int
do_daemonize(void)
{
pid_t child;
unsigned int i;
if ((child = fork()) == (pid_t) -1) {
logger_error(NULL, "Unable to fork() in order to daemonize");
return -1;
} else if (child != (pid_t) 0) {
_exit(0);
}
if (setsid() == (pid_t) -1) {
logger_error(NULL, "Unable to setsid()");
}
i = open_max();
do {
if (isatty((int) i)) {
(void) close((int) i);
}
i--;
} while (i > 2U);
if (closedesc_all(1) != 0) {
logger_error(NULL, _PATH_DEVNULL " duplication");
return -1;
}
return 0;
}
void hmsg_monitor(void)
{
int i, maxi, listenfd, clifd, nread;
char buf[MAXLINE];
uid_t uid;
struct pollfd *pollfd;
if ((pollfd = malloc(open_max() * sizeof(struct pollfd))) == NULL)
dlog(L_ERR, "malloc error");
/* obtain fd to listen for client requests on */
if ((listenfd = msg_listen(MSG_PATH)) < 0)
dlog(L_ERR, "msg_listen error");
client_add(listenfd, 0); /* we use [0] for listenfd */
pollfd[0].fd = listenfd;
pollfd[0].events = POLLIN;
maxi = 0;
for ( ; ; ) {
if (poll(pollfd, maxi + 1, -1) < 0)
dlog(L_ERR, "poll error");
if (pollfd[0].revents & POLLIN) {
/* accept new client request */
if ((clifd = serv_accept(listenfd, &uid)) < 0)
dlog(L_ERR, "serv_accept error: %d", clifd);
i = client_add(clifd, uid);
pollfd[i].fd = clifd;
pollfd[i].events = POLLIN;
if (i > maxi)
maxi = i;
dlog(L_INFO, "new connection: uid %d, fd %d\n", uid, clifd);
}
for (i = 1; i <= maxi; i++) {
if ((clifd = client[i].fd) < 0)
continue;
if (pollfd[i].revents & POLLHUP) {
goto hungup;
} else if (pollfd[i].revents & POLLIN) {
/* read argument buffer from client */
if ((nread = read(clifd, buf, MAXLINE)) < 0) {
dlog(L_ERR, "read error on fd %d\n", clifd);
} else if (nread == 0) {
hungup:
dlog(L_INFO, "closed: uid %d, fd %d\n",
client[i].uid, clifd);
client_del(clifd); /* client has closed conn */
pollfd[i].fd = -1;
close(clifd);
} else { /* process client's request */
msg_parse_arg(buf, nread, clifd, client[i].uid);
}
}
}
}
}
FILE *
popen(const char *cmdstring, const char *type)
{
int i;
int pfd[2];
pid_t pid;
FILE *fp;
if ((type[0] != 'r' && type[0] != 'w') || type[1] != 0) {
errno = EINVAL;
return (NULL);
}
if (childpid == NULL) {
maxfd = open_max();
if ((childpid = calloc(maxfd, sizeof(pid_t))) == NULL)
return NULL;
}
if (pipe(pfd) < 0){
return (NULL);
} else if (pid == 0) {
if (*type == 'r') {
close(pfd[0]);
if (pfd[1] != STDOUT_FILENO) {
dup2(pfd[1], STDOUT_FILENO);
close(pfd[1]);
}
} else {
close(pfd[1]);
if (pfd[0] != STDIN_FILENO) {
dup2(pfd[0], STDIN_FILENO);
close(pfd[0]);
}
}
for (i = 0; i < maxfd; i++)
if (childpid[i] > 0)
close(i);
execl("/bin/sh", "sh", "-c", cmdstring, (char *)0);
_exit(127);
}
if (*type == 'r') {
close(pfd[1]);
if ((fp = fdopen(pfd[0], type)) == NULL)
return (NULL);
} else {
close(pfd[0]);
if ((fp = fopen(pfd[1], type)) == NULL)
return (NULL);
}
childpid[fileno(fp)] = pid;
return (fp);
}
int
main(int argc, char **argv) {
struct rlimit rlp;
if (getrlimit(RLIMIT_NOFILE, &rlp) != 0) {
fprintf(stderr, "Unable to get per process rlimit: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
printf("This user could open %d file descriptors.\n", open_max());
printf("This process could open %d file descriptors.\n", (int)rlp.rlim_cur);
return EXIT_SUCCESS;
}
static int fdwalk(int (*func)(void *data, int fd), void *data){
int rv = 0;
int fd;
#ifdef PROC_SELF_FD_DIR
DIR *dir = opendir(PROC_SELF_FD_DIR);
if(dir){ /* procfs may not be mounted... */
struct dirent *ent;
int saved_errno;
int dir_fd = dirfd(dir);
while((ent = readdir(dir))){
char *err = NULL;
if(ent->d_name[0] == '.')
