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explain_freopen

explain_freopen

Section: C Library Functions (3)
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NAME

explain_freopen - explain freopen(3) errors  

SYNOPSIS

#include <libexplain/freopen.h>
const char *explain_freopen(const char *pathname, const char *flags, FILE *fp);
const char *explain_errno_freopen(int errnum, const char *pathname, const char *flags, FILE *fp);
void explain_message_freopen(char *message, int message_size, const char *pathname, const char *flags, FILE *fp);
void explain_message_errno_freopen(char *message, int message_size, int errnum, const char *pathname, const char *flags, FILE *fp);  

DESCRIPTION

These functions may be used to obtain explanations for freopen(3) errors.  

explain_freopen

const char *explain_freopen(const char *pathname, const char *flags, FILE *fp);

The explain_freopen function is used to obtain an explanation of an error returned by the freopen(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 (!freopen(pathname, flags, fp))
{
    fprintf(stderr, '%s, explain_freopen(pathname, flags, fp));
    exit(EXIT_FAILURE);
}
pathname
The original pathname, exactly as passed to the freopen(3) system call.
flags
The original flags, exactly as passed to the freopen(3) system call.
fp
The original fp, exactly as passed to the freopen(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_freopen

const char *explain_errno_freopen(int errnum, const char *pathname, const char *flags, FILE *fp);

The explain_errno_freopen function is used to obtain an explanation of an error returned by the freopen(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 (freopen(pathname, flags, fp))
{
    int err = errno;
    fprintf(stderr, '%s, explain_errno_freopen(err, pathname,
        flags, 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.
pathname
The original pathname, exactly as passed to the freopen(3) system call.
flags
The original flags, exactly as passed to the freopen(3) system call.
fp
The original fp, exactly as passed to the freopen(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_freopen

void explain_message_freopen(char *message, int message_size, const char *pathname, const char *flags, FILE *fp);

The explain_message_freopen function is used to obtain an explanation of an error returned by the freopen(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 (!freopen(pathname, flags, fp))
{
    char message[3000];
    explain_message_freopen(message, sizeof(message), pathname, flags,
        fp);
    fprintf(stderr, '%s, 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.
pathname
The original pathname, exactly as passed to the freopen(3) system call.
flags
The original flags, exactly as passed to the freopen(3) system call.
fp
The original fp, exactly as passed to the freopen(3) system call.
 

explain_message_errno_freopen

void explain_message_errno_freopen(char *message, int message_size, int errnum, const char *pathname, const char *flags, FILE *fp);

The explain_message_errno_freopen function is used to obtain an explanation of an error returned by the freopen(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 (!freopen(pathname, flags, fp))
{
    int err = errno;
    char message[3000];
    explain_message_errno_freopen(message, sizeof(message), err,
        pathname, flags, fp);
    fprintf(stderr, '%s, 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.
pathname
The original pathname, exactly as passed to the freopen(3) system call.
flags
The original flags, exactly as passed to the freopen(3) system call.
fp
The original fp, exactly as passed to the freopen(3) system call.
 

COPYRIGHT

libexplain version 0.37
Copyright (C) 2008 Peter Miller  

AUTHOR

Written by Peter Miller <pmiller@opensource.org.au>


 

Index

NAME
SYNOPSIS
DESCRIPTION
explain_freopen
explain_errno_freopen
explain_message_freopen
explain_message_errno_freopen
COPYRIGHT
AUTHOR

This document was created by man2html, using the manual pages.
Time: 21:45:48 GMT, April 16, 2011