---

mallopt()

Control the extra checking for memory allocation

Synopsis:

#include <malloc.h>

int mallopt( int cmd,
             int value );

Arguments:

cmd

Options used to enable additional checks in the library.

• MALLOC_CKACCESS
• MALLOC_FILLAREA
• MALLOC_CKCHAIN
• MALLOC_VERIFY
• MALLOC_FATAL
• MALLOC_WARN

See the Description section for more details.

value

A value corresponding to the command; see below:

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The mallopt() function controls the extra checking of memory allocation.

Options used to enable additional checks in the library include:

MALLOC_CKACCESS

Turn on (or off) boundary checking for memory and string operations.
Environment variable: MALLOC_CKACCESS.

The value argument can be:

• zero to disable the checking
• nonzero to enable it.

MALLOC_FILLAREA

Turn on (or off) fill-area boundary checking.
Environment variable: MALLOC_FILLAREA.

The value argument can be:

• zero to disable the checking
• nonzero to enable it.

MALLOC_CKCHAIN

Enable (or disable) full-chain checking. For each of the above options, an integer argument value of one indicates that the given type of checking should be enabled from that point onward.
Environment variable: MALLOC_CKCHAIN.

The value argument can be:

• zero to disable the checking
• nonzero to enable it.

MALLOC_VERIFY

Perform a chain check. If an error is found, perform error handling. The value argument is currently ignored; pass 1 for it.

MALLOC_FATAL

Specify the malloc fatal handler.
Environment variable: MALLOC_FATAL.

Use one of the following for the value arguments:

Symbolic name	Value	Description
M_HANDLE_IGNORE	0	Cause the program to dump a core file.
M_HANDLE_ABORT	1	Terminate execution with a call to abort()
M_HANDLE_ABORT	2	Exit immediately
M_HANDLE_CORE	3	Cause the program to dump a core file
M_HANDLE_SIGNAL	4	Stop the program when this error occurs

MALLOC_WARN

Specify the malloc warning handler. The values are similar to MALLOC_FATAL; see above.
Environment variable: MALLOC_WARN.

For details, see "Controlling the level of checking" in the Heap Analysis: Making Memory Errors a Thing of the Past chapter of the Neutrino Programmer's Guide.

Returns:

0 on success, or -1 if an error occurs (errno is set).

Classification:

QNX Neutrino

Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	No
Thread	Yes

See also:

calloc(), free(), mallinfo(), malloc(), realloc()

Heap Analysis: Making Memory Errors a Thing of the Past chapter of the Neutrino Programmer's Guide

---