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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:23:18 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:23:18 +0000 |
commit | 43a123c1ae6613b3efeed291fa552ecd909d3acf (patch) | |
tree | fd92518b7024bc74031f78a1cf9e454b65e73665 /src/bytes/boundary_test.go | |
parent | Initial commit. (diff) | |
download | golang-1.20-upstream.tar.xz golang-1.20-upstream.zip |
Adding upstream version 1.20.14.upstream/1.20.14upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | src/bytes/boundary_test.go | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/src/bytes/boundary_test.go b/src/bytes/boundary_test.go new file mode 100644 index 0000000..f9855fc --- /dev/null +++ b/src/bytes/boundary_test.go @@ -0,0 +1,100 @@ +// Copyright 2017 The Go 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 linux + +package bytes_test + +import ( + . "bytes" + "syscall" + "testing" +) + +// This file tests the situation where byte operations are checking +// data very near to a page boundary. We want to make sure those +// operations do not read across the boundary and cause a page +// fault where they shouldn't. + +// These tests run only on linux. The code being tested is +// not OS-specific, so it does not need to be tested on all +// operating systems. + +// dangerousSlice returns a slice which is immediately +// preceded and followed by a faulting page. +func dangerousSlice(t *testing.T) []byte { + pagesize := syscall.Getpagesize() + b, err := syscall.Mmap(0, 0, 3*pagesize, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_ANONYMOUS|syscall.MAP_PRIVATE) + if err != nil { + t.Fatalf("mmap failed %s", err) + } + err = syscall.Mprotect(b[:pagesize], syscall.PROT_NONE) + if err != nil { + t.Fatalf("mprotect low failed %s\n", err) + } + err = syscall.Mprotect(b[2*pagesize:], syscall.PROT_NONE) + if err != nil { + t.Fatalf("mprotect high failed %s\n", err) + } + return b[pagesize : 2*pagesize] +} + +func TestEqualNearPageBoundary(t *testing.T) { + t.Parallel() + b := dangerousSlice(t) + for i := range b { + b[i] = 'A' + } + for i := 0; i <= len(b); i++ { + Equal(b[:i], b[len(b)-i:]) + Equal(b[len(b)-i:], b[:i]) + } +} + +func TestIndexByteNearPageBoundary(t *testing.T) { + t.Parallel() + b := dangerousSlice(t) + for i := range b { + idx := IndexByte(b[i:], 1) + if idx != -1 { + t.Fatalf("IndexByte(b[%d:])=%d, want -1\n", i, idx) + } + } +} + +func TestIndexNearPageBoundary(t *testing.T) { + t.Parallel() + q := dangerousSlice(t) + if len(q) > 64 { + // Only worry about when we're near the end of a page. + q = q[len(q)-64:] + } + b := dangerousSlice(t) + if len(b) > 256 { + // Only worry about when we're near the end of a page. + b = b[len(b)-256:] + } + for j := 1; j < len(q); j++ { + q[j-1] = 1 // difference is only found on the last byte + for i := range b { + idx := Index(b[i:], q[:j]) + if idx != -1 { + t.Fatalf("Index(b[%d:], q[:%d])=%d, want -1\n", i, j, idx) + } + } + q[j-1] = 0 + } + + // Test differing alignments and sizes of q which always end on a page boundary. + q[len(q)-1] = 1 // difference is only found on the last byte + for j := 0; j < len(q); j++ { + for i := range b { + idx := Index(b[i:], q[j:]) + if idx != -1 { + t.Fatalf("Index(b[%d:], q[%d:])=%d, want -1\n", i, j, idx) + } + } + } + q[len(q)-1] = 0 +} |