我无法让csapp.c工作。即使定义了它，我仍然会收到“未定义的引用错误”。例如，如果我想在名为main.c的程序中使用它 - 我会按照建议Here运行该程序，但它似乎仍然无法解决我的问题：
gcc -c csapp.c
gcc -c main.c
gcc -o test csapp.o main.o
我会得到：
/tmp/cc2ejuRL.o: In function `Pthread_create':
csapp.c:(.text+0x1044): undefined reference to `pthread_create'
/tmp/cc2ejuRL.o: In function `Pthread_cancel':
csapp.c:(.text+0x1076): undefined reference to `pthread_cancel'
/tmp/cc2ejuRL.o: In function `Pthread_join':
csapp.c:(.text+0x10b3): undefined reference to `pthread_join'
/tmp/cc2ejuRL.o: In function `Pthread_detach':
csapp.c:(.text+0x10e5): undefined reference to `pthread_detach'
/tmp/cc2ejuRL.o: In function `Pthread_once':
csapp.c:(.text+0x1145): undefined reference to `pthread_once'
/tmp/cc2ejuRL.o: In function `Sem_init':
csapp.c:(.text+0x116d): undefined reference to `sem_init'
/tmp/cc2ejuRL.o: In function `P':
csapp.c:(.text+0x1195): undefined reference to `sem_wait'
/tmp/cc2ejuRL.o: In function `V':
csapp.c:(.text+0x11bd): undefined reference to `sem_post'
collect2: error: ld returned 1 exit status
我也尝试过从其他线程推荐的方法但没有成功 Link2 Link3
csapp.h
/* $begin csapp.h */
#ifndef __CSAPP_H__
#define __CSAPP_H__
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <setjmp.h>
#include <signal.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <errno.h>
#include <math.h>
#include <pthread.h>
#include <semaphore.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
/* Default file permissions are DEF_MODE & ~DEF_UMASK */
/* $begin createmasks */
#define DEF_MODE S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH
#define DEF_UMASK S_IWGRP|S_IWOTH
/* $end createmasks */
/* Simplifies calls to bind(), connect(), and accept() */
/* $begin sockaddrdef */
typedef struct sockaddr SA;
/* $end sockaddrdef */
/* Persistent state for the robust I/O (Rio) package */
/* $begin rio_t */
#define RIO_BUFSIZE 8192
typedef struct {
int rio_fd; /* descriptor for this internal buf */
int rio_cnt; /* unread bytes in internal buf */
char *rio_bufptr; /* next unread byte in internal buf */
char rio_buf[RIO_BUFSIZE]; /* internal buffer */
} rio_t;
/* $end rio_t */
/* External variables */
extern int h_errno; /* defined by BIND for DNS errors */
extern char **environ; /* defined by libc */
/* Misc constants */
#define MAXLINE 8192 /* max text line length */
#define MAXBUF 8192 /* max I/O buffer size */
#define LISTENQ 1024 /* second argument to listen() */
/* Our own error-handling functions */
void unix_error(char *msg);
void posix_error(int code, char *msg);
void dns_error(char *msg);
void app_error(char *msg);
/* Process control wrappers */
pid_t Fork(void);
void Execve(const char *filename, char *const argv[], char *const envp[]);
pid_t Wait(int *status);
pid_t Waitpid(pid_t pid, int *iptr, int options);
void Kill(pid_t pid, int signum);
unsigned int Sleep(unsigned int secs);
void Pause(void);
unsigned int Alarm(unsigned int seconds);
void Setpgid(pid_t pid, pid_t pgid);
pid_t Getpgrp();
/* Signal wrappers */
typedef void handler_t(int);
handler_t *Signal(int signum, handler_t *handler);
void Sigprocmask(int how, const sigset_t *set, sigset_t *oldset);
void Sigemptyset(sigset_t *set);
void Sigfillset(sigset_t *set);
void Sigaddset(sigset_t *set, int signum);
void Sigdelset(sigset_t *set, int signum);
int Sigismember(const sigset_t *set, int signum);
/* Unix I/O wrappers */
int Open(const char *pathname, int flags, mode_t mode);
ssize_t Read(int fd, void *buf, size_t count);
ssize_t Write(int fd, const void *buf, size_t count);
