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// SPDX-License-Identifier: MPL-2.0
// (c) Hare authors <https://harelang.org>
// This is a very simple "debug" allocator which works by allocating only via
// mmap and returning pointers to the end of the segment such that any writes
// beyond the end will cause an immediate segfault to occur.
//
// Ultimately, this should be replaced with a much more sophisticated debugging
// allocator.
let pagesz: size = 4096;
def AUXV_PAGESZ: u64 = 6;
type auxv64 = struct {
a_type: u64,
union {
a_val: u64,
a_ptr: *opaque,
a_fnc: *fn() void,
}
};
@init fn init() void = {
let i = 0;
for (envp[i] != null) {
i += 1;
};
let auxv = &envp[i + 1]: *[*]auxv64;
for (let i = 0z; auxv[i].a_type != 0; i += 1) {
if (auxv[i].a_type == AUXV_PAGESZ) {
pagesz = auxv[i].a_val: size;
break;
};
};
};
export fn malloc(n: size) nullable *opaque = {
if (n == 0) {
return null;
};
let z = n + size(*opaque) + size(size);
if (z % pagesz != 0) {
z += pagesz - z % pagesz;
};
let seg = match (segmalloc(z)) {
case null =>
return null;
case let ptr: *opaque =>
yield ptr;
};
let user = &(seg: *[*]u8)[z - n];
let segptr = &(user: *[*]*opaque)[-1];
let szptr = &(segptr: *[*]size)[-1];
*segptr = seg;
*szptr = n;
return user;
};
export @symbol("rt.free") fn free_(_p: nullable *opaque) void = {
if (_p != null) {
let user = _p: *opaque;
let segptr = &(user: *[*]*opaque)[-1];
let szptr = &(segptr: *[*]size)[-1];
let z = *szptr + size(*opaque) + size(size);
if (z % pagesz != 0) {
z += pagesz - z % pagesz;
};
segfree(*segptr, z);
};
};
export fn realloc(user: nullable *opaque, n: size) nullable *opaque = {
if (n == 0) {
free(user);
return null;
} else if (user == null) {
return malloc(n);
};
let user = user: *opaque;
let segptr = &(user: *[*]*opaque)[-1];
let szptr = &(segptr: *[*]size)[-1];
let z = *szptr;
let new = malloc(n);
if (new != null) {
memcpy(new: *opaque, user, if (z < n) z else n);
free(user);
};
return new;
};
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