
 *  Returns the process id of this process. Not available on all
 *  platforms.
 *
 *     Process.pid   #=> 27415
 */

static VALUE
get_pid(void)
{
    rb_secure(2);
    return PIDT2NUM(getpid());
}


/*
 *  call-seq:
 *     Process.ppid   -> fixnum
 *
 *  Returns the process id of the parent of this process. Returns
 *  untrustworthy value on Win32/64. Not available on all platforms.
 *
 *     puts "I am #{Process.pid}"
 *     Process.fork { puts "Dad is #{Process.ppid}" }
 *
 *  <em>produces:</em>
 *
 *     I am 27417
 *     Dad is 27417
 */

static VALUE
get_ppid(void)
{
    rb_secure(2);
    return PIDT2NUM(getppid());
}


/*********************************************************************
 *
 * Document-class: Process::Status
 *
 *  <code>Process::Status</code> encapsulates the information on the
 *  status of a running or terminated system process. The built-in
 *  variable <code>$?</code> is either +nil+ or a
 *  <code>Process::Status</code> object.
 *
 *     fork { exit 99 }   #=> 26557
 *     Process.wait       #=> 26557
 *     $?.class           #=> Process::Status
 *     $?.to_i            #=> 25344
 *     $? >> 8            #=> 99
 *     $?.stopped?        #=> false
 *     $?.exited?         #=> true
 *     $?.exitstatus      #=> 99
 *
 *  Posix systems record information on processes using a 16-bit
 *  integer.  The lower bits record the process status (stopped,
 *  exited, signaled) and the upper bits possibly contain additional
 *  information (for example the program's return code in the case of
 *  exited processes). Pre Ruby 1.8, these bits were exposed directly
 *  to the Ruby program. Ruby now encapsulates these in a
 *  <code>Process::Status</code> object. To maximize compatibility,
 *  however, these objects retain a bit-oriented interface. In the
 *  descriptions that follow, when we talk about the integer value of
 *  _stat_, we're referring to this 16 bit value.
 */

static VALUE rb_cProcessStatus;

VALUE
rb_last_status_get(void)
{
    return GET_THREAD()->last_status;
}

void
rb_last_status_set(int status, rb_pid_t pid)
{
    rb_thread_t *th = GET_THREAD();
    th->last_status = rb_obj_alloc(rb_cProcessStatus);
    rb_iv_set(th->last_status, "status", INT2FIX(status));
    rb_iv_set(th->last_status, "pid", PIDT2NUM(pid));
}

void
rb_last_status_clear(void)
{
    GET_THREAD()->last_status = Qnil;
}

/*
 *  call-seq:
 *     stat.to_i     -> fixnum
 *     stat.to_int   -> fixnum
 *
 *  Returns the bits in _stat_ as a <code>Fixnum</code>. Poking
 *  around in these bits is platform dependent.
 *
 *     fork { exit 0xab }         #=> 26566
 *     Process.wait               #=> 26566
 *     sprintf('%04x', $?.to_i)   #=> "ab00"
 */

static VALUE
pst_to_i(VALUE st)
{
    return rb_iv_get(st, "status");
}

#define PST2INT(st) NUM2INT(pst_to_i(st))

/*
 *  call-seq:
 *     stat.pid   -> fixnum
 *
 *  Returns the process ID that this status object represents.
 *
 *     fork { exit }   #=> 26569
 *     Process.wait    #=> 26569
 *     $?.pid          #=> 26569
 */

static VALUE
pst_pid(VALUE st)
{
    return rb_attr_get(st, rb_intern("pid"));
}

static void
pst_message(VALUE str, rb_pid_t pid, int status)
{
    rb_str_catf(str, "pid %ld", (long)pid);
    if (WIFSTOPPED(status)) {
	int stopsig = WSTOPSIG(status);
	const char *signame = ruby_signal_name(stopsig);
	if (signame) {
	    rb_str_catf(str, " stopped SIG%s (signal %d)", signame, stopsig);
	}
	else {
	    rb_str_catf(str, " stopped signal %d", stopsig);
	}
    }
    if (WIFSIGNALED(status)) {
	int termsig = WTERMSIG(status);
	const char *signame = ruby_signal_name(termsig);
	if (signame) {
	    rb_str_catf(str, " SIG%s (signal %d)", signame, termsig);
	}
	else {
	    rb_str_catf(str, " signal %d", termsig);
	}
    }
    if (WIFEXITED(status)) {
	rb_str_catf(str, " exit %d", WEXITSTATUS(status));
    }
#ifdef WCOREDUMP
    if (WCOREDUMP(status)) {
	rb_str_cat2(str, " (core dumped)");
    }
#endif
}


/*
 *  call-seq:
 *     stat.to_s   -> string
 *
 *  Show pid and exit status as a string.
 *
 *    system("false")
 *    p $?.to_s         #=> "pid 12766 exit 1"
 *
 */

static VALUE
pst_to_s(VALUE st)
{
    rb_pid_t pid;
    int status;
    VALUE str;

    pid = NUM2PIDT(pst_pid(st));
    status = PST2INT(st);

    str = rb_str_buf_new(0);
    pst_message(str, pid, status);
    return str;
}


/*
 *  call-seq:
 *     stat.inspect   -> string
 *
 *  Override the inspection method.
 *
 *    system("false")
 *    p $?.inspect #=> "#<Process::Status: pid 12861 exit 1>"
 *
 */

static VALUE
pst_inspect(VALUE st)
{
    rb_pid_t pid;
    int status;
    VALUE vpid, str;

    vpid = pst_pid(st);
    if (NIL_P(vpid)) {
        return rb_sprintf("#<%s: uninitialized>", rb_class2name(CLASS_OF(st)));
    }
    pid = NUM2PIDT(vpid);
    status = PST2INT(st);

    str = rb_sprintf("#<%s: ", rb_class2name(CLASS_OF(st)));
    pst_message(str, pid, status);
    rb_str_cat2(str, ">");
    return str;
}


/*
 *  call-seq:
 *     stat == other   -> true or false
 *
 *  Returns +true+ if the integer value of _stat_
 *  equals <em>other</em>.
 */

static VALUE
pst_equal(VALUE st1, VALUE st2)
{
    if (st1 == st2) return Qtrue;
    return rb_equal(pst_to_i(st1), st2);
}