off_t Lseek(int fildes, off_t offset, int whence);
void Close(int fd);
int Select(int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
struct timeval *timeout);
int Dup2(int fd1, int fd2);
void Stat(const char *filename, struct stat *buf);
void Fstat(int fd, struct stat *buf) ;
/* Memory mapping wrappers */
void *Mmap(void *addr, size_t len, int prot, int flags, int fd, off_t offset);
void Munmap(void *start, size_t length);
/* Standard I/O wrappers */
void Fclose(FILE *fp);
FILE *Fdopen(int fd, const char *type);
char *Fgets(char *ptr, int n, FILE *stream);
FILE *Fopen(const char *filename, const char *mode);
void Fputs(const char *ptr, FILE *stream);
size_t Fread(void *ptr, size_t size, size_t nmemb, FILE *stream);
void Fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream);
/* Dynamic storage allocation wrappers */
void *Malloc(size_t size);
void *Realloc(void *ptr, size_t size);
void *Calloc(size_t nmemb, size_t size);
void Free(void *ptr);
/* Sockets interface wrappers */
int Socket(int domain, int type, int protocol);
void Setsockopt(int s, int level, int optname, const void *optval, int optlen);
void Bind(int sockfd, struct sockaddr *my_addr, int addrlen);
void Listen(int s, int backlog);
int Accept(int s, struct sockaddr *addr, socklen_t *addrlen);
void Connect(int sockfd, struct sockaddr *serv_addr, int addrlen);
/* DNS wrappers */
struct hostent *Gethostbyname(const char *name);
struct hostent *Gethostbyaddr(const char *addr, int len, int type);
/* Pthreads thread control wrappers */
void Pthread_create(pthread_t *tidp, pthread_attr_t *attrp,
void * (*routine)(void *), void *argp);
void Pthread_join(pthread_t tid, void **thread_return);
void Pthread_cancel(pthread_t tid);
void Pthread_detach(pthread_t tid);
void Pthread_exit(void *retval);
pthread_t Pthread_self(void);
void Pthread_once(pthread_once_t *once_control, void (*init_function)());
/* POSIX semaphore wrappers */
void Sem_init(sem_t *sem, int pshared, unsigned int value);
void P(sem_t *sem);
void V(sem_t *sem);
/* Rio (Robust I/O) package */
ssize_t rio_readn(int fd, void *usrbuf, size_t n);
ssize_t rio_writen(int fd, void *usrbuf, size_t n);
void rio_readinitb(rio_t *rp, int fd);
ssize_t rio_readnb(rio_t *rp, void *usrbuf, size_t n);
ssize_t rio_readlineb(rio_t *rp, void *usrbuf, size_t maxlen);
/* Wrappers for Rio package */
ssize_t Rio_readn(int fd, void *usrbuf, size_t n);
void Rio_writen(int fd, void *usrbuf, size_t n);
void Rio_readinitb(rio_t *rp, int fd);
ssize_t Rio_readnb(rio_t *rp, void *usrbuf, size_t n);
ssize_t Rio_readlineb(rio_t *rp, void *usrbuf, size_t maxlen);
/* Client/server helper functions */
int open_clientfd(char *hostname, int portno);
int open_listenfd(int portno);
/* Wrappers for client/server helper functions */
int Open_clientfd(char *hostname, int port);
int Open_listenfd(int port);
#endif /* __CSAPP_H__ */
/* $end csapp.h */
csapp.c
/* $begin csapp.c */
#include "csapp.h"
/**************************
* Error-handling functions
**************************/
/* $begin errorfuns */
/* $begin unixerror */
void unix_error(char *msg) /* unix-style error */
{
fprintf(stderr, "%s: %s\n", msg, strerror(errno));
exit(0);
}
/* $end unixerror */
void posix_error(int code, char *msg) /* posix-style error */
{
fprintf(stderr, "%s: %s\n", msg, strerror(code));
exit(0);
}
void dns_error(char *msg) /* dns-style error */
{
fprintf(stderr, "%s: DNS error %d\n", msg, h_errno);
exit(0);
}
