1  /*
       2   * No copyright is claimed.  This code is in the public domain; do with
       3   * it what you wish.
       4   */
       5  #ifndef UTIL_LINUX_CLOSESTREAM_H
       6  #define UTIL_LINUX_CLOSESTREAM_H
       7  
       8  #include <stdio.h>
       9  #ifdef HAVE_STDIO_EXT_H
      10  #include <stdio_ext.h>
      11  #endif
      12  #include <unistd.h>
      13  
      14  #include "c.h"
      15  #include "nls.h"
      16  
      17  #ifndef CLOSE_EXIT_CODE
      18  # define CLOSE_EXIT_CODE EXIT_FAILURE
      19  #endif
      20  
      21  static inline int
      22  close_stream(FILE * stream)
      23  {
      24  #ifdef HAVE___FPENDING
      25  	const int some_pending = (__fpending(stream) != 0);
      26  #endif
      27  	const int prev_fail = (ferror(stream) != 0);
      28  	const int fclose_fail = (fclose(stream) != 0);
      29  
      30  	if (prev_fail || (fclose_fail && (
      31  #ifdef HAVE___FPENDING
      32  					  some_pending ||
      33  #endif
      34  					  errno != EBADF))) {
      35  		if (!fclose_fail && !(errno == EPIPE))
      36  			errno = 0;
      37  		return EOF;
      38  	}
      39  	return 0;
      40  }
      41  
      42  static inline int
      43  flush_standard_stream(FILE *stream)
      44  {
      45  	int fd;
      46  
      47  	errno = 0;
      48  
      49  	if (ferror(stream) != 0 || fflush(stream) != 0)
      50  		goto error;
      51  
      52  	/*
      53  	 * Calling fflush is not sufficient on some filesystems
      54  	 * like e.g. NFS, which may defer the actual flush until
      55  	 * close. Calling fsync would help solve this, but would
      56  	 * probably result in a performance hit. Thus, we work
      57  	 * around this issue by calling close on a dup'd file
      58  	 * descriptor from the stream.
      59  	 */
      60  	if ((fd = fileno(stream)) < 0 || (fd = dup(fd)) < 0 || close(fd) != 0)
      61  		goto error;
      62  
      63  	return 0;
      64  error:
      65  	return (errno == EBADF) ? 0 : EOF;
      66  }
      67  
      68  /* Meant to be used atexit(close_stdout); */
      69  static inline void
      70  close_stdout(void)
      71  {
      72  	if (flush_standard_stream(stdout) != 0 && !(errno == EPIPE)) {
      73  		if (errno)
      74  			warn(_("write error"));
      75  		else
      76  			warnx(_("write error"));
      77  		_exit(CLOSE_EXIT_CODE);
      78  	}
      79  
      80  	if (flush_standard_stream(stderr) != 0)
      81  		_exit(CLOSE_EXIT_CODE);
      82  }
      83  
      84  static inline void
      85  close_stdout_atexit(void)
      86  {
      87  	/*
      88  	 * Note that close stdout at exit disables ASAN to report memory leaks
      89  	 */
      90  #if !HAS_FEATURE_ADDRESS_SANITIZER
      91  	atexit(close_stdout);
      92  #endif
      93  }
      94  
      95  #ifndef HAVE_FSYNC
      96  static inline int
      97  fsync(int fd __attribute__((__unused__)))
      98  {
      99  	return 0;
     100  }
     101  #endif
     102  
     103  static inline int
     104  close_fd(int fd)
     105  {
     106  	const int fsync_fail = (fsync(fd) != 0);
     107  	const int close_fail = (close(fd) != 0);
     108  
     109  	if (fsync_fail || close_fail)
     110  		return EOF;
     111  	return 0;
     112  }
     113  
     114  #endif /* UTIL_LINUX_CLOSESTREAM_H */