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Implement some more options for posix_spawn
POSIX_SPAWN_CLOEXEC_DEFAULT is set to close all fds inherited by the new process except for those explicitly marked as inheritable (or those newly created by posix_spawn actions). We can replicate this by adding O_CLOEXEC to all open fds in the child before performing our actions (except special fds like commpage).
Other than that, some new actions have also been implemented: chdir, fchdir, and inherit. chdir and fchdir change the cwd of the child to the given path or fd. inherit ensures the given fd is inherited by the child (i.e. that O_CLOEXEC is not set on it).
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+110
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src/kernel/emulation/linux/process/posix_spawn.c
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src/kernel/emulation/linux/process/posix_spawn.c
···
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#include <stddef.h>
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#include <stdint.h>
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#include <sys/spawn.h>
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#include "../unistd/chdir.h"
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#include "../unistd/fchdir.h"
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#include "../fcntl/fcntl.h"
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#include "../dirent/getdirentries.h"
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// for debugging only; remove before committing
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#include "../signal/kill.h"
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#include "../unistd/getpid.h"
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#ifndef _POSIX_SPAWN_DISABLE_ASLR
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#define _POSIX_SPAWN_DISABLE_ASLR 0x0100
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#endif
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#define LINUX_ADDR_NO_RANDOMIZE 0x40000
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-
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long sys_posix_spawn(int* pid, const char* path, const struct _posix_spawn_args_desc* desc,
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char** argvp, char** envp)
···
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lkm_call(NR_stop_after_exec, NULL);
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}
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if (desc->attrp->psa_flags & POSIX_SPAWN_CLOEXEC_DEFAULT) {
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// set O_CLOEXEC on everything
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int dir = sys_open("/proc/self/fd", BSD_O_RDONLY, 0);
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char buf[4096];
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int len = 0;
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//__simple_kprintf("asked for cloexec default\n");
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if (dir < 0) {
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ret = dir;
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goto fail;
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}
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while ((len = LINUX_SYSCALL(__NR_getdents64, dir, buf, sizeof(buf))) > 0) {
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struct linux_dirent64* dirent = (struct linux_dirent64*)&buf[0];
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for (int i = 0; i < len; i += dirent->d_reclen, dirent = (struct linux_dirent64*)&buf[i]) {
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int fd = -1;
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//__simple_kprintf("dentry name: %s\n", dirent->d_name);
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if (dirent->d_name[0] == '.') {
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continue;
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}
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fd = __simple_atoi(dirent->d_name, NULL);
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// FIXME: pretty sure this should not be hardcoded
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if (fd == 1023) {
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// special commpage fd
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continue;
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}
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//__simple_kprintf("setting cloexec on %d\n", fd);
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ret = sys_fcntl(fd, F_GETFD, 0);
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if (ret < 0) {
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close_internal(dir);
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goto fail;
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}
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ret = sys_fcntl(fd, F_SETFD, ret | FD_CLOEXEC);
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if (ret < 0) {
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close_internal(dir);
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goto fail;
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}
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}
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}
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close_internal(dir);
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if (len < 0) {
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ret = len;
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goto fail;
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}
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}
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// TODO: other attributes
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}
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if (desc && desc->factp)
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{
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int i;
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//__simple_kprintf("act count: %d\n", desc->factp->psfa_act_count);
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//sys_kill(sys_getpid(), SIGSTOP, 0);
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for (i = 0; i < desc->factp->psfa_act_count; i++)
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{
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const struct _psfa_action* act;
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act = &desc->factp->psfa_act_acts[i];
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if (act->psfaa_filedes == pipe[1])
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//__simple_kprintf("act count (on iter %d): %d\n", i, desc->factp->psfa_act_count);
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if (act->psfaa_filedes == pipe[1] || (act->psfaa_type == PSFA_DUP2 && act->psfaa_dup2args.psfad_newfiledes == pipe[1]))
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{
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ret = sys_dup(pipe[1]);
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if (ret < 0)
···
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switch (act->psfaa_type)
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{
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case PSFA_CLOSE:
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//__simple_kprintf("closing %d\n", act->psfaa_filedes);
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ret = close_internal(act->psfaa_filedes);
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if (ret != 0)
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goto fail;
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break;
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case PSFA_DUP2:
