diff --git a/CLAUDE.md b/CLAUDE.md
index 6a15a87..3242962 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -39,13 +39,13 @@ Everything happens in `main()` in `main.go`, in a straight-line pipeline:
- `go.abhg.dev/goldmark/mermaid` with `NoScript: true` (diagram rendering is handled ourselves)
- `html.WithUnsafe()` (raw HTML passthrough is required for the image-tag handling above)
4. **Title extraction** (`getTitleFromAST`/`extractText`) — walks the parsed AST for the first H1 to use as the ``.
-5. **Mermaid script embedding** (`embedMermaidScript`) — only injects the embedded `mermaid.min.js` + an init script (with light/dark theme detection via `prefers-color-scheme`) if the rendered HTML actually contains a mermaid block, keeping non-diagram output lean.
-6. **Templating & output** — `template.html` and `github-markdown.css` are embedded via `//go:embed` and combined with the rendered content via `fmt.Fprintf`. `-bare` skips the CSS. Output goes to `-o <path>` if given, otherwise a random temp filename (see below).
+5. **Mermaid script embedding** (`embedMermaidScript`) — only injects the embedded `mermaid.min.js` + an init script (with light/dark theme detection via `prefers-color-scheme`) if the parsed AST contains a mermaid block (`hasMermaidBlock`; raw HTML that mentions `class="mermaid"` does not count), keeping non-diagram output lean.
+6. **Templating & output** — `template.html` and `github-markdown.css` are embedded via `//go:embed` and combined with the rendered content via `fmt.Fprintf`. `-bare` skips the CSS. `writeOutput` writes the file and reports write and close errors. Output goes to `-o <path>` if given, otherwise a random temp filename (see below).
7. **Launch** — opens the resulting HTML file via `github.com/pkg/browser`.
### Temp file / Snap sandboxing (`getTempDir`, `isSnap`)
-Output location resolution order: `MDVIEW_DIR` env var → (if running as a Snap, per `SNAP_USER_COMMON` env var) `~/mdview-temp` → OS default temp dir. This exists because Snap-sandboxed browsers (e.g. Snap Firefox) can't read from `/tmp`, only from the user's home directory — `check()` also prints a Snap-specific hint on file errors for this reason.
+Output location resolution order: `MDVIEW_DIR` env var → (if running as a Snap, per `SNAP_USER_COMMON` env var) `~/mdview-temp` → OS default temp dir. `MDVIEW_DIR` and `~/mdview-temp` are created with `MkdirAll`. Before writing a temp file, `removeStaleTempFiles` deletes generated `mdview<32 hex>.html` files older than 24 hours from that directory (the browser reads the new file after mdview exits, so mdview cannot delete it right away). This exists because Snap-sandboxed browsers (e.g. Snap Firefox) can't read from `/tmp`, only from the user's home directory — `check()` writes errors to stderr, names the failing path, and prints a Snap-specific hint for permission and not-found errors for this reason.
