libexplain/calloc.h File Reference

explain calloc(3) errors More...

#include <libexplain/gcc_attributes.h>
#include <libexplain/large_file_support.h>

Go to the source code of this file.

Functions
void *	explain_calloc_or_die (size_t nmemb, size_t size) LIBEXPLAIN_ATTRIBUTE_MALLOC LIBEXPLAIN_WARN_UNUSED_RESULT
void *	explain_calloc_on_error (size_t nmemb, size_t size) LIBEXPLAIN_ATTRIBUTE_MALLOC LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_calloc (size_t nmemb, size_t size) LIBEXPLAIN_ATTRIBUTE_MALLOC LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_errno_calloc (int errnum, size_t nmemb, size_t size) LIBEXPLAIN_WARN_UNUSED_RESULT
void	explain_message_calloc (char *message, int message_size, size_t nmemb, size_t size) LIBEXPLAIN_ATTRIBUTE_ALLOC_SIZE2(2
void void	explain_message_errno_calloc (char *message, int message_size, int errnum, size_t nmemb, size_t size) LIBEXPLAIN_ATTRIBUTE_ALLOC_SIZE2(4

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Detailed Description

explain calloc(3) errors

These functions may be used to obtain explanations for errors returned by the calloc(3) system call.

Definition in file calloc.h.

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Function Documentation

const char* explain_calloc	(	size_t	nmemb,
		size_t	size
	)

The explain_calloc function is used to obtain an explanation of an error returned by the calloc(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.

Parameters:

nmemb	The original nmemb, exactly as passed to the calloc(3) system call.
size	The original size, exactly as passed to the calloc(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.

Example:

This function is intended to be used in a fashion similar to the following example:

 errno = 0;
 void *result = calloc(nmemb, size);
 if (!result && errno != 0)
 {
     fprintf(stderr, "%s\n", explain_calloc(nmemb, size));
     exit(EXIT_FAILURE);
 }

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

void* explain_calloc_on_error	(	size_t	nmemb,
		size_t	size
	)

The explain_calloc_on_error function is used to call the calloc(3) system call. On failure an explanation will be printed to stderr, obtained from the explain_calloc(3) function.

Parameters:

nmemb	The nmemb, exactly as to be passed to the calloc(3) system call.
size	The size, exactly as to be passed to the calloc(3) system call.

Returns:

The value returned by the wrapped calloc(3) system call.

Example:

This function is intended to be used in a fashion similar to the following example:

 errno = 0;
 void *result = explain_calloc_on_error(nmemb, size);
 if (!result && errno != 0)
 {
     ...cope with error
     ...no need to print error message
 }

void* explain_calloc_or_die	(	size_t	nmemb,
		size_t	size
	)

The explain_calloc_or_die function is used to call the calloc(3) system call. On failure an explanation will be printed to stderr, obtained from the explain_calloc(3) function, and then the process terminates by calling exit(EXIT_FAILURE).

Parameters:

nmemb	The nmemb, exactly as to be passed to the calloc(3) system call.
size	The size, exactly as to be passed to the calloc(3) system call.

Returns:

This function only returns on success, see calloc(3) for more information. On failure, prints an explanation and exits, it does not return.

Example:

This function is intended to be used in a fashion similar to the following example:

 void *result = explain_calloc_or_die(nmemb, size);

const char* explain_errno_calloc	(	int	errnum,
		size_t	nmemb,
		size_t	size
	)

The explain_errno_calloc function is used to obtain an explanation of an error returned by the calloc(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.

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.
nmemb	The original nmemb, exactly as passed to the calloc(3) system call.
size	The original size, exactly as passed to the calloc(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.

Example:

This function is intended to be used in a fashion similar to the following example:

 errno = 0;
 void *result = calloc(nmemb, size);
 if (!result && errno != 0)
 {
     int err = errno;
     fprintf(stderr, "%s\n", explain_errno_calloc(err, nmemb, size));
     exit(EXIT_FAILURE);
 }

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

void explain_message_calloc	(	char *	message,
		int	message_size,
		size_t	nmemb,
		size_t	size
	)

The explain_message_calloc function is used to obtain an explanation of an error returned by the calloc(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.

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.
nmemb	The original nmemb, exactly as passed to the calloc(3) system call.
size	The original size, exactly as passed to the calloc(3) system call.

Example:

This function is intended to be used in a fashion similar to the following example:

 errno = 0;
 void *result = calloc(nmemb, size);
 if (!result && errno != 0)
 {
     char message[3000];
     explain_message_calloc(message, sizeof(message), nmemb, size);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

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

void void explain_message_errno_calloc	(	char *	message,
		int	message_size,
		int	errnum,
		size_t	nmemb,
		size_t	size
	)

The explain_message_errno_calloc function is used to obtain an explanation of an error returned by the calloc(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.

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.
nmemb	The original nmemb, exactly as passed to the calloc(3) system call.
size	The original size, exactly as passed to the calloc(3) system call.

Example:

This function is intended to be used in a fashion similar to the following example:

 errno = 0;
 void *result = calloc(nmemb, size);
 if (!result && errno != 0)
 {
     int err = errno;
     char message[3000];
     explain_message_errno_calloc(message, sizeof(message), err, nmemb,
         size);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

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