explain_vfprintf_or_die(3) [debian man page]

explain_vfprintf_or_die(3)				     Library Functions Manual					explain_vfprintf_or_die(3)

NAME

       explain_vfprintf_or_die - formatted output conversion and report errors

SYNOPSIS

       #include <libexplain/vfprintf.h>
       void explain_vfprintf_or_die(FILE *fp, const char *format, va_list ap);
       int explain_vfprintf_on_error(FILE *fp, const char *format, va_list ap);

DESCRIPTION

       The  explain_vfprintf_or_die  function  is  used  to call the vfprintf(3) system call. On failure an explanation will be printed to stderr,
       obtained from the explain_vfprintf(3) function, and then the process terminates by calling exit(EXIT_FAILURE).

       The explain_vfprintf_on_error function is used to call the vfprintf(3) system call. On failure an explanation will be  printed  to  stderr,
       obtained from the explain_vfprintf(3) function, but still returns to the caller.

       fp      The fp, exactly as to be passed to the vfprintf(3) system call.

       format  The format, exactly as to be passed to the vfprintf(3) system call.

       ap      The ap, exactly as to be passed to the vfprintf(3) system call.

RETURN VALUE

       The  explain_vfprintf_or_die  function only returns on success, see vfprintf(3) for more information. On failure, prints an explanation and
       exits, it does not return.

       The explain_vfprintf_on_error function always returns the value return by the wrapped vfprintf(3) system call.

EXAMPLE

       The explain_vfprintf_or_die function is intended to be used in a fashion similar to the following example:
	      explain_vfprintf_or_die(fp, format, ap);

SEE ALSO

       vfprintf(3)
	       formatted output conversion

       explain_vfprintf(3)
	       explain vfprintf(3) errors

       exit(2) terminate the calling process

COPYRIGHT

       libexplain version 0.52
       Copyright (C) 2010 Peter Miller

															explain_vfprintf_or_die(3)

explain_vfprintf(3)					     Library Functions Manual					       explain_vfprintf(3)

NAME

       explain_vfprintf - explain vfprintf(3) errors

SYNOPSIS

       #include <libexplain/vfprintf.h>
       const char *explain_vfprintf(FILE *fp, const char *format, va_list ap);
       const char *explain_errno_vfprintf(int errnum, FILE *fp, const char *format, va_list ap);
       void explain_message_vfprintf(char *message, int message_size, FILE *fp, const char *format, va_list ap);
       void explain_message_errno_vfprintf(char *message, int message_size, int errnum, FILE *fp, const char *format, va_list ap);

DESCRIPTION

       These functions may be used to obtain explanations for errors returned by the vfprintf(3) system call.

   explain_vfprintf
       const char *explain_vfprintf(FILE *fp, const char *format, va_list ap);

       The  explain_vfprintf  function is used to obtain an explanation of an error returned by the vfprintf(3) system call. The least the message
       will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail.

       The errno global variable will be used to obtain the error value to be decoded.

       fp      The original fp, exactly as passed to the vfprintf(3) system call.

       format  The original format, exactly as passed to the vfprintf(3) system call.

       ap      The original ap, exactly as passed to the vfprintf(3) system call.

       Returns:
	       The message explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer  in  their
	       argument  list.	 This  will  be  overwritten by the next call to any libexplain function which shares this buffer, including other
	       threads.

       Note: This function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library.

       Example: This function is intended to be used in a fashion similar to the following example:
	      errno = EINVAL; if (vfprintf(fp, format, ap) < 0)
	      {
		  fprintf(stderr, "%s
", explain_vfprintf(fp, format, ap));
		  exit(EXIT_FAILURE);
	      }

       The above code example is available pre-packaged as the explain_vfprintf_or_die(3) function.

   explain_errno_vfprintf
       const char *explain_errno_vfprintf(int errnum, FILE *fp, const char *format, va_list ap);

       The explain_errno_vfprintf function is used to obtain an explanation of an error returned by the vfprintf(3) system call.   The	least  the
       message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail.

       errnum  The  error value to be decoded, usually obtained from the errno global variable just before this function is called. This is neces-
	       sary if you need to call any code between the system call to be explained and this function, because many libc functions will alter
	       the value of errno.

       fp      The original fp, exactly as passed to the vfprintf(3) system call.

       format  The original format, exactly as passed to the vfprintf(3) system call.

       ap      The original ap, exactly as passed to the vfprintf(3) system call.

       Returns:
	       The  message  explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer in their
	       argument list.  This will be overwritten by the next call to any libexplain function which  shares  this  buffer,  including  other
	       threads.

       Note: This function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library.

       Example: This function is intended to be used in a fashion similar to the following example:
	      errno = EINVAL; if (vfprintf(fp, format, ap) < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s
", explain_errno_vfprintf(err, fp, format, ap));
		  exit(EXIT_FAILURE);
	      }

       The above code example is available pre-packaged as the explain_vfprintf_or_die(3) function.

   explain_message_vfprintf
       void explain_message_vfprintf(char *message, int message_size, FILE *fp, const char *format, va_list ap);

       The  explain_message_vfprintf function is used to obtain an explanation of an error returned by the vfprintf(3) system call.  The least the
       message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail.

       The errno global variable will be used to obtain the error value to be decoded.

       message The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe.

       message_size
	       The size in bytes of the location in which to store the returned message.

       fp      The original fp, exactly as passed to the vfprintf(3) system call.

       format  The original format, exactly as passed to the vfprintf(3) system call.

       ap      The original ap, exactly as passed to the vfprintf(3) system call.

       Example: This function is intended to be used in a fashion similar to the following example:
	      errno = EINVAL; if (vfprintf(fp, format, ap) < 0)
	      {
		  char message[3000];
		  explain_message_vfprintf(message, sizeof(message), fp, format, ap);
		  fprintf(stderr, "%s
", message);
		  exit(EXIT_FAILURE);
	      }

       The above code example is available pre-packaged as the explain_vfprintf_or_die(3) function.

   explain_message_errno_vfprintf
       void explain_message_errno_vfprintf(char *message, int message_size, int errnum, FILE *fp, const char *format, va_list ap);

       The explain_message_errno_vfprintf function is used to obtain an explanation of an error returned by  the  vfprintf(3)  system  call.   The
       least  the  message  will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in
       more detail.

       message The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe.

       message_size
	       The size in bytes of the location in which to store the returned message.

       errnum  The error value to be decoded, usually obtained from the errno global variable just before this function is called. This is  neces-
	       sary if you need to call any code between the system call to be explained and this function, because many libc functions will alter
	       the value of errno.

       fp      The original fp, exactly as passed to the vfprintf(3) system call.

       format  The original format, exactly as passed to the vfprintf(3) system call.

       ap      The original ap, exactly as passed to the vfprintf(3) system call.

       Example: This function is intended to be used in a fashion similar to the following example:
	      errno = EINVAL; if (vfprintf(fp, format, ap) < 0)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_vfprintf(message, sizeof(message), err, fp, format, ap);
		  fprintf(stderr, "%s
", message);
		  exit(EXIT_FAILURE);
	      }

       The above code example is available pre-packaged as the explain_vfprintf_or_die(3) function.

SEE ALSO

       vfprintf(3)
	       formatted output conversion

       explain_vfprintf_or_die(3)
	       formatted output conversion and report errors

COPYRIGHT

       libexplain version 0.52
       Copyright (C) 2010 Peter Miller

															       explain_vfprintf(3)