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ret = sys_dup2(act->psfaa_filedes, act->psfaa_openargs.psfao_oflag);
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//__simple_kprintf("duping %d to %d\n", act->psfaa_filedes, act->psfaa_dup2args.psfad_newfiledes);
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ret = sys_dup2(act->psfaa_filedes, act->psfaa_dup2args.psfad_newfiledes);
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if (ret < 0)
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goto fail;
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break;
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case PSFA_OPEN:
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{
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//__simple_kprintf("opening %s to %d\n", act->psfaa_openargs.psfao_path, act->psfaa_filedes);
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ret = sys_open(act->psfaa_openargs.psfao_path,
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act->psfaa_openargs.psfao_oflag, act->psfaa_openargs.psfao_mode);
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if (ret < 0)
···
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}
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break;
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}
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case PSFA_CHDIR: {
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//__simple_kprintf("chdiring to %s\n", act->psfaa_chdirargs.psfac_path);
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ret = sys_chdir(act->psfaa_chdirargs.psfac_path);
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if (ret < 0) {
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goto fail;
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}
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} break;
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case PSFA_FCHDIR: {
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//__simple_kprintf("fchdiring to %d\n", act->psfaa_filedes);
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ret = sys_fchdir(act->psfaa_filedes);
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if (ret < 0) {
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goto fail;
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}
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} break;
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// unset CLOEXEC on this fd
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case PSFA_INHERIT: {
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//__simple_kprintf("inheriting %d\n", act->psfaa_filedes);
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ret = sys_fcntl(act->psfaa_filedes, F_GETFD, 0);
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if (ret < 0) {
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goto fail;
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}
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ret = sys_fcntl(act->psfaa_filedes, F_SETFD, ret & ~FD_CLOEXEC);
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if (ret < 0) {
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goto fail;
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}
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} break;
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default:
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//__simple_kprintf("unknown PSFA type %d\n", act->psfaa_type);
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;
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}
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}
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//__simple_kprintf("act count (on finish): %d\n", desc->factp->psfa_act_count);
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}
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char binprefs[64];
···
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ret = sys_execve((char*) path, argvp, envp);
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fail:
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//__simple_kprintf("posix_spawn is failing with %d\n", ret);
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if (desc && desc->attrp && desc->attrp->psa_flags & POSIX_SPAWN_SETEXEC)
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{
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// no_fork case
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src/kernel/emulation/linux/process/posix_spawn.h
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src/kernel/emulation/linux/process/posix_spawn.h
···
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#ifndef LINUX_POSIX_SPAWN_H
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#define LINUX_POSIX_SPAWN_H
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#include <sys/types.h>
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#include <limits.h>
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#include <mach/mach_port.h>
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typedef enum {
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PSFA_OPEN = 0,
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PSFA_CLOSE = 1,
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PSFA_DUP2 = 2,
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PSFA_INHERIT = 3
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PSFA_OPEN = 0,
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PSFA_CLOSE = 1,
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PSFA_DUP2 = 2,
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PSFA_INHERIT = 3,
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PSFA_FILEPORT_DUP2 = 4,
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PSFA_CHDIR = 5,
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PSFA_FCHDIR = 6
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} psfa_t;
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struct _posix_spawnattr
···
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struct _psfa_action
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{
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psfa_t psfaa_type;
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int psfaa_filedes;
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struct _psfaa_open
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{
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int psfao_oflag;
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unsigned short psfao_mode;
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char psfao_path[1024];
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} psfaa_openargs;
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union {
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int psfaa_filedes;
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mach_port_name_t psfaa_fileport;
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};
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union {
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struct _psfaa_open {
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int psfao_oflag;
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mode_t psfao_mode;
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char psfao_path[PATH_MAX];
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} psfaa_openargs;
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struct {
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int psfad_newfiledes;
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} psfaa_dup2args;
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struct {
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char psfac_path[PATH_MAX];
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} psfaa_chdirargs;
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};
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};
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struct _posix_spawn_file_actions