Libc-498.1.7.tar.gz

[apple/libc.git] / sys / posix_spawn.c

/*
 * Copyright (c) 2006 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */

/*
 * [SPN] Support for _POSIX_SPAWN
 */

#include <sys/types.h> /* for user_size_t */
#include <spawn.h>
#include <sys/spawn_internal.h>
#include <stdlib.h>
#include <errno.h>
#include <limits.h>     /* for OPEN_MAX, PATH_MAX */
#include <stddef.h>     /* for offsetof() */
#include <string.h>     /* for strlcpy() */
#include <paths.h>      /* for _PATH_DEFPATH */
#include <sys/stat.h>   /* for struct stat */
#include <mach/port.h>
#include <mach/exception_types.h>


/*
 * posix_spawnattr_init
 *
 * Description: Initialize a spawn attributes object attr with default values
 *
 * Parameters:  attr                    The spawn attributes object to be
 *                                      initialized
 *
 * Returns:     0                       Success
 *              ENOMEM                  Insufficient memory exists to
 *                                      initialize the spawn attributes object.
 *
 * Note:        As an implementation detail, the externally visibily type
 *              posix_spawnattr_t is defined to be a void *, and initialization
 *              involves allocation of a memory object.  Subsequent changes to
 *              the spawn attributes may result in reallocation under the
 *              covers.
 *
 *              Reinitialization of an already initialized spawn attributes
 *              object will result in memory being leaked.  Because spawn
 *              attributes are not required to be used in conjunction with a
 *              static initializer, there is no way to distinguish a spawn
 *              attribute with stack garbage from one that's been initialized.
 *              This is arguably an API design error.
 */
int
posix_spawnattr_init(posix_spawnattr_t *attr)
{
        _posix_spawnattr_t *psattrp = (_posix_spawnattr_t *)attr;
        int     err = 0;

        if ((*psattrp = (_posix_spawnattr_t)malloc(sizeof(struct _posix_spawnattr))) == NULL) {
                err = ENOMEM;
        } else {

                /*
                 * The default value of this attribute shall be as if no
                 * flags were set
                 */
                (*psattrp)->psa_flags = 0;

                /*
                 * The default value of this attribute shall be an empty
                 * signal set
                 */
                (*psattrp)->psa_sigdefault = 0;

                /* The default value of this attribute is unspecified */
                (*psattrp)->psa_sigmask = 0;

                /* The default value of this attribute shall be zero */
                (*psattrp)->psa_pgroup = 0;     /* doesn't matter */

                /* Default is no binary preferences, i.e. use normal grading */
                memset((*psattrp)->psa_binprefs, 0, 
                                sizeof((*psattrp)->psa_binprefs));

                /* Default is no port actions to take */
                (*psattrp)->psa_ports = NULL;
        }

        return (err);
}


/*
 * posix_spawnattr_destroy
 *
 * Description: Destroy a spawn attributes object that was previously
 *              initialized via posix_spawnattr_init() by freeing any
 *              memory associated with it and setting it to an invalid value.
 *
 * Parameters:  attr                    The spawn attributes object to be
 *                                      destroyed.
 *
 * Returns:     0                       Success
 *
 * Notes:       The destroyed spawn attribute results in the void * pointer
 *              being set to NULL; subsequent use without reinitialization
 *              will result in explicit program failure (rather than merely
 *              "undefined behaviour").
 *
 * NOTIMP:      Allowed failures (checking NOT required):
 *              EINVAL  The value specified by attr is invalid.
 */
int
posix_spawnattr_destroy(posix_spawnattr_t *attr)
{
        _posix_spawnattr_t psattr;

        if (attr == NULL || *attr == NULL)
                return EINVAL;

        psattr = *(_posix_spawnattr_t *)attr;
        posix_spawn_destroyportactions_np(attr);

        free(psattr);
        *attr = NULL;

        return (0);
}


/*
 * posix_spawnattr_setflags
 *
 * Description: Set the spawn flags attribute for the spawn attribute object
 *              referred to by 'attr'.
 *
 * Parameters:  attr                    The spawn attributes object whose flags
 *                                      are to be set
 *              flags                   The flags value to set
 *
 * Returns:     0                       Success
 *
 * NOTIMP:      Allowed failures (checking NOT required):
 *              EINVAL  The value specified by attr is invalid.
 *              EINVAL  The value of the attribute being set is not valid.
 */
int
posix_spawnattr_setflags(posix_spawnattr_t *attr, short flags)
{
        _posix_spawnattr_t psattr;

        if (attr == NULL || *attr == NULL)
                return EINVAL;

        psattr = *(_posix_spawnattr_t *)attr;
        psattr->psa_flags = flags;

