const char *explain_ungetc(int c, FILE *fp);
const char *explain_errno_ungetc(int errnum, int c, FILE *fp);
void explain_message_ungetc(char *message, int message_size, int c, FILE
*fp);
void explain_message_errno_ungetc(char *message, int message_size, int
errnum, int c, FILE *fp);
DESCRIPTION
These functions may be used to obtain explanations for errors returned by
the ungetc(3) system call.
explain_ungetc
const char *explain_ungetc(int c, FILE *fp);
The explain_ungetc function is used to obtain an explanation of an
error returned by the ungetc(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.
c
The original c, exactly as passed to the ungetc(3) system call.
fp
The original fp, exactly as passed to the ungetc(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:
if (ungetc(c, fp) < 0)
{
fprintf(stderr, "%s\n", explain_ungetc(c, fp));
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the
explain_ungetc_or_die(3) function.
explain_errno_ungetc
const char *explain_errno_ungetc(int errnum, int c, FILE *fp);
The explain_errno_ungetc function is used to obtain an explanation
of an error returned by the ungetc(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 necessary 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.
c
The original c, exactly as passed to the ungetc(3) system call.
fp
The original fp, exactly as passed to the ungetc(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:
The above code example is available pre-packaged as the
explain_ungetc_or_die(3) function.
explain_message_ungetc
void explain_message_ungetc(char *message, int message_size, int c, FILE
*fp);
The explain_message_ungetc function is used to obtain an
explanation of an error returned by the ungetc(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.
c
The original c, exactly as passed to the ungetc(3) system call.
fp
The original fp, exactly as passed to the ungetc(3) system call.
Example: This function is intended to be used in a fashion similar
to the following example:
The above code example is available pre-packaged as the
explain_ungetc_or_die(3) function.
explain_message_errno_ungetc
void explain_message_errno_ungetc(char *message, int message_size, int
errnum, int c, FILE *fp);
The explain_message_errno_ungetc function is used to obtain an
explanation of an error returned by the ungetc(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 necessary 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.
c
The original c, exactly as passed to the ungetc(3) system call.
fp
The original fp, exactly as passed to the ungetc(3) system call.
Example: This function is intended to be used in a fashion similar
to the following example: