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diff --git a/c_src/spawner.c b/c_src/spawner.c
index ce42775..e8d11f8 100644
--- a/c_src/spawner.c
+++ b/c_src/spawner.c
@@ -1,206 +1,228 @@
+#ifndef _POSIX_C_SOURCE
+#define _POSIX_C_SOURCE 200809L
+#endif
+
#include <fcntl.h>
+#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/wait.h>
#include <unistd.h>
+#ifndef CMSG_LEN
+socklen_t CMSG_LEN(size_t len) {
+ return (CMSG_DATA((struct cmsghdr *)NULL) - (unsigned char *)NULL) + len;
+}
+#endif
+
+#ifndef CMSG_SPACE
+socklen_t CMSG_SPACE(size_t len) {
+ struct msghdr msg;
+ struct cmsghdr cmsg;
+ msg.msg_control = &cmsg;
+ msg.msg_controllen = ~0; /* To maximize the chance that CMSG_NXTHDR won't return NULL */
+ cmsg.cmsg_len = CMSG_LEN(len);
+ return (unsigned char *)CMSG_NXTHDR(&msg, &cmsg) - (unsigned char *)&cmsg;
+}
+#endif
+
// #define DEBUG
#ifdef DEBUG
#define debug(...) \
do { \
fprintf(stderr, "%s:%d\t(fn \"%s\") - ", __FILE__, __LINE__, __func__); \
fprintf(stderr, __VA_ARGS__); \
} while (0)
#else
#define debug(...)
#endif
#define error(...) \
do { \
fprintf(stderr, "%s:%d\t(fn: \"%s\") - ", __FILE__, __LINE__, __func__); \
fprintf(stderr, __VA_ARGS__); \
} while (0)
static const int PIPE_READ = 0;
static const int PIPE_WRITE = 1;
/* We are choosing an exit code which is not reserved see:
* https://www.tldp.org/LDP/abs/html/exitcodes.html. */
static const int FORK_EXEC_FAILURE = 125;
static int set_flag(int fd, int flags) {
return fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | flags);
}
static int send_io_fds(int socket, int read_fd, int write_fd) {
struct msghdr msg = {0};
struct cmsghdr *cmsg;
int fds[2];
char buf[CMSG_SPACE(2 * sizeof(int))], dup[256];
memset(buf, '\0', sizeof(buf));
struct iovec io = {.iov_base = &dup, .iov_len = sizeof(dup)};
msg.msg_iov = &io;
msg.msg_iovlen = 1;
msg.msg_control = buf;
msg.msg_controllen = sizeof(buf);
cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(2 * sizeof(int));
fds[0] = read_fd;
fds[1] = write_fd;
memcpy((int *)CMSG_DATA(cmsg), fds, 2 * sizeof(int));
if (sendmsg(socket, &msg, 0) < 0) {
debug("Failed to send message");
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}
/* This is not ideal, but as of now there is no portable way to do this */
/*
static void close_all_fds() {
int fd_limit = (int)sysconf(_SC_OPEN_MAX);
for (int i = STDERR_FILENO + 1; i < fd_limit; i++)
close(i);
}
*/
static void close_all(int pipes[2][2]) {
for (int i = 0; i < 2; i++) {
if (pipes[i][PIPE_READ] > 0)
close(pipes[i][PIPE_READ]);
if (pipes[i][PIPE_WRITE] > 0)
close(pipes[i][PIPE_WRITE]);
}
}
static int exec_process(char const *bin, char *const *args, int socket) {
int pipes[2][2] = {{0, 0}, {0, 0}};
if (pipe(pipes[STDIN_FILENO]) == -1 || pipe(pipes[STDOUT_FILENO]) == -1) {
perror("[spawner] failed to create pipes");
close_all(pipes);
return 1;
}
debug("[spawner] pipe: done\r\n");
const int r_cmdin = pipes[STDIN_FILENO][PIPE_READ];
const int w_cmdin = pipes[STDIN_FILENO][PIPE_WRITE];
const int r_cmdout = pipes[STDOUT_FILENO][PIPE_READ];
const int w_cmdout = pipes[STDOUT_FILENO][PIPE_WRITE];
if (set_flag(r_cmdin, O_CLOEXEC) < 0 || set_flag(w_cmdout, O_CLOEXEC) < 0 ||
set_flag(w_cmdin, O_CLOEXEC | O_NONBLOCK) < 0 ||
set_flag(r_cmdout, O_CLOEXEC | O_NONBLOCK) < 0) {
perror("[spawner] failed to set flags for pipes");
close_all(pipes);
return 1;
}
debug("[spawner] set_flag done\r\n");
if (send_io_fds(socket, w_cmdin, r_cmdout) != EXIT_SUCCESS) {
perror("[spawner] failed to send fd via socket");
close_all(pipes);
return 1;
}
debug("[spawner] send_io_fds: done\r\n");
// TODO: close all fds including socket
// close_all_fds();
debug("[spawner] w_cmdin: %d r_cmdout: %d\r\n", w_cmdin, w_cmdout);
debug("[spawner] argv: %s\r\n", args[1]);
close(w_cmdin);
close(r_cmdout);
close(STDIN_FILENO);
if (dup2(r_cmdin, STDIN_FILENO) < 0) {
perror("[spawner] failed to dup to stdin");
_exit(FORK_EXEC_FAILURE);
}
close(STDOUT_FILENO);
if (dup2(w_cmdout, STDOUT_FILENO) < 0) {
perror("[spawner] failed to dup to stdout");
_exit(FORK_EXEC_FAILURE);
}
execvp(bin, args);
perror("[spawner] execvp(): failed");
_exit(FORK_EXEC_FAILURE);
}
static int handle(const char *sock_path, const char *bin, char *const *args) {
int sfd;
struct sockaddr_un addr;
debug("[spawner] hadle\r\n");
sfd = socket(AF_UNIX, SOCK_STREAM, 0);
if (sfd == -1) {
debug("Failed to create socket");
return EXIT_FAILURE;
}
memset(&addr, 0, sizeof(struct sockaddr_un));
addr.sun_family = AF_UNIX;
strncpy(addr.sun_path, sock_path, sizeof(addr.sun_path) - 1);
debug("[spawner] connect\r\n");
if (connect(sfd, (struct sockaddr *)&addr, sizeof(struct sockaddr_un)) ==
-1) {
debug("Failed to connect to socket");
return EXIT_FAILURE;
}
debug("[spawner] exec_process\r\n");
if (exec_process(bin, args, sfd) != 0)
return -1;
// we never reach here
return 0;
}
int main(int argc, const char *argv[]) {
int status = EXIT_SUCCESS;
const char **proc_argv;
debug("[spawner] argc: %d\r\n", argc);
if (argc < 3) {
debug("[spawner] exit\r\n");
status = EXIT_FAILURE;
} else {
proc_argv = malloc((argc - 2 + 1) * sizeof(char *));
int i;
for (i = 2; i < argc; i++)
proc_argv[i - 2] = argv[i];
proc_argv[i - 2] = NULL;
debug("[spawner] exec: %s\r\n", argv[2]);
status = handle(argv[1], argv[2], (char *const *)proc_argv);
}
exit(status);
}

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