        return (0);
}


/*
 * posix_spawnattr_getflags
 *
 * Description: Retrieve the spawn attributes flag for the spawn attributes
 *              object referenced by 'attr' and place them in the memory
 *              location referenced by 'flagsp'
 *
 * Parameters:  attr                    The spawn attributes object whose flags
 *                                      are to be retrieved
 *              flagsp                  A pointer to a short value to receive
 *                                      the flags
 *
 * Returns:     0                       Success
 *
 * Implicit Returns:
 *              *flagps (modified)      The flags value from the spawn
 *                                      attributes object
 *
 * NOTIMP:      Allowed failures (checking NOT required):
 *              EINVAL  The value specified by attr is invalid.
 *              EINVAL  The value of the attribute being set is not valid.
 */
int
posix_spawnattr_getflags(const posix_spawnattr_t * __restrict attr,
        short * __restrict flagsp)
{
        _posix_spawnattr_t psattr;

        if (attr == NULL || *attr == NULL)
                return EINVAL;

        psattr = *(_posix_spawnattr_t *)attr;
        *flagsp = psattr->psa_flags;

        return (0);
}


/*
 * posix_spawnattr_getsigdefault
 *
 * Description: Retrieve the set of signals to be set to default according to
 *              the spawn attribute value referenced by 'attr' and place the
 *              result into the memory containing the sigset_t referenced by
 *              'sigdefault'
 *
 * Parameters:  attr                    The spawn attributes object whose
 *                                      signal set for default signals is to
 *                                      be retrieved
 *              sigdefault              A pointer to the sigset_t to receive
 *                                      the signal set
 *
 * Returns:     0                       Success
 *
 * Implicit Returns:
 *              *sigdefault (modified)  The signal set of signals to default
 *                                      from the spawn attributes object
 */
int
posix_spawnattr_getsigdefault(const posix_spawnattr_t * __restrict attr,
                sigset_t * __restrict sigdefault)
{
        _posix_spawnattr_t psattr;

        if (attr == NULL || *attr == NULL)
                return EINVAL;

        psattr = *(_posix_spawnattr_t *)attr;
        *sigdefault = psattr->psa_sigdefault;

        return (0);
}


/*
 * posix_spawnattr_getpgroup
 *
 * Description: Obtain the value of the spawn process group attribute from the
 *              spawn attributes object referenced by 'attr' and place the
 *              results in the memory location referenced by 'pgroup'
 *
 * Parameters:  attr                    The spawn attributes object whose
 *                                      process group information is to be
 *                                      retrieved
 *              pgroup                  A pointer to the pid_t to receive the
 *                                      process group
 *
 * Returns:     0                       Success
 *
 * Implicit Returns:
 *              *pgroup (modified)      The process group information from the
 *                                      spawn attributes object
 */
int
posix_spawnattr_getpgroup(const posix_spawnattr_t * __restrict attr,
                pid_t * __restrict pgroup)
{
        _posix_spawnattr_t psattr;

        if (attr == NULL || *attr == NULL)
                return EINVAL;

        psattr = *(_posix_spawnattr_t *)attr;
        *pgroup = psattr->psa_pgroup;

        return (0);
}


/*
 * posix_spawnattr_getsigmask
 *
 * Description: Obtain the value of the spawn signal mask attribute from the
 *              spawn attributes object referenced by 'attr' and place the
 *              result into the memory containing the sigset_t referenced by
 *              'sigmask'
 *
 * Parameters:  attr                    The spawn attributes object whose
 *                                      signal set for masked signals is to
 *                                      be retrieved
 *              sigmask         A pointer to the sigset_t to receive
 *                                      the signal set
 *
 * Returns:     0                       Success
 *
 * Implicit Returns:
 *              *sigmask (modified)     The signal set of signals to mask
 *                                      from the spawn attributes object
 */
int
posix_spawnattr_getsigmask(const posix_spawnattr_t * __restrict attr,
                sigset_t * __restrict sigmask)
{
        _posix_spawnattr_t psattr;

        if (attr == NULL || *attr == NULL)
                return EINVAL;

        psattr = *(_posix_spawnattr_t *)attr;
        *sigmask = psattr->psa_sigmask;

        return (0);
}

/*
 * posix_spawnattr_getbinpref_np
 *
 * Description: Obtain the value of the spawn binary preferences attribute from 
 *              the spawn attributes object referenced by 'attr' and place the
 *              result into the memory referenced by 'pref'.
 *
 * Parameters:  attr                    The spawn attributes object whose
 *                                      binary preferences are to be retrieved
 *              count                   The size of the cpu_type_t array
 *              pref                    An array of cpu types
 *              ocount                  The actual number copied
 *
 * Returns:     0                       No binary preferences found
 *              > 0                     The number of cpu types (less than 
 *                                      count) copied over from 'attr'.
 *
 * Implicit Returns:
 *              *pref (modified)        The binary preferences array 
 *                                      from the spawn attributes object
 */
int
posix_spawnattr_getbinpref_np(const posix_spawnattr_t * __restrict attr,
                size_t count, cpu_type_t *pref, size_t * __restrict ocount)
{
        _posix_spawnattr_t psattr;
        int i = 0;

