COMS 4995 Advanced Systems Programming

Index of 2024-9/code/10

Parent directory
Makefile
apue.h
clrfl.c
error.c
logger.c
nonblockw.c
setfl.c

Makefile

CC = gcc
CFLAGS  = -g -Wall

executables = nonblockw logger
util_objs   = clrfl.o setfl.o error.o

.PHONY: default
default: $(executables)

nonblockw: nonblockw.o $(util_objs)

logger: logger.o

nonblockw.o $(util_objs): apue.h

.PHONY: clean
clean:
	rm -f *~ *.out *.o $(executables)

.PHONY: all
all: clean default

apue.h

/*
 * Our own header, to be included before all standard system headers.
 */
#ifndef	_APUE_H
#define	_APUE_H

#define _POSIX_C_SOURCE 200809L

#if defined(SOLARIS)		/* Solaris 10 */
#define _XOPEN_SOURCE 600
#else
#define _XOPEN_SOURCE 700
#endif

#include <sys/types.h>		/* some systems still require this */
#include <sys/stat.h>
#include <sys/termios.h>	/* for winsize */
#if defined(MACOS) || !defined(TIOCGWINSZ)
#include <sys/ioctl.h>
#endif

#include <stdio.h>		/* for convenience */
#include <stdlib.h>		/* for convenience */
#include <stddef.h>		/* for offsetof */
#include <string.h>		/* for convenience */
#include <unistd.h>		/* for convenience */
#include <signal.h>		/* for SIG_ERR */

#define	MAXLINE	4096			/* max line length */

/*
 * Default file access permissions for new files.
 */
#define	FILE_MODE	(S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)

/*
 * Default permissions for new directories.
 */
#define	DIR_MODE	(FILE_MODE | S_IXUSR | S_IXGRP | S_IXOTH)

typedef	void	Sigfunc(int);	/* for signal handlers */

#define	min(a,b)	((a) < (b) ? (a) : (b))
#define	max(a,b)	((a) > (b) ? (a) : (b))

/*
 * Prototypes for our own functions.
 */
char	*path_alloc(size_t *);				/* {Prog pathalloc} */
long	 open_max(void);					/* {Prog openmax} */

int		 set_cloexec(int);					/* {Prog setfd} */
void	 clr_fl(int, int);
void	 set_fl(int, int);					/* {Prog setfl} */

void	 pr_exit(int);						/* {Prog prexit} */

void	 pr_mask(const char *);				/* {Prog prmask} */
Sigfunc	*signal_intr(int, Sigfunc *);		/* {Prog signal_intr_function} */

void	 daemonize(const char *);			/* {Prog daemoninit} */

void	 sleep_us(unsigned int);			/* {Ex sleepus} */
ssize_t	 readn(int, void *, size_t);		/* {Prog readn_writen} */
ssize_t	 writen(int, const void *, size_t);	/* {Prog readn_writen} */

int		 fd_pipe(int *);					/* {Prog sock_fdpipe} */
int		 recv_fd(int, ssize_t (*func)(int,
		         const void *, size_t));	/* {Prog recvfd_sockets} */
int		 send_fd(int, int);					/* {Prog sendfd_sockets} */
int		 send_err(int, int,
		          const char *);			/* {Prog senderr} */
int		 serv_listen(const char *);			/* {Prog servlisten_sockets} */
int		 serv_accept(int, uid_t *);			/* {Prog servaccept_sockets} */
int		 cli_conn(const char *);			/* {Prog cliconn_sockets} */
int		 buf_args(char *, int (*func)(int,
		          char **));				/* {Prog bufargs} */

int		 tty_cbreak(int);					/* {Prog raw} */
int		 tty_raw(int);						/* {Prog raw} */
int		 tty_reset(int);					/* {Prog raw} */
void	 tty_atexit(void);					/* {Prog raw} */
struct termios	*tty_termios(void);			/* {Prog raw} */

int		 ptym_open(char *, int);			/* {Prog ptyopen} */
int		 ptys_open(char *);					/* {Prog ptyopen} */
#ifdef	TIOCGWINSZ
pid_t	 pty_fork(int *, char *, int, const struct termios *,
		          const struct winsize *);	/* {Prog ptyfork} */
#endif