/*
 *  call-seq:
 *     stat & num   -> fixnum
 *
 *  Logical AND of the bits in _stat_ with <em>num</em>.
 *
 *     fork { exit 0x37 }
 *     Process.wait
 *     sprintf('%04x', $?.to_i)       #=> "3700"
 *     sprintf('%04x', $? & 0x1e00)   #=> "1600"
 */

static VALUE
pst_bitand(VALUE st1, VALUE st2)
{
    int status = PST2INT(st1) & NUM2INT(st2);

    return INT2NUM(status);
}


/*
 *  call-seq:
 *     stat >> num   -> fixnum
 *
 *  Shift the bits in _stat_ right <em>num</em> places.
 *
 *     fork { exit 99 }   #=> 26563
 *     Process.wait       #=> 26563
 *     $?.to_i            #=> 25344
 *     $? >> 8            #=> 99
 */

static VALUE
pst_rshift(VALUE st1, VALUE st2)
{
    int status = PST2INT(st1) >> NUM2INT(st2);

    return INT2NUM(status);
}


/*
 *  call-seq:
 *     stat.stopped?   -> true or false
 *
 *  Returns +true+ if this process is stopped. This is only
 *  returned if the corresponding <code>wait</code> call had the
 *  <code>WUNTRACED</code> flag set.
 */

static VALUE
pst_wifstopped(VALUE st)
{
    int status = PST2INT(st);

    if (WIFSTOPPED(status))
	return Qtrue;
    else
	return Qfalse;
}


/*
 *  call-seq:
 *     stat.stopsig   -> fixnum or nil
 *
 *  Returns the number of the signal that caused _stat_ to stop
 *  (or +nil+ if self is not stopped).
 */

static VALUE
pst_wstopsig(VALUE st)
{
    int status = PST2INT(st);

    if (WIFSTOPPED(status))
	return INT2NUM(WSTOPSIG(status));
    return Qnil;
}


/*
 *  call-seq:
 *     stat.signaled?   -> true or false
 *
 *  Returns +true+ if _stat_ terminated because of
 *  an uncaught signal.
 */

static VALUE
pst_wifsignaled(VALUE st)
{
    int status = PST2INT(st);

    if (WIFSIGNALED(status))
	return Qtrue;
    else
	return Qfalse;
}


/*
 *  call-seq:
 *     stat.termsig   -> fixnum or nil
 *
 *  Returns the number of the signal that caused _stat_ to
 *  terminate (or +nil+ if self was not terminated by an
 *  uncaught signal).
 */

static VALUE
pst_wtermsig(VALUE st)
{
    int status = PST2INT(st);

    if (WIFSIGNALED(status))
	return INT2NUM(WTERMSIG(status));
    return Qnil;
}


/*
 *  call-seq:
 *     stat.exited?   -> true or false
 *
 *  Returns +true+ if _stat_ exited normally (for
 *  example using an <code>exit()</code> call or finishing the
 *  program).
 */

static VALUE
pst_wifexited(VALUE st)
{
    int status = PST2INT(st);

    if (WIFEXITED(status))
	return Qtrue;
    else
	return Qfalse;
}


/*
 *  call-seq:
 *     stat.exitstatus   -> fixnum or nil
 *
 *  Returns the least significant eight bits of the return code of
 *  _stat_. Only available if <code>exited?</code> is
 *  +true+.
 *
 *     fork { }           #=> 26572
 *     Process.wait       #=> 26572
 *     $?.exited?         #=> true
 *     $?.exitstatus      #=> 0
 *
 *     fork { exit 99 }   #=> 26573
 *     Process.wait       #=> 26573
 *     $?.exited?         #=> true
 *     $?.exitstatus      #=> 99
 */

static VALUE
pst_wexitstatus(VALUE st)
{
    int status = PST2INT(st);

    if (WIFEXITED(status))
	return INT2NUM(WEXITSTATUS(status));
    return Qnil;
}


/*
 *  call-seq:
 *     stat.success?   -> true, false or nil
 *
 *  Returns +true+ if _stat_ is successful, +false+ if not.
 *  Returns +nil+ if <code>exited?</code> is not +true+.
 */

static VALUE
pst_success_p(VALUE st)
{
    int status = PST2INT(st);

    if (!WIFEXITED(status))
	return Qnil;
    return WEXITSTATUS(status) == EXIT_SUCCESS ? Qtrue : Qfalse;
}


/*
 *  call-seq:
 *     stat.coredump?   -> true or false
 *
 *  Returns +true+ if _stat_ generated a coredump
 *  when it terminated. Not available on all platforms.
 */

static VALUE
pst_wcoredump(VALUE st)
{
#ifdef WCOREDUMP
    int status = PST2INT(st);

    if (WCOREDUMP(status))
	return Qtrue;
    else
	return Qfalse;
#else
    return Qfalse;
#endif
}

#if !defined(HAVE_WAITPID) && !defined(HAVE_WAIT4)
#define NO_WAITPID
static st_table *pid_tbl;

struct wait_data {
    rb_pid_t pid;
    int status;
};

static int
wait_each(rb_pid_t pid, int status, struct wait_data *data)
{
    if (data->status != -1) return ST_STOP;

    data->pid = pid;
    data->status = status;
    return ST_DELETE;
}

static int
waitall_each(rb_pid_t pid, int status, VALUE ary)
{
    rb_last_status_set(status, pid);
    rb_ary_push(ary, rb_assoc_new(PIDT2NUM(pid), rb_last_status_get()));
    return ST_DELETE;
}
#else
struct waitpid_arg {
    rb_pid_t pid;
    int *st;
    int flags;
};
#endif

static void *
rb_waitpid_blocking(void *data)
{
    rb_pid_t result;
#ifndef NO_WAITPID
    struct waitpid_arg *arg = data;
#endif

#if defined NO_WAITPID
    result = wait(data);
#elif defined HAVE_WAITPID
    result = waitpid(arg->pid, arg->st, arg->flags);
#else  /* HAVE_WAIT4 */
    result = wait4(arg->pid, arg->st, arg->flags, NULL);
#endif

    return (void *)(VALUE)result;
}

rb_pid_t
rb_waitpid(rb_pid_t pid, int *st, int flags)
{
    rb_pid_t result;
#ifndef NO_WAITPID
    struct waitpid_arg arg;

  retry:
    arg.pid = pid;
    arg.st = st;
    arg.flags = flags;
    result = (rb_pid_t)(VALUE)rb_thread_call_without_gvl(rb_waitpid_blocking, &arg,
							 RUBY_UBF_PROCESS, 0);
    if (result < 0) {
	if (errno == EINTR) {
            RUBY_VM_CHECK_INTS(GET_THREAD());
            goto retry;
        }
	return (rb_pid_t)-1;
    }
#else  /* NO_WAITPID */
    if (pid_tbl) {
	st_data_t status, piddata = (st_data_t)pid;
	if (pid == (rb_pid_t)-1) {
	    struct wait_data data;
	    data.pid = (rb_pid_t)-1;
	    data.status = -1;
	    st_foreach(pid_tbl, wait_each, (st_data_t)&data);
	    if (data.status != -1) {
		rb_last_status_set(data.status, data.pid);
		return data.pid;
	    }
	}
	else if (st_delete(pid_tbl, &piddata, &status)) {
	    rb_last_status_set(*st = (int)status, pid);
	    return pid;
	}
    }

    if (flags) {
	rb_raise(rb_eArgError, "can't do waitpid with flags");
    }

    for (;;) {
	result = (rb_pid_t)(VALUE)rb_thread_blocking_region(rb_waitpid_blocking,
							    st, RUBY_UBF_PROCESS, 0);
	if (result < 0) {
	    if (errno == EINTR) {
		rb_thread_schedule();
		continue;
	    }
	    return (rb_pid_t)-1;
	}
	if (result == pid || pid == (rb_pid_t)-1) {
	    break;
	}
	if (!pid_tbl)
	    pid_tbl = st_init_numtable();
	st_insert(pid_tbl, pid, (st_data_t)st);
	if (!rb_thread_alone()) rb_thread_schedule();
    }
#endif
    if (result > 0) {
	rb_last_status_set(*st, result);
    }
    return result;
}


/* [MG]:FIXME: I wasn't sure how this should be done, since ::wait()
   has historically been documented as if it didn't take any arguments
   despite the fact that it's just an alias for ::waitpid(). The way I
   have it below is more truthful, but a little confusing.