        if (attr == NULL || *attr == NULL)
                return EINVAL;

        psattr = *(_posix_spawnattr_t *)attr;
        for (i = 0; i < count && i < 4; i++) {
                pref[i] = psattr->psa_binprefs[i];
        }

        if (ocount)
                *ocount = i;
        return 0;
}
/*
 * posix_spawnattr_setsigdefault
 *
 * Description: Set the set of signals to be set to default for the spawn
 *              attribute value referenced by 'attr' from the memory
 *              containing the sigset_t referenced by 'sigdefault'
 *
 * Parameters:  attr                    The spawn attributes object whose
 *                                      signal set for default signals is to
 *                                      be set
 *              sigdefault              A pointer to the sigset_t from which to
 *                                      obtain the signal set
 *
 * Returns:     0                       Success
 */
int
posix_spawnattr_setsigdefault(posix_spawnattr_t * __restrict attr,
                const sigset_t * __restrict sigdefault)
{
        _posix_spawnattr_t psattr;

        if (attr == NULL || *attr == NULL)
                return EINVAL;

        psattr = *(_posix_spawnattr_t *)attr;
        psattr->psa_sigdefault = *sigdefault;

        return (0);
}


/*
 * posix_spawnattr_setpgroup
 *
 * Description: Set the value of the spawn process group attribute for the
 *              spawn attributes object referenced by 'attr' from the value
 *              of 'pgroup'
 *
 * Parameters:  attr                    The spawn attributes object for which
 *                                      the process group information is to be
 *                                      set
 *              pgroup                  The process group to set
 *
 * Returns:     0                       Success
 */
int
posix_spawnattr_setpgroup(posix_spawnattr_t * attr, pid_t pgroup)
{
        _posix_spawnattr_t psattr;

        if (attr == NULL || *attr == NULL)
                return EINVAL;

        psattr = *(_posix_spawnattr_t *)attr;
        psattr->psa_pgroup = pgroup;

        return (0);
}


/*
 * posix_spawnattr_setsigmask
 *
 * Description: Set the set of signals to be masked for the spawn attribute
 *              value referenced by 'attr' from the memory containing the
 *              sigset_t referenced by 'sigmask'
 *
 * Parameters:  attr                    The spawn attributes object whose
 *                                      signal set for masked signals is to
 *                                      be set
 *              sigmask         A pointer to the sigset_t from which to
 *                                      obtain the signal set
 *
 * Returns:     0                       Success
 */
int
posix_spawnattr_setsigmask(posix_spawnattr_t * __restrict attr,
                const sigset_t * __restrict sigmask)
{
        _posix_spawnattr_t psattr;

        if (attr == NULL || *attr == NULL)
                return EINVAL;

        psattr = *(_posix_spawnattr_t *)attr;
        psattr->psa_sigmask = *sigmask;

        return (0);
}


/*
 * posix_spawnattr_setbinpref_np
 *
 * Description: Set the universal binary preferences for the spawn attribute
 *              value referenced by 'attr' from the memory containing the
 *              cpu_type_t array referenced by 'pref', size of 'count'
 *
 * Parameters:  attr                    The spawn attributes object whose
 *                                      binary preferences are to be set
 *              count                   Size of the array pointed to by 'pref'
 *              pref                    cpu_type_t array of binary preferences
 *              ocount                  The actual number copied
 *
 * Returns:     0                       No preferences copied
 *              > 0                     Number of preferences copied
 *
 * Note:        The posix_spawnattr_t currently only holds four cpu_type_t's. 
 *              If the caller provides more preferences than this limit, they
 *              will be ignored, as reflected in the return value.
 */
int
posix_spawnattr_setbinpref_np(posix_spawnattr_t * __restrict attr,
                size_t count, cpu_type_t *pref, size_t * __restrict ocount)
{
        _posix_spawnattr_t psattr;
        int i = 0;

        if (attr == NULL || *attr == NULL)
                return EINVAL;

        psattr = *(_posix_spawnattr_t *)attr;
        for (i = 0; i < count && i < 4; i++) {
                psattr->psa_binprefs[i] = pref[i];
        }

        /* return number of binprefs copied over */
        if (ocount)
                *ocount = i;
        return 0;
}