int		lock_reg(int, int, int, off_t, int, off_t); /* {Prog lockreg} */

#define	read_lock(fd, offset, whence, len) \
			lock_reg((fd), F_SETLK, F_RDLCK, (offset), (whence), (len))
#define	readw_lock(fd, offset, whence, len) \
			lock_reg((fd), F_SETLKW, F_RDLCK, (offset), (whence), (len))
#define	write_lock(fd, offset, whence, len) \
			lock_reg((fd), F_SETLK, F_WRLCK, (offset), (whence), (len))
#define	writew_lock(fd, offset, whence, len) \
			lock_reg((fd), F_SETLKW, F_WRLCK, (offset), (whence), (len))
#define	un_lock(fd, offset, whence, len) \
			lock_reg((fd), F_SETLK, F_UNLCK, (offset), (whence), (len))

pid_t	lock_test(int, int, off_t, int, off_t);		/* {Prog locktest} */

#define	is_read_lockable(fd, offset, whence, len) \
			(lock_test((fd), F_RDLCK, (offset), (whence), (len)) == 0)
#define	is_write_lockable(fd, offset, whence, len) \
			(lock_test((fd), F_WRLCK, (offset), (whence), (len)) == 0)

void	err_msg(const char *, ...);			/* {App misc_source} */
void	err_dump(const char *, ...) __attribute__((noreturn));
void	err_quit(const char *, ...) __attribute__((noreturn));
void	err_cont(int, const char *, ...);
void	err_exit(int, const char *, ...) __attribute__((noreturn));
void	err_ret(const char *, ...);
void	err_sys(const char *, ...) __attribute__((noreturn));

void	log_msg(const char *, ...);			/* {App misc_source} */
void	log_open(const char *, int, int);
void	log_quit(const char *, ...) __attribute__((noreturn));
void	log_ret(const char *, ...);
void	log_sys(const char *, ...) __attribute__((noreturn));
void	log_exit(int, const char *, ...) __attribute__((noreturn));

void	TELL_WAIT(void);		/* parent/child from {Sec race_conditions} */
void	TELL_PARENT(pid_t);
void	TELL_CHILD(pid_t);
void	WAIT_PARENT(void);
void	WAIT_CHILD(void);

#endif	/* _APUE_H */

clrfl.c

#include "apue.h"
#include <fcntl.h>

void
clr_fl(int fd, int flags)
				/* flags are the file status flags to turn off */
{
	int		val;

	if ((val = fcntl(fd, F_GETFL, 0)) < 0)
		err_sys("fcntl F_GETFL error");

	val &= ~flags;		/* turn flags off */

	if (fcntl(fd, F_SETFL, val) < 0)
		err_sys("fcntl F_SETFL error");
}

error.c

#include "apue.h"
#include <errno.h>		/* for definition of errno */
#include <stdarg.h>		/* ISO C variable aruments */

static void	err_doit(int, int, const char *, va_list);

/*
 * Nonfatal error related to a system call.
 * Print a message and return.
 */
void
err_ret(const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, errno, fmt, ap);
	va_end(ap);
}

/*
 * Fatal error related to a system call.
 * Print a message and terminate.
 */
void
err_sys(const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, errno, fmt, ap);
	va_end(ap);
	exit(1);
}

/*
 * Nonfatal error unrelated to a system call.
 * Error code passed as explict parameter.
 * Print a message and return.
 */
void
err_cont(int error, const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, error, fmt, ap);
	va_end(ap);
}

/*
 * Fatal error unrelated to a system call.
 * Error code passed as explict parameter.
 * Print a message and terminate.
 */
void
err_exit(int error, const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, error, fmt, ap);
	va_end(ap);
	exit(1);
}

/*
 * Fatal error related to a system call.
 * Print a message, dump core, and terminate.
 */
void
err_dump(const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, errno, fmt, ap);
	va_end(ap);
	abort();		/* dump core and terminate */
	exit(1);		/* shouldn't get here */
}

/*
 * Nonfatal error unrelated to a system call.
 * Print a message and return.
 */
void
err_msg(const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(0, 0, fmt, ap);
	va_end(ap);
}

/*
 * Fatal error unrelated to a system call.
 * Print a message and terminate.
 */
void
err_quit(const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(0, 0, fmt, ap);
	va_end(ap);
	exit(1);
}