   I also took the liberty of putting in the pid values, as they're
   pretty useful, and it looked as if the original 'ri' output was
   supposed to contain them after "[...]depending on the value of
   aPid:".

   The 'ansi' and 'bs' formats of the ri output don't display the
   definition list for some reason, but the plain text one does.
 */

/*
 *  call-seq:
 *     Process.wait()                     -> fixnum
 *     Process.wait(pid=-1, flags=0)      -> fixnum
 *     Process.waitpid(pid=-1, flags=0)   -> fixnum
 *
 *  Waits for a child process to exit, returns its process id, and
 *  sets <code>$?</code> to a <code>Process::Status</code> object
 *  containing information on that process. Which child it waits on
 *  depends on the value of _pid_:
 *
 *  > 0::   Waits for the child whose process ID equals _pid_.
 *
 *  0::     Waits for any child whose process group ID equals that of the
 *          calling process.
 *
 *  -1::    Waits for any child process (the default if no _pid_ is
 *          given).
 *
 *  < -1::  Waits for any child whose process group ID equals the absolute
 *          value of _pid_.
 *
 *  The _flags_ argument may be a logical or of the flag values
 *  <code>Process::WNOHANG</code> (do not block if no child available)
 *  or <code>Process::WUNTRACED</code> (return stopped children that
 *  haven't been reported). Not all flags are available on all
 *  platforms, but a flag value of zero will work on all platforms.
 *
 *  Calling this method raises a SystemCallError if there are no child
 *  processes. Not available on all platforms.
 *
 *     include Process
 *     fork { exit 99 }                 #=> 27429
 *     wait                             #=> 27429
 *     $?.exitstatus                    #=> 99
 *
 *     pid = fork { sleep 3 }           #=> 27440
 *     Time.now                         #=> 2008-03-08 19:56:16 +0900
 *     waitpid(pid, Process::WNOHANG)   #=> nil
 *     Time.now                         #=> 2008-03-08 19:56:16 +0900
 *     waitpid(pid, 0)                  #=> 27440
 *     Time.now                         #=> 2008-03-08 19:56:19 +0900
 */

static VALUE
proc_wait(int argc, VALUE *argv)
{
    VALUE vpid, vflags;
    rb_pid_t pid;
    int flags, status;

    rb_secure(2);
    flags = 0;
    if (argc == 0) {
	pid = -1;
    }
    else {
	rb_scan_args(argc, argv, "02", &vpid, &vflags);
	pid = NUM2PIDT(vpid);
	if (argc == 2 && !NIL_P(vflags)) {
	    flags = NUM2UINT(vflags);
	}
    }
    if ((pid = rb_waitpid(pid, &status, flags)) < 0)
	rb_sys_fail(0);
    if (pid == 0) {
	rb_last_status_clear();
	return Qnil;
    }
    return PIDT2NUM(pid);
}


/*
 *  call-seq:
 *     Process.wait2(pid=-1, flags=0)      -> [pid, status]
 *     Process.waitpid2(pid=-1, flags=0)   -> [pid, status]
 *
 *  Waits for a child process to exit (see Process::waitpid for exact
 *  semantics) and returns an array containing the process id and the
 *  exit status (a <code>Process::Status</code> object) of that
 *  child. Raises a SystemCallError if there are no child processes.
 *
 *     Process.fork { exit 99 }   #=> 27437
 *     pid, status = Process.wait2
 *     pid                        #=> 27437
 *     status.exitstatus          #=> 99
 */

static VALUE
proc_wait2(int argc, VALUE *argv)
{
    VALUE pid = proc_wait(argc, argv);
    if (NIL_P(pid)) return Qnil;
    return rb_assoc_new(pid, rb_last_status_get());
}


/*
 *  call-seq:
 *     Process.waitall   -> [ [pid1,status1], ...]
 *
 *  Waits for all children, returning an array of
 *  _pid_/_status_ pairs (where _status_ is a
 *  <code>Process::Status</code> object).
 *
 *     fork { sleep 0.2; exit 2 }   #=> 27432
 *     fork { sleep 0.1; exit 1 }   #=> 27433
 *     fork {            exit 0 }   #=> 27434
 *     p Process.waitall
 *
 *  <em>produces</em>:
 *
 *     [[30982, #<Process::Status: pid 30982 exit 0>],
 *      [30979, #<Process::Status: pid 30979 exit 1>],
 *      [30976, #<Process::Status: pid 30976 exit 2>]]
 */

static VALUE
proc_waitall(void)
{
    VALUE result;
    rb_pid_t pid;
    int status;

    rb_secure(2);
    result = rb_ary_new();
#ifdef NO_WAITPID
    if (pid_tbl) {
	st_foreach(pid_tbl, waitall_each, result);
    }
#else
    rb_last_status_clear();
#endif

    for (pid = -1;;) {
#ifdef NO_WAITPID
	pid = wait(&status);
#else
	pid = rb_waitpid(-1, &status, 0);
#endif
	if (pid == -1) {
	    if (errno == ECHILD)
		break;
#ifdef NO_WAITPID
	    if (errno == EINTR) {
		rb_thread_schedule();
		continue;
	    }
#endif
	    rb_sys_fail(0);
	}
#ifdef NO_WAITPID
	rb_last_status_set(status, pid);
#endif
	rb_ary_push(result, rb_assoc_new(PIDT2NUM(pid), rb_last_status_get()));
    }
    return result;
}

static inline ID
id_pid(void)
{
    ID pid;
    CONST_ID(pid, "pid");
    return pid;
}

static VALUE
detach_process_pid(VALUE thread)
{
    return rb_thread_local_aref(thread, id_pid());
}

static VALUE
detach_process_watcher(void *arg)
{
    rb_pid_t cpid, pid = (rb_pid_t)(VALUE)arg;
    int status;

    while ((cpid = rb_waitpid(pid, &status, 0)) == 0) {
	/* wait while alive */
    }
    return rb_last_status_get();
}

