本章内容主要是为了学习UNIX的基本知识和一些最基本的系统函数。
学习的关键就是跟随者书本敲代码。本节遇到的第一个问题就死本书的apue.h这个文件：一开始没有注意这个文件，盲目的去百度，一番百度之后发现，其实这个文件的源码就在书的附录里面。这个给我一个教训，学习还是静下心来学习，没有一颗安定的心无法学习好，这是个教训啊，以后再也不能犯了。
关于apue.h这个文件的源码先贴在本章中便于复制
/* Our own header, to be included before all standard system headers */
#ifndef _APUE_H
#define _APUE_H
#if defined(SOLARIS)
#define _XOPEN_SOURCE 500 /* Single UNIX Specification, Version 2 for Solaris 9 */
#define CMSG_LEN(x) _CMSG_DATA_ALIGN(sizeof(struct cmsghdr)+(x))
#elif !defined(BSD)
#define _XOPEN_SOURCE 600 /* Single UNIX Specification, Version 3 */
#endif
#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 offsetof */
#include <string.h> /* for convenience */
#include <unistd.h> /* for convenience */
#include <signal.h> /* for SIG_ERR */
#include <errno.h>
#include <stdarg.h>
#include <syslog.h>
#include <error.h>
#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 *); /* {Prog pathalloc} */
long 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 <termios.h> 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_writen} */
ssize_t writen(int, const void *, size_t); /* {Prog readn_writen} */
void daemonize(const char *); /* {Prog daemoninit} */
int s_pipe(int *); /* {Progs streams_spipe sock_spipe} */
int recv_fd(int, ssize_t (*func)(int,
const void *, size_t));/* {Progs recvfd_streams recvfd_sockets} */
int send_fd(int, int); /* {Progs sendfd_streams sendfd_sockets} */
int send_err(int, int,
const char *); /* {Prog senderr} */
int serv_listen(const char *); /* {Progs servlisten_streams servlisten_sockets} */
int serv_accept(int, uid_t *); /* {Progs servaccept_streams servaccept_sockets} */
int cli_conn(const char *); /* {Progs cliconn_streams cliconn_sockets} */
int buf_args(char *, int (*func)(int,
char **)); /* {Prog bufargs} */
int ptym_open(char *, int); /* {Progs3 ptyopen_streams ptyopen_bsd ptyopen_linux} */
int ptys_open(char *); /* {Progs3 ptyopen_streams ptyopen_bsd ptyopen_linux} */
#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_dump(const char *, ...); /* {App misc_source} */
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 *, ...); /* {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);
#endif /* _APUE_H */
还有error.c文件的源码也贴出来
#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 */ }
最后就是关于代码的编译，直接gcc -o LS.C error.c，目前不会写makefile文件，也就这样将就下，正打算把这些都拿下。