explain_snprintf(3)					     Library Functions Manual					       explain_snprintf(3)

NAME

       explain_snprintf - explain snprintf(3) errors

SYNOPSIS

       #include <libexplain/snprintf.h>
       const char *explain_snprintf(char *data, size_t data_size, const char *format);
       const char *explain_errno_snprintf(int errnum, char *data, size_t data_size, const char *format);
       void explain_message_snprintf(char *message, int message_size, char *data, size_t data_size, const char *format);
       void explain_message_errno_snprintf(char *message, int message_size, int errnum, char *data, size_t data_size, const char *format);

DESCRIPTION

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

   explain_snprintf
       const char *explain_snprintf(char *data, size_t data_size, const char *format);

       The  explain_snprintf  function is used to obtain an explanation of an error returned by the snprintf(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.

       data    The original data, exactly as passed to the snprintf(3) system call.

       data_size
	       The original data_size, exactly as passed to the snprintf(3) system call.

       format  The original format, exactly as passed to the snprintf(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 = 0;
	      int result = snprintf(data, data_size, format);
	      if (result < 0 && errno != 0)
	      {
		  fprintf(stderr, "%s
", explain_snprintf(data, data_size, format));
		  exit(EXIT_FAILURE);
	      }

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

   explain_errno_snprintf
       const char *explain_errno_snprintf(int errnum, char *data, size_t data_size, const char *format);

       The explain_errno_snprintf function is used to obtain an explanation of an error returned by the snprintf(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.

       data    The original data, exactly as passed to the snprintf(3) system call.

       data_size
	       The original data_size, exactly as passed to the snprintf(3) system call.

       format  The original format, exactly as passed to the snprintf(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 = 0;
	      int result = snprintf(data, data_size, format);
	      if (result < 0 && errno != 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s
", explain_errno_snprintf(err, data, data_size, format));
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_snprintf
       void explain_message_snprintf(char *message, int message_size, char *data, size_t data_size, const char *format);

       The  explain_message_snprintf function is used to obtain an explanation of an error returned by the snprintf(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.

       data    The original data, exactly as passed to the snprintf(3) system call.

       data_size
	       The original data_size, exactly as passed to the snprintf(3) system call.

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

       Example: This function is intended to be used in a fashion similar to the following example:
	      errno = 0;
	      int result = snprintf(data, data_size, format);
	      if (result < 0 && errno != 0)
	      {
		  char message[3000];
		  explain_message_snprintf(message, sizeof(message), data, data_size, format);
		  fprintf(stderr, "%s
", message);
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_errno_snprintf
       void explain_message_errno_snprintf(char *message, int message_size, int errnum, char *data, size_t data_size, const char *format);

       The explain_message_errno_snprintf function is used to obtain an explanation of an error returned by  the  snprintf(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.

       data    The original data, exactly as passed to the snprintf(3) system call.

       data_size
	       The original data_size, exactly as passed to the snprintf(3) system call.

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

       Example: This function is intended to be used in a fashion similar to the following example:
	      errno = 0;
	      int result = snprintf(data, data_size, format);
	      if (result < 0 && errno != 0)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_snprintf(message, sizeof(message), err, data, data_size, format);
		  fprintf(stderr, "%s
", message);
		  exit(EXIT_FAILURE);
	      }

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

SEE ALSO

       snprintf(3)
	       formatted output conversion

       explain_snprintf_or_die(3)
	       formatted output conversion and report errors

COPYRIGHT

       libexplain version 0.52
       Copyright (C) 2010 Peter Miller

															       explain_snprintf(3)