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, " "); 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, " "); 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 ", 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