diff options
| -rw-r--r-- | modules/music-config.el | 22 | ||||
| -rw-r--r-- | tests/test-music-config--append-track-to-m3u-file.el | 67 |
2 files changed, 81 insertions, 8 deletions
diff --git a/modules/music-config.el b/modules/music-config.el index 0834aae8..47863e41 100644 --- a/modules/music-config.el +++ b/modules/music-config.el @@ -696,14 +696,20 @@ M3U-FILE should be an existing, writable M3U file path." track-path (let ((rel (file-relative-name track-path dir))) (if (string-prefix-p "../" rel) track-path rel))))) - ;; Determine if we need a leading newline - (let ((needs-prefix-newline nil) - (file-size (file-attribute-size (file-attributes m3u-file)))) - (when (> file-size 0) - ;; Read the last character of the file to check if it ends with newline - (with-temp-buffer - (insert-file-contents m3u-file nil (max 0 (1- file-size)) file-size) - (setq needs-prefix-newline (not (= (char-after (point-min)) ?\n))))) + ;; Does the file need a separating newline first? Read the content and look + ;; at its last character, rather than seeking to a byte offset derived from + ;; `file-attributes'. That call does not follow symlinks, so on a + ;; stow-deployed playlist it measures the link string instead of the file: + ;; every symlinked playlist read the wrong byte and gained a blank line per + ;; append, and where the link string was the longer of the two the range fell + ;; outside the file entirely and the append died on a nil `char-after'. + ;; Playlists are small text files, so reading one is cheaper than being + ;; clever about offsets. + (let ((needs-prefix-newline + (with-temp-buffer + (insert-file-contents m3u-file) + (and (> (buffer-size) 0) + (/= (char-before (point-max)) ?\n))))) ;; Append the track with proper newline handling (with-temp-buffer diff --git a/tests/test-music-config--append-track-to-m3u-file.el b/tests/test-music-config--append-track-to-m3u-file.el index 9e5d0578..cc40438c 100644 --- a/tests/test-music-config--append-track-to-m3u-file.el +++ b/tests/test-music-config--append-track-to-m3u-file.el @@ -307,6 +307,73 @@ it." (concat existing-content relative-path "\n"))))) (test-music-config--append-track-to-m3u-file-teardown))) +;;; Boundary Cases: symlinked playlists + +(defun test-music-config--append--make-symlinked-playlist (base content link-depth) + "Create a playlist whose deployed path is a symlink, and return that path. +CONTENT is written to the real file. LINK-DEPTH controls how long the link +string is, which is the whole point: `file-attributes' does not follow +symlinks, so a writer sizing the file that way reads the length of the link +rather than the content." + (let* ((deployed (expand-file-name "deployed/" base)) + (deep (expand-file-name (mapconcat #'identity + (make-list link-depth "longdirname") + "/") + base)) + (real (expand-file-name "p.m3u" deep)) + (link (expand-file-name "p.m3u" deployed))) + (make-directory deep t) + (make-directory deployed t) + (with-temp-buffer (insert content) (write-file real)) + (make-symbolic-link (file-relative-name real deployed) link t) + link)) + +(ert-deftest test-music-config--append-track-to-m3u-file-boundary-symlink-longer-than-content () + "Boundary: appending to a symlinked playlist whose link string is longer than +its content must not signal. Sizing the file with `file-attributes' returns +the link's length, so the read range falls outside the file, nothing is +inserted, and `char-after' hands nil to a numeric comparison. Measured on the +real deployed set: 31 of 100 symlinked playlists are in this state." + (test-music-config--append-track-to-m3u-file-setup) + (unwind-protect + (let* ((base (cj/create-test-base-dir)) + (m3u-file (test-music-config--append--make-symlinked-playlist + base "https://example.com/s.mp3\n" 8)) + (track-path (expand-file-name "song.mp3" (file-name-directory m3u-file)))) + (should (> (file-attribute-size (file-attributes m3u-file)) + (file-attribute-size (file-attributes (file-truename m3u-file))))) + (cj/music--append-track-to-m3u-file track-path m3u-file) + ;; The seeded line is a stream URL, which the reader passes through, so + ;; both entries come back. + (should (equal (cj/music--m3u-file-tracks m3u-file) + (list "https://example.com/s.mp3" track-path)))) + (test-music-config--append-track-to-m3u-file-teardown))) + +(ert-deftest test-music-config--append-track-to-m3u-file-boundary-symlink-no-spurious-blank-line () + "Boundary: a symlinked playlist already ending in a newline gains no blank line. +The trailing-newline probe reads a byte chosen from the wrong size, so it +misreads a terminated file as unterminated and prepends a newline. All 100 +symlinked playlists in the deployed set read the wrong byte this way." + (test-music-config--append-track-to-m3u-file-setup) + (unwind-protect + ;; Content deliberately longer than the link string, so the misread byte + ;; still lands inside the file. That separates this from the sibling test + ;; above: here the probe reads a valid but wrong byte and silently + ;; misjudges, rather than reading past the end and signalling. + (let* ((base (cj/create-test-base-dir)) + (content (mapconcat (lambda (i) (format "track-%03d-with-a-longish-name.mp3" i)) + (number-sequence 1 12) "\n")) + (m3u-file (test-music-config--append--make-symlinked-playlist + base (concat content "\n") 2)) + (track-path (expand-file-name "second.mp3" (file-name-directory m3u-file)))) + (should (< (file-attribute-size (file-attributes m3u-file)) + (file-attribute-size (file-attributes (file-truename m3u-file))))) + (cj/music--append-track-to-m3u-file track-path m3u-file) + (with-temp-buffer + (insert-file-contents m3u-file) + (should (string= (buffer-string) (concat content "\nsecond.mp3\n"))))) + (test-music-config--append-track-to-m3u-file-teardown))) + ;;; Error Cases (ert-deftest test-music-config--append-track-to-m3u-file-error-nonexistent-file-signals-error () |