socket编程中错误处理封装函数

系统调用不能保证每次都成功，需要进行必要的出错处理，这样才能保证程序逻辑运行正常和出错的时候迅速找到出错的原因。

socket编程中的一些错误，写在主函数中显得代码繁琐复杂，下面将这些错误处理包装成了新的函数，做成一个模块。

（1）myerr.h

#ifndef __MYERR_H_
#define __MYERR_H_
void perr_exit(const char *s);
int Accept(int fd, struct sockaddr *sa, socklen_t *salenptr);
int Bind(int fd, const struct sockaddr *sa, socklen_t salen);
int Connect(int fd, const struct sockaddr *sa, socklen_t salen);
int Listen(int fd, int backlog);
int Socket(int family, int type, int protocol);
ssize_t Read(int fd, void *ptr, size_t nbytes);
ssize_t Write(int fd, const void *ptr, size_t nbytes);
int Close(int fd);
ssize_t Readn(int fd, void *vptr, size_t n);
ssize_t Writen(int fd, const void *vptr, size_t n);
ssize_t my_read(int fd, char *ptr);
ssize_t Readline(int fd, void *vptr, size_t maxlen);
#endif

（2）myerr.c

#include <stdlib.h>
#include <errno.h>
#include <sys/socket.h>
void perr_exit(const char *s)
{
  perror(s);
  exit(1);
}
int Accept(int fd, struct sockaddr *sa, socklen_t *salenptr)
{
  int n;
  again:
  if ( (n = accept(fd, sa, salenptr)) < 0) {
    if ((errno == ECONNABORTED) || (errno == EINTR))
      goto again;
    else
      perr_exit("accept error");
  }
  return n;
}
int Bind(int fd, const struct sockaddr *sa, socklen_t salen)
{
  int n;
  if ((n = bind(fd, sa, salen)) < 0)
    perr_exit("bind error");
  return n;
}
int Connect(int fd, const struct sockaddr *sa, socklen_t salen)
{
  int n;
  if ((n = connect(fd, sa, salen)) < 0)
    perr_exit("connect error");
  return n;
}
int Listen(int fd, int backlog)
{
  int n;
  if ((n = listen(fd, backlog)) < 0)
    perr_exit("listen error");
  return n;
}
int Socket(int family, int type, int protocol)
{
  int n;
  if ( (n = socket(family, type, protocol)) < 0)
    perr_exit("socket error");
  return n;
}
ssize_t Read(int fd, void *ptr, size_t nbytes)
{
  ssize_t n;
again:
  if ( (n = read(fd, ptr, nbytes)) == -1) {
    if (errno == EINTR)
      goto again;
    else
      return -1;
  }
  return n;
}
ssize_t Write(int fd, const void *ptr, size_t nbytes)
{
  ssize_t n;
again:
  if ( (n = write(fd, ptr, nbytes)) == -1) {
    if (errno == EINTR)
      goto again;
    else
      return -1;
  }
  return n;
}
int Close(int fd)
{
  int n;
  if ((n = close(fd)) == -1)
    perr_exit("close error");
  return n;
}
ssize_t Readn(int fd, void *vptr, size_t n)
{
  size_t nleft;
  ssize_t nread;
  char *ptr;

  ptr = vptr;
  nleft = n;

  while (nleft > 0) {
    if ( (nread = read(fd, ptr, nleft)) < 0) {
      if (errno == EINTR)
        nread = 0;
      else
        return -1;
    } else if (nread == 0)
      break;
    nleft -= nread;
    ptr += nread;
  }
  return n - nleft;
}

ssize_t Writen(int fd, const void *vptr, size_t n)
{
  size_t nleft;
  ssize_t nwritten;
  const char *ptr;

  ptr = vptr;
  nleft = n;

  while (nleft > 0) {
    if ( (nwritten = write(fd, ptr, nleft)) <= 0) {
      if (nwritten < 0 && errno == EINTR)
        nwritten = 0;
      else
        return -1;
    }
    nleft -= nwritten;
    ptr += nwritten;
  }
  return n;
}
static ssize_t my_read(int fd, char *ptr)
{
  static int read_cnt;
  static char *read_ptr;
  static char read_buf[100];

  if (read_cnt <= 0) {
again:
    if ((read_cnt = read(fd, read_buf, sizeof(read_buf))) < 0) {
      if (errno == EINTR)
        goto again;
      return -1;  
    } else if (read_cnt == 0)
      return 0;
    read_ptr = read_buf;
  }
  read_cnt--;
  *ptr = *read_ptr++;
  return 1;
}

ssize_t Readline(int fd, void *vptr, size_t maxlen)
{
  ssize_t n, rc;
  char c, *ptr;
  ptr = vptr;

  for (n = 1; n < maxlen; n++) {
    if ( (rc = my_read(fd, &c)) == 1) {
      *ptr++ = c;
      if (c == '\n')
        break;
    } else if (rc == 0) {
      *ptr = 0;
      return n - 1;
    } else
      return -1;
  }
  *ptr = 0;
  return n;
}