VALUE
rb_detach_process(rb_pid_t pid)
{
    VALUE watcher = rb_thread_create(detach_process_watcher, (void*)(VALUE)pid);
    rb_thread_local_aset(watcher, id_pid(), PIDT2NUM(pid));
    rb_define_singleton_method(watcher, "pid", detach_process_pid, 0);
    return watcher;
}


/*
 *  call-seq:
 *     Process.detach(pid)   -> thread
 *
 *  Some operating systems retain the status of terminated child
 *  processes until the parent collects that status (normally using
 *  some variant of <code>wait()</code>. If the parent never collects
 *  this status, the child stays around as a <em>zombie</em> process.
 *  <code>Process::detach</code> prevents this by setting up a
 *  separate Ruby thread whose sole job is to reap the status of the
 *  process _pid_ when it terminates. Use <code>detach</code>
 *  only when you do not intent to explicitly wait for the child to
 *  terminate.
 *
 *  The waiting thread returns the exit status of the detached process
 *  when it terminates, so you can use <code>Thread#join</code> to
 *  know the result.  If specified _pid_ is not a valid child process
 *  ID, the thread returns +nil+ immediately.
 *
 *  The waiting thread has <code>pid</code> method which returns the pid.
 *
 *  In this first example, we don't reap the first child process, so
 *  it appears as a zombie in the process status display.
 *
 *     p1 = fork { sleep 0.1 }
 *     p2 = fork { sleep 0.2 }
 *     Process.waitpid(p2)
 *     sleep 2
 *     system("ps -ho pid,state -p #{p1}")
 *
 *  <em>produces:</em>
 *
 *     27389 Z
 *
 *  In the next example, <code>Process::detach</code> is used to reap
 *  the child automatically.
 *
 *     p1 = fork { sleep 0.1 }
 *     p2 = fork { sleep 0.2 }
 *     Process.detach(p1)
 *     Process.waitpid(p2)
 *     sleep 2
 *     system("ps -ho pid,state -p #{p1}")
 *
 *  <em>(produces no output)</em>
 */

static VALUE
proc_detach(VALUE obj, VALUE pid)
{
    rb_secure(2);
    return rb_detach_process(NUM2PIDT(pid));
}

static int forked_child = 0;

#ifdef SIGPIPE
static RETSIGTYPE (*saved_sigpipe_handler)(int) = 0;
#endif

#ifdef SIGPIPE
static RETSIGTYPE
sig_do_nothing(int sig)
{
}
#endif

/* This function should be async-signal-safe.  Actually it is. */
static void
before_exec_async_signal_safe(void)
{
#ifdef SIGPIPE
    /*
     * Some OS commands don't initialize signal handler properly. Thus we have
     * to reset signal handler before exec(). Otherwise, system() and similar
     * child process interaction might fail. (e.g. ruby -e "system 'yes | ls'")
     * [ruby-dev:12261]
     */
    saved_sigpipe_handler = signal(SIGPIPE, sig_do_nothing); /* async-signal-safe */
#endif
}

static void
before_exec_non_async_signal_safe(void)
{
    if (!forked_child) {
	/*
	 * On Mac OS X 10.5.x (Leopard) or earlier, exec() may return ENOTSUPP
	 * if the process have multiple threads. Therefore we have to kill
	 * internal threads temporary. [ruby-core:10583]
	 * This is also true on Haiku. It returns Errno::EPERM against exec()
	 * in multiple threads.
	 */
	rb_thread_stop_timer_thread(0);
    }
}

static void
before_exec(void)
{
    before_exec_non_async_signal_safe();
    before_exec_async_signal_safe();
}

/* This function should be async-signal-safe.  Actually it is. */
static void
after_exec_async_signal_safe(void)
{
#ifdef SIGPIPE
    signal(SIGPIPE, saved_sigpipe_handler); /* async-signal-safe */
#endif
}

static void
after_exec_non_async_signal_safe(void)
{
    rb_thread_reset_timer_thread();
    rb_thread_start_timer_thread();

    forked_child = 0;
}

static void
after_exec(void)
{
    after_exec_async_signal_safe();
    after_exec_non_async_signal_safe();
}

#define before_fork() before_exec()
#define after_fork() (rb_threadptr_pending_interrupt_clear(GET_THREAD()), after_exec())

#include "dln.h"

static void
security(const char *str)
{
    if (rb_env_path_tainted()) {
	if (rb_safe_level() > 0) {
	    rb_raise(rb_eSecurityError, "Insecure PATH - %s", str);
	}
    }
}

#if defined(HAVE_FORK) && !defined(__native_client__)

/* try_with_sh and exec_with_sh should be async-signal-safe. Actually it is.*/
#define try_with_sh(prog, argv, envp) ((saved_errno == ENOEXEC) ? exec_with_sh((prog), (argv), (envp)) : (void)0)
static void
exec_with_sh(const char *prog, char **argv, char **envp)
{
    *argv = (char *)prog;
    *--argv = (char *)"sh";
    if (envp)
        execve("/bin/sh", argv, envp); /* async-signal-safe */
    else
        execv("/bin/sh", argv); /* async-signal-safe */
}

#else
#define try_with_sh(prog, argv, envp) (void)0
#endif

/* This function should be async-signal-safe.  Actually it is. */
static int
proc_exec_cmd(const char *prog, VALUE argv_str, VALUE envp_str)
{
#ifdef __native_client__
    rb_notimplement();
    UNREACHABLE;
#else
    char **argv;
    char **envp;
# if defined(__EMX__) || defined(OS2)
    char **new_argv = NULL;
# endif

    argv = ARGVSTR2ARGV(argv_str);

    if (!prog) {
	errno = ENOENT;
	return -1;
    }

# if defined(__EMX__) || defined(OS2)
    {
#  define COMMAND "cmd.exe"
	char *extension;

	if ((extension = strrchr(prog, '.')) != NULL && STRCASECMP(extension, ".bat") == 0) {
	    char *p;
	    int n;

	    for (n = 0; argv[n]; n++)
		/* no-op */;
	    new_argv = ALLOC_N(char*, n + 2);
	    for (; n > 0; n--)
		new_argv[n + 1] = argv[n];
	    new_argv[1] = strcpy(ALLOC_N(char, strlen(argv[0]) + 1), argv[0]);
	    for (p = new_argv[1]; *p != '\0'; p++)
		if (*p == '/')
		    *p = '\\';
	    new_argv[0] = COMMAND;
	    argv = new_argv;
	    prog = dln_find_exe_r(argv[0], 0, fbuf, sizeof(fbuf));
	    if (!prog) {
		errno = ENOENT;
		return -1;
	    }
	}
    }
# endif /* __EMX__ */
    envp = envp_str ? (char **)RSTRING_PTR(envp_str) : NULL;
    if (envp_str)
        execve(prog, argv, envp); /* async-signal-safe */
    else
        execv(prog, argv); /* async-signal-safe */
    preserving_errno(try_with_sh(prog, argv, envp)); /* try_with_sh() is async-signal-safe. */
# if defined(__EMX__) || defined(OS2)
    if (new_argv) {
	xfree(new_argv[0]);
	xfree(new_argv);
    }
# endif
    return -1;
#endif
}

