WIP rewrite in C
$ ls -l result/bin/luad src/luad -r-xr-xr-x 1 root root 415032 Jan 1 1970 result/bin/luad -rwxr-xr-x 1 dan users 21872 May 14 23:18 src/luad it's difficult to argue against that size saving, and we weren't doing much except calling libraries written in C anyway this is WIP as in it's functional mostly but it's a first pass, may contain bugs, needs lint, hardcodes the socket path
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#include <unistd.h>
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#include <lua.h>
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#include <lauxlib.h>
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#include <lualib.h>
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#include <sys/socket.h>
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#include <string.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <sys/un.h>
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#include <signal.h>
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#include <sys/wait.h>
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#include <poll.h>
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#include <arpa/inet.h>
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static int sigchild_fd = -1;
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static void handle_sigchld(int num) {
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if(sigchild_fd >= 0) {
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write(sigchild_fd, "\n", 1);
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}
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}
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int open_socket(char * pathname) {
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struct sockaddr_un addr;
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addr.sun_family = AF_UNIX;
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strncpy(addr.sun_path, pathname, sizeof(addr.sun_path) - 1);
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int fd = socket(AF_LOCAL, SOCK_DGRAM, PF_LOCAL);
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if(fd < 0) {
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perror("socket");
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exit(EXIT_FAILURE);
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}
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if((bind(fd, (struct sockaddr *) &addr, sizeof addr)) < 0) {
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perror("bind");
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exit(EXIT_FAILURE);
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}
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return fd;
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}
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int * fds_from_msg(struct msghdr *msg, size_t peer_fds_count) {
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int *peer_fds = (int *) calloc(peer_fds_count, sizeof(int));
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for (struct cmsghdr* cmsg = CMSG_FIRSTHDR(msg);
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cmsg != NULL;
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cmsg = CMSG_NXTHDR(msg, cmsg)) {
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if(cmsg->cmsg_level == SOL_SOCKET &&
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cmsg->cmsg_type == SCM_RIGHTS) {
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memcpy(peer_fds, CMSG_DATA(cmsg), peer_fds_count * sizeof(int));
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}
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}
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return peer_fds;
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}
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int start_lua_child(lua_State *L,
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char * command_line, int command_line_length,
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int * fds, int fds_count) {
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char * word = command_line;
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char * command_line_end = command_line + command_line_length;
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char * pathname = NULL;
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int i = 0;
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fflush(stdout); fflush(stderr);
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for(int i=0; i < fds_count; i++) {
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if(fds[i] > 0) dup2(fds[i], i);
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}
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lua_newtable(L); /* arg */
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while(word < command_line_end) {
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char * word_end = memchr(word, '\0', command_line_end - word);
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if(!word_end) break;
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if(!pathname) {
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pathname = strndup(word, (word_end - word));
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}
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lua_pushlstring(L, word, (word_end - word));
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lua_seti(L, -2, i++);
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word = word_end + 1;
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}
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lua_setglobal(L, "arg");
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int status = luaL_dofile(L, pathname);
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if (status) {
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fprintf(stderr, "Error: %s\n", lua_tostring(L, -1));
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return 1;
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} else {
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return 0;
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}
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}
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pid_t fork_lua(lua_State *L,
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char * command_line, int command_line_length,
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int * fds, int fds_count) {
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pid_t pid = fork();
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if(pid == 0) {
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exit(start_lua_child(L, command_line, command_line_length,
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fds, fds_count));
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} else if(pid > 0) {
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free(command_line);
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return pid;
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} else {
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perror("fork");
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return -1;
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}
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}
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struct peer_entry {
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pid_t pid;
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int addrlen;
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struct sockaddr_un addr;
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};
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int register_peer(struct peer_entry *table, pid_t pid, struct sockaddr_un *addr, int addrlen) {
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if(addrlen > sizeof (struct sockaddr_un))
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return -1;
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struct peer_entry *p = table;
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while(p->pid != 0 && p->pid != -1)
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p++;
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if(p->pid == -1)
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return -1;
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p->pid = pid;
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p->addrlen = addrlen;
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memcpy(&(p->addr), addr, addrlen);
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}
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struct peer_entry* find_peer(struct peer_entry *table, pid_t pid) {
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while(table->pid != -1) {
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if(table->pid == pid)
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return table;
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table++;
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}
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return NULL;
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}
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int main(int argc, char **argv)
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{
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int status;
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lua_State *L = luaL_newstate();
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luaL_openlibs(L);
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int sigpipe_fds[2];
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struct peer_entry * peer_table = calloc(501, sizeof (struct peer_entry));
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peer_table[500].pid = -1;
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if(pipe(sigpipe_fds) < 0) {
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perror("pipe");
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exit(EXIT_FAILURE);
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}
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sigchild_fd = sigpipe_fds[1];
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signal(SIGCHLD, handle_sigchld);
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if (argc >= 2) {
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if (!access(argv[1], F_OK) == 0) {
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fprintf(stderr, "File %s does not exist!\n", argv[1]);
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exit(1);
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}
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status = luaL_dofile(L, argv[1]);
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if (status) {
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fprintf(stderr, "Error: %s\n", lua_tostring(L, -1));
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return 1;
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}
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}
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int socket = open_socket("/tmp/mysock"); /* FIXME hardcoded */
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struct sockaddr_un peer_addr;
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socklen_t peer_addr_len;
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char buf[1025];
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struct iovec iov[1];
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iov[0].iov_base = buf;
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iov[0].iov_len = sizeof buf;
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struct cmsghdr* cmsg = (struct cmsghdr *) calloc(1000, 1);
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struct msghdr msg = {
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.msg_name = &peer_addr,
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.msg_namelen = sizeof peer_addr,
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.msg_iov = iov,
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.msg_iovlen = 1,
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.msg_control = cmsg,
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.msg_controllen = 1000
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};
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struct pollfd pollfds[2] = {
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{
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.fd = socket,
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.events = POLLIN,
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.revents = 0
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},
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{
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.fd = sigpipe_fds[0],
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.events = POLLIN,
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.revents = 0
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},
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};
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while(1) {
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if(poll(pollfds, 2, 10000) == 0)
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continue;
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if(pollfds[0].revents) {
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int len = recvmsg(socket, &msg , 0);
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int *peer_fds = fds_from_msg(&msg, 5);
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char *argline = malloc(len);
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memmove(argline, buf, len);
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pid_t child_pid = fork_lua(L, argline, len, peer_fds, 5);
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if(child_pid >= 0) {
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register_peer(peer_table, child_pid, &peer_addr, msg.msg_namelen);
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}
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}
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if(pollfds[1].revents) {
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pid_t pid;
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int wstatus;
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read(pollfds[1].fd, buf, sizeof buf);
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while((pid=waitpid(0, &wstatus, WNOHANG)) > 0) {
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struct peer_entry *peer = find_peer(peer_table, pid);
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if(peer) {
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uint32_t ret = 0;
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if(WIFEXITED(wstatus)) {
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ret = htonl(WEXITSTATUS(wstatus));
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} else if(WIFSIGNALED(wstatus)) {
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ret = htonl(128 + WTERMSIG(wstatus));
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}
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sendto(socket, (void *) &ret, 4, 0,
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(const struct sockaddr *) &(peer->addr),
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peer->addrlen);
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peer->pid = 0;
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}
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}
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}
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}
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return 0;
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}
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