128 lines
3.3 KiB
C
128 lines
3.3 KiB
C
#include <sys/types.h>
|
|
#include <sys/wait.h>
|
|
|
|
#include <assert.h>
|
|
#include <ctype.h>
|
|
#include <errno.h>
|
|
#include <fcntl.h>
|
|
#include <limits.h>
|
|
#include <math.h>
|
|
#include <poll.h>
|
|
#include <setjmp.h>
|
|
#include <stdarg.h>
|
|
#include <stdint.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
|
|
#include "scheme.h"
|
|
|
|
static void warn(const char *msg) { fprintf(stderr, "%s\n", msg); }
|
|
|
|
static void warnsys(const char *msg)
|
|
{
|
|
fprintf(stderr, "%s: %s\n", msg, strerror(errno));
|
|
}
|
|
|
|
static void diesys(const char *msg)
|
|
{
|
|
warnsys(msg);
|
|
exit(1);
|
|
}
|
|
|
|
static void set_close_on_exec(int fd)
|
|
{
|
|
int flags;
|
|
|
|
if ((flags = fcntl(fd, F_GETFD)) == -1) {
|
|
diesys("cannot get file descriptor flags");
|
|
}
|
|
flags |= FD_CLOEXEC;
|
|
if (fcntl(fd, F_SETFD, flags) == -1) {
|
|
diesys("cannot set close-on-exec");
|
|
}
|
|
}
|
|
|
|
value_t builtin_spawn(value_t *args, uint32_t nargs)
|
|
{
|
|
pid_t child;
|
|
int status, exec_errno;
|
|
int fds[2];
|
|
struct pollfd pollfd;
|
|
ssize_t nbyte;
|
|
value_t unix_argv_obj;
|
|
struct sv_accum unix_argv;
|
|
|
|
// TODO: memory leak: unix_argv not freed on type error
|
|
argcount("spawn", nargs, 1);
|
|
unix_argv_obj = args[0];
|
|
if (unix_argv_obj == FL_NIL) {
|
|
lerror(ArgError, "executable argument list is empty");
|
|
}
|
|
sv_accum_init(&unix_argv);
|
|
do {
|
|
if (!iscons(unix_argv_obj)) {
|
|
lerror(ArgError, "executable arguments not a proper list");
|
|
}
|
|
sv_accum_strdup(&unix_argv,
|
|
tostring(car_(unix_argv_obj), "executable argument"));
|
|
unix_argv_obj = cdr_(unix_argv_obj);
|
|
} while (unix_argv_obj != FL_NIL);
|
|
// TODO: Signal mask for the child process.
|
|
if (pipe(fds) == -1) {
|
|
diesys("cannot create pipe");
|
|
}
|
|
set_close_on_exec(fds[0]);
|
|
set_close_on_exec(fds[1]);
|
|
if ((child = fork()) == -1) {
|
|
diesys("cannot fork");
|
|
}
|
|
if (!child) {
|
|
// We are in the new child process.
|
|
close(fds[0]);
|
|
execvp(unix_argv.vec[0], unix_argv.vec);
|
|
exec_errno = errno;
|
|
nbyte = write(fds[1], &exec_errno, sizeof(exec_errno));
|
|
if (nbyte == (ssize_t)-1) {
|
|
warnsys("completely borked (child)");
|
|
} else if (nbyte != (ssize_t)sizeof(exec_errno)) {
|
|
warn("completely borked (child)");
|
|
}
|
|
_exit(126);
|
|
}
|
|
// We are in the old parent process.
|
|
close(fds[1]);
|
|
memset(&pollfd, 0, sizeof(pollfd));
|
|
pollfd.fd = fds[0];
|
|
pollfd.events = POLLIN;
|
|
if (poll(&pollfd, 1, -1) == -1) {
|
|
diesys("cannot poll");
|
|
}
|
|
exec_errno = 0;
|
|
if (pollfd.revents & POLLIN) {
|
|
nbyte = read(pollfd.fd, &exec_errno, sizeof(exec_errno));
|
|
if (nbyte == 0) {
|
|
// We don't get any data, means the pipe was closed.
|
|
} else if (nbyte == (ssize_t)-1) {
|
|
warnsys("completely borked (parent)");
|
|
} else if (nbyte != (ssize_t)sizeof(exec_errno)) {
|
|
warn("completely borked (parent)");
|
|
}
|
|
}
|
|
if (waitpid(child, &status, 0) == -1) {
|
|
warnsys("cannot wait for child process");
|
|
return FL_NIL;
|
|
}
|
|
if (!WIFEXITED(status)) {
|
|
warn("child process did not exit normally");
|
|
return FL_NIL;
|
|
}
|
|
if (exec_errno != 0) {
|
|
errno = exec_errno;
|
|
warnsys("cannot execute command");
|
|
return FL_NIL;
|
|
}
|
|
return fixnum(WEXITSTATUS(status));
|
|
}
|