Stable growable array based on virtual memory (linux)

reserve_commit.c

#include <stdint.h>
#include <stdio.h>

#include <sys/mman.h>

struct bc_vm {
    uint8_t *base;
    uint64_t size;
    uint64_t commited;
};

static struct bc_vm
mapping_reserve(uint64_t size)
{
    struct bc_vm result = { 0 };
    
    uint8_t *region = mmap(NULL, size, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); /* PROT_NONE + MAP_ANONYMOUS = do not commit */
    
    if (region == MAP_FAILED) {
        perror("mmap (reserve)");
        return(result);
    }
    
    result.base = region;
    result.size = size;
    result.commited = 0;
    
    return(result);
}

static int
mapping_commit(struct bc_vm *vm, uint64_t offset, uint64_t size)
{
    if (offset + size > vm->size) {
        return(1);
    }
    
    if (mprotect(vm->base + offset, size, PROT_READ | PROT_WRITE)) {
        perror("mprotect (commit)");
        return(1);
    }
    
    return(0);
}