|
| 1 | +// Copyright 2020 The Bazel Authors. All rights reserved. |
| 2 | +// |
| 3 | +// Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | +// you may not use this file except in compliance with the License. |
| 5 | +// You may obtain a copy of the License at |
| 6 | +// |
| 7 | +// http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | +// |
| 9 | +// Unless required by applicable law or agreed to in writing, software |
| 10 | +// distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | +// See the License for the specific language governing permissions and |
| 13 | +// limitations under the License. |
| 14 | + |
| 15 | +// Package chdir provides an init function that changes the current working |
| 16 | +// directory to RunDir when the test executable is started by Bazel |
| 17 | +// (when TEST_SRCDIR and TEST_WORKSPACE are set). |
| 18 | +// |
| 19 | +// This hides a difference between Bazel and 'go test': 'go test' starts test |
| 20 | +// executables in the package source directory, while Bazel starts test |
| 21 | +// executables in a directory made to look like the repository root directory. |
| 22 | +// Tests frequently refer to testdata files using paths relative to their |
| 23 | +// package directory, so open source tests frequently break unless they're |
| 24 | +// written with Bazel specifically in mind (using go/runfiles). |
| 25 | +// |
| 26 | +// For this init function to work, it must be called before init functions |
| 27 | +// in all user packages. |
| 28 | +// |
| 29 | +// In Go 1.20 and earlier, the package initialization order was underspecified, |
| 30 | +// other than a requirement that each package is initialized after all its |
| 31 | +// transitively imported packages. We relied on the linker initializing |
| 32 | +// packages in the order their imports appeared in source, so we import |
| 33 | +// bzltestutil (and transitively, this package) from the generated test main |
| 34 | +// before other packages. |
| 35 | +// |
| 36 | +// In Go 1.21, the package initialization order was clarified, and the |
| 37 | +// linker implementation was changed. See |
| 38 | +// https://go.dev/ref/spec#Program_initialization or |
| 39 | +// https://go.dev/doc/go1.21#language. |
| 40 | +// |
| 41 | +// > Given the list of all packages, sorted by import path, in each step the |
| 42 | +// > first uninitialized package in the list for which all imported packages |
| 43 | +// > (if any) are already initialized is initialized. This step is repeated |
| 44 | +// > until all packages are initialized. |
| 45 | +// |
| 46 | +// To ensure this package is initialized before user code without injecting |
| 47 | +// edges into the dependency graph, we implement the following hack: |
| 48 | +// |
| 49 | +// 1. Add the prefix '+initfirst/' to this package's path with the 'importmap' |
| 50 | +// attribute. '+' is the first allowed character that sorts higher than |
| 51 | +// letters. Because we're using 'importmap' and not 'importpath', this |
| 52 | +// package may be imported in .go files without the prefix. |
| 53 | +// 2. Put this init function in a separate package that only imports "os". |
| 54 | +// Previously, this function was in bzltestutil, but bzltest util imports |
| 55 | +// several other std packages may be get initialized later. For example, |
| 56 | +// the "sync" package is initialized after a user package named |
| 57 | +// "github.com/a/b" that only imports "os", and because bzltestutil imports |
| 58 | +// "sync", it would get initialized even later. A user package that imports |
| 59 | +// nothing may still be initialized before "os", but we assume "os" |
| 60 | +// is needed to observe the current directory. |
| 61 | +package chdir |
| 62 | + |
| 63 | +// This package should import nothing other than "os" |
| 64 | +// and packages imported by "os" (run 'go list -deps os'). |
| 65 | +import "os" |
| 66 | + |
| 67 | +var ( |
| 68 | + // Initialized by linker. |
| 69 | + RunDir string |
| 70 | + |
| 71 | + // Initial working directory. |
| 72 | + TestExecDir string |
| 73 | +) |
| 74 | + |
| 75 | +const isWindows = os.PathSeparator == '\\' |
| 76 | + |
| 77 | +func init() { |
| 78 | + var err error |
| 79 | + TestExecDir, err = os.Getwd() |
| 80 | + if err != nil { |
| 81 | + panic(err) |
| 82 | + } |
| 83 | + |
| 84 | + // Check if we're being run by Bazel and change directories if so. |
| 85 | + // TEST_SRCDIR and TEST_WORKSPACE are set by the Bazel test runner, so that makes a decent proxy. |
| 86 | + testSrcDir, hasSrcDir := os.LookupEnv("TEST_SRCDIR") |
| 87 | + testWorkspace, hasWorkspace := os.LookupEnv("TEST_WORKSPACE") |
| 88 | + if hasSrcDir && hasWorkspace && RunDir != "" { |
| 89 | + abs := RunDir |
| 90 | + if !filepathIsAbs(RunDir) { |
| 91 | + abs = filepathJoin(testSrcDir, testWorkspace, RunDir) |
| 92 | + } |
| 93 | + err := os.Chdir(abs) |
| 94 | + // Ignore the Chdir err when on Windows, since it might have have runfiles symlinks. |
| 95 | + // https://github.com/bazelbuild/rules_go/pull/1721#issuecomment-422145904 |
| 96 | + if err != nil && !isWindows { |
| 97 | + panic("could not change to test directory: " + err.Error()) |
| 98 | + } |
| 99 | + if err == nil { |
| 100 | + os.Setenv("PWD", abs) |
| 101 | + } |
| 102 | + } |
| 103 | +} |
| 104 | + |
| 105 | +// filepathIsAbs is a primitive version of filepath.IsAbs. It handles the |
| 106 | +// cases we are likely to encounter but is not specialized at compile time |
| 107 | +// and does not support DOS device paths (\\.\UNC\host\share\...) nor |
| 108 | +// Plan 9 absolute paths (starting with #). |
| 109 | +func filepathIsAbs(path string) bool { |
| 110 | + if isWindows { |
| 111 | + // Drive-letter path |
| 112 | + if len(path) >= 3 && |
| 113 | + ('A' <= path[0] && path[0] <= 'Z' || 'a' <= path[0] && path[0] <= 'z') && |
| 114 | + path[1] == ':' && |
| 115 | + (path[2] == '\\' || path[2] == '/') { |
| 116 | + return true |
| 117 | + } |
| 118 | + |
| 119 | + // UNC path |
| 120 | + if len(path) >= 2 && path[0] == '\\' && path[1] == '\\' { |
| 121 | + return true |
| 122 | + } |
| 123 | + return false |
| 124 | + } |
| 125 | + |
| 126 | + return len(path) > 0 && path[0] == '/' |
| 127 | +} |
| 128 | + |
| 129 | +// filepathJoin is a primitive version of filepath.Join. It only joins |
| 130 | +// its arguments with os.PathSeparator. It does not clean arguments first. |
| 131 | +func filepathJoin(base string, parts ...string) string { |
| 132 | + n := len(base) |
| 133 | + for _, part := range parts { |
| 134 | + n += 1 + len(part) |
| 135 | + } |
| 136 | + buf := make([]byte, 0, n) |
| 137 | + buf = append(buf, []byte(base)...) |
| 138 | + for _, part := range parts { |
| 139 | + buf = append(buf, os.PathSeparator) |
| 140 | + buf = append(buf, []byte(part)...) |
| 141 | + } |
| 142 | + return string(buf) |
| 143 | +} |
0 commit comments