Serge Bazanski | 0f8e5a2 | 2021-10-16 20:53:51 +0000 | [diff] [blame] | 1 | package workspace |
| 2 | |
| 3 | import ( |
| 4 | "fmt" |
| 5 | "os" |
| 6 | "path" |
| 7 | "sync" |
| 8 | "syscall" |
| 9 | ) |
| 10 | |
| 11 | // isWorkspace returns whether a given string is a valid path pointing to a |
| 12 | // Bazel workspace directory. |
| 13 | func isWorkspace(dir string) bool { |
| 14 | w := path.Join(dir, "WORKSPACE") |
| 15 | if _, err := os.Stat(w); err == nil { |
| 16 | return true |
| 17 | } |
| 18 | return false |
| 19 | } |
| 20 | |
| 21 | // getPathFSID returns an opaque filesystem identifier for a given path. |
| 22 | func getPathFSID(dir string) (uint64, error) { |
| 23 | st, err := os.Stat(dir) |
| 24 | if err != nil { |
| 25 | // No need to wrap err, as stat errors are already quite explicit |
| 26 | // (they also include the stat'd path). |
| 27 | return 0, err |
| 28 | } |
| 29 | switch x := st.Sys().(type) { |
| 30 | case *syscall.Stat_t: |
| 31 | return x.Dev, nil |
| 32 | default: |
| 33 | return 0, fmt.Errorf("unsupported operating system (got stat type %+v)", st.Sys()) |
| 34 | } |
| 35 | } |
| 36 | |
| 37 | // lookForWorkspace recurses up a directory until it finds a WORKSPACE, the |
| 38 | // root, or crosses a filesystem boundary. |
| 39 | func lookForWorkspace(dir string) (string, error) { |
| 40 | fsid, err := getPathFSID(dir) |
| 41 | if err != nil { |
| 42 | return "", fmt.Errorf("could not get initial FSID: %w", err) |
| 43 | } |
| 44 | for { |
| 45 | if dir == "." || dir == "/" || dir == "" { |
| 46 | return "", fmt.Errorf("got up to root before finding workspace") |
| 47 | } |
| 48 | |
| 49 | fsid2, err := getPathFSID(dir) |
| 50 | if err != nil { |
| 51 | return "", fmt.Errorf("could not get parent FWID: %w", err) |
| 52 | } |
| 53 | if fsid2 != fsid { |
| 54 | return "", fmt.Errorf("crossed filesystem boundaries before finding workspace") |
| 55 | } |
| 56 | |
| 57 | if isWorkspace(dir) { |
| 58 | return dir, nil |
| 59 | } |
| 60 | dir = path.Dir(dir) |
| 61 | } |
| 62 | } |
| 63 | |
| 64 | // Get returns the workspace directory from which a given |
| 65 | // command line tool is running. This handles the following |
| 66 | // cases: |
| 67 | // |
| 68 | // 1. The command line tool was invoked via `bazel run`. |
| 69 | // 2. The command line tool was started in the workspace directory or a |
| 70 | // subdirectory. |
| 71 | // |
| 72 | // If the workspace directory path cannot be inferred based on the above |
| 73 | // assumptions, an error is returned. |
| 74 | func Get() (string, error) { |
| 75 | workspaceOnce.Do(func() { |
| 76 | workspace, workspaceErr = get() |
| 77 | }) |
| 78 | return workspace, workspaceErr |
| 79 | } |
| 80 | |
| 81 | var ( |
| 82 | workspace string |
| 83 | workspaceErr error |
| 84 | workspaceOnce sync.Once |
| 85 | ) |
| 86 | |
| 87 | func get() (string, error) { |
| 88 | if p := os.Getenv("BUILD_WORKSPACE_DIRECTORY"); p != "" && isWorkspace(p) { |
| 89 | return p, nil |
| 90 | } |
| 91 | |
| 92 | wd, err := os.Getwd() |
| 93 | if err != nil { |
| 94 | return "", err |
| 95 | } |
| 96 | p, err := lookForWorkspace(wd) |
| 97 | if err != nil { |
| 98 | return "", fmt.Errorf("not invoked from `bazel run` and could not find workspace root by traversing upwards: %w", err) |
| 99 | } |
| 100 | return p, nil |
| 101 | } |