continue;
errno = 0;
fd = (int)strtol(ent->d_name, &err, 10);
if (errno || ! err || *err || fd == dir_fd)
continue;
if ((rv = func(data, fd)))
break;
}
saved_errno = errno;
closedir(dir);
errno = saved_errno;
} else
#endif /* PROC_SELF_FD_DIR */
{
int maxfd = open_max();
for(fd = 0; fd < maxfd; fd++){
/* use fcntl to detect whether fd is a valid file descriptor */
errno = 0;
if(fcntl(fd, F_GETFD) < 0)
continue;
errno = 0;
if ((rv = func(data, fd)))
break;
}
}
return rv;
}
/*
* call-seq:
* IO.closefrom(lowfd)
*
* Close all open file descriptors (associated with the current process) that
* are greater than or equal to +lowfd+.
*
* This method uses your system's builtin closefrom() function, if supported.
* Otherwise, it uses a manual, and (probably) less efficient approach.
*
*--
* The manual approach was copied from the closefrom() man page on Solaris 9.
*/
static VALUE io_closefrom(VALUE klass, VALUE v_low_fd){
#if defined(HAVE_CLOSEFROM) && !defined(HAVE_RB_RESERVED_FD_P)
/* we can't safely use closefrom() if the RubyVM reserves FDs */
closefrom(NUM2INT(v_low_fd));
#else
int i, lowfd;
int maxfd = open_max();
lowfd = NUM2INT(v_low_fd);
for(i = lowfd; i < maxfd; i++) {
if(!RB_RESERVED_FD_P(i))
close(i);
}
#endif
return klass;
}
FILE *
popen(const char *cmdstring, const char *type)
{
int i;
int pfd[2];
pid_t pid;
FILE *fp;
/* only allow "r" or "w" */
if ((type[0] != 'r' && type[0] != 'w') || type[1] != 0) {
errno = EINVAL;
return(NULL);
}
if (childpid == NULL) { /* first time throught */
/* allocate zeroed out array for child pids */
maxfd = open_max();
if ((childpid = calloc(maxfd, sizeof(pid_t))) == NULL)
return(NULL);
}
if (pipe(pfd) < 0)
return(NULL); /* errno set by pipe() */
if (pfd[0] >= maxfd || pfd[1] >= maxfd) {
close(pfd[0]);
close(pfd[1]);
errno = EMFILE;
return(NULL);
}
if ((pid = fork()) < 0) {
return(NULL); /* errno set by fork() */
} else if (pid == 0) { /* child */
if (*type == 'r') {
close(pfd[0]);
if (pfd[1] != STDOUT_FILENO) {
dup2(pfd[1], STDOUT_FILENO);
close(pfd[1]);
}
} else if (*type == 'w') {
close(pfd[1]);
if (pfd[0] != STDIN_FILENO) {
dup2(pfd[0], STDIN_FILENO);
close(pfd[0]);
}
}
/* close all descriptors in childpid[] */
for (i = 0; i < maxfd; i++)
if (childpid[i] > 0)
close(i);
execl("/bin/sh", "sh", "-c", cmdstring, (char*)0);
_exit(127);
}
/* parent continues... */
if (*type == 'r') {
close(pfd[1]);
if ((fp = fdopen(pfd[0], type)) == NULL)
return(NULL);
} else {
close(pfds[0]);
if ((fp = fdopen(pfd[1], type)) == NULL)
return(NULL);
}
childpid[fileno(fp)] = pid; /* remeber child pid for this fd */
return(fp);
}
int main()
{
int size = open_max();
printf("size: %d\n", size);
return 0;
}
int main()
{
long ans = open_max();
printf("%ld\n", ans);
return 0;
}
#include <poll.h> #include <limits.h> /* for open_max() */ #include <netdb.h> /* POSIX requires that an #include of <poll.h> DefinE INFTIM, but many systems still DefinE it in <sys/stropts.h>. We don't want to include all the STREAMS stuff if it's not needed, so we just DefinE INFTIM here. This is the standard value, but there's no guarantee it is -1. */ #define INFTIM (-1) /* infinite poll timeout */ #define HAVE_POLL #ifdef OPEN_MAX static long openmax = open_max(); #else static long openmax = 0; #endif /* * If open_max() is indeterminate, we're not * guaranteed that this is adequate. */ #define OPEN_MAX_GUESS 256 void err_sys(const char *fmt, ...); long open_max(void)
FILE *popen(const char *cmdstring, const char *type)
{
int i;
int pfd[2];