### Packaging
diff --git a/main.go b/main.go
index 3b48418..4d359ab 100644
--- a/main.go
+++ b/main.go
@@ -18,6 +18,7 @@ import (
"path/filepath"
"regexp"
"strings"
+ "time"
"github.com/pkg/browser"
"github.com/yuin/goldmark"
@@ -123,32 +124,27 @@ func main() {
// Render to HTML
var buf bytes.Buffer
- if err := md.Renderer().Render(&buf, dat, doc); err != nil {
- log.Fatal(err)
- }
+ check(md.Renderer().Render(&buf, dat, doc))
htmlContent := buf.String()
-
+
// Add embedded Mermaid.js and initialization script when diagrams are present
- htmlContent = embedMermaidScript(htmlContent)
+ if hasMermaidBlock(doc) {
+ htmlContent = embedMermaidScript(htmlContent)
+ }
outfilePath := *outfilePtr
if outfilePath == "" {
- outfilePath = tempFileName("mdview", ".html")
+ tempDir := getTempDir()
+ removeStaleTempFiles(tempDir, staleTempFileAge)
+ outfilePath = tempFileName(tempDir, "mdview", ".html")
}
- f, err := os.Create(outfilePath)
- check(err)
- defer f.Close()
- var actualStyle string
+ actualStyle := style
if *barePtr {
actualStyle = ""
- } else {
- actualStyle = style
}
- _, err = fmt.Fprintf(f, template, actualStyle, stdhtml.EscapeString(title), htmlContent)
- check(err)
- f.Sync()
+ check(writeOutput(outfilePath, actualStyle, stdhtml.EscapeString(title), htmlContent))
browser.Stderr = nil
browser.Stdout = nil
err = browser.OpenFile(outfilePath)
@@ -189,54 +185,102 @@ func stdinIsTerminal() bool {
return err == nil && info.Mode()&os.ModeCharDevice != 0
}
-func tempFileName(prefix, suffix string) string {
+// writeOutput writes the HTML document to path and reports any write or close error
+func writeOutput(path string, style string, title string, content string) error {
+ f, err := os.Create(path)
+ if err != nil {
+ return err
+ }
+ if _, err := fmt.Fprintf(f, template, style, title, content); err != nil {
+ f.Close()
+ return err
+ }
+ if err := f.Sync(); err != nil {
+ f.Close()
+ return err
+ }
+ return f.Close()
+}
+
+func tempFileName(dir, prefix, suffix string) string {
randBytes := make([]byte, 16)
rand.Read(randBytes)
- return filepath.Join(getTempDir(), prefix+hex.EncodeToString(randBytes)+suffix)
+ return filepath.Join(dir, prefix+hex.EncodeToString(randBytes)+suffix)
+}
+
+// staleTempFileAge is how old a generated temp file must be before mdview removes it
+const staleTempFileAge = 24 * time.Hour
+
+// tempFileRegex matches the names produced by tempFileName, so cleanup never touches other files
+var tempFileRegex = regexp.MustCompile(`^mdview[0-9a-f]{32}\.html$`)
+
+// removeStaleTempFiles deletes generated temp files in dir that are older than maxAge.
+// The browser reads the current file after mdview exits, so only older files are removed.
+func removeStaleTempFiles(dir string, maxAge time.Duration) {
+ entries, err := os.ReadDir(dir)
+ if err != nil {
+ return
+ }
+ for _, entry := range entries {
+ if !entry.Type().IsRegular() || !tempFileRegex.MatchString(entry.Name()) {
+ continue
+ }
+ if info, err := entry.Info(); err == nil && time.Since(info.ModTime()) > maxAge {
+ os.Remove(filepath.Join(dir, entry.Name()))
+ }
+ }
}
func getTempDir() string {
if os.Getenv("MDVIEW_DIR") != "" {
var tempDir = os.Getenv(("MDVIEW_DIR"))
- if _, err := os.Stat(tempDir); os.IsNotExist(err) {
- err = os.Mkdir(tempDir, 0700)
- check(err)
- }
-
+ check(os.MkdirAll(tempDir, 0700))
return tempDir
}
if isSnap() {
var tmpdir = os.Getenv("HOME") + "/mdview-temp"
- if _, err := os.Stat(tmpdir); os.IsNotExist(err) {
- err = os.Mkdir(tmpdir, 0700)
- check(err)
- }
+ check(os.MkdirAll(tmpdir, 0700))
return tmpdir
}
return os.TempDir()
}
+// check prints a failure to standard error and exits with status 1
func check(e error) {
- if e != nil {
- if errors.Is(e, fs.ErrPermission) {
- fmt.Println("There was a permission error accessing the file.")
- }
+ if e == nil {
+ return
+ }
- if errors.Is(e, fs.ErrNotExist) {
- fmt.Println("mdview was unable to find the file.")
- }
+ permission := errors.Is(e, fs.ErrPermission)
+ notExist := errors.Is(e, fs.ErrNotExist)
- if isSnap() {
- fmt.Println("Since mdview was installed as a Snap, it can only access files in your HOME directory.")
