libexplain/malloc.h File Reference

explain malloc(3) errors More...

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

Go to the source code of this file.

Functions
void *	explain_malloc_or_die (size_t size) LIBEXPLAIN_ATTRIBUTE_MALLOC LIBEXPLAIN_ATTRIBUTE_ALLOC_SIZE(1)
void *	explain_malloc_on_error (size_t size) LIBEXPLAIN_ATTRIBUTE_MALLOC LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_malloc (size_t size) LIBEXPLAIN_ATTRIBUTE_MALLOC LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_errno_malloc (int errnum, size_t size) LIBEXPLAIN_WARN_UNUSED_RESULT
void	explain_message_malloc (char *message, int message_size, size_t size) LIBEXPLAIN_ATTRIBUTE_ALLOC_SIZE(3)
void	explain_message_errno_malloc (char *message, int message_size, int errnum, size_t size) LIBEXPLAIN_ATTRIBUTE_ALLOC_SIZE(4)

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Detailed Description

explain malloc(3) errors

Definition in file malloc.h.

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Function Documentation

const char* explain_errno_malloc	(	int	errnum,
		size_t	size
	)

The explain_errno_malloc function is used to obtain an explanation of an error returned by the malloc(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:

 void *result = malloc(size);
 if (!result)
 {
     int err = errno;
     fprintf(stderr, "%s\n", explain_errno_malloc(err, size));
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_malloc_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.
size	The original size, exactly as passed to the malloc(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.

const char* explain_malloc

(

size_t

size

)

The explain_malloc function is used to obtain an explanation of an error returned by the malloc(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:

 void *result = malloc(size);
 if (!result)
 {
     fprintf(stderr, "%s\n", explain_malloc(size));
     exit(EXIT_FAILURE);
 }

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

Parameters:

size	The original size, exactly as passed to the malloc(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.

void* explain_malloc_on_error

(

size_t

size

)

The explain_malloc_on_error function is used to call the malloc(3) system call. On failure an explanation will be printed to stderr, obtained from the explain_malloc(3) function.

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

 void *result = explain_malloc_on_error(size);
 if (!p)
 {
     ...cope with error
     ...no need to print error message
 }

Parameters:

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

Returns:

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

void* explain_malloc_or_die

(

size_t

size

)

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

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

 void *result = explain_malloc_or_die(size);

Parameters:

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

Returns:

This function only returns on success. On failure, prints an explanation and exits, it does not return.

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

The explain_message_errno_malloc function is used to obtain an explanation of an error returned by the malloc(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:

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

The above code example is available pre-packaged as the explain_malloc_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.
size	The original size, exactly as passed to the malloc(3) system call.

void explain_message_malloc	(	char *	message,
		int	message_size,
		size_t	size
	)

The explain_message_malloc function is used to obtain an explanation of an error returned by the malloc(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:

 void *result = malloc(size);
 if (!result)
 {
     char message[3000];
     explain_message_malloc(message, sizeof(message), size);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_malloc_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.
size	The original size, exactly as passed to the malloc(3) system call.