/*
 * Print a message and return to caller.
 * Caller specifies "errnoflag".
 */
static void
err_doit(int errnoflag, int error, const char *fmt, va_list ap)
{
	char	buf[MAXLINE];

	vsnprintf(buf, MAXLINE-1, fmt, ap);
	if (errnoflag)
		snprintf(buf+strlen(buf), MAXLINE-strlen(buf)-1, ": %s",
		  strerror(error));
	strcat(buf, "\n");
	fflush(stdout);		/* in case stdout and stderr are the same */
	fputs(buf, stderr);
	fflush(NULL);		/* flushes all stdio output streams */
}

logger.c

#include <stdio.h>
#include <errno.h>
#include <netdb.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

static void die(const char *s) { perror(s); exit(1); }

int init_server_socket(unsigned short port)
{
    int servsock;
    if ((servsock = socket(AF_INET, SOCK_STREAM, 0)) < 0)
        die("socket() failed");

    struct sockaddr_in servaddr;
    memset(&servaddr, 0, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(port);
    if (bind(servsock, (struct sockaddr *) &servaddr, sizeof(servaddr)) < 0)
        die("bind() failed");

    if (listen(servsock, 5) < 0)
        die("listen() failed");

    return servsock;
}

static void sig_handler(int sig) {}

int main(int argc, char **argv)
{
    int i;
    int sock;
    char buf[100];
    socklen_t size;
    struct sockaddr_in client_name;
    fd_set active_fd_set, read_fd_set;

    if (argc != 2) {
        fprintf(stderr, "%s <port>\n", argv[0]);
        exit(1);
    }
    sock = init_server_socket(atoi(argv[1]));

    // catch SIGINT
    struct sigaction act, oact;
    act.sa_handler = sig_handler;
    sigemptyset(&act.sa_mask);
    act.sa_flags = 0;
    act.sa_flags |= SA_RESTART;
    if (sigaction(SIGINT, &act, &oact) < 0)
        die("sigaction failed");

    FD_ZERO(&active_fd_set);
    FD_SET(sock, &active_fd_set);
    FD_SET(STDIN_FILENO, &active_fd_set);

    while (1) {
        read_fd_set = active_fd_set;

        if (select(FD_SETSIZE, &read_fd_set, NULL, NULL, NULL) < 0) {
            if (errno == EINTR) {
                fprintf(stderr, "%s\n", "select interrupted");
                continue;
            }
            die("select failed");
        }

        for (i = 0; i < FD_SETSIZE; ++i) {
            if (FD_ISSET(i, &read_fd_set)) {
                if (i == sock) {
                    size = sizeof(client_name);
                    int new = accept(sock,
                                     (struct sockaddr *) &client_name, &size);
                    if (new < 0) {
                        die("accept failed");
                    } else {
                        fprintf(stderr, "new connection from %s (fd:%d)\n",
                                inet_ntoa(client_name.sin_addr), new);
                        FD_SET(new, &active_fd_set);
                    }
                }
                else if (i == STDIN_FILENO) {
                    buf[0] = '\0';
                    read(i, buf, sizeof(buf));
                    if (strncmp(buf, "quit\n", 5) == 0) {
                        exit(0);
                    } else {
                        fprintf(stderr, "unknown command\n");
                    }
                }
                else{
                    int r = read(i, buf, sizeof(buf));
                    if (r < 0) {
                        die("read failed");
                    } else if (r == 0) {
                        fprintf(stderr, "connection closed (fd:%d)\n", i);
                        close(i);
                        FD_CLR(i, &active_fd_set);
                    } else {
                        write(STDOUT_FILENO, buf, r);
                    }
                }
            }
        }
    }
}

nonblockw.c

#include "apue.h"
#include <errno.h>
#include <fcntl.h>

char	buf[500000];

int
main(void)
{
	int		ntowrite, nwrite;
	char	*ptr;

	ntowrite = read(STDIN_FILENO, buf, sizeof(buf));
	fprintf(stderr, "read %d bytes\n", ntowrite);

	set_fl(STDOUT_FILENO, O_NONBLOCK);	/* set nonblocking */

	ptr = buf;
	while (ntowrite > 0) {
		errno = 0;
		nwrite = write(STDOUT_FILENO, ptr, ntowrite);
		fprintf(stderr, "nwrite = %d, errno = %d\n", nwrite, errno);

		if (nwrite > 0) {
			ptr += nwrite;
			ntowrite -= nwrite;
		}
	}

	clr_fl(STDOUT_FILENO, O_NONBLOCK);	/* clear nonblocking */

	exit(0);
}

setfl.c

#include "apue.h"
#include <fcntl.h>

void
set_fl(int fd, int flags) /* flags are file status flags to turn on */
{
	int		val;

	if ((val = fcntl(fd, F_GETFL, 0)) < 0)
		err_sys("fcntl F_GETFL error");

	val |= flags;		/* turn on flags */

	if (fcntl(fd, F_SETFL, val) < 0)
		err_sys("fcntl F_SETFL error");
}