- fmt.Println("If you need to use it with files outside of your HOME directory, choose a different installation method.")
- fmt.Println("https://github.com/mapitman/mdview?tab=readme-ov-file#installation")
- fmt.Println()
- }
+ // Name the path, because the failing file can be the input, the output or the output directory
+ target := "the file"
+ var pathErr *fs.PathError
+ if errors.As(e, &pathErr) {
+ target = pathErr.Path
+ }
- log.Fatal(e)
+ if permission {
+ fmt.Fprintf(os.Stderr, "There was a permission error accessing %s.\n", target)
}
+
+ if notExist {
+ fmt.Fprintf(os.Stderr, "mdview was unable to find %s.\n", target)
+ }
+
+ // The Snap sandbox only blocks file access, so show its hint for those errors only
+ if isSnap() && (permission || notExist) {
+ fmt.Fprintln(os.Stderr, "Since mdview was installed as a Snap, it can only access files in your HOME directory.")
+ fmt.Fprintln(os.Stderr, "If you need to use it with files outside of your HOME directory, choose a different installation method.")
+ fmt.Fprintln(os.Stderr, "https://github.com/mapitman/mdview?tab=readme-ov-file#installation")
+ fmt.Fprintln(os.Stderr)
+ }
+
+ fmt.Fprintln(os.Stderr, "mdview:", e)
+ os.Exit(1)
}
func getTitleFromAST(doc ast.Node, source []byte) string {
@@ -533,15 +577,23 @@ func getMimeType(path string) string {
return ""
}
+// hasMermaidBlock reports whether the document contains a mermaid code block.
+// Checking the AST ignores raw HTML that merely mentions class="mermaid".
+func hasMermaidBlock(doc ast.Node) bool {
+ found := false
+ _ = ast.Walk(doc, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
+ if entering && n.Kind() == mermaid.Kind {
+ found = true
+ return ast.WalkStop, nil
+ }
+ return ast.WalkContinue, nil
+ })
+ return found
+}
+
// embedMermaidScript adds the embedded Mermaid.js library to the HTML content
// Since we set NoScript: true on the Mermaid extender, we need to manually add the script
func embedMermaidScript(htmlContent string) string {
- // Check if there are any mermaid diagrams in the content
- // The Goldmark mermaid extension uses class="mermaid" for diagram blocks
- if !strings.Contains(htmlContent, `class="mermaid"`) {
- return htmlContent // No mermaid diagrams, don't add the script
- }
-
// Escape any </script> tags (with closing >) inside the mermaid.js code
// to prevent premature script closure. The standard way is to escape the forward slash.
escapedMermaidJS := strings.ReplaceAll(mermaidJS, "</script>", "<\\/script>")
diff --git a/main_test.go b/main_test.go
index 4d4c620..2b5b8c8 100644
--- a/main_test.go
+++ b/main_test.go
@@ -10,6 +10,7 @@ import (
"reflect"
"strings"
"testing"
+ "time"
"github.com/yuin/goldmark"
"github.com/yuin/goldmark/text"
@@ -274,3 +275,116 @@ func TestParseFlags(t *testing.T) {
})
}
}
+
+func TestHasMermaidBlock(t *testing.T) {
+ tests := []struct {
+ name string
+ markdown string
+ want bool
+ }{
+ {"mermaid fence", "```mermaid\ngraph TD; A-->B\n```\n", true},
+ {"other fence", "```go\nfmt.Println()\n```\n", false},
+ {"no code", "# Title\n\ntext\n", false},
+ {"raw html mentioning mermaid", "<pre class=\"mermaid\">graph TD</pre>\n", false},
+ {"code span mentioning mermaid", "Use `class=\"mermaid\"` in HTML.\n", false},