/* deprecated */
static int
proc_exec_v(char **argv, const char *prog)
{
    char fbuf[MAXPATHLEN];

    if (!prog)
        prog = argv[0];
    prog = dln_find_exe_r(prog, 0, fbuf, sizeof(fbuf));
    if (!prog) {
        errno = ENOENT;
        return -1;
    }
    before_exec();
    execv(prog, argv);
    preserving_errno(try_with_sh(prog, argv, 0); after_exec());
    return -1;
}

/* deprecated */
int
rb_proc_exec_n(int argc, VALUE *argv, const char *prog)
{
#define ARGV_COUNT(n) ((n)+1)
#define ARGV_SIZE(n) (sizeof(char*) * ARGV_COUNT(n))
#define ALLOC_ARGV(n, v) ALLOCV_N(char*, (v), ARGV_COUNT(n))

    char **args;
    int i;
    int ret = -1;
    VALUE v;

    args = ALLOC_ARGV(argc+1, v);
    for (i=0; i<argc; i++) {
	args[i] = RSTRING_PTR(argv[i]);
    }
    args[i] = 0;
    if (args[0]) {
	ret = proc_exec_v(args, prog);
    }
    ALLOCV_END(v);
    return ret;

#undef ARGV_COUNT
#undef ARGV_SIZE
#undef ALLOC_ARGV
}

/* This function should be async-signal-safe.  Actually it is. */
static int
proc_exec_sh(const char *str, VALUE envp_str)
{
#ifdef __native_client__
    rb_notimplement();
    UNREACHABLE;
#else
    const char *s;

    s = str;
    while (*s == ' ' || *s == '\t' || *s == '\n')
	s++;

    if (!*s) {
        errno = ENOENT;
        return -1;
    }

#ifdef _WIN32
    rb_w32_spawn(P_OVERLAY, (char *)str, 0);
    return -1;
#else
#if defined(__CYGWIN32__) || defined(__EMX__)
    {
        char fbuf[MAXPATHLEN];
        char *shell = dln_find_exe_r("sh", 0, fbuf, sizeof(fbuf));
        int status = -1;
        if (shell)
            execl(shell, "sh", "-c", str, (char *) NULL);
        else
            status = system(str);
        if (status != -1)
            exit(status);
    }
#else
    if (envp_str)
        execle("/bin/sh", "sh", "-c", str, (char *)NULL, (char **)RSTRING_PTR(envp_str)); /* async-signal-safe */
    else
        execl("/bin/sh", "sh", "-c", str, (char *)NULL); /* async-signal-safe */
#endif
    return -1;
#endif	/* _WIN32 */
#endif
}

int
rb_proc_exec(const char *str)
{
    int ret;
    before_exec();
    ret = proc_exec_sh(str, Qfalse);
    preserving_errno(after_exec());
    return ret;
}

static void
mark_exec_arg(void *ptr)
{
    struct rb_execarg *eargp = ptr;
    if (eargp->use_shell)
        rb_gc_mark(eargp->invoke.sh.shell_script);
    else {
        rb_gc_mark(eargp->invoke.cmd.command_name);
        rb_gc_mark(eargp->invoke.cmd.command_abspath);
        rb_gc_mark(eargp->invoke.cmd.argv_str);
        rb_gc_mark(eargp->invoke.cmd.argv_buf);
    }
    rb_gc_mark(eargp->redirect_fds);
    rb_gc_mark(eargp->envp_str);
    rb_gc_mark(eargp->envp_buf);
    rb_gc_mark(eargp->dup2_tmpbuf);
    rb_gc_mark(eargp->rlimit_limits);
    rb_gc_mark(eargp->fd_dup2);
    rb_gc_mark(eargp->fd_close);
    rb_gc_mark(eargp->fd_open);
    rb_gc_mark(eargp->fd_dup2_child);
    rb_gc_mark(eargp->env_modification);
    rb_gc_mark(eargp->chdir_dir);
}

static void
free_exec_arg(void *ptr)
{
    xfree(ptr);
}

static size_t
memsize_exec_arg(const void *ptr)
{
    return ptr ? sizeof(struct rb_execarg) : 0;
}

static const rb_data_type_t exec_arg_data_type = {
  "exec_arg",
  {mark_exec_arg, free_exec_arg, memsize_exec_arg},
};

#if defined(_WIN32)
#define HAVE_SPAWNV 1
#endif

#if !defined(HAVE_FORK) && defined(HAVE_SPAWNV)
# define USE_SPAWNV 1
#else
# define USE_SPAWNV 0
#endif
#ifndef P_NOWAIT
# define P_NOWAIT _P_NOWAIT
#endif

#if USE_SPAWNV
#if defined(_WIN32)
#define proc_spawn_cmd_internal(argv, prog) rb_w32_aspawn(P_NOWAIT, (prog), (argv))
#else
static rb_pid_t
proc_spawn_cmd_internal(char **argv, char *prog)
{
    char fbuf[MAXPATHLEN];
    rb_pid_t status;

    if (!prog)
	prog = argv[0];
    security(prog);
    prog = dln_find_exe_r(prog, 0, fbuf, sizeof(fbuf));
    if (!prog)
	return -1;

    before_exec();
    status = spawnv(P_NOWAIT, prog, (const char **)argv);
    if (status == -1 && errno == ENOEXEC) {
	*argv = (char *)prog;
	*--argv = (char *)"sh";
	status = spawnv(P_NOWAIT, "/bin/sh", (const char **)argv);
	after_exec();
	if (status == -1) errno = ENOEXEC;
    }
    rb_last_status_set(status == -1 ? 127 : status, 0);
    return status;
}
#endif

static rb_pid_t
proc_spawn_cmd(char **argv, VALUE prog, struct rb_execarg *eargp)
{
    rb_pid_t pid = -1;

    if (argv[0]) {
#if defined(_WIN32)
	DWORD flags = 0;
	if (eargp->new_pgroup_given && eargp->new_pgroup_flag) {
	    flags = CREATE_NEW_PROCESS_GROUP;
	}
	pid = rb_w32_aspawn_flags(P_NOWAIT, prog ? RSTRING_PTR(prog) : 0, argv, flags);
#else
	pid = proc_spawn_cmd_internal(argv, prog ? RSTRING_PTR(prog) : 0);
#endif
    }
    return pid;
}