pid_t pid;
FILE *fp;
/* only allow "r" or "w" */
if ((type[0] != 'r' && type[0] != 'w') || type[1] != '\0') {
errno = EINVAL;
return (NULL);
}
if (childpid == NULL) {
maxfd = open_max();
if ((childpid = calloc(maxfd, sizeof(pid_t))) == NULL)
return (NULL);
}
if (pipe(pfd) < 0)
return (NULL);
if (pfd[0] >= maxfd || pfd[1] >= maxfd) {
close(pfd[0]);
close(pfd[1]);
errno = EMFILE;
return (NULL);
}
if ((pid = fork()) < 0) {
return (NULL);
} else if (pid == 0) {
if (*type == 'r') {
close(pfd[0]);
if (pfd[1] != STDOUT_FILENO) {
dup2(pfd[1], STDOUT_FILENO);
close(pfd[0]);
}
} else {
close(pfd[1]);
if (pfd[0] != STDOUT_FILENO) {
dup2(pfd[0], STDOUT_FILENO);
close(pfd[0]);
}
}
/* close all descriptors in childpid */
for (i = 0; i < maxfd; i++)
close(i);
execl("/bin/sh", "sh", "-c", cmdstring, (char *)0);
_exit(127); /* if it executes, that would be a error */
}
/* parent continue */
if (*type == 'r') {
close(pfd[1]);
if ((fp = fdopen(pfd[0], type)) == NULL)
return (NULL);
} else {
close(pfd[0]);
if ((fp = fdopen(pfd[1], type)) == NULL)
return (NULL);
}
childpid[fileno(fp)] = pid;
return (fp);
}
FILE *
spopen (const char *cmdstring)
{
char *env[2];
char *cmd = NULL;
char **argv = NULL;
char *str, *tmp;
int argc;
int i = 0, pfd[2], pfderr[2];
pid_t pid;
#ifdef RLIMIT_CORE
/* do not leave core files */
struct rlimit limit;
getrlimit (RLIMIT_CORE, &limit);
limit.rlim_cur = 0;
setrlimit (RLIMIT_CORE, &limit);
#endif
env[0] = strdup("LC_ALL=C");
env[1] = '\0';
/* if no command was passed, return with no error */
if (cmdstring == NULL)
return (NULL);
/* make copy of command string so strtok() doesn't silently modify it */
/* (the calling program may want to access it later) */
cmd = malloc (strlen (cmdstring) + 1);
if (cmd == NULL)
return NULL;
strcpy (cmd, cmdstring);
/* This is not a shell, so we don't handle "???" */
if (strstr (cmdstring, "\""))
return NULL;
/* allow single quotes, but only if non-whitesapce doesn't occur on both sides */
if (strstr (cmdstring, " ' ") || strstr (cmdstring, "'''"))
return NULL;
/* there cannot be more args than characters */
argc = strlen (cmdstring) + 1; /* add 1 for NULL termination */
argv = malloc (sizeof(char*)*argc);
if (argv == NULL) {
printf ("%s\n", _("Could not malloc argv array in popen()"));
return NULL;
}
/* loop to get arguments to command */
while (cmd) {
str = cmd;
str += strspn (str, " \t\r\n"); /* trim any leading whitespace */
if (i >= argc - 2) {
printf ("%s\n",_("CRITICAL - You need more args!!!"));
return (NULL);
}
if (strstr (str, "'") == str) { /* handle SIMPLE quoted strings */
str++;
if (!strstr (str, "'"))
return NULL; /* balanced? */
cmd = 1 + strstr (str, "'");
str[strcspn (str, "'")] = 0;
}
else if (strcspn(str,"'") < strcspn (str, " \t\r\n")) {
/* handle --option='foo bar' strings */
tmp = str + strcspn(str, "'") + 1;
if (!strstr (tmp, "'"))
return NULL; /* balanced? */
tmp += strcspn(tmp,"'") + 1;
*tmp = 0;
cmd = tmp + 1;
} else {
if (strpbrk (str, " \t\r\n")) {
cmd = 1 + strpbrk (str, " \t\r\n");
str[strcspn (str, " \t\r\n")] = 0;
}
else {
cmd = NULL;
}
}
if (cmd && strlen (cmd) == strspn (cmd, " \t\r\n"))
cmd = NULL;
argv[i++] = str;
}
argv[i] = NULL;
if (childpid == NULL) { /* first time through */
maxfd = open_max (); /* allocate zeroed out array for child pids */
if ((childpid = calloc ((size_t)maxfd, sizeof (pid_t))) == NULL)
return (NULL);
}
if (child_stderr_array == NULL) { /* first time through */
maxfd = open_max (); /* allocate zeroed out array for child pids */