void app_error(char *msg) /* application error */
{
fprintf(stderr, "%s\n", msg);
exit(0);
}
/* $end errorfuns */
/*********************************************
* Wrappers for Unix process control functions
********************************************/
/* $begin forkwrapper */
pid_t Fork(void)
{
pid_t pid;
if ((pid = fork()) < 0)
unix_error("Fork error");
return pid;
}
/* $end forkwrapper */
void Execve(const char *filename, char *const argv[], char *const envp[])
{
if (execve(filename, argv, envp) < 0)
unix_error("Execve error");
}
/* $begin wait */
pid_t Wait(int *status)
{
pid_t pid;
if ((pid = wait(status)) < 0)
unix_error("Wait error");
return pid;
}
/* $end wait */
pid_t Waitpid(pid_t pid, int *iptr, int options)
{
pid_t retpid;
if ((retpid = waitpid(pid, iptr, options)) < 0)
unix_error("Waitpid error");
return(retpid);
}
/* $begin kill */
void Kill(pid_t pid, int signum)
{
int rc;
if ((rc = kill(pid, signum)) < 0)
unix_error("Kill error");
}
/* $end kill */
void Pause()
{
(void)pause();
return;
}
unsigned int Sleep(unsigned int secs)
{
unsigned int rc;
if ((rc = sleep(secs)) < 0)
unix_error("Sleep error");
return rc;
}
unsigned int Alarm(unsigned int seconds) {
return alarm(seconds);
}
void Setpgid(pid_t pid, pid_t pgid) {
int rc;
if ((rc = setpgid(pid, pgid)) < 0)
unix_error("Setpgid error");
return;
}
pid_t Getpgrp(void) {
return getpgrp();
}
/************************************
* Wrappers for Unix signal functions
***********************************/
/* $begin sigaction */
handler_t *Signal(int signum, handler_t *handler)
{
struct sigaction action, old_action;
action.sa_handler = handler;
sigemptyset(&action.sa_mask); /* block sigs of type being handled */
action.sa_flags = SA_RESTART; /* restart syscalls if possible */
if (sigaction(signum, &action, &old_action) < 0)
unix_error("Signal error");
return (old_action.sa_handler);
}
/* $end sigaction */
void Sigprocmask(int how, const sigset_t *set, sigset_t *oldset)
{
if (sigprocmask(how, set, oldset) < 0)
unix_error("Sigprocmask error");
return;
}
void Sigemptyset(sigset_t *set)
{
if (sigemptyset(set) < 0)
unix_error("Sigemptyset error");
return;
}
void Sigfillset(sigset_t *set)
{
if (sigfillset(set) < 0)
unix_error("Sigfillset error");
return;
}
void Sigaddset(sigset_t *set, int signum)
{
if (sigaddset(set, signum) < 0)
unix_error("Sigaddset error");
return;
}
void Sigdelset(sigset_t *set, int signum)
{
if (sigdelset(set, signum) < 0)
unix_error("Sigdelset error");
return;
}
int Sigismember(const sigset_t *set, int signum)
{
int rc;
if ((rc = sigismember(set, signum)) < 0)
unix_error("Sigismember error");
return rc;
}
/********************************
* Wrappers for Unix I/O routines
********************************/
int Open(const char *pathname, int flags, mode_t mode)
{
int rc;
if ((rc = open(pathname, flags, mode)) < 0)
unix_error("Open error");
return rc;
}
ssize_t Read(int fd, void *buf, size_t count)
{
ssize_t rc;
if ((rc = read(fd, buf, count)) < 0)
unix_error("Read error");
return rc;
}
ssize_t Write(int fd, const void *buf, size_t count)
{
ssize_t rc;
if ((rc = write(fd, buf, count)) < 0)
unix_error("Write error");
return rc;
}
off_t Lseek(int fildes, off_t offset, int whence)
{
off_t rc;
if ((rc = lseek(fildes, offset, whence)) < 0)
unix_error("Lseek error");
return rc;
}
void Close(int fd)
{
int rc;
if ((rc = close(fd)) < 0)
unix_error("Close error");
}
int Select(int n, fd_set *readfds, fd_set *writefds,
fd_set *exceptfds, struct timeval *timeout)