#if defined(_WIN32)
#define proc_spawn_sh(str) rb_w32_spawn(P_NOWAIT, (str), 0)
#else
static rb_pid_t
proc_spawn_sh(char *str)
{
    char fbuf[MAXPATHLEN];
    rb_pid_t status;

    char *shell = dln_find_exe_r("sh", 0, fbuf, sizeof(fbuf));
    before_exec();
    status = spawnl(P_NOWAIT, (shell ? shell : "/bin/sh"), "sh", "-c", str, (char*)NULL);
    rb_last_status_set(status == -1 ? 127 : status, 0);
    after_exec();
    return status;
}
#endif
#endif

static VALUE
hide_obj(VALUE obj)
{
    RBASIC(obj)->klass = 0;
    return obj;
}

static VALUE
check_exec_redirect_fd(VALUE v, int iskey)
{
    VALUE tmp;
    int fd;
    if (FIXNUM_P(v)) {
        fd = FIX2INT(v);
    }
    else if (SYMBOL_P(v)) {
        ID id = SYM2ID(v);
        if (id == rb_intern("in"))
            fd = 0;
        else if (id == rb_intern("out"))
            fd = 1;
        else if (id == rb_intern("err"))
            fd = 2;
        else
            goto wrong;
    }
    else if (!NIL_P(tmp = rb_check_convert_type(v, T_FILE, "IO", "to_io"))) {
        rb_io_t *fptr;
        GetOpenFile(tmp, fptr);
        if (fptr->tied_io_for_writing)
            rb_raise(rb_eArgError, "duplex IO redirection");
        fd = fptr->fd;
    }
    else {
        rb_raise(rb_eArgError, "wrong exec redirect");
    }
    if (fd < 0) {
      wrong:
        rb_raise(rb_eArgError, "negative file descriptor");
    }
#ifdef _WIN32
    else if (fd >= 3 && iskey) {
        rb_raise(rb_eArgError, "wrong file descriptor (%d)", fd);
    }
#endif
    return INT2FIX(fd);
}

static VALUE
check_exec_redirect1(VALUE ary, VALUE key, VALUE param)
{
    if (ary == Qfalse) {
        ary = hide_obj(rb_ary_new());
    }
    if (!RB_TYPE_P(key, T_ARRAY)) {
        VALUE fd = check_exec_redirect_fd(key, !NIL_P(param));
        rb_ary_push(ary, hide_obj(rb_assoc_new(fd, param)));
    }
    else {
        int i, n=0;
        for (i = 0 ; i < RARRAY_LEN(key); i++) {
            VALUE v = RARRAY_PTR(key)[i];
            VALUE fd = check_exec_redirect_fd(v, !NIL_P(param));
            rb_ary_push(ary, hide_obj(rb_assoc_new(fd, param)));
            n++;
        }
    }
    return ary;
}

static void
check_exec_redirect(VALUE key, VALUE val, struct rb_execarg *eargp)
{
    VALUE param;
    VALUE path, flags, perm;
    VALUE tmp;
    ID id;

    switch (TYPE(val)) {
      case T_SYMBOL:
        id = SYM2ID(val);
        if (id == rb_intern("close")) {
            param = Qnil;
            eargp->fd_close = check_exec_redirect1(eargp->fd_close, key, param);
        }
        else if (id == rb_intern("in")) {
            param = INT2FIX(0);
            eargp->fd_dup2 = check_exec_redirect1(eargp->fd_dup2, key, param);
        }
        else if (id == rb_intern("out")) {
            param = INT2FIX(1);
            eargp->fd_dup2 = check_exec_redirect1(eargp->fd_dup2, key, param);
        }
        else if (id == rb_intern("err")) {
            param = INT2FIX(2);
            eargp->fd_dup2 = check_exec_redirect1(eargp->fd_dup2, key, param);
        }
        else {
            rb_raise(rb_eArgError, "wrong exec redirect symbol: %s",
                                   rb_id2name(id));
        }
        break;

      case T_FILE:
      io:
        val = check_exec_redirect_fd(val, 0);
        /* fall through */
      case T_FIXNUM:
        param = val;
        eargp->fd_dup2 = check_exec_redirect1(eargp->fd_dup2, key, param);
        break;

      case T_ARRAY:
        path = rb_ary_entry(val, 0);
        if (RARRAY_LEN(val) == 2 && SYMBOL_P(path) &&
            SYM2ID(path) == rb_intern("child")) {
            param = check_exec_redirect_fd(rb_ary_entry(val, 1), 0);
            eargp->fd_dup2_child = check_exec_redirect1(eargp->fd_dup2_child, key, param);
        }
        else {
            FilePathValue(path);
            flags = rb_ary_entry(val, 1);
            if (NIL_P(flags))
                flags = INT2NUM(O_RDONLY);
            else if (RB_TYPE_P(flags, T_STRING))
                flags = INT2NUM(rb_io_modestr_oflags(StringValueCStr(flags)));
            else
                flags = rb_to_int(flags);
            perm = rb_ary_entry(val, 2);
            perm = NIL_P(perm) ? INT2FIX(0644) : rb_to_int(perm);
            param = hide_obj(rb_ary_new3(3, hide_obj(rb_str_dup(path)),
                                            flags, perm));
            eargp->fd_open = check_exec_redirect1(eargp->fd_open, key, param);
        }
        break;

      case T_STRING:
        path = val;
        FilePathValue(path);
        if (RB_TYPE_P(key, T_FILE))
            key = check_exec_redirect_fd(key, 1);
        if (FIXNUM_P(key) && (FIX2INT(key) == 1 || FIX2INT(key) == 2))
            flags = INT2NUM(O_WRONLY|O_CREAT|O_TRUNC);
        else
            flags = INT2NUM(O_RDONLY);
        perm = INT2FIX(0644);
        param = hide_obj(rb_ary_new3(3, hide_obj(rb_str_dup(path)),
                                        flags, perm));
        eargp->fd_open = check_exec_redirect1(eargp->fd_open, key, param);
        break;

      default:
	tmp = val;
	val = rb_io_check_io(tmp);
	if (!NIL_P(val)) goto io;
        rb_raise(rb_eArgError, "wrong exec redirect action");
    }

}

#if defined(HAVE_SETRLIMIT) && defined(NUM2RLIM)
static int rlimit_type_by_lname(const char *name);
#endif

int
rb_execarg_addopt(VALUE execarg_obj, VALUE key, VALUE val)
{
    struct rb_execarg *eargp = rb_execarg_get(execarg_obj);

