NAME
explain_fgets - explain fgets(3) errors
SYNOPSIS
#include <libexplain/fgets.h>
const char *explain_fgets(char *data, int data_size, FILE *fp);
const char *explain_errno_fgets(int errnum, char *data, int data_size,
FILE *fp);
void explain_message_fgets(char *message, int message_size, char *data,
int data_size, FILE *fp);
void explain_message_errno_fgets(char *message, int message_size, int
errnum, char *data, int data_size, FILE *fp);
DESCRIPTION
These functions may be used to obtain explanations for errors returned
by the fgets(3) system call.
explain_fgets
const char *explain_fgets(char *data, int data_size, FILE *fp);
The explain_fgets function is used to obtain an explanation of an error
returned by the fgets(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.
This function is intended to be used in a fashion similar to the
following example:
if (fgets(data, data_size, fp) < 0)
{
fprintf(stderr, "%s\n", explain_fgets(data, data_size, fp));
exit(EXIT_FAILURE);
}
data The original data, exactly as passed to the fgets(3) system
call.
data_size
The original data_size, exactly as passed to the fgets(3)
system call.
fp The original fp, exactly as passed to the fgets(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.
explain_errno_fgets
const char *explain_errno_fgets(int errnum, char *data, int data_size,
FILE *fp);
The explain_errno_fgets function is used to obtain an explanation of an
error returned by the fgets(3) system call. The least the message will
contain is the value of strerror(errnum), but usually it will do much
better, and indicate the underlying cause in more detail.
This function is intended to be used in a fashion similar to the
following example:
if (fgets(data, data_size, fp) < 0)
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_fgets(err, data, data_size, fp));
exit(EXIT_FAILURE);
}
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.
data The original data, exactly as passed to the fgets(3) system
call.
data_size
The original data_size, exactly as passed to the fgets(3)
system call.
fp The original fp, exactly as passed to the fgets(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.
explain_message_fgets
void explain_message_fgets(char *message, int message_size, char *data,
int data_size, FILE *fp);
The explain_message_fgets function may be used to obtain an
explanation of an error returned by the fgets(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.
This function is intended to be used in a fashion similar to the
following example:
if (fgets(data, data_size, fp) < 0)
{
char message[3000];
explain_message_fgets(message, sizeof(message), data, data_size, fp);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
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 fgets(3) system
call.
data_size
The original data_size, exactly as passed to the fgets(3)
system call.
fp The original fp, exactly as passed to the fgets(3) system call.
explain_message_errno_fgets
void explain_message_errno_fgets(char *message, int message_size, int
errnum, char *data, int data_size, FILE *fp);
The explain_message_errno_fgets function may be used to obtain an
explanation of an error returned by the fgets(3) system call. The
least the message will contain is the value of strerror(errnum), but
usually it will do much better, and indicate the underlying cause in
more detail.
This function is intended to be used in a fashion similar to the
following example:
if (fgets(data, data_size, fp) < 0)
{
int err = errno;
char message[3000];
explain_message_errno_fgets(message, sizeof(message), err,
data, data_size, fp);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
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.
data The original data, exactly as passed to the fgets(3) system
call.
data_size
The original data_size, exactly as passed to the fgets(3)
system call.
fp The original fp, exactly as passed to the fgets(3) system call.
SEE ALSO
fgets(3)
input of strings
explain_fgets_or_die(3)
input of strings and report errors
COPYRIGHT
libexplain version 0.19
Copyright (C) 2008 Peter Miller
explain_fgets(3)