// license that can be found in the LICENSE file.

// This package is a lightly modified version of the mmap code
// in github.com/google/codesearch/index.

// The mmap package provides an abstraction for memory mapping files
// on different platforms.
package mmap

import (
	"os"
)

// Data is mmap'ed read-only data from a file.
// The backing file is never closed, so Data

// license that can be found in the LICENSE file.

// This package is a lightly modified version of the mmap code
// in github.com/google/codesearch/index.

// The mmap package provides an abstraction for memory mapping files
// on different platforms.
package mmap

import (
	"os"
)

// The backing file is never closed, so Data
// remains valid for the lifetime of the process.

package runtime

import "unsafe"

// mmap calls the mmap system call. It is implemented in assembly.
// We only pass the lower 32 bits of file offset to the
// assembly routine; the higher bits (if required), should be provided
// by the assembly routine as 0.
// The err result is an OS error code such as ENOMEM.
func mmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) (p unsafe.Pointer, err int)

import _ "unsafe"

// When using cgo, call the C library for mmap, so that we call into
// any sanitizer interceptors. This supports using the memory
// sanitizer with Go programs. The memory sanitizer only applies to
// C/C++ code; this permits that code to see the Go code as normal
// program addresses that have been initialized.

// To support interceptors that look for both mmap and munmap,
// also call the C library for munmap.

#include <errno.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/mman.h>

#include "libcgo.h"

uintptr_t
x_cgo_mmap(void *addr, uintptr_t length, int32_t prot, int32_t flags, int32_t fd, uint32_t offset) {
	void *p;

	_cgo_tsan_acquire();
	p = mmap(addr, length, prot, flags, fd, offset);
	_cgo_tsan_release();
	if (p == MAP_FAILED) {

#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>

#ifdef _AIX
// On AIX, SIGSTKSZ is too small to handle Go sighandler.
#define CSIGSTKSZ 0x4000
#else
#define CSIGSTKSZ SIGSTKSZ
#endif

extern void SigStackCallback();

static void* WithSigStack(void* arg __attribute__((unused))) {
	// Set up an alternate system stack.
	void* base = mmap(0, CSIGSTKSZ, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);

	}

	// Mmap should fail at a half page into the buffer.
	_, err = runtime.Mmap(unsafe.Pointer(uintptr(b)+ps/2), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0)
	if err == 0 {
		t.Errorf("Mmap should have failed with half-page alignment %d, but succeeded: %v", ps/2, err)
	}

	// Mmap should succeed at a full page into the buffer.

//go:linkname _cgo_munmap _cgo_munmap
var _cgo_munmap unsafe.Pointer

// mmap is used to route the mmap system call through C code when using cgo, to
// support sanitizer interceptors. Don't allow stack splits, since this function
// (used by sysAlloc) is called in a lot of low-level parts of the runtime and
// callers often assume it won't acquire any locks.
//
//go:nosplit

//go:build unix && (!solaris || go1.20)

package mmap

import (
	"fmt"
	"io/fs"
	"os"
	"syscall"
)

func mmapFile(f *os.File, _ *Data) (Data, error) {
	st, err := f.Stat()
	if err != nil {
		return Data{}, err
	}
	size := st.Size()
	pagesize := int64(os.Getpagesize())
	if int64(int(size+(pagesize-1))) != size+(pagesize-1) {
		return Data{}, fmt.Errorf("%s: too large for mmap", f.Name())
	}
	n := int(size)

func sysFaultOS(v unsafe.Pointer, n uintptr) {
	mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE|_MAP_FIXED, -1, 0)
}

func sysReserveOS(v unsafe.Pointer, n uintptr) unsafe.Pointer {
	p, err := mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE, -1, 0)
	if err != 0 {
		return nil
	}
	return p
}

const _ENOMEM = 12

func sysMapOS(v unsafe.Pointer, n uintptr) {