    ID id;
#if defined(HAVE_SETRLIMIT) && defined(NUM2RLIM)
    int rtype;
#endif

    rb_secure(2);

    switch (TYPE(key)) {
      case T_SYMBOL:
        id = SYM2ID(key);
#ifdef HAVE_SETPGID
        if (id == rb_intern("pgroup")) {
            pid_t pgroup;
            if (eargp->pgroup_given) {
                rb_raise(rb_eArgError, "pgroup option specified twice");
            }
            if (!RTEST(val))
                pgroup = -1; /* asis(-1) means "don't call setpgid()". */
            else if (val == Qtrue)
                pgroup = 0; /* new process group. */
            else {
                pgroup = NUM2PIDT(val);
                if (pgroup < 0) {
                    rb_raise(rb_eArgError, "negative process group ID : %ld", (long)pgroup);
                }
            }
            eargp->pgroup_given = 1;
            eargp->pgroup_pgid = pgroup;
        }
        else
#endif
#ifdef _WIN32
        if (id == rb_intern("new_pgroup")) {
            if (eargp->new_pgroup_given) {
                rb_raise(rb_eArgError, "new_pgroup option specified twice");
            }
            eargp->new_pgroup_given = 1;
            eargp->new_pgroup_flag = RTEST(val) ? 1 : 0;
        }
        else
#endif
#if defined(HAVE_SETRLIMIT) && defined(NUM2RLIM)
        if (strncmp("rlimit_", rb_id2name(id), 7) == 0 &&
            (rtype = rlimit_type_by_lname(rb_id2name(id)+7)) != -1) {
            VALUE ary = eargp->rlimit_limits;
            VALUE tmp, softlim, hardlim;
            if (eargp->rlimit_limits == Qfalse)
                ary = eargp->rlimit_limits = hide_obj(rb_ary_new());
            else
                ary = eargp->rlimit_limits;
            tmp = rb_check_array_type(val);
            if (!NIL_P(tmp)) {
                if (RARRAY_LEN(tmp) == 1)
                    softlim = hardlim = rb_to_int(rb_ary_entry(tmp, 0));
                else if (RARRAY_LEN(tmp) == 2) {
                    softlim = rb_to_int(rb_ary_entry(tmp, 0));
                    hardlim = rb_to_int(rb_ary_entry(tmp, 1));
                }
                else {
                    rb_raise(rb_eArgError, "wrong exec rlimit option");
                }
            }
            else {
                softlim = hardlim = rb_to_int(val);
            }
            tmp = hide_obj(rb_ary_new3(3, INT2NUM(rtype), softlim, hardlim));
            rb_ary_push(ary, tmp);
        }
        else
#endif
        if (id == rb_intern("unsetenv_others")) {
            if (eargp->unsetenv_others_given) {
                rb_raise(rb_eArgError, "unsetenv_others option specified twice");
            }
            eargp->unsetenv_others_given = 1;
            eargp->unsetenv_others_do = RTEST(val) ? 1 : 0;
        }
        else if (id == rb_intern("chdir")) {
            if (eargp->chdir_given) {
                rb_raise(rb_eArgError, "chdir option specified twice");
            }
            FilePathValue(val);
            eargp->chdir_given = 1;
            eargp->chdir_dir = hide_obj(rb_str_dup(val));
        }
        else if (id == rb_intern("umask")) {
	    mode_t cmask = NUM2MODET(val);
            if (eargp->umask_given) {
                rb_raise(rb_eArgError, "umask option specified twice");
            }
            eargp->umask_given = 1;
            eargp->umask_mask = cmask;
        }
        else if (id == rb_intern("close_others")) {
            if (eargp->close_others_given) {
                rb_raise(rb_eArgError, "close_others option specified twice");
            }
            eargp->close_others_given = 1;
            eargp->close_others_do = RTEST(val) ? 1 : 0;
        }
        else if (id == rb_intern("in")) {
            key = INT2FIX(0);
            goto redirect;
        }
        else if (id == rb_intern("out")) {
            key = INT2FIX(1);
            goto redirect;
        }
        else if (id == rb_intern("err")) {
            key = INT2FIX(2);
            goto redirect;
        }
	else if (id == rb_intern("uid")) {
#ifdef HAVE_SETUID
	    if (eargp->uid_given) {
		rb_raise(rb_eArgError, "uid option specified twice");
	    }
	    check_uid_switch();
	    {
		PREPARE_GETPWNAM;
		eargp->uid = OBJ2UID(val);
		eargp->uid_given = 1;
	    }
#else
	    rb_raise(rb_eNotImpError,
		     "uid option is unimplemented on this machine");
#endif
	}
	else if (id == rb_intern("gid")) {
#ifdef HAVE_SETGID
	    if (eargp->gid_given) {
		rb_raise(rb_eArgError, "gid option specified twice");
	    }
	    check_gid_switch();
	    {
		PREPARE_GETGRNAM;
		eargp->gid = OBJ2GID(val);
		eargp->gid_given = 1;
	    }
#else
	    rb_raise(rb_eNotImpError,
		     "gid option is unimplemented on this machine");
#endif
	}
        else {
	    return ST_STOP;
        }
        break;

      case T_FIXNUM:
      case T_FILE:
      case T_ARRAY:
redirect:
        check_exec_redirect(key, val, eargp);
        break;

      default:
	return ST_STOP;
    }

    RB_GC_GUARD(execarg_obj);
    return ST_CONTINUE;
}

int
rb_exec_arg_addopt(struct rb_exec_arg *e, VALUE key, VALUE val)
{
    return rb_execarg_addopt(e->execarg_obj, key, val);
}

static int
check_exec_options_i(st_data_t st_key, st_data_t st_val, st_data_t arg)
{
    VALUE key = (VALUE)st_key;
    VALUE val = (VALUE)st_val;
    VALUE execarg_obj = (VALUE)arg;
    if (rb_execarg_addopt(execarg_obj, key, val) != ST_CONTINUE) {
	if (SYMBOL_P(key))
	    rb_raise(rb_eArgError, "wrong exec option symbol: %"PRIsVALUE,
		     key);
	rb_raise(rb_eArgError, "wrong exec option");
    }
    return ST_CONTINUE;
}

static int
check_exec_options_i_extract(st_data_t st_key, st_data_t st_val, st_data_t arg)
{
    VALUE key = (VALUE)st_key;
    VALUE val = (VALUE)st_val;
    VALUE *args = (VALUE *)arg;
    VALUE execarg_obj = args[0];
    if (rb_execarg_addopt(execarg_obj, key, val) != ST_CONTINUE) {
	VALUE nonopts = args[1];
	if (NIL_P(nonopts)) args[1] = nonopts = rb_hash_new();
	rb_hash_aset(nonopts, key, val);
    }
    return ST_CONTINUE;
}

static int
check_exec_fds_1(struct rb_execarg *eargp, VALUE h, int maxhint, VALUE ary)
{
    long i;

    if (ary != Qfalse) {
        for (i = 0; i < RARRAY_LEN(ary); i++) {
            VALUE elt = RARRAY_PTR(ary)[i];
            int fd = FIX2INT(RARRAY_PTR(elt)[0]);
            if (RTEST(rb_hash_lookup(h, INT2FIX(fd)))) {
                rb_raise(rb_eArgError, "fd %d specified twice", fd);
            }
            if (ary == eargp->fd_open || ary == eargp->fd_dup2)
                rb_hash_aset(h, INT2FIX(fd), Qtrue);
            else if (ary == eargp->fd_dup2_child)
                rb_hash_aset(h, INT2FIX(fd), RARRAY_PTR(elt)[1]);
            else /* ary == eargp->fd_close */
                rb_hash_aset(h, INT2FIX(fd), INT2FIX(-1));
            if (maxhint < fd)
                maxhint = fd;
            if (ary == eargp->fd_dup2 || ary == eargp->fd_dup2_child) {
                fd = FIX2INT(RARRAY_PTR(elt)[1]);
                if (maxhint < fd)
                    maxhint = fd;
            }
        }
    }
    return maxhint;
}