/*
 * posix_spawn_createportactions_np
 * Description: create a new posix_spawn_port_actions struct and link
 *      it into the posix_spawnattr.
 */
int
posix_spawn_createportactions_np(posix_spawnattr_t *attr)
{
        _posix_spawnattr_t psattr;
        _posix_spawn_port_actions_t acts;

        if (attr == NULL || *attr == NULL)
                return EINVAL;

        psattr = *(_posix_spawnattr_t *)attr;
        acts = (_posix_spawn_port_actions_t)malloc(PS_PORT_ACTIONS_SIZE(2));
        if (acts == NULL)
                return ENOMEM;
        
        acts->pspa_alloc = 2;
        acts->pspa_count = 0;

        psattr->psa_ports = acts;
        return 0;
}

/*
 * posix_spawn_growportactions_np
 * Description: Enlarge the size of portactions if necessary 
 */
int
posix_spawn_growportactions_np(posix_spawnattr_t *attr)
{
        _posix_spawnattr_t psattr;
        _posix_spawn_port_actions_t acts; 
        int newnum;

        if (attr == NULL || *attr == NULL)
                return EINVAL;

        psattr = *(_posix_spawnattr_t *)attr;
        acts = psattr->psa_ports; 
        if (acts == NULL)
                return EINVAL;
        
        /* Double number of port actions allocated for */
        newnum = 2 * acts->pspa_alloc;
        acts = realloc(acts, PS_PORT_ACTIONS_SIZE(newnum));
        if (acts == NULL)
                return ENOMEM;
        
        acts->pspa_alloc = newnum;
        return 0;
}

/*
 * posix_spawn_destroyportactions_np
 * Description: clean up portactions struct in posix_spawnattr_t attr
 */
int
posix_spawn_destroyportactions_np(posix_spawnattr_t *attr)
{
        _posix_spawnattr_t psattr;
        _posix_spawn_port_actions_t acts; 

        if (attr == NULL || *attr == NULL)
                return EINVAL;

        psattr = *(_posix_spawnattr_t *)attr;
        acts = psattr->psa_ports; 
        if (acts == NULL)
                return EINVAL;
        
        free(acts);
        return 0;
}


/*
 * posix_spawnattr_setspecialport_np
 *
 * Description: Set a new value for a mach special port in the spawned task. 
 *
 * Parameters:  attr                    The spawn attributes object for the
 *                                      new process
 *              new_port                The new value for the special port
 *              which                   The particular port to be set
 *                                      (see task_set_special_port for details)
 *
 * Returns:     0                       Success
 *              ENOMEM                  Couldn't allocate memory
 */
int    
posix_spawnattr_setspecialport_np(
                posix_spawnattr_t *attr,
                mach_port_t      new_port,
                int             which)
{
        _posix_spawnattr_t psattr;
        int err = 0;
        _ps_port_action_t *action;
        _posix_spawn_port_actions_t ports;

        if (attr == NULL || *attr == NULL)
                return EINVAL;

        psattr = *(_posix_spawnattr_t *)attr;
        ports = psattr->psa_ports;
        /* Have any port actions been created yet? */
        if (ports == NULL) {
                err = posix_spawn_createportactions_np(attr);
                if (err) 
                        return err;
                ports = psattr->psa_ports;
        }
        
        /* Is there enough room? */
        if (ports->pspa_alloc == ports->pspa_count) {
                err = posix_spawn_growportactions_np(attr);
                if (err)
                        return err;
        }

        /* Add this action to next spot in array */
        action = &ports->pspa_actions[ports->pspa_count];
        action->port_type = PSPA_SPECIAL;
        action->new_port = new_port;
        action->which = which;
        
        ports->pspa_count++;
        return err;
}

/*
 * posix_spawnattr_setexceptionports_np
 *
 * Description: Set a new port for a set of exception ports in the spawned task.
 *
 * Parameters:  attr                    The spawn attributes object for the
 *                                      new process
 *              mask                    A bitfield indicating which exceptions
 *                                      to associate the port with
 *              new_port                The new value for the exception port
 *              behavior                The default behavior for the port
 *              flavor                  The default flavor for the port
 *                                      (see task_set_exception_ports)
 *
 * Returns:     0                       Success
 */
int    
posix_spawnattr_setexceptionports_np(
                posix_spawnattr_t       *attr,
                exception_mask_t        mask,
                mach_port_t              new_port,
                exception_behavior_t    behavior,
                thread_state_flavor_t   flavor)
{
        _posix_spawnattr_t psattr;
        int err = 0;
        _ps_port_action_t *action;
        _posix_spawn_port_actions_t ports;

        if (attr == NULL || *attr == NULL)
                return EINVAL;

        psattr = *(_posix_spawnattr_t *)attr;
        ports = psattr->psa_ports;
        /* Have any port actions been created yet? */
        if (ports == NULL) {
                err = posix_spawn_createportactions_np(attr);
                if (err) 
                        return err;
                ports = psattr->psa_ports;
        }
        
