malloc
subject: https://cdn.intra.42.fr/pdf/pdf/1192/ft_malloc.en.pdf
void *malloc(size_t size): see man 3 malloc
void *realloc(void *ptr, size_t size): see man 3 realloc
void free(void *ptr): see man 3 free
void *calloc(size_t nbmem, size_t size): see man 3 calloc
void *reallocf(void *ptr, size_t size): https://linux.die.net/man/3/reallocf
void show_alloc_mem(void): print information on allocated memory in the form:
TINY : 0xA0000
0xA0020 - 0xA004A : 42 bytes
0xA006A - 0xA00BE : 84 bytes
SMALL : 0xAD000
0xAD020 - 0xADEAD : 3725 bytes
LARGE : 0xB0000
0xB0020 - 0xBBEEF : 48847 bytes
Total : 52698 octets
Environement variables:
| name | values | example | implemented | description |
|---|---|---|---|---|
| MALLOC_SCRIBBLE | char (hexa or int) | MALLOC_SCRIBBLE=0x42 | yes | use scribble as default value to apply to free data, usefull to see accessed then freed data |
| MALLOC_GUARD_EDGES | int (hexa or int) | MALLOC_GUARD_EDGES=0x10 | yes | add bytes before and after allocated data as a protection against overflow |
| MALLOC_ALLOC_LOG | none | MALLOC_ALLOC_LOG= | yes | print additional information in stdout on alloc or reallocation of memory |
| MALLOC_FREE_LOG | none | MALLOC_FREE_LOG= | yes | print additional information in stdout on free or reallocation of memory |
| MALLOC_SHOW_UNALLOCATED | none | MALLOC_SHOW_UNALLOCATED= | yes | force show_alloc_mem and the hexdump variant to also print unallocated block |
| MALLOC_HEXDUMP | none | MALLOC_HEXDUMP= | yes | change the default behavior of show_alloc_mem() to have a look similar to hexdump -C |
| MALLOC_HEXDUMP_LENGTH | int (hexa or int) | MALLOC_HEXDUMP_LENGTH=256 | yes | determine how much of the memory will be printed using show_alloc_mem() with the HEXDUMP option |
| MALLOC_NO_FREE | none | MALLOC_NO_FREE= | yes | do not set as free freed memory, increase drastically the page mapping, used for debbuging purpose only, free is still simulated, so if combined with log/invalid pointer it will output informations, but will not use the scribble option |
| MALLOC_EXIT_ON_ERROR | none | MALLOC_EXIT_ON_ERROR= | yes | explicit, will exit on any error and will force a log of the error |
| MALLOC_LOG_FILE | path to file | MALLOC_LOG_FILE="./malloc.log" | yes | will output all log information in the file located at $MALLOC_LOG_FILE location (in append mode) instead of stderr, by default, if ALLOC_LOG and FREE_LOG arrent set, will only store errors and warnings |