gotosocial/vendor/modernc.org/libc/mem_brk_musl.go

305 lines
6.9 KiB
Go

// Copyright 2023 The Libc Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build libc.membrk && !libc.memgrind && linux && (amd64 || loong64)
// This is a debug-only version of the memory handling functions. When a
// program is built with -tags=libc.membrk a simple but safe version of malloc
// and friends is used that works like sbrk(2). Additionally free becomes a
// nop.
// The fixed heap is initially filled with random bytes from a full cycle PRNG,
// program startup time is substantially prolonged.
package libc // import "modernc.org/libc/v2"
import (
"fmt"
"math"
"math/bits"
"runtime"
"strings"
"time"
"unsafe"
"modernc.org/mathutil"
)
const (
isMemBrk = true
heapSize = 1 << 30
)
var (
brkIndex uintptr
heap [heapSize]byte
heapP uintptr
heap0 uintptr
heapRecords []heapRecord
heapUsable = map[uintptr]Tsize_t{}
heapFree = map[uintptr]struct{}{}
rng *mathutil.FC32
)
type heapRecord struct {
p uintptr
pc uintptr
}
func (r *heapRecord) String() string {
return fmt.Sprintf("[p=%#0x usable=%v pc=%s]", r.p, Xmalloc_usable_size(nil, r.p), pc2origin(r.pc))
}
func init() {
if roundup(heapGuard, heapAlign) != heapGuard {
panic("internal error")
}
heap0 = uintptr(unsafe.Pointer(&heap[0]))
heapP = roundup(heap0, heapAlign)
var err error
if rng, err = mathutil.NewFC32(math.MinInt32, math.MaxInt32, true); err != nil {
panic(err)
}
rng.Seed(time.Now().UnixNano())
for i := range heap {
heap[i] = byte(rng.Next())
}
}
func pc2origin(pc uintptr) string {
f := runtime.FuncForPC(pc)
var fn, fns string
var fl int
if f != nil {
fn, fl = f.FileLine(pc)
fns = f.Name()
if x := strings.LastIndex(fns, "."); x > 0 {
fns = fns[x+1:]
}
}
return fmt.Sprintf("%s:%d:%s", fn, fl, fns)
}
func malloc0(tls *TLS, pc uintptr, n0 Tsize_t, zero bool) (r uintptr) {
usable := roundup(uintptr(n0), heapAlign)
rq := usable + 2*heapGuard
if brkIndex+rq > uintptr(len(heap)) {
tls.setErrno(ENOMEM)
return 0
}
r, brkIndex = heapP+brkIndex, brkIndex+rq
heapRecords = append(heapRecords, heapRecord{p: r, pc: pc})
r += heapGuard
heapUsable[r] = Tsize_t(usable)
if zero {
n := uintptr(n0)
for i := uintptr(0); i < n; i++ {
*(*byte)(unsafe.Pointer(r + i)) = 0
}
}
return r
}
func Xmalloc(tls *TLS, n Tsize_t) (r uintptr) {
if __ccgo_strace {
trc("tls=%v n=%v, (%v:)", tls, n, origin(2))
defer func() { trc("-> %v", r) }()
}
if n > math.MaxInt {
tls.setErrno(ENOMEM)
return 0
}
if n == 0 {
// malloc(0) should return unique pointers
// (often expected and gnulib replaces malloc if malloc(0) returns 0)
n = 1
}
allocatorMu.Lock()
defer allocatorMu.Unlock()
pc, _, _, _ := runtime.Caller(1)
return malloc0(tls, pc, n, false)
}
func Xcalloc(tls *TLS, m Tsize_t, n Tsize_t) (r uintptr) {
if __ccgo_strace {
trc("tls=%v m=%v n=%v, (%v:)", tls, m, n, origin(2))
defer func() { trc("-> %v", r) }()
}
hi, rq := bits.Mul(uint(m), uint(n))
if hi != 0 || rq > math.MaxInt {
tls.setErrno(ENOMEM)
return 0
}
if rq == 0 {
rq = 1
}
allocatorMu.Lock()
defer allocatorMu.Unlock()
pc, _, _, _ := runtime.Caller(1)
return malloc0(tls, pc, Tsize_t(rq), true)
}
func Xrealloc(tls *TLS, p uintptr, n Tsize_t) (r uintptr) {
if __ccgo_strace {
trc("tls=%v p=%v n=%v, (%v:)", tls, p, n, origin(2))
defer func() { trc("-> %v", r) }()
}
if n == 0 {
Xfree(tls, p)
return 0
}
allocatorMu.Lock()
defer allocatorMu.Unlock()
