Short answer: Not likely In order for this to work, you absolutely would have to use a 64-bit processor. Secondly, it would depend on the Operating System support for allocating more than 4G of RAM to a single process. In theory, it would be possible, but you would have to read the documentation for the … Read more
The C99 standard (actually WG14/N1124. Committee Draft — May 6, 2005. ISO/IEC 9899:TC2) says about malloc(): The pointer returned points to the start (lowest byte address) of the allocated space. If the space cannot be allocated, a null pointer is returned. If the size of the space requested is zero, the behavior is implementation defined: … Read more
You have a few options: GLIBC-specific solution (mostly Linux). If your compilation environment is glibc with gcc, the preferred way is to use malloc hooks. Not only it lets you specify custom malloc and free, but will also identify the caller by the return address on the stack. POSIX-specific solution. Define malloc and free as … Read more
The draft n4296 for C11 is explicit that pointing one past an array is perfecly defined: 6.5.6 Language / Expressions / Additive operators: ยง 8 When an expression that has integer type is added to or subtracted from a pointer, the result has the type of the pointer operand. … Moreover, if the expression P … Read more
Several points: C allows void pointers to be implicitly converted to any other object pointer type. C++ does not. Casting the result of malloc() in C will supress a useful diagnostic if you forget to include stdlib.h or otherwise don’t have a declaration for malloc() in scope. Remember that if C sees a function call … Read more
OK, so I’ve managed to overcome this issue. First of all – A practical cause to “corrupted size vs. prev_size” is quite simple – memory chunk control structure fields in the adjacent following chunk are being overwritten due to out-of-bounds access by the code. if you allocate x bytes for pointer p but wind up … Read more
Besides Klatchko’s correct point that the standard does not provide for it, real malloc/free implementations often allocate more space then you ask for. E.g. if you ask for 12 bytes it may provide 16 (see A Memory Allocator, which notes that 16 is a common size). So it doesn’t need to know you asked for … Read more
I always do it this way: #define _GNU_SOURCE #include <stdio.h> #include <dlfcn.h> static void* (*real_malloc)(size_t)=NULL; static void mtrace_init(void) { real_malloc = dlsym(RTLD_NEXT, “malloc”); if (NULL == real_malloc) { fprintf(stderr, “Error in `dlsym`: %s\n”, dlerror()); } } void *malloc(size_t size) { if(real_malloc==NULL) { mtrace_init(); } void *p = NULL; fprintf(stderr, “malloc(%d) = “, size); p = … Read more
The <malloc.h> header is deprecated (and quite Linux specific, on which it defines non-standard functions like mallinfo(3)). Use <stdlib.h> instead if you simply need malloc(3) and related standard functions (e.g. free, calloc, realloc ….). Notice that <stdlib.h> is defined by C89 (and later) standards, but not <malloc.h> Look into /usr/include/malloc.h you’ll find there some non-standard … Read more
Here is the original answer from Stack Overflow. As others have mentioned, you need snprintf not sprintf. Make sure the second argument to snprintf is zero. That will prevent snprintf from writing to the NULL string that is the first argument. The second argument is needed because it tells snprintf that enough space is not … Read more