{
int rc;
if ((rc = select(n, readfds, writefds, exceptfds, timeout)) < 0)
unix_error("Select error");
return rc;
}
int Dup2(int fd1, int fd2)
{
int rc;
if ((rc = dup2(fd1, fd2)) < 0)
unix_error("Dup2 error");
return rc;
}
void Stat(const char *filename, struct stat *buf)
{
if (stat(filename, buf) < 0)
unix_error("Stat error");
}
void Fstat(int fd, struct stat *buf)
{
if (fstat(fd, buf) < 0)
unix_error("Fstat error");
}
/***************************************
* Wrappers for memory mapping functions
***************************************/
void *Mmap(void *addr, size_t len, int prot, int flags, int fd, off_t offset)
{
void *ptr;
if ((ptr = mmap(addr, len, prot, flags, fd, offset)) == ((void *) -1))
unix_error("mmap error");
return(ptr);
}
void Munmap(void *start, size_t length)
{
if (munmap(start, length) < 0)
unix_error("munmap error");
}
/***************************************************
* Wrappers for dynamic storage allocation functions
***************************************************/
void *Malloc(size_t size)
{
void *p;
if ((p = malloc(size)) == NULL)
unix_error("Malloc error");
return p;
}
void *Realloc(void *ptr, size_t size)
{
void *p;
if ((p = realloc(ptr, size)) == NULL)
unix_error("Realloc error");
return p;
}
void *Calloc(size_t nmemb, size_t size)
{
void *p;
if ((p = calloc(nmemb, size)) == NULL)
unix_error("Calloc error");
return p;
}
void Free(void *ptr)
{
free(ptr);
}
/******************************************
* Wrappers for the Standard I/O functions.
******************************************/
void Fclose(FILE *fp)
{
if (fclose(fp) != 0)
unix_error("Fclose error");
}
FILE *Fdopen(int fd, const char *type)
{
FILE *fp;
if ((fp = fdopen(fd, type)) == NULL)
unix_error("Fdopen error");
return fp;
}
char *Fgets(char *ptr, int n, FILE *stream)
{
char *rptr;
if (((rptr = fgets(ptr, n, stream)) == NULL) && ferror(stream))
app_error("Fgets error");
return rptr;
}
FILE *Fopen(const char *filename, const char *mode)
{
FILE *fp;
if ((fp = fopen(filename, mode)) == NULL)
unix_error("Fopen error");
return fp;
}
void Fputs(const char *ptr, FILE *stream)
{
if (fputs(ptr, stream) == EOF)
unix_error("Fputs error");
}
size_t Fread(void *ptr, size_t size, size_t nmemb, FILE *stream)
{
size_t n;
if (((n = fread(ptr, size, nmemb, stream)) < nmemb) && ferror(stream))
unix_error("Fread error");
return n;
}
void Fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream)
{
if (fwrite(ptr, size, nmemb, stream) < nmemb)
unix_error("Fwrite error");
}
/****************************
* Sockets interface wrappers
****************************/
int Socket(int domain, int type, int protocol)
{
int rc;
if ((rc = socket(domain, type, protocol)) < 0)
unix_error("Socket error");
return rc;
}
void Setsockopt(int s, int level, int optname, const void *optval, int optlen)
{
int rc;
if ((rc = setsockopt(s, level, optname, optval, optlen)) < 0)
unix_error("Setsockopt error");
}
void Bind(int sockfd, struct sockaddr *my_addr, int addrlen)
{
int rc;
if ((rc = bind(sockfd, my_addr, addrlen)) < 0)
unix_error("Bind error");
}
void Listen(int s, int backlog)
{
int rc;
if ((rc = listen(s, backlog)) < 0)
unix_error("Listen error");
}
int Accept(int s, struct sockaddr *addr, socklen_t *addrlen)
{
int rc;
if ((rc = accept(s, addr, addrlen)) < 0)
unix_error("Accept error");
return rc;
}
void Connect(int sockfd, struct sockaddr *serv_addr, int addrlen)
{
int rc;
if ((rc = connect(sockfd, serv_addr, addrlen)) < 0)
