#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "ourhdr.h"
#include <errno.h> /* for definition of errno */
#include <stdarg.h> /* ANSI C header file */
#include "ourhdr.h"
#include <signal.h>
#include <sys/types.h> /* required for some of our prototypes */
#include <stdio.h> /* for convenience */
#include <stdlib.h> /* for convenience */
#include <string.h> /* for convenience */
#include <unistd.h> /* for convenience */
static void err_doit(int, const char *, va_list);
#define MAXLINE 4096 /* max line length */
#define FILE_MODE (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)
/* default file access permissions for new files */
#define DIR_MODE (FILE_MODE | S_IXUSR | S_IXGRP | S_IXOTH)
/* default permissions for new directories */
//typedef void Sigfunc(int); /* for signal handlers */
/* 4.3BSD Reno doesn't define SIG_ERR */
#if defined(SIG_IGN) && !defined(SIG_ERR)
#define SIG_ERR ((Sigfunc *)-1)
#endif
#define min(a,b) ((a) < (b) ? (a) : (b))
#define max(a,b) ((a) > (b) ? (a) : (b))
/* prototypes for our own functions */
char *path_alloc(int *); /* {Prog pathalloc} */
int open_max(void); /* {Prog openmax} */
void clr_fl(int, int); /* {Prog setfl} */
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} */
int tty_cbreak(int); /* {Prog raw} */
int tty_raw(int); /* {Prog raw} */
int tty_reset(int); /* {Prog raw} */
void tty_atexit(void); /* {Prog raw} */
#ifdef ECHO /* only if has been included */
struct termios *tty_termios(void); /* {Prog raw} */
#endif
void sleep_us(unsigned int); /* {Ex sleepus} */
ssize_t readn(int, void *, size_t);/* {Prog readn} */
ssize_t writen(int, const void *, size_t);/* {Prog writen} */
int daemon_init(void); /* {Prog daemoninit} */
int s_pipe(int *); /* {Progs svr4_spipe bsd_spipe} */
int recv_fd(int, ssize_t (*func)(int, const void *, size_t));
/* {Progs recvfd_svr4 recvfd_43bsd} */
int send_fd(int, int); /* {Progs sendfd_svr4 sendfd_43bsd} */
int send_err(int, int, const char *);/* {Prog senderr} */
int serv_listen(const char *); /* {Progs servlisten_svr4 servlisten_44bsd} */
int serv_accept(int, uid_t *); /* {Progs servaccept_svr4 servaccept_44bsd} */
int cli_conn(const char *); /* {Progs cliconn_svr4 cliconn_44bsd} */
int buf_args(char *, int (*func)(int, char **));
/* {Prog bufargs} */
int ptym_open(char *); /* {Progs ptyopen_svr4 ptyopen_44bsd} */
int ptys_open(int, char *); /* {Progs ptyopen_svr4 ptyopen_44bsd} */
#ifdef TIOCGWINSZ
pid_t pty_fork(int *, char *, 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_readlock(fd, offset, whence, len) \
lock_test(fd, F_RDLCK, offset, whence, len)
#define is_writelock(fd, offset, whence, len) \
lock_test(fd, F_WRLCK, offset, whence, len)
void err_dump(const char *, ...); /* {App misc_source} */
void err_msg(const char *, ...);
void err_quit(const char *, ...);
void err_ret(const char *, ...);
void err_sys(const char *, ...);
void log_msg(const char *, ...); /* {App misc_source} */
void log_open(const char *, int, int);
void log_quit(const char *, ...);
void log_ret(const char *, ...);
void log_sys(const char *, ...);
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);
char *pname = NULL; /* caller can set this from argv[0] */
/* 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, fmt, ap);
va_end(ap);
return;
}
/* 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, 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, 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, fmt, ap);
va_end(ap);
return;
}
/* 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, fmt, ap);
va_end(ap);
exit(1);
}
/* Print a message and return to caller.
* Caller specifies "errnoflag". */
static void
err_doit(int errnoflag, const char *fmt, va_list ap)
{
int errno_save;
char buf[MAXLINE];
errno_save = errno; /* value caller might want printed */
vsprintf(buf, fmt, ap);
if (errnoflag)
sprintf(buf+strlen(buf), ": %s", strerror(errno_save));
strcat(buf, "\n");
fflush(stdout); /* in case stdout and stderr are the same */
fputs(buf, stderr);
fflush(NULL); /* flushes all stdio output streams */
return;
}
static volatile sig_atomic_t sigflag;
/* set nonzero by signal handler */
static sigset_t newmask, oldmask, zeromask;
static void
sig_usr(int signo) /* one signal handler for SIGUSR1 and SIGUSR2 */
{
sigflag = 1;
return;
}
void
TELL_WAIT()
{
if (signal(SIGUSR1, sig_usr) == SIG_ERR)
err_sys("signal(SIGINT) error");
if (signal(SIGUSR2, sig_usr) == SIG_ERR)
err_sys("signal(SIGQUIT) error");
sigemptyset(&zeromask);
sigemptyset(&newmask);
sigaddset(&newmask, SIGUSR1);
sigaddset(&newmask, SIGUSR2);
/* block SIGUSR1 and SIGUSR2, and save current signal mask */
if (sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0)
err_sys("SIG_BLOCK error");
}
void
TELL_PARENT(pid_t pid)
{
kill(pid, SIGUSR2); /* tell parent we're done */
}
void
WAIT_PARENT(void)
{
while (sigflag == 0)
sigsuspend(&zeromask); /* and wait for parent */
sigflag = 0;
/* reset signal mask to original value */
if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)
err_sys("SIG_SETMASK error");
}
void
TELL_CHILD(pid_t pid)
{
kill(pid, SIGUSR1); /* tell child we're done */
}
void
WAIT_CHILD(void)
{
while (sigflag == 0)
sigsuspend(&zeromask); /* and wait for child */
sigflag = 0;
/* reset signal mask to original value */
if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)
err_sys("SIG_SETMASK error");
}
static void lockabyte(const char *, int, off_t);
int
main(void)
{
int fd;
pid_t pid;
/* Create a file and write two bytes to it */
if ( (fd = creat("templock", FILE_MODE)) < 0)
err_sys("creat error");
if (write(fd, "ab", 2) != 2)
err_sys("write error");
TELL_WAIT();
if ( (pid = fork()) < 0)
err_sys("fork error");
else if (pid == 0) { /* child */
lockabyte("child", fd, 0);
TELL_PARENT(getppid());
WAIT_PARENT();
lockabyte("child", fd, 1);
} else { /* parent */
lockabyte("parent", fd, 1);
TELL_CHILD(pid);
WAIT_CHILD();
lockabyte("parent", fd, 0);
}
exit(0);
}
int
lock_reg(int fd, int cmd, int type, off_t offset, int whence, off_t len)
{
struct flock lock;
lock.l_type = type; /* F_RDLCK, F_WRLCK, F_UNLCK */
lock.l_start = offset; /* byte offset, relative to l_whence */
lock.l_whence = whence; /* SEEK_SET, SEEK_CUR, SEEK_END */
lock.l_len = len; /* #bytes (0 means to EOF) */
return( fcntl(fd, cmd, &lock) );
}
static void
lockabyte(const char *name, int fd, off_t offset)
{
if (writew_lock(fd, offset, SEEK_SET, 1) < 0)
err_sys("%s: writew_lock error", name);
printf("%s: got the lock, byte %d\n", name, offset);
}
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