        /* Is there enough room? */
        if (ports->pspa_alloc == ports->pspa_count) {
                err = posix_spawn_growportactions_np(attr);
                if (err)
                        return err;
        }

        /* Add this action to next spot in array */
        action = &ports->pspa_actions[ports->pspa_count];
        action->port_type = PSPA_EXCEPTION;
        action->mask = mask;
        action->new_port = new_port;
        action->behavior = behavior;
        action->flavor = flavor;
        
        ports->pspa_count++;
        return err;
}


/*
 * posix_spawn_file_actions_init
 *
 * Description: Initialize a spawn file actions object attr with default values
 *
 * Parameters:  file_actions            The spawn file actions object to be
 *                                      initialized
 *
 * Returns:     0                       Success
 *              ENOMEM                  Insufficient memory exists to
 *                                      initialize the spawn file actions
 *                                      object.
 *
 * Note:        As an implementation detail, the externally visibily type
 *              posix_spawn_file_actions_t is defined to be a void *, and
 *              initialization involves allocation of a memory object.
 *              Subsequent changes to the spawn file actions may result in
 *              reallocation under the covers.
 *
 *              Reinitialization of an already initialized spawn file actions
 *              object will result in memory being leaked.  Because spawn
 *              file actions are not required to be used in conjunction with a
 *              static initializer, there is no way to distinguish a spawn
 *              file actions with stack garbage from one that's been
 *              initialized.  This is arguably an API design error.
 */
int
posix_spawn_file_actions_init(posix_spawn_file_actions_t *file_actions)
{
        _posix_spawn_file_actions_t *psactsp = (_posix_spawn_file_actions_t *)file_actions;
        int     err = 0;

        if ((*psactsp = (_posix_spawn_file_actions_t)malloc(PSF_ACTIONS_SIZE(PSF_ACTIONS_INIT_COUNT))) == NULL) {
                err = ENOMEM;
        } else {
                (*psactsp)->psfa_act_alloc = PSF_ACTIONS_INIT_COUNT;
                (*psactsp)->psfa_act_count = 0;
        }

        return (err);
}


/*
 * posix_spawn_file_actions_destroy
 *
 * Description: Destroy a spawn file actions object that was previously
 *              initialized via posix_spawn_file_actions_init() by freeing any
 *              memory associated with it and setting it to an invalid value.
 *
 * Parameters:  attr                    The spawn file actions object to be
 *                                      destroyed.
 *
 * Returns:     0                       Success
 *
 * Notes:       The destroyed spawn file actions results in the void * pointer
 *              being set to NULL; subsequent use without reinitialization
 *              will result in explicit program failure (rather than merely
 *              "undefined behaviour").
 *
 * NOTIMP:      Allowed failures (checking NOT required):
 *              EINVAL  The value specified by file_actions is invalid.
 */
int
posix_spawn_file_actions_destroy(posix_spawn_file_actions_t *file_actions)
{
        _posix_spawn_file_actions_t psacts;

        if (file_actions == NULL || *file_actions == NULL)
                return EINVAL;

        psacts = *(_posix_spawn_file_actions_t *)file_actions;
        free(psacts);
        *file_actions = NULL;

        return (0);
}


/*
 * _posix_spawn_file_actions_grow
 *
 * Description: Grow the available list of file actions associated with the
 *              pointer to the structure provided; replace the contents of the
 *              pointer as a side effect.
 *
 * Parameters:  psactsp                 Pointer to _posix_spawn_file_actions_t
 *                                      to grow
 *
 * Returns:     0                       Success
 *              ENOMEM                  Insufficient memory for operation
 *
 * Notes:       This code is common to all posix_spawn_file_actions_*()
 *              functions, since we use a naieve data structure implementation
 *              at present.  Future optimization will likely change this.
 */
static int
_posix_spawn_file_actions_grow(_posix_spawn_file_actions_t *psactsp)
{
        int     new_alloc = (*psactsp)->psfa_act_alloc * 2;
        _posix_spawn_file_actions_t new_psacts;

