write和read(被信号终端的处理)

原文参见：
http://blog.roodo.com/rocksaying/archives/2159383.html

// The prototype of POSIX of read() is:
//   ssize_t read(int fd, void *buf, size_t nbyte);
ssize_t saferead(int fd, void *buf, size_t nbyte) {
  size_t nbr;   /* number of bytes readed */
  ssize_t rc;   /* return code of read() */
  void* bp;
  bp = buf;
  nbr = nbyte;
  while( (rc=read(fd, bp, nbr)) < nbr ) {
    if( rc > 0 ) {
      bp += rc;
      nbr -= rc;
    }
    else if( errno != EINTR )
      abort();
  }
}

// The prototype of POSIX of write() is:
//   ssize_t write(int fd, void *buf, size_t nbyte) {
ssize_t safewrite(int fd, void *buf, size_t nbyte) {
  size_t nbw;   /* number of bytes written */
  ssize_t rc;   /* return code of write() */
  void* bp;
  bp = buf;
  nbw = nbyte;
  while( (rc=write(fd, bp, nbw)) < nbw ) {
    if( rc > 0 ) {
      bp += rc;
      nbw -= rc;
    }
    else if( errno != EINTR )
      abort();
  }
}