static VALUE
check_exec_fds(struct rb_execarg *eargp)
{
    VALUE h = rb_hash_new();
    VALUE ary;
    int maxhint = -1;
    long i;

    maxhint = check_exec_fds_1(eargp, h, maxhint, eargp->fd_dup2);
    maxhint = check_exec_fds_1(eargp, h, maxhint, eargp->fd_close);
    maxhint = check_exec_fds_1(eargp, h, maxhint, eargp->fd_open);
    maxhint = check_exec_fds_1(eargp, h, maxhint, eargp->fd_dup2_child);

    if (eargp->fd_dup2_child) {
        ary = eargp->fd_dup2_child;
        for (i = 0; i < RARRAY_LEN(ary); i++) {
            VALUE elt = RARRAY_PTR(ary)[i];
            int newfd = FIX2INT(RARRAY_PTR(elt)[0]);
            int oldfd = FIX2INT(RARRAY_PTR(elt)[1]);
            int lastfd = oldfd;
            VALUE val = rb_hash_lookup(h, INT2FIX(lastfd));
            long depth = 0;
            while (FIXNUM_P(val) && 0 <= FIX2INT(val)) {
                lastfd = FIX2INT(val);
                val = rb_hash_lookup(h, val);
                if (RARRAY_LEN(ary) < depth)
                    rb_raise(rb_eArgError, "cyclic child fd redirection from %d", oldfd);
                depth++;
            }
            if (val != Qtrue)
                rb_raise(rb_eArgError, "child fd %d is not redirected", oldfd);
            if (oldfd != lastfd) {
                VALUE val2;
                rb_ary_store(elt, 1, INT2FIX(lastfd));
                rb_hash_aset(h, INT2FIX(newfd), INT2FIX(lastfd));
                val = INT2FIX(oldfd);
                while (FIXNUM_P(val2 = rb_hash_lookup(h, val))) {
                    rb_hash_aset(h, val, INT2FIX(lastfd));
                    val = val2;
                }
            }
        }
    }

    eargp->close_others_maxhint = maxhint;
    return h;
}

static void
rb_check_exec_options(VALUE opthash, VALUE execarg_obj)
{
    if (RHASH_EMPTY_P(opthash))
        return;
    st_foreach(RHASH_TBL(opthash), check_exec_options_i, (st_data_t)execarg_obj);
}

VALUE
rb_execarg_extract_options(VALUE execarg_obj, VALUE opthash)
{
    VALUE args[2];
    if (RHASH_EMPTY_P(opthash))
        return Qnil;
    args[0] = execarg_obj;
    args[1] = Qnil;
    st_foreach(RHASH_TBL(opthash), check_exec_options_i_extract, (st_data_t)args);
    return args[1];
}

static int
check_exec_env_i(st_data_t st_key, st_data_t st_val, st_data_t arg)
{
    VALUE key = (VALUE)st_key;
    VALUE val = (VALUE)st_val;
    VALUE env = (VALUE)arg;
    char *k;

    k = StringValueCStr(key);
    if (strchr(k, '='))
        rb_raise(rb_eArgError, "environment name contains a equal : %s", k);

    if (!NIL_P(val))
        StringValueCStr(val);

    rb_ary_push(env, hide_obj(rb_assoc_new(key, val)));

    return ST_CONTINUE;
}

static VALUE
rb_check_exec_env(VALUE hash)
{
    VALUE env;

    env = hide_obj(rb_ary_new());
    st_foreach(RHASH_TBL(hash), check_exec_env_i, (st_data_t)env);

    return env;
}

static VALUE
rb_check_argv(int argc, VALUE *argv)
{
    VALUE tmp, prog;
    int i;
    const char *name = 0;

    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);

    prog = 0;
    tmp = rb_check_array_type(argv[0]);
    if (!NIL_P(tmp)) {
	if (RARRAY_LEN(tmp) != 2) {
	    rb_raise(rb_eArgError, "wrong first argument");
	}
	prog = RARRAY_PTR(tmp)[0];
	argv[0] = RARRAY_PTR(tmp)[1];
	SafeStringValue(prog);
	StringValueCStr(prog);
	prog = rb_str_new_frozen(prog);
	name = RSTRING_PTR(prog);
    }
    for (i = 0; i < argc; i++) {
	SafeStringValue(argv[i]);
	argv[i] = rb_str_new_frozen(argv[i]);
	StringValueCStr(argv[i]);
    }
    security(name ? name : RSTRING_PTR(argv[0]));
    return prog;
}

static VALUE
rb_exec_getargs(int *argc_p, VALUE **argv_p, int accept_shell, VALUE *env_ret, VALUE *opthash_ret)
{
    VALUE hash, prog;

    if (0 < *argc_p) {
        hash = rb_check_hash_type((*argv_p)[*argc_p-1]);
        if (!NIL_P(hash)) {
            *opthash_ret = hash;
            (*argc_p)--;
        }
    }

    if (0 < *argc_p) {
        hash = rb_check_hash_type((*argv_p)[0]);
        if (!NIL_P(hash)) {
            *env_ret = hash;
            (*argc_p)--;
            (*argv_p)++;
        }
    }
    prog = rb_check_argv(*argc_p, *argv_p);
    if (!prog) {
        prog = (*argv_p)[0];
        if (accept_shell && *argc_p == 1) {
            *argc_p = 0;
            *argv_p = 0;
        }
    }
    return prog;
}

#ifndef _WIN32
struct string_part {
    const char *ptr;
    size_t len;
};

static int
compare_posix_sh(const void *key, const void *el)
{
    const struct string_part *word = key;
    int ret = strncmp(word->ptr, el, word->len);
    if (!ret && ((const char *)el)[word->len]) ret = -1;
    return ret;
}
#endif

static void
rb_exec_fillarg(VALUE prog, int argc, VALUE *argv, VALUE env, VALUE opthash, VALUE execarg_obj)
{
    struct rb_execarg *eargp = rb_execarg_get(execarg_obj);
    char fbuf[MAXPATHLEN];

    MEMZERO(eargp, struct rb_execarg, 1);

    if (!NIL_P(opthash)) {
        rb_check_exec_options(opthash, execarg_obj);
    }
    if (!NIL_P(env)) {
        env = rb_check_exec_env(env);
        eargp->env_modification = env;
    }

    eargp->use_shell = argc == 0;
    if (eargp->use_shell)
        eargp->invoke.sh.shell_script = prog;
    else
        eargp->invoke.cmd.command_name = prog;

#ifndef _WIN32
    if (eargp->use_shell) {
	static const char posix_sh_cmds[][9] = {
	    "!",		/* reserved */
	    ".",		/* special built-in */
	    ":",		/* special built-in */
	    "break",		/* special built-in */
	    "case",		/* reserved */
	    "continue",		/* special …