unix_error("Connect error");
}
/************************
* DNS interface wrappers
***********************/
/* $begin gethostbyname */
struct hostent *Gethostbyname(const char *name)
{
struct hostent *p;
if ((p = gethostbyname(name)) == NULL)
dns_error("Gethostbyname error");
return p;
}
/* $end gethostbyname */
struct hostent *Gethostbyaddr(const char *addr, int len, int type)
{
struct hostent *p;
if ((p = gethostbyaddr(addr, len, type)) == NULL)
dns_error("Gethostbyaddr error");
return p;
}
/************************************************
* Wrappers for Pthreads thread control functions
************************************************/
void Pthread_create(pthread_t *tidp, pthread_attr_t *attrp,
void * (*routine)(void *), void *argp)
{
int rc;
if ((rc = pthread_create(tidp, attrp, routine, argp)) != 0)
posix_error(rc, "Pthread_create error");
}
void Pthread_cancel(pthread_t tid) {
int rc;
if ((rc = pthread_cancel(tid)) != 0)
posix_error(rc, "Pthread_cancel error");
}
void Pthread_join(pthread_t tid, void **thread_return) {
int rc;
if ((rc = pthread_join(tid, thread_return)) != 0)
posix_error(rc, "Pthread_join error");
}
/* $begin detach */
void Pthread_detach(pthread_t tid) {
int rc;
if ((rc = pthread_detach(tid)) != 0)
posix_error(rc, "Pthread_detach error");
}
/* $end detach */
void Pthread_exit(void *retval) {
pthread_exit(retval);
}
pthread_t Pthread_self(void) {
return pthread_self();
}
void Pthread_once(pthread_once_t *once_control, void (*init_function)()) {
pthread_once(once_control, init_function);
}
/*******************************
* Wrappers for Posix semaphores
*******************************/
void Sem_init(sem_t *sem, int pshared, unsigned int value)
{
if (sem_init(sem, pshared, value) < 0)
unix_error("Sem_init error");
}
void P(sem_t *sem)
{
if (sem_wait(sem) < 0)
unix_error("P error");
}
void V(sem_t *sem)
{
if (sem_post(sem) < 0)
unix_error("V error");
}
/*********************************************************************
* The Rio package - robust I/O functions
**********************************************************************/
/*
* rio_readn - robustly read n bytes (unbuffered)
*/
/* $begin rio_readn */
ssize_t rio_readn(int fd, void *usrbuf, size_t n)
{
size_t nleft = n;
ssize_t nread;
char *bufp = usrbuf;
while (nleft > 0) {
if ((nread = read(fd, bufp, nleft)) < 0) {
if (errno == EINTR) /* interrupted by sig handler return */
nread = 0; /* and call read() again */
else
return -1; /* errno set by read() */
}
else if (nread == 0)
break; /* EOF */
nleft -= nread;
bufp += nread;
}
return (n - nleft); /* return >= 0 */
}
/* $end rio_readn */
/*
* rio_writen - robustly write n bytes (unbuffered)
*/
/* $begin rio_writen */
ssize_t rio_writen(int fd, void *usrbuf, size_t n)
{
size_t nleft = n;
ssize_t nwritten;
char *bufp = usrbuf;
while (nleft > 0) {
if ((nwritten = write(fd, bufp, nleft)) <= 0) {
if (errno == EINTR) /* interrupted by sig handler return */
nwritten = 0; /* and call write() again */
else
return -1; /* errorno set by write() */
}
nleft -= nwritten;
bufp += nwritten;
}
return n;
}
/* $end rio_writen */
/*
* rio_read - This is a wrapper for the Unix read() function that
* transfers min(n, rio_cnt) bytes from an internal buffer to a user
* buffer, where n is the number of bytes requested by the user and
* rio_cnt is the number of unread bytes in the internal buffer. On
* entry, rio_read() refills the internal buffer via a call to
* read() if the internal buffer is empty.
