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Full Discussion: memory allocation
Top Forums UNIX for Dummies Questions & Answers memory allocation Post 12696 by Neo on Saturday 5th of January 2002 10:53:29 PM
Old 01-06-2002
Memory allocation is a housekeeping function of the structure of the program (how it is written and memory is allocated). You can 'reallocate' more memory to a running program or compiled binary.... at least I've never heard of a way to do it!

You can rewrite the program to allocation more memory, however, if you have access to the source code..... try taking a look at the malloc man page.

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MCHECK(3)						     Linux Programmer's Manual							 MCHECK(3)

mcheck, mcheck_check_all, mcheck_pedantic, mprobe - heap consistency checking SYNOPSIS
#include <mcheck.h> int mcheck(void (*abortfunc)(enum mcheck_status mstatus)); int mcheck_pedantic(void (*abortfunc)(enum mcheck_status mstatus)); void mcheck_check_all(void); enum mcheck_status mprobe(void *ptr); DESCRIPTION
The mcheck() function installs a set of debugging hooks for the malloc(3) family of memory-allocation functions. These hooks cause certain consistency checks to be performed on the state of the heap. The checks can detect application errors such as freeing a block of memory more than once or corrupting the bookkeeping data structures that immediately precede a block of allocated memory. To be effective, the mcheck() function must be called before the first call to malloc(3) or a related function. In cases where this is difficult to ensure, linking the program with -mcheck inserts an implicit call to mcheck() (with a NULL argument) before the first call to a memory-allocation function. The mcheck_pedantic() function is similar to mcheck(), but performs checks on all allocated blocks whenever one of the memory-allocation functions is called. This can be very slow! The mcheck_check_all() function causes an immediate check on all allocated blocks. This call is only effective if mcheck() is called beforehand. If the system detects an inconsistency in the heap, the caller-supplied function pointed to by abortfunc is invoked with a single argument argument, mstatus, that indicates what type of inconsistency was detected. If abortfunc is NULL, a default function prints an error mes- sage on stderr and calls abort(3). The mprobe() function performs a consistency check on the block of allocated memory pointed to by ptr. The mcheck() function should be called beforehand (otherwise mprobe() returns MCHECK_DISABLED). The following list describes the values returned by mprobe() or passed as the mstatus argument when abortfunc is invoked: MCHECK_DISABLED (mprobe() only) mcheck() was not called before the first memory allocation function was called. Consistency checking is not possible. MCHECK_OK (mprobe() only) No inconsistency detected. MCHECK_HEAD Memory preceding an allocated block was clobbered. MCHECK_TAIL Memory following an allocated block was clobbered. MCHECK_FREE A block of memory was freed twice. RETURN VALUE
mcheck() and mcheck_pedantic() return 0 on success, or -1 on error. VERSIONS
The mcheck_pedantic() and mcheck_check_all() functions are available since glibc 2.2. The mcheck() and mprobe() functions are present since at least glibc 2.0 CONFORMING TO
These functions are GNU extensions. NOTES
Linking a program with -lmcheck and using the MALLOC_CHECK_ environment variable (described in mallopt(3)) cause the same kinds of errors to be detected. But, using MALLOC_CHECK_ does not require the application to be relinked. EXAMPLE
The program below calls mcheck() with a NULL argument and then frees the same block of memory twice. The following shell session demon- strates what happens when running the program: $ ./a.out About to free About to free a second time block freed twice Aborted (core dumped) Program source #include <stdlib.h> #include <stdio.h> #include <mcheck.h> int main(int argc, char *argv[]) { char *p; if (mcheck(NULL) != 0) { fprintf(stderr, "mcheck() failed "); exit(EXIT_FAILURE); } p = malloc(1000); fprintf(stderr, "About to free "); free(p); fprintf(stderr, " About to free a second time "); free(p); exit(EXIT_SUCCESS); } SEE ALSO
malloc(3), mallopt(3), mtrace(3) COLOPHON
This page is part of release 3.44 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at GNU
2012-04-18 MCHECK(3)

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