libexplain/freopen.c File Reference

#include <libexplain/ac/errno.h>
#include <libexplain/ac/stdio.h>
#include <libexplain/buffer/errno/freopen.h>
#include <libexplain/common_message_buffer.h>
#include <libexplain/freopen.h>

Go to the source code of this file.

Functions
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)

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Function Documentation

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\n", explain_errno_freopen(err, pathname, flags,
         fp));
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_freopen_or_die function.

Parameters:

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.

Definition at line 36 of file freopen.c.

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\n", explain_freopen(pathname, flags, fp));
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_freopen_or_die function.

Parameters:

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.

Definition at line 29 of file freopen.c.

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\n", message);
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_freopen_or_die function.

Parameters:

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.
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.

Definition at line 69 of file freopen.c.

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(errnum), 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\n", message);
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_freopen_or_die function.

Parameters:

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.
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.

Definition at line 53 of file freopen.c.