*/
/* $begin rio_read */
static ssize_t rio_read(rio_t *rp, char *usrbuf, size_t n)
{
int cnt;
while (rp->rio_cnt <= 0) { /* refill if buf is empty */
rp->rio_cnt = read(rp->rio_fd, rp->rio_buf,
sizeof(rp->rio_buf));
if (rp->rio_cnt < 0) {
if (errno != EINTR) /* interrupted by sig handler return */
return -1;
}
else if (rp->rio_cnt == 0) /* EOF */
return 0;
else
rp->rio_bufptr = rp->rio_buf; /* reset buffer ptr */
}
/* Copy min(n, rp->rio_cnt) bytes from internal buf to user buf */
cnt = n;
if (rp->rio_cnt < n)
cnt = rp->rio_cnt;
memcpy(usrbuf, rp->rio_bufptr, cnt);
rp->rio_bufptr += cnt;
rp->rio_cnt -= cnt;
return cnt;
}
/* $end rio_read */
/*
* rio_readinitb - Associate a descriptor with a read buffer and reset buffer
*/
/* $begin rio_readinitb */
void rio_readinitb(rio_t *rp, int fd)
{
rp->rio_fd = fd;
rp->rio_cnt = 0;
rp->rio_bufptr = rp->rio_buf;
}
/* $end rio_readinitb */
/*
* rio_readnb - Robustly read n bytes (buffered)
*/
/* $begin rio_readnb */
ssize_t rio_readnb(rio_t *rp, void *usrbuf, size_t n)
{
size_t nleft = n;
ssize_t nread;
char *bufp = usrbuf;
while (nleft > 0) {
if ((nread = rio_read(rp, bufp, nleft)) < 0) {
if (errno == EINTR) /* interrupted by sig handler return */
nread = 0; /* call read() again */
else
return -1; /* errno set by read() */
}
else if (nread == 0)
break; /* EOF */
nleft -= nread;
bufp += nread;
}
return (n - nleft); /* return >= 0 */
}
/* $end rio_readnb */
/*
* rio_readlineb - robustly read a text line (buffered)
*/
/* $begin rio_readlineb */
ssize_t rio_readlineb(rio_t *rp, void *usrbuf, size_t maxlen)
{
int n, rc;
char c, *bufp = usrbuf;
for (n = 1; n < maxlen; n++) {
if ((rc = rio_read(rp, &c, 1)) == 1) {
*bufp++ = c;
if (c == '\n')
break;
} else if (rc == 0) {
if (n == 1)
return 0; /* EOF, no data read */
else
break; /* EOF, some data was read */
} else
return -1; /* error */
}
*bufp = 0;
return n;
}
/* $end rio_readlineb */
/**********************************
* Wrappers for robust I/O routines
**********************************/
ssize_t Rio_readn(int fd, void *ptr, size_t nbytes)
{
ssize_t n;
if ((n = rio_readn(fd, ptr, nbytes)) < 0)
unix_error("Rio_readn error");
return n;
}
void Rio_writen(int fd, void *usrbuf, size_t n)
{
if (rio_writen(fd, usrbuf, n) != n)
unix_error("Rio_writen error");
}
void Rio_readinitb(rio_t *rp, int fd)
{
rio_readinitb(rp, fd);
}
ssize_t Rio_readnb(rio_t *rp, void *usrbuf, size_t n)
{
ssize_t rc;
if ((rc = rio_readnb(rp, usrbuf, n)) < 0)
unix_error("Rio_readnb error");
return rc;
}
ssize_t Rio_readlineb(rio_t *rp, void *usrbuf, size_t maxlen)
{
ssize_t rc;
if ((rc = rio_readlineb(rp, usrbuf, maxlen)) < 0)
unix_error("Rio_readlineb error");
return rc;
}
/********************************
* Client/server helper functions
********************************/
/*
* open_clientfd - open connection to server at <hostname, port>
* and return a socket descriptor ready for reading and writing.