        /*
         * XXX may want to impose an administrative limit here; POSIX does
         * XXX not provide for an administrative error return in this case,
         * XXX so it's probably acceptable to just fail catastrophically
         * XXX instead of implementing one.
         */
        if ((new_psacts = (_posix_spawn_file_actions_t)realloc((*psactsp), PSF_ACTIONS_SIZE(new_alloc))) == NULL) {
                return (ENOMEM);
        }
        new_psacts->psfa_act_alloc = new_alloc;
        *psactsp = new_psacts;

        return (0);
}


/*
 * posix_spawn_file_actions_addopen
 *
 * Description: Add an open action to the object referenced by 'file_actions'
 *              that will cause the file named by 'path' to be attempted to be
 *              opened with flags 'oflag' and mode 'mode', and, if successful,
 *              return as descriptor 'filedes' to the spawned process.
 *
 * Parameters:  file_actions            File action object to add open to
 *              filedes                 fd that open is to use
 *              path                    path to file to open
 *              oflag                   open file flags
 *              mode                    open file mode
 *
 * Returns:     0                       Success
 *              EBADF                   The value specified by fildes is
 *                                      negative or greater than or equal to
 *                                      {OPEN_MAX}.
 *              ENOMEM                  Insufficient memory exists to add to
 *                                      the spawn file actions object.
 *
 * NOTIMP:      Allowed failures (checking NOT required):
 *              EINVAL  The value specified by file_actions is invalid.
 */
int
posix_spawn_file_actions_addopen(
                posix_spawn_file_actions_t * __restrict file_actions,
                int filedes, const char * __restrict path, int oflag,
                mode_t mode)
{
        _posix_spawn_file_actions_t *psactsp;
        _psfa_action_t *psfileact;

        if (file_actions == NULL || *file_actions == NULL)
                return EINVAL;

        psactsp = (_posix_spawn_file_actions_t *)file_actions;
        /* Range check; required by POSIX */
        if (filedes < 0 || filedes >= OPEN_MAX)
                return (EBADF);

        /* If we do not have enough slots, grow the structure */
        if ((*psactsp)->psfa_act_count == (*psactsp)->psfa_act_alloc) {
                /* need to grow file actions structure */
                if (_posix_spawn_file_actions_grow(psactsp))
                        return (ENOMEM);
        }

        /*
         * Allocate next available slot and fill it out
         */
        psfileact = &(*psactsp)->psfa_act_acts[(*psactsp)->psfa_act_count++];

        psfileact->psfaa_type = PSFA_OPEN;
        psfileact->psfaa_filedes = filedes;
        psfileact->psfaa_openargs.psfao_oflag = oflag;
        psfileact->psfaa_openargs.psfao_mode = mode;
        strlcpy(psfileact->psfaa_openargs.psfao_path, path, PATH_MAX);

        return (0);
}


/*
 * posix_spawn_file_actions_addclose
 *
 * Description: Add a close action to the object referenced by 'file_actions'
 *              that will cause the file referenced by 'filedes' to be
 *              attempted to be closed in the spawned process.
 *
 * Parameters:  file_actions            File action object to add open to
 *              filedes                 fd to close
 *
 * Returns:     0                       Success
 *              EBADF                   The value specified by fildes is
 *                                      negative or greater than or equal to
 *                                      {OPEN_MAX}.
 *              ENOMEM                  Insufficient memory exists to add to
 *                                      the spawn file actions object.
 *
 * NOTIMP:      Allowed failures (checking NOT required):
 *              EINVAL  The value specified by file_actions is invalid.
 */
int
posix_spawn_file_actions_addclose(posix_spawn_file_actions_t *file_actions,
                int filedes)
{
        _posix_spawn_file_actions_t *psactsp;
        _psfa_action_t *psfileact;

        if (file_actions == NULL || *file_actions == NULL)
                return EINVAL;

        psactsp = (_posix_spawn_file_actions_t *)file_actions;
        /* Range check; required by POSIX */
        if (filedes < 0 || filedes >= OPEN_MAX)
                return (EBADF);

        /* If we do not have enough slots, grow the structure */
        if ((*psactsp)->psfa_act_count == (*psactsp)->psfa_act_alloc) {
                /* need to grow file actions structure */
                if (_posix_spawn_file_actions_grow(psactsp))
                        return (ENOMEM);
        }

        /*
         * Allocate next available slot and fill it out
         */
        psfileact = &(*psactsp)->psfa_act_acts[(*psactsp)->psfa_act_count++];

        psfileact->psfaa_type = PSFA_CLOSE;
        psfileact->psfaa_filedes = filedes;