+ }
+ for _, tt := range tests {
+ t.Run(tt.name, func(t *testing.T) {
+ source := []byte(tt.markdown)
+ doc := newMarkdown(".").Parser().Parse(text.NewReader(source))
+ if got := hasMermaidBlock(doc); got != tt.want {
+ t.Fatalf("hasMermaidBlock = %v, want %v", got, tt.want)
+ }
+ })
+ }
+}
+
+func TestEmbedMermaidScript(t *testing.T) {
+ out := embedMermaidScript("<p>x</p>")
+ if !strings.HasPrefix(out, "<p>x</p><script>") || !strings.Contains(out, "mermaid.initialize") {
+ t.Fatalf("mermaid script was not appended: %.80s", out)
+ }
+ if strings.Count(out, "</script>") != 2 {
+ t.Fatalf("expected exactly two closing script tags, got %d", strings.Count(out, "</script>"))
+ }
+}
+
+func TestGetTempDir(t *testing.T) {
+ t.Run("MDVIEW_DIR is created with parents", func(t *testing.T) {
+ dir := filepath.Join(t.TempDir(), "a", "b", "c")
+ t.Setenv("MDVIEW_DIR", dir)
+ if got := getTempDir(); got != dir {
+ t.Fatalf("getTempDir = %q, want %q", got, dir)
+ }
+ if info, err := os.Stat(dir); err != nil || !info.IsDir() {
+ t.Fatalf("directory was not created: %v", err)
+ }
+ })
+
+ t.Run("snap uses mdview-temp in HOME", func(t *testing.T) {
+ home := t.TempDir()
+ t.Setenv("MDVIEW_DIR", "")
+ t.Setenv("SNAP_USER_COMMON", "/snap/common")
+ t.Setenv("HOME", home)
+ want := filepath.Join(home, "mdview-temp")
+ if got := getTempDir(); got != want {
+ t.Fatalf("getTempDir = %q, want %q", got, want)
+ }
+ })
+
+ t.Run("default is the OS temp dir", func(t *testing.T) {
+ t.Setenv("MDVIEW_DIR", "")
+ t.Setenv("SNAP_USER_COMMON", "")
+ if got := getTempDir(); got != os.TempDir() {
+ t.Fatalf("getTempDir = %q, want %q", got, os.TempDir())
+ }
+ })
+}
+
+func TestWriteOutput(t *testing.T) {
+ dir := t.TempDir()
+ path := filepath.Join(dir, "out.html")
+ if err := writeOutput(path, "body{}", "T", "<p>hi</p>"); err != nil {
+ t.Fatal(err)
+ }
+ got, err := os.ReadFile(path)
+ if err != nil || !strings.Contains(string(got), "<title>T") || !strings.Contains(string(got), "hi
") {
+ t.Fatalf("unexpected output (err %v): %s", err, got)
+ }
+ if err := writeOutput(filepath.Join(dir, "missing", "out.html"), "", "T", ""); err == nil {
+ t.Fatal("expected an error for a missing directory")
+ }
+}
+
+func TestRemoveStaleTempFiles(t *testing.T) {
+ dir := t.TempDir()
+ name := func(c string) string { return "mdview" + strings.Repeat(c, 32) + ".html" }
+ old := time.Now().Add(-48 * time.Hour)
+
+ files := map[string]time.Time{
+ name("a"): old, // stale generated file: removed
+ name("b"): time.Now(), // fresh generated file: kept
+ "notes.html": old, // other file: kept
+ "mdview-old.html": old, // wrong name pattern: kept
+ name("c") + "x": old, // wrong suffix: kept
+ }
+ for file, mtime := range files {
+ path := filepath.Join(dir, file)
+ if err := os.WriteFile(path, []byte("x"), 0644); err != nil {
+ t.Fatal(err)
+ }
+ if err := os.Chtimes(path, mtime, mtime); err != nil {
+ t.Fatal(err)
+ }
+ }
+
+ removeStaleTempFiles(dir, staleTempFileAge)
+
+ for file := range files {
+ _, err := os.Stat(filepath.Join(dir, file))
+ wantRemoved := file == name("a")
+ if wantRemoved != os.IsNotExist(err) {
+ t.Errorf("%s: removed = %v, want %v", file, os.IsNotExist(err), wantRemoved)
+ }
+ }
+}