if ((child_stderr_array = calloc ((size_t)maxfd, sizeof (int))) == NULL)
return (NULL);
}
if (pipe (pfd) < 0)
return (NULL); /* errno set by pipe() */
if (pipe (pfderr) < 0)
return (NULL); /* errno set by pipe() */
#ifdef REDHAT_SPOPEN_ERROR
if (signal (SIGCHLD, popen_sigchld_handler) == SIG_ERR) {
usage4 (_("Cannot catch SIGCHLD"));
}
#endif
if ((pid = fork ()) < 0)
return (NULL); /* errno set by fork() */
else if (pid == 0) { /* child */
close (pfd[0]);
if (pfd[1] != STDOUT_FILENO) {
dup2 (pfd[1], STDOUT_FILENO);
close (pfd[1]);
}
close (pfderr[0]);
if (pfderr[1] != STDERR_FILENO) {
dup2 (pfderr[1], STDERR_FILENO);
close (pfderr[1]);
}
/* close all descriptors in childpid[] */
for (i = 0; i < maxfd; i++)
if (childpid[i] > 0)
close (i);
execve (argv[0], argv, env);
_exit (0);
}
close (pfd[1]); /* parent */
if ((child_process = fdopen (pfd[0], "r")) == NULL)
return (NULL);
close (pfderr[1]);
childpid[fileno (child_process)] = pid; /* remember child pid for this fd */
child_stderr_array[fileno (child_process)] = pfderr[0]; /* remember STDERR */
return (child_process);
}
int main()
{
printf("openmax = %ld\n", open_max());
return 0;
}
FILE* mypopen(const char *cmdstring, const char *type){
int i;
int pfd[2];
pid_t pid;
FILE *fp;
/*only allow "r" or "w"*/
if((type[0] != 'r' && type[0] != 'w') || type[1] != 0){
errno = EINVAL;/*required by POSIX*/
return(NULL);
}
if(childpid == NULL){/*first time through*/
/*allocate zeroed out array for child pids*/
maxfd = open_max();
if((childpid = calloc(maxfd, sizeof(pid_t))) == NULL)
return(NULL);
}
if(pipe(pfd) < 0)
return(NULL);/*errno set by pipe()*/
if((pid = fork()) < 0){
return(NULL);/*errno set by fork()*/
}else if(pid == 0){/*child*/
if(*type == 'r'){
close(pfd[0]);/*close the read end.*/
if(pfd[1] != STDOUT_FILENO){
dup2(pfd[1], STDOUT_FILENO);
close(pfd[1]);
}
}else{
close(pfd[1]);/*close the read end.*/
if(pfd[0] != STDIN_FILENO){
dup2(pfd[0], STDIN_FILENO);
close(pfd[0]);
}
}
/*close all descriptors in childpid[]*/
for(i = 0; i < maxfd; i++){
if(childpid[i] > 0)
close(i);
}
execl("/bin/sh", "sh", "-c", cmdstring, (char *) 0);
_exit(127);/*when execl run normal, this will not run.*/
}
/*parent continues...*/
if(*type == 'r'){
close(pfd[1]);
/*change fd to FILE pointer.*/
if((fp = fdopen(pfd[0], type)) == NULL)
return NULL;
}else{
close(pfd[0]);
if((fp = fdopen(pfd[1], type)) == NULL)
return NULL;
}
childpid[fileno(fp)] = pid;/*remember child pid for this fd*/
return fp;
}
int main(int argc, char *argv[])
{
printf("max file descriptors number is %ld\n", open_max());
return 0;
}
int main( int argc, char *argv[] )
{
printf( "openmax = %ld\n", open_max() );
exit(0);
}
FILE *popen_l(const char *cmd, const char *type)
{
int i, pfd[2];
FILE *fp;
pid_t pid;
/* only allow "r" or "w" */
if ((type[0] != 'r' && type[0] != 'w') || type[1] != '\0') {
errno = EINVAL; /* required by POSIX */
return NULL;
}
if (childpid == NULL) { /* first time through */
/* allocate zeroed out array for child pids */
maxfd = open_max();
if ((childpid = calloc(maxfd, sizeof(childpid))) == NULL) {
return NULL;
}
}
if (pipe(pfd) < 0)
return NULL; /* errno set by pipe() */
if ((pid = fork()) < 0) {
return NULL; /* errno set by fork() */
}
else if (pid == 0) { /* child */
if (type[0] == 'r') {
close(pfd[0]);
if (pfd[1] != STDOUT_FILENO) {
dup2(pfd[1], STDOUT_FILENO);
close(pfd[1]);
}
}
else {
close(pfd[1]);
if (pfd[0] != STDIN_FILENO) {
dup2(pfd[0], STDIN_FILENO);
close(pfd[0]);
}
}
/* close all descriptors in childpid[].
