libexplain/gethostname.c File Reference

#include <libexplain/ac/errno.h>
#include <libexplain/ac/unistd.h>
#include <libexplain/buffer/errno/gethostname.h>
#include <libexplain/common_message_buffer.h>
#include <libexplain/gethostname.h>

Go to the source code of this file.

Functions
const char *	explain_gethostname (char *data, size_t data_size)
const char *	explain_errno_gethostname (int errnum, char *data, size_t data_size)
void	explain_message_gethostname (char *message, int message_size, char *data, size_t data_size)
void	explain_message_errno_gethostname (char *message, int message_size, int errnum, char *data, size_t data_size)

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Function Documentation

const char* explain_errno_gethostname	(	int	errnum,
		char *	data,
		size_t	data_size
	)

The explain_errno_gethostname function is used to obtain an explanation of an error returned by the gethostname(2) 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 (gethostname(data, data_size) < 0)
 {
     int err = errno;
     fprintf(stderr, "%s\n", explain_gethostname(err, data, data_size));
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_gethostname_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.
data	The original data, exactly as passed to the gethostname(2) system call.
data_size	The original data_size, exactly as passed to the gethostname(2) 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 35 of file gethostname.c.

const char* explain_gethostname	(	char *	data,
		size_t	data_size
	)

The explain_gethostname function is used to obtain an explanation of an error returned by the gethostname(2) 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 (gethostname(data, data_size) < 0)
 {
     fprintf(stderr, "%s\n", explain_gethostname(data, data_size));
     exit(EXIT_FAILURE);
 }

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

Parameters:

data	The original data, exactly as passed to the gethostname(2) system call.
data_size	The original data_size, exactly as passed to the gethostname(2) 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 28 of file gethostname.c.

void explain_message_errno_gethostname	(	char *	message,
		int	message_size,
		int	errnum,
		char *	data,
		size_t	data_size
	)

The explain_message_errno_gethostname function is used to obtain an explanation of an error returned by the gethostname(2) 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 (gethostname(data, data_size) < 0)
 {
     int err = errno;
     char message[3000];
     explain_message_errno_gethostname(message, sizeof(message), err, data,
         data_size);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_gethostname_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.
data	The original data, exactly as passed to the gethostname(2) system call.
data_size	The original data_size, exactly as passed to the gethostname(2) system call.

Definition at line 65 of file gethostname.c.

void explain_message_gethostname	(	char *	message,
		int	message_size,
		char *	data,
		size_t	data_size
	)

The explain_message_gethostname function is used to obtain an explanation of an error returned by the gethostname(2) 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 (gethostname(data, data_size) < 0)
 {
     char message[3000];
     explain_message_gethostname(message, sizeof(message), data, data_size);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_gethostname_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.
data	The original data, exactly as passed to the gethostname(2) system call.
data_size	The original data_size, exactly as passed to the gethostname(2) system call.

Definition at line 50 of file gethostname.c.