Realloc v0.1.0

Package: Memory

Signature

func Realloc(
    ptr: *opaque,
    size: uint
) -> *var opaque;

Parameters

Returns

A pointer to the resized block, which may differ from ptr — the block is allowed to move, and once it has, the old pointer must not be used again. Two arguments are treated as shorthands rather than errors:

• Realloc(null, size) allocates a fresh block, exactly like Alloc.
• Realloc(ptr, 0) releases the block and returns null, exactly like Free.

Growing keeps every byte of the old block and leaves the bytes past the old size uninitialized; shrinking keeps the surviving prefix and discards the rest.

The return is null if the platform could not satisfy the request. In that case the original block is untouched and still valid, so it must still be freed — assigning the result straight back over ptr leaks it.

Example

import Memory::{ Alloc, Free, Realloc, Set };

func Main() -> int {
    var buffer = Alloc(8);
    Set(buffer, 8, 0xAB);

    let grown = Realloc(buffer, 64); // the first 8 bytes are still 0xAB
    if grown == null {
        Free(buffer); // the old block survived the failure
        return 1;
    }

    buffer = grown;
    Free(buffer);
    return 0;
}

See also

• Memory — the package overview
• Alloc — allocate the block in the first place
• Free — release the block when it is no longer needed
• Copy — move bytes between blocks by hand