README.md

scoped_alloc

A simple C scoped allocated pointer library.

Enter a new scope with enter_alloc_scope(user_function, optional_user_args...).

Within user_function, any calls to scope_alloc() or scope_malloc() (scope_malloc() is the simpler version of the two) will call an allocation function and register a destructor/deallocator function. When user_function() returns, any pointers created by scoped_alloc()/scoped_malloc() will have their destructors called.

Any calls to scoped_alloc()/scope_malloc() made before calling enter_alloc_scope() must be handled by a previous/parent call to enter_alloc_scope().

Simple allocated pointer scopes

Simplest usage is to replace calls to malloc() with scoped_malloc().

#include <stdio.h>
#include "scoped_alloc.h"

struct user_struct_t {
    int a;
    int b;
} s_init {
    .a = 1
};

void scoped_user_function(int b) {
    s_t* p = scope_malloc(user_struct_t); // allocate scoped pointer to a user_struct_t
    *p = s_init;
    p->b = b;
    printf("user_struct: a[%d], b[%d]\n", p->a, p->b);
    // no manual free
}

int main() {
    enter_alloc_scope(user_function, 4);
    // scoped pointer p is now deallocated
    return 0;
}

Potential output:

$ ./a.out
user_struct: a[1], b[4]
$

Custom constructor and destructor allocations

scoped_alloc() allows for more complex allocation operations, specifying the destructor and constructor (with any necessary arguments).

#include <stdio.h>
#include "scoped_alloc.h"

struct user_struct_t {
    int a;
    int b;
};

user_struct_t* alloc_user_struct(int b) {
    user_struct_t* p = malloc(sizeof(user_struct_t));
    p->a = 1;
    p->b = b;
    return p;
}

void destroy_user_struct(void* v) {
    printf("Destroying user_struct\n");
    free(v);
}

void scoped_user_function() {
    // allocate scoped pointer with custom functions
    s_t* p = scope_alloc(destroy_user_struct, alloc_user_struct, 5); 
    printf("user_struct: a[%d], b[%d]\n", p->a, p->b);
    // no manual free
}

int main() {
    enter_alloc_scope(scoped_user_function);
    // scoped pointer p is now deallocated
    return 0;
}

Potential output:

$ ./a.out
user_struct: a[1], b[5]
Destroying user_struct
$