unix环境高级编程附录 B 通用代码

0、说明：
在测试 unix 环境高级编程中的代码时，需要一些作者事先写好的代码，
如: apue.h 包含某些标准系统头文件，定义许多常量及函数原型
还有两个作者自编的函数来对错误进行处理
1、epue.h 源码

/*
* =====================================================================================
*
*       Filename:  apue.h
*
*    Description:
*
*        Version:  1.0
*        Created:  05/27/2016 03:21:09 PM
*       Revision:  none
*       Compiler:  gcc
*
*         Author:  YOUR NAME (),
*   Organization:
*
* =====================================================================================
*/
/* our own header, to be included before all standard system headers */
#ifndef _APUE_H
#define _APUE_H

#define _XOPEN_SOURCE 600 /* Single UNIX Specification Version 3 */

#include <sys/types.h>  /* some systems still require this */
#include <sys/stat.h>
#include <sys/termios.h> /* for winsize */
#ifndef TIOCGWINSZ
#include <sys/ioctl.h>
#endif
#include <stdio.h>  /* for convenience */
#include <stdlib.h> /* for convenience */
#include <stddef.h> /* for convenience */
#include <string.h> /* for convenience */
#include <unistd.h> /* for convenience */
#include <signal.h> /* for convenience */
#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 */
#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 *);
long open_max(void);
void clr_fl(int, int);
void set_fl(int, int);
void pr_exit(int);
void pr_mask(const char *);
Sigfunc *signal_intr (int, Sigfunc *);

int tty_cbreak(int);
int tty_raw(int);
int tty_reset(int);
void tty_atexit(void);
#ifdef ECHO /* only if <termios.h> has been included */
struct termios *tty_termios(void);
#endif

void sleep_us(unsigned int);
ssize_t readn(int, void *, size_t);
ssize_t writen(int, const void *, size_t);
void daemonize(const char *);

int s_pipe(int *);
int recv_fd(int, ssize_t (*func)(int, const void *, size_t));
int send_fd(int, int);
int send_err(int, int, const char *);
int serv_listen(const char *);
int serv_accept(int, uid_t *);
int cli_conn(const char *);
int buf_args(char *, int (*func)(int, char **));
int ptym_open(char *, int);
int ptys_open(char *);
#ifdef TIOCGWINSZ
pid_t pty_fork(int *, char *, int, const struct termios *, const struct winsize *);
#endif

int lock_reg(int, int, int, off_t, int, off_t);
#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);

#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_dump(const char *, ...);
void err_msg(const char *, ...);
void err_quit(const char *, ...);
void err_exit(int, const char *, ...);
void err_ret(const char *, ...);
void err_sys(const char *, ...);

void log_msg(const char *, ...);
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);
void TELL_PARENT(pid_t);
void TELL_CHILD(pid_t);
void WAIT_PARENT(void);
void WAIT_CHILD(void);

#endif /* _APUE_H */

2、err.c 源码

/*
* =====================================================================================
*
*       Filename:  err.c
*
*    Description:
*
*        Version:  1.0
*        Created:  05/27/2016 04:06:55 PM
*       Revision:  none
*       Compiler:  gcc
*
*         Author:  YOUR NAME (),
*   Organization:
*
* =====================================================================================
*/

#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);
}

/*
* 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, fmt, ap);
if (errnoflag)
{
snprintf(buf+strlen(buf), MAXLINE-strlen(buf), ": %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  */
}

3、log.c 源码
下面程序给出了各 log_xxx 出错处理函数，若进程不以守护进程方式运行，那么这些函数要求调用者定义变量 log_to_stderr, 并将其设置为非0值。在这种情况下出错消息被送至标准出错文件。若log_to_stderr 标志位0，则使用 syslog 设置

/*
* =====================================================================================
*
*       Filename:  log.c
*
*    Description:
*
*        Version:  1.0
*        Created:  05/27/2016 04:30:15 PM
*       Revision:  none
*       Compiler:  gcc
*
*         Author:  YOUR NAME (),
*   Organization:
*
* =====================================================================================
*/

/*
* Error routines for programs that can run as a daemon
* */
#include "apue.h"
#include <errno.h>
#include <stdarg.h>
#include <syslog.h>

static void log_doit(int, int, const char *, va_list ap);

/*
* Caller must define and set this: nonzero if
* interactive, zero if daemon
* */
extern int log_to_stderr;

/*
* Initialize syslog(), if running as daemon.
* */
void log_open(const char *ident, int option, int facility)
{
if (log_to_stderr == 0)
{
openlog(ident, option, facility);
}
}

/*
* Nonfatal error related to a system call.
* Print a message with the system`s errno value and return.
* */
void log_ret(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
log_doit(1, LOG_ERR, fmt, ap);
va_end(ap);
}

/*
* Fatal error related to a system call.
* Print a message and terminate.
*
* */
void log_sys(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
log_doit(1, LOG_ERR, fmt, ap);
va_end(ap);
exit(2);

}

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

va_start(ap, fmt);
log_doit(0, LOG_ERR, fmt, ap);
va_end(ap);
}

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

va_start(ap, fmt);
log_doit(0, LOG_ERR, fmt, ap);
va_end(ap);
exit(2);
}

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

errno_save = errno; /* value caller might want printed  */
vsnprintf(buf, MAXLINE, fmt, ap);
if (errnoflag)
{
snprintf (buf+strlen(buf), MAXLINE-strlen(buf), ": %s", strerror(errno_save));
strcat(buf, "\n");
if (log_to_stderr)
{
fflush(stdout);
fputs(buf, stderr);
fflush(stderr);
}else{
syslog(priority, buf);
}
}
}

4、测试源码
下面是一个测试管道的源码

/*
* =====================================================================================
*
*       Filename:  main.c
*
*    Description:
*
*        Version:  1.0
*        Created:  05/27/2016 06:04:12 PM
*       Revision:  none
*       Compiler:  gcc
*
*         Author:  YOUR NAME (),
*   Organization:
*
* =====================================================================================
*/
#include "apue.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

int log_to_stderr = 0;
int main()
{
int n;
int fd[2];
pid_t pid;
char line[MAXLINE];

if (pipe(fd) < 0)
{
err_sys ("pipe error");
}
if ((pid = fork()) < 0)
{
err_sys ("fork error");
} else if (pid > 0) {
close (fd[0]);
write (fd[1], "hello world\n", 12);
} else {
close (fd[1]);
n = read (fd[0], line, MAXLINE);
write (STDOUT_FILENO, line, n);
}

exit(0);
}

编译：

gcc *.c

./a.out

打印出 hell world