        return (0);
}


/*
 * posix_spawn_file_actions_adddup2
 *
 * Description: Add a dpu2 action to the object referenced by 'file_actions'
 *              that will cause the file referenced by 'filedes' to be
 *              attempted to be dup2'ed to the descriptor 'newfiledes' in the
 *              spawned process.
 *
 * Parameters:  file_actions            File action object to add open to
 *              filedes                 fd to dup2
 *              newfiledes              fd to dup2 it to
 *
 * Returns:     0                       Success
 *              EBADF                   The value specified by either fildes
 *                                      or by newfiledes is negative or greater
 *                                      than or equal to {OPEN_MAX}.
 *              ENOMEM                  Insufficient memory exists to add to
 *                                      the spawn file actions object.
 *
 * NOTIMP:      Allowed failures (checking NOT required):
 *              EINVAL  The value specified by file_actions is invalid.
 */
int
posix_spawn_file_actions_adddup2(posix_spawn_file_actions_t *file_actions,
                int filedes, int newfiledes)
{
        _posix_spawn_file_actions_t *psactsp;
        _psfa_action_t *psfileact;

        if (file_actions == NULL || *file_actions == NULL)
                return EINVAL;

        psactsp = (_posix_spawn_file_actions_t *)file_actions;
        /* Range check; required by POSIX */
        if (filedes < 0 || filedes >= OPEN_MAX ||
            newfiledes < 0 || newfiledes >= OPEN_MAX)
                return (EBADF);

        /* If we do not have enough slots, grow the structure */
        if ((*psactsp)->psfa_act_count == (*psactsp)->psfa_act_alloc) {
                /* need to grow file actions structure */
                if (_posix_spawn_file_actions_grow(psactsp))
                        return (ENOMEM);
        }

        /*
         * Allocate next available slot and fill it out
         */
        psfileact = &(*psactsp)->psfa_act_acts[(*psactsp)->psfa_act_count++];

        psfileact->psfaa_type = PSFA_DUP2;
        psfileact->psfaa_filedes = filedes;
        psfileact->psfaa_openargs.psfao_oflag = newfiledes;

        return (0);
}


/*
 * posix_spawnp
 *
 * Description: Create a new process from the process image corresponding to
 *              the supplied 'file' argument and the parent processes path
 *              environment.
 *
 * Parameters:  pid                             Pointer to pid_t to receive the
 *                                              PID of the spawned process, if
 *                                              successful and 'pid' != NULL
 *              file                            Name of image file to spawn
 *              file_actions                    spawn file actions object which
 *                                              describes file actions to be
 *                                              performed during the spawn
 *              attrp                           spawn attributes object which
 *                                              describes attributes to be
 *                                              applied during the spawn
 *              argv                            argument vector array; NULL
 *                                              terminated
 *              envp                            environment vector array; NULL
 *                                              terminated
 *
 * Returns:     0                               Success
 *              !0                              An errno value indicating the
 *                                              cause of the failure to spawn
 *
 * Notes:       Much of this function is derived from code from execvP() from
 *              exec.c in libc; this common code should be factored out at
 *              some point to prevent code duplication or desynchronization vs.
 *              bug fixes applied to one set of code but not the other.
 */
int
posix_spawnp(pid_t * __restrict pid, const char * __restrict file,
                const posix_spawn_file_actions_t *file_actions,
                const posix_spawnattr_t * __restrict attrp,
                char *const argv[ __restrict], char *const envp[ __restrict])
{
        const char *env_path;
        char *bp;
        char *cur;
        char *p;
        char **memp;
        int lp;
        int ln;
        int cnt;
        int err = 0;
        int eacces = 0;
        struct stat sb;
        char path_buf[PATH_MAX];

        if ((env_path = getenv("PATH")) == NULL)
                env_path = _PATH_DEFPATH;

        /* If it's an absolute or relative path name, it's easy. */
        if (index(file, '/')) {
                bp = (char *)file;
                cur = NULL;
                goto retry;
        }
        bp = path_buf;

        /* If it's an empty path name, fail in the usual POSIX way. */
        if (*file == '\0')
                return (ENOENT);

        if ((cur = alloca(strlen(env_path) + 1)) == NULL)
                return ENOMEM;
        strcpy(cur, env_path);
        while ((p = strsep(&cur, ":")) != NULL) {
                /*
                 * It's a SHELL path -- double, leading and trailing colons
                 * mean the current directory.
                 */
                if (*p == '\0') {
                        p = ".";
                        lp = 1;
                } else {
                        lp = strlen(p);
                }
                ln = strlen(file);