* Returns -1 and sets errno on Unix error.
* Returns -2 and sets h_errno on DNS (gethostbyname) error.
*/
/* $begin open_clientfd */
int open_clientfd(char *hostname, int port)
{
int clientfd;
struct hostent *hp;
struct sockaddr_in serveraddr;
if ((clientfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
return -1; /* check errno for cause of error */
/* Fill in the server's IP address and port */
if ((hp = gethostbyname(hostname)) == NULL)
return -2; /* check h_errno for cause of error */
bzero((char *) &serveraddr, sizeof(serveraddr));
serveraddr.sin_family = AF_INET;
bcopy((char *)hp->h_addr_list[0],
(char *)&serveraddr.sin_addr.s_addr, hp->h_length);
serveraddr.sin_port = htons(port);
/* Establish a connection with the server */
if (connect(clientfd, (SA *) &serveraddr, sizeof(serveraddr)) < 0)
return -1;
return clientfd;
}
/* $end open_clientfd */
/*
* open_listenfd - open and return a listening socket on port
* Returns -1 and sets errno on Unix error.
*/
/* $begin open_listenfd */
int open_listenfd(int port)
{
int listenfd, optval=1;
struct sockaddr_in serveraddr;
/* Create a socket descriptor */
if ((listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
return -1;
/* Eliminates "Address already in use" error from bind. */
if (setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR,
(const void *)&optval , sizeof(int)) < 0)
return -1;
/* Listenfd will be an endpoint for all requests to port
on any IP address for this host */
bzero((char *) &serveraddr, sizeof(serveraddr));
serveraddr.sin_family = AF_INET;
serveraddr.sin_addr.s_addr = htonl(INADDR_ANY);
serveraddr.sin_port = htons((unsigned short)port);
if (bind(listenfd, (SA *)&serveraddr, sizeof(serveraddr)) < 0)
return -1;
/* Make it a listening socket ready to accept connection requests */
if (listen(listenfd, LISTENQ) < 0)
return -1;
return listenfd;
}
/* $end open_listenfd */
/******************************************
* Wrappers for the client/server helper routines
******************************************/
int Open_clientfd(char *hostname, int port)
{
int rc;
if ((rc = open_clientfd(hostname, port)) < 0) {
if (rc == -1)
unix_error("Open_clientfd Unix error");
else
dns_error("Open_clientfd DNS error");
}
return rc;
}
int Open_listenfd(int port)
{
int rc;
if ((rc = open_listenfd(port)) < 0)
unix_error("Open_listenfd error");
return rc;
}
/* $end csapp.c */
的main.c
#include "csapp.h"
int main() {
int fd1, fd2;
fd1 = Open("foo.txt", O_RDONLY, 0);
fd2 = Open("bar.txt", O_RDONLY, 0);
Close(fd2);
fd2 = Open("baz.txt", O_RDONLY, 0);
printf("fd2 = %d\n", fd2);
exit(0);
}