106 lines
2.9 KiB
Go
106 lines
2.9 KiB
Go
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// Copyright 2021 The Libc Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build libc.membrk && !libc.memgrind
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// +build libc.membrk,!libc.memgrind
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// This is a debug-only version of the memory handling functions. When a
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// program is built with -tags=libc.membrk a simple but safe version of malloc
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// and friends is used that works like sbrk(2). Additionally free becomes a
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// nop.
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package libc // import "modernc.org/libc"
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import (
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"unsafe"
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"modernc.org/libc/errno"
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"modernc.org/libc/sys/types"
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)
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const (
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heapSize = 20 << 30 // Adjust for your debugging session requirements and system RAM size.
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heapAlign = 16
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memgrind = false
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)
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var (
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heap = make([]byte, heapSize)
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heapP = uintptr(unsafe.Pointer(&heap[heapAlign]))
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heapLast = uintptr(unsafe.Pointer(&heap[heapSize-1]))
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)
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// void *malloc(size_t size);
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func Xmalloc(t *TLS, n types.Size_t) uintptr {
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if n == 0 {
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return 0
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}
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allocMu.Lock()
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defer allocMu.Unlock()
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n2 := uintptr(n) + uintptrSize // reserve space for recording block size
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p := roundup(heapP, 16)
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if p+uintptr(n2) >= heapLast {
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t.setErrno(errno.ENOMEM)
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return 0
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}
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heapP = p + uintptr(n2)
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*(*uintptr)(unsafe.Pointer(p - uintptrSize)) = uintptr(n)
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return p
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}
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// void *calloc(size_t nmemb, size_t size);
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func Xcalloc(t *TLS, n, size types.Size_t) uintptr {
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return Xmalloc(t, n*size)
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}
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// void *realloc(void *ptr, size_t size);
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func Xrealloc(t *TLS, ptr uintptr, size types.Size_t) uintptr {
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switch {
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case ptr != 0 && size != 0:
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p := Xmalloc(t, size)
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sz0 := UsableSize(ptr)
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if p != 0 {
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copy((*RawMem)(unsafe.Pointer(p))[:size:size], (*RawMem)(unsafe.Pointer(ptr))[:sz0:sz0])
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}
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return p
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case ptr == 0 && size != 0:
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return Xmalloc(t, size)
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}
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return 0
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}
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// void free(void *ptr);
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func Xfree(t *TLS, p uintptr) {}
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func UsableSize(p uintptr) types.Size_t {
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return types.Size_t(*(*uintptr)(unsafe.Pointer(p - uintptrSize)))
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}
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// MemAuditStart locks the memory allocator, initializes and enables memory
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// auditing. Finaly it unlocks the memory allocator.
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//
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// Some memory handling errors, like double free or freeing of unallocated
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// memory, will panic when memory auditing is enabled.
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//
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// This memory auditing functionality has to be enabled using the libc.memgrind
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// build tag.
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//
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// It is intended only for debug/test builds. It slows down memory allocation
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// routines and it has additional memory costs.
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func MemAuditStart() {}
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// MemAuditReport locks the memory allocator, reports memory leaks, if any.
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// Finally it disables memory auditing and unlocks the memory allocator.
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//
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// This memory auditing functionality has to be enabled using the libc.memgrind
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// build tag.
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//
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// It is intended only for debug/test builds. It slows down memory allocation
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// routines and it has additional memory costs.
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func MemAuditReport() error { return nil }
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