EINTR handling.

eintr-handling.c

// Examples of EINTR handling for reentrant functions.

#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

//m=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
// Open can be interupted when blocked, waiting for a slow device such as a
// FIFO to open.
int myopen(char const* pathname, int flags)
{
  int ret_val;
  do
  {
    errno = 0;
    ret_val = open(pathname, flags);
  } 
  while(ret_val == -1 && errno == EINTR);

  return ret_val;
}

//m=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
ssize_t myread(int fildes, void* buf, size_t nbyte)
{
  ssize_t numbytes = 0;

  // Loop while the read function is interupted.  Set errno in the loop
  // to make sure that another system call has not set it.
  do
  {
    errno = 0;
    numbytes = read(fildes, buf, nbyte);
  }
  while (numbytes == -1 && errno == EINTR);
  
  return numbytes;
}



//m=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
ssize_t mywrite(int fildes, void const* buf, size_t nbyte)
{
  // Loop while the write function is interupted.  Set errno in the loop
  // to make sure that another system call has not set it.
  ssize_t numbytes = 0;
  do
  {
    errno = 0;
    numbytes = write(fildes, buf, nbyte);
  }
  while (numbytes == -1 && errno == EINTR);

  return numbytes;
}



//m=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
int myclose(int fd)
{
  int ret_val;
  do
  {
    errno = 0;
    ret_val = close(fd);
  } 
  while(ret_val == -1 && errno == EINTR);

  return ret_val;
}