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/*
* wnix, a Unix-like operating system for WebAssembly applications.
* Copyright (C) 2025 Xavier Del Campo Romero
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <errno.h>
#include <unistd.h>
#include <stddef.h>
#include <stdint.h>
void *sbrk(const intptr_t increment)
{
const unsigned pagesize = 64 << 10;
extern char __heap_base[];
static char *cur = __heap_base, *end;
if (increment < 0)
{
errno = EINVAL;
return NULL;
}
else if (!end)
end = cur + __builtin_wasm_memory_size(0) * pagesize;
if (increment >= (intptr_t)end || cur >= end - increment)
{
const unsigned long pages = (uintptr_t)increment / pagesize,
new_end = __builtin_wasm_memory_grow(0, pages);
if (!new_end)
{
errno = ENOMEM;
return NULL;
}
end = (void *)new_end;
}
void *ret = cur;
cur += increment;
return ret;
}
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