* 书中提到, POSIX.1 requires that popen() close any streams that
* are still open in the child from previous call to popen(). To
* do this, we go through the childpid array in the child, closing
* any descriptors that are still open.
* POSIX.1标准中,对这个要求的原始描述是: The popen() function shall
* ensure that any streams from previous popen() calls that remain
* open in the parent process are closed in the new child process.
* 即,假设已经调用过一次popen(),父进程得到一个FILE *类型的fp指针,然
* 后父进程再调用popen()时,popen()创建的子进程也拥有一个fp指针,但是
* 子进程不需要该fp指针,所以子进程要关闭它.
*/
for (i = 0; i < maxfd; ++i)
if (childpid[i] > 0)
close(i);
/* sh 命令的 -c 选项表示: Read commands from the command_string
* operand nsteand of from the standard input.
*/
execl("/bin/sh", "sh", "-c", cmd, (char *)0);
_exit(127);
}
/* parent continues... */
if (type[0] == 'r') {
close(pfd[1]);
if ((fp = fdopen(pfd[0], type)) == NULL)
return NULL;
}
else {
close(pfd[0]);
if ((fp = fdopen(pfd[1], type)) == NULL)
return NULL;
}
childpid[fileno(fp)] = pid; /* remember child pid for this fd */
return fp;
}
int geekhttpd_daemon(void)
{
int fd0, fd1, fd2; /* stdin, stdout, stderr */
long openmax, i;
pid_t pid;
char cwd[256];
struct sigaction sa; /*信号处理 */
/*由于子进程继承了父进程的file mode creation mask，
* 所以子进程要创建文件时也会用这个mask值进行与之后的结
* 果来创建文件， 所以为了不影响文件的创建，把它清零 */
umask(0);
if ((pid = fork()) < 0){
printf("cann't fork!\n");
return -1;
}
else if( pid != 0) /* parent */
exit(0); /* 父进程退出*/
/* 把子进程变以一个session leader, process
* group leader, 并且没有控制终端 */
setsid();
/* 确保子进程没有分配终端*/
sa.sa_handler = SIG_IGN;
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0;
if (sigaction(SIGHUP, &sa, NULL) < 0) {
printf("sigaction error, SIGHUP");
return(-1);
}
/* TODO: 处理SIGTERM */
/* 把工作目录切换到服务器所在的工作目录， 防止目前工作目前可能被umount而受影响 */
if((access(g_geekhttpd_doc_path, F_OK|R_OK|X_OK)) == -1) {
perror("Cannot access GEEKHTTP_DOC_PATH");
return(-1);
}
if (chdir(g_geekhttpd_doc_path) < 0) {
printf("cannot change work directory to GEEKHTTP_DOC_PATH\n");
return(-1);
}
if (getcwd(cwd, 256) == NULL)
printf("getcwd error\n");
printf("[cwd]: %s\n", cwd);
/* Close all open file descriptors. */
openmax = open_max();
for (i = 0; i< openmax; i++)
close(i);
/* 把标准输入输出和出错文件描述符重定位到/dev/null */
fd0 = open("/dev/null", O_RDWR);
fd1 = dup(0);
fd2 = dup(0);
/* 到目前为止就不能使用printf来输出信息了，
* 只有通过syslog
*/
openlog("geekhttpd", LOG_CONS, LOG_DAEMON);
if (fd0 != 0 || fd1 != 1 || fd2 != 2) {
syslog(LOG_ERR, "unexpected file descriptors %d %d %d", \
fd0, fd1, fd2);
return(-1);
}
}