pc, _, _, _ := runtime.Caller(1)
if p == 0 {
return malloc0(tls, pc, n, false)
}
usable := heapUsable[p]
if usable == 0 {
panic(todo("realloc of unallocated memory: %#0x", p))
}
if usable >= n { // in place
return p
}
// malloc
r = malloc0(tls, pc, n, false)
copy(unsafe.Slice((*byte)(unsafe.Pointer(r)), usable), unsafe.Slice((*byte)(unsafe.Pointer(p)), usable))
Xfree(tls, p)
return r
}
func Xfree(tls *TLS, p uintptr) {
if __ccgo_strace {
trc("tls=%v p=%v, (%v:)", tls, p, origin(2))
}
allocatorMu.Lock()
defer allocatorMu.Unlock()
if p == 0 {
return
}
if _, ok := heapUsable[p]; !ok {
panic(todo("free of unallocated memory: %#0x", p))
}
if _, ok := heapFree[p]; ok {
panic(todo("double free: %#0x", p))
}
heapFree[p] = struct{}{}
}
func Xmalloc_usable_size(tls *TLS, p uintptr) (r Tsize_t) {
if __ccgo_strace {
trc("tls=%v p=%v, (%v:)", tls, p, origin(2))
defer func() { trc("-> %v", r) }()
}
if p == 0 {
return 0
}
allocatorMu.Lock()
defer allocatorMu.Unlock()
return heapUsable[p]
}
func MemAudit() (r []*MemAuditError) {
allocatorMu.Lock()
defer allocatorMu.Unlock()
a := heapRecords
auditP := heap0
rng.Seek(0)
for _, v := range a {
heapP := v.p
mallocP := heapP + heapGuard
usable := heapUsable[mallocP]
for ; auditP < mallocP; auditP++ {
if g, e := *(*byte)(unsafe.Pointer(auditP)), byte(rng.Next()); g != e {
r = append(r, &MemAuditError{Caller: pc2origin(v.pc), Message: fmt.Sprintf("guard area before %#0x, %v is corrupted at %#0x, got %#02x, expected %#02x", mallocP, usable, auditP, g, e)})
}
}
for i := 0; Tsize_t(i) < usable; i++ {
rng.Next()
}
auditP = mallocP + uintptr(usable)
z := roundup(auditP, heapAlign)
z += heapGuard
for ; auditP < z; auditP++ {
if g, e := *(*byte)(unsafe.Pointer(auditP)), byte(rng.Next()); g != e {
r = append(r, &MemAuditError{Caller: pc2origin(v.pc), Message: fmt.Sprintf("guard area after %#0x, %v is corrupted at %#0x, got %#02x, expected %#02x", mallocP, usable, auditP, g, e)})
}
}
}
z := heap0 + uintptr(len(heap))
for ; auditP < z; auditP++ {
if g, e := *(*byte)(unsafe.Pointer(auditP)), byte(rng.Next()); g != e {
r = append(r, &MemAuditError{Caller: "-", Message: fmt.Sprintf("guard area after used heap is corrupted at %#0x, got %#02x, expected %#02x", auditP, g, e)})
return r // Report only the first fail
}
}
return r
}
func UsableSize(p uintptr) Tsize_t {
if p == 0 {
return 0
}
allocatorMu.Lock()
defer allocatorMu.Unlock()
return heapUsable[p]
}
// MemAuditStart locks the memory allocator, initializes and enables memory
// auditing. Finaly it unlocks the memory allocator.
//
// Some memory handling errors, like double free or freeing of unallocated
// memory, will panic when memory auditing is enabled.
//
// This memory auditing functionality has to be enabled using the libc.memgrind
// build tag.
//
// It is intended only for debug/test builds. It slows down memory allocation
// routines and it has additional memory costs.
func MemAuditStart() {}
// MemAuditReport locks the memory allocator, reports memory leaks, if any.
// Finally it disables memory auditing and unlocks the memory allocator.
//
// This memory auditing functionality has to be enabled using the libc.memgrind
// build tag.
//
// It is intended only for debug/test builds. It slows down memory allocation
// routines and it has additional memory costs.
func MemAuditReport() error { return nil }