NAME
explain_fclose - explain fclose(3) errors
SYNOPSIS
#include <libexplain/fclose.h>
const char *explain_fclose(FILE *fp);
const char *explain_errno_fclose(int errnum, FILE *fp);
void explain_message_fclose(char *message, int message_size, FILE *fp);
void explain_message_errno_fclose(char *message, int message_size, int
errnum, FILE *fp);
DESCRIPTION
These functions may be used to obtain explanations of fclose(3) errors.
explain_fclose
const char *explain_fclose(FILE * fp);
The explain_fclose function is used to obtain an explanation of an
error returned by the fclose(3) function. 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 (fclose(fp))
{
fprintf(stderr, "%s\n", explain_fclose(fp));
exit(EXIT_FAILURE);
}
fp The original fp, exactly as passed to the fclose(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.
Note: This function may be of little diagnostic value, because libc may
have destroyed any useful context, leaving nothing for libexplain to
work with (this is true of glibc in particular). For files that are
open for writing, you will obtain more useful information by first
calling fflush(3), as in the following example
if (fflush(fp))
{
fprintf(stderr, "%s\n", explain_fflush(fp));
exit(EXIT_FAILURE);
}
if (fclose(fp))
{
fprintf(stderr, "%s\n", explain_fclose(fp));
exit(EXIT_FAILURE);
}
explain_errno_fclose
const char *explain_errno_fclose(int errnum, FILE * fp);
The explain_errno_fclose function is used to obtain an explanation of
an error returned by the fclose(3) function. 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 (fclose(fp))
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_fclose(err, 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.
fp The original fp, exactly as passed to the fclose(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.
Note: This function may be of little diagnostic value, because libc may
have destroyed any useful context, leaving nothing for libexplain to
work with (this is true of glibc in particular). For files that are
open for writing, you will obtain more useful information by first
calling fflush(3), as in the following example
if (fflush(fp))
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_fflush(err, fp));
exit(EXIT_FAILURE);
}
if (fclose(fp))
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_fclose(err, fp));
exit(EXIT_FAILURE);
}
explain_message_fclose
void explain_message_fclose(char *message, int message_size, FILE *fp);
The explain_message_fclose function is used to obtain an explanation of
an error returned by the fclose(3) function. 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 (fclose(fp))
{
char message[3000];
explain_message_fclose(message, sizeof(message), fp);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
message The location in which to store the returned message. Because a
message return buffer has been 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 fclose(3) system
call.
Note: This function may be of little diagnostic value, because libc may
have destroyed any useful context, leaving nothing for libexplain to
work with (this is true of glibc in particular). For files that are
open for writing, you will obtain more useful information by first
calling fflush(3), as in the following example
if (fflush(fp))
{
char message[3000];
explain_message_fflush(message, sizeof(message), fp);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
if (fclose(fp))
{
char message[3000];
explain_message_fclose(message, sizeof(message), fp);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
explain_message_errno_fclose
void explain_message_errno_fclose(char *message, int message_size, int
errnum, FILE *fp);
The explain_message_errno_fclose function is used to obtain an
explanation of an error returned by the fclose(3) function. 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 exameple:
if (fclose(fp))
{
int err = errno;
char message[3000];
explain_message_errno_fclose(message, sizeof(message),
err, fp);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
message The location in which to store the returned message. Because a
message return buffer has been 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.
fp The original fp, exactly as passed to the fclose(3) system
call.
Note: This function may be of little diagnostic value, because libc may
have destroyed any useful context, leaving nothing for libexplain to
work with (this is true of glibc in particular). For files that are
open for writing, you will obtain more useful information by first
calling fflush(3), as in the following example
if (fflush(fp))
{
int err = errno;
char message[3000];
explain_message_errno_fflush(message, sizeof(message),
err, fp);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
if (fclose(fp))
{
int err = errno;
char message[3000];
explain_message_errno_fclose(message, sizeof(message),
err, fp);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
COPYRIGHT
libexplain version
Copyright (C) 2008 Peter Miller
AUTHOR
Written by Peter Miller <pmiller@opensource.org.au>
explain_fclose(3)