                /*
                 * If the path is too long complain.  This is a possible
                 * security issue; given a way to make the path too long
                 * the user may spawn the wrong program.
                 */
                if (lp + ln + 2 > sizeof(path_buf)) {
                        err = ENAMETOOLONG;
                        goto done;
                }
                bcopy(p, path_buf, lp);
                path_buf[lp] = '/';
                bcopy(file, path_buf + lp + 1, ln);
                path_buf[lp + ln + 1] = '\0';

retry:          err = posix_spawn(pid, bp, file_actions, attrp, argv, envp);
                switch (err) {
                case E2BIG:
                case ENOMEM:
                case ETXTBSY:
                        goto done;
                case ELOOP:
                case ENAMETOOLONG:
                case ENOENT:
                case ENOTDIR:
                        break;
                case ENOEXEC:
                        for (cnt = 0; argv[cnt]; ++cnt)
                                ;
                        memp = alloca((cnt + 2) * sizeof(char *));
                        if (memp == NULL) {
                                /* errno = ENOMEM; XXX override ENOEXEC? */
                                goto done;
                        }
                        memp[0] = "sh";
                        memp[1] = bp;
                        bcopy(argv + 1, memp + 2, cnt * sizeof(char *));
                        err = posix_spawn(pid, _PATH_BSHELL, file_actions, attrp, memp, envp);
                        goto done;
                default:
                        /*
                         * EACCES may be for an inaccessible directory or
                         * a non-executable file.  Call stat() to decide
                         * which.  This also handles ambiguities for EFAULT
                         * and EIO, and undocumented errors like ESTALE.
                         * We hope that the race for a stat() is unimportant.
                         */
                        if (stat(bp, &sb) != 0)
                                break;
                        if (err == EACCES) {
                                eacces = 1;
                                continue;
                        }
                        goto done;
                }
        }
        if (eacces)
                err = EACCES;
        else
                err = ENOENT;
done:
        return (err);
}


/*
 * posix_spawn
 *
 * Description: Create a new process from the process image corresponding to
 *              the supplied 'path' argument.
 *
 * Parameters:  pid                             Pointer to pid_t to receive the
 *                                              PID of the spawned process, if
 *                                              successful and 'pid' != NULL
 *              path                            Path of image file to spawn
 *              file_actions                    spawn file actions object which
 *                                              describes file actions to be
 *                                              performed during the spawn
 *              attrp                           spawn attributes object which
 *                                              describes attributes to be
 *                                              applied during the spawn
 *              argv                            argument vector array; NULL
 *                                              terminated
 *              envp                            environment vector array; NULL
 *                                              terminated
 *
 * Returns:     0                               Success
 *              !0                              An errno value indicating the
 *                                              cause of the failure to spawn
 *
 * Notes:       Unlike other system calls, the return value of this system
 *              call is expected to either be a 0 or an errno, rather than a
 *              0 or a -1, with the 'errno' variable being set.
 */
extern int __posix_spawn(pid_t * __restrict, const char * __restrict,
                struct _posix_spawn_args_desc *,
                char *const argv[ __restrict], char *const envp[ __restrict]);

int
posix_spawn(pid_t * __restrict pid, const char * __restrict path,
                const posix_spawn_file_actions_t *file_actions,
                const posix_spawnattr_t * __restrict attrp,
                char *const argv[ __restrict], char *const envp[ __restrict])
{
        int saveerrno = errno;
        int ret;
        /*
         * Only do extra work if we have file actions or attributes to push
         * down.  We use a descriptor to push this information down, since we
         * want to have size information, which will let us (1) preallocate a
         * single chunk of memory for the copyin(), and (2) allow us to do a
         * single copyin() per attributes or file actions as a monlithic block.
         *
         * Note:        A future implementation may attempt to do the same
         *              thing for the argv/envp data, which could potentially
         *              result in a performance improvement due to increased
         *              kernel efficiency, even though it would mean copying
         *              the data in user space.
         */
        if ((file_actions != NULL && (*file_actions != NULL) && (*(_posix_spawn_file_actions_t *)file_actions)->psfa_act_count > 0) || attrp != NULL) {
                struct _posix_spawn_args_desc   ad;

                memset(&ad, 0, sizeof(ad));
                if (attrp != NULL && *attrp != NULL) {
                        _posix_spawnattr_t psattr = *(_posix_spawnattr_t *)attrp;
                        ad.attr_size = sizeof(struct _posix_spawnattr);
                        ad.attrp = psattr;

                        if (psattr->psa_ports != NULL) {
                                ad.port_actions = psattr->psa_ports;
                                ad.port_actions_size = PS_PORT_ACTIONS_SIZE(
                                                ad.port_actions->pspa_count);
                        }
                }
                if (file_actions != NULL && *file_actions != NULL) {
                        _posix_spawn_file_actions_t psactsp =
                                *(_posix_spawn_file_actions_t *)file_actions;

                        if (psactsp->psfa_act_count > 0) {
                                ad.file_actions_size = PSF_ACTIONS_SIZE(psactsp->psfa_act_count);
                                ad.file_actions = psactsp;
                        }
                }

                ret = __posix_spawn(pid, path, &ad, argv, envp);
        } else
                ret = __posix_spawn(pid, path, NULL, argv, envp);

        if (ret < 0)
                ret = errno;
        errno = saveerrno;
        return ret;
}