diff options
| -rw-r--r-- | emms-info-native.el | 108 |
1 files changed, 42 insertions, 66 deletions
diff --git a/emms-info-native.el b/emms-info-native.el index dc2bbbd..91b3ff5 100644 --- a/emms-info-native.el +++ b/emms-info-native.el @@ -425,8 +425,11 @@ header.") ;;;; FLAC code (defconst emms-info-native--flac-metadata-block-header-bindat-spec - '((block-type u8) - (block-length u24)) + '((flags u8) + (length u24) + (eval (when (or (> last emms-info-native--max-peek-size) + (= last 0)) + (error "FLAC block length %s is invalid" last)))) "FLAC metadata block header specification.") (defconst emms-info-native--flac-comment-block-bindat-spec @@ -436,12 +439,12 @@ header.") (vendor-string vec (vendor-length)) (user-comments-list-length u32r) (eval (when (> last emms-info-native--max-num-vorbis-comments) - (error "FLAC user comment list length %s is too long" last))) + (error "FLAC user comment list length %s is too long" + last))) (user-comments repeat (user-comments-list-length) (struct emms-info-native--vorbis-comment-field-bindat-spec))) - "FLAC Vorbis comment block specification. -Too long vendor string and comment list will trigger an error.") + "FLAC Vorbis comment block specification.") (defun emms-info-native--has-flac-signature (filename) "Check for FLAC stream marker at the beginning of FILENAME. @@ -451,74 +454,47 @@ Return t if there is a valid stream marker, nil otherwise." (insert-file-contents-literally filename nil 0 4) (looking-at "fLaC"))) -(defun emms-info-native--flac-decode-block-header (filename offset) - "Read and decode FLAC metadata block header from FILENAME starting at OFFSET. -Return a list (TYPE NEXT-OFFSET LAST). Here, TYPE is the FLAC -metadata block type; NEXT-OFFSET is the starting offset of the -next block; and LAST is t if this was the last metadata block in -the stream, otherwise nil." - (let (block-header - block-type - block-length - end - last-flag) - (insert-file-contents-literally filename nil offset (+ offset 4) t) - (setq offset (+ offset 4)) - (setq block-header - (bindat-unpack emms-info-native--flac-metadata-block-header-bindat-spec - (buffer-string))) - (setq block-type - (logand (bindat-get-field block-header 'block-type) - #x7F)) - (setq block-length (bindat-get-field block-header 'block-length)) - (when (> block-type 6) - (error "FLAC block type error: expected <= 6, got %s" block-type)) - (when (= block-length 0) - (error "FLAC block length error: expected >0, got zero")) - (setq last-flag (= (logand (bindat-get-field block-header 'block-type) - #x80) - 1)) - (setq end (+ offset block-length)) - (list block-type end last-flag))) - -(defun emms-info-native--flac-decode-comment-block (filename) - "Find and decode a comment block from FLAC file FILENAME. -Return the comment block in a vector. Trigger an error if any -metadata block larger than ‘emms-info-native--max-peek-size’ is -encountered." +(defun emms-info-native--decode-flac-comment-block (filename) + "Read and decode a comment block from FLAC file FILENAME. +Return the comment block data in a vector." (with-temp-buffer (set-buffer-multibyte nil) - (unless (emms-info-native--has-flac-signature filename) - (error "Invalid FLAC stream")) - (let ((offset 4) - (comment-block (vector)) - block-type - end - last-flag) - (while (not last-flag) - (cl-multiple-value-setq (block-type - end - last-flag) - (emms-info-native--flac-decode-block-header filename offset)) - (when (> (- end offset) emms-info-native--max-peek-size) - (error "FLAC metadata block is too large: %s" (- end offset))) - (when (= block-type 4) - ;; Comment block found, extract it. - (insert-file-contents-literally filename nil (+ offset 4) end t) - (setq comment-block (vconcat (buffer-string)) - last-flag t)) - (setq offset end)) + (let (comment-block + last-flag + (offset 4)) + (while (and (not comment-block) (not last-flag)) + (insert-file-contents-literally filename + nil + offset + (cl-incf offset 4)) + (let* ((header (bindat-unpack emms-info-native--flac-metadata-block-header-bindat-spec + (buffer-string))) + (end (+ offset (bindat-get-field header 'length))) + (flags (bindat-get-field header 'flags)) + (block-type (logand flags #x7F))) + (setq last-flag (> (logand flags #x80) 0)) + (when (> block-type 6) + (error "FLAC block type error: expected ≤ 6, got %s" + block-type)) + (when (= block-type 4) + ;; Comment block found, extract it. + (insert-file-contents-literally filename nil offset end t) + (setq comment-block (vconcat (buffer-string)))) + (setq offset end))) comment-block))) -(defun emms-info-native--flac-decode-comments (filename) +(defun emms-info-native--decode-flac-comments (filename) "Read and decode comments from FLAC file FILENAME. Return comments in a list of (FIELD . VALUE) cons cells. Only FIELDs that are listed in ‘emms-info-native--accepted-vorbis-fields’ are returned." - (let* ((comment-block (bindat-unpack emms-info-native--flac-comment-block-bindat-spec - (emms-info-native--flac-decode-comment-block filename))) - (user-comments (bindat-get-field comment-block - 'user-comments))) + (unless (emms-info-native--has-flac-signature filename) + (error "Invalid FLAC stream")) + (let* ((block (emms-info-native--decode-flac-comment-block + filename)) + (unpacked (bindat-unpack emms-info-native--flac-comment-block-bindat-spec + block)) + (user-comments (bindat-get-field unpacked 'user-comments))) (emms-info-native--extract-vorbis-comments user-comments))) ;;;; id3v2 (MP3) code @@ -715,7 +691,7 @@ strings." (cond ((or (eq stream-type 'vorbis) (eq stream-type 'opus)) (emms-info-native--decode-ogg-comments filename stream-type)) ((eq stream-type 'flac) - (emms-info-native--flac-decode-comments filename)) + (emms-info-native--decode-flac-comments filename)) ((eq stream-type 'mp3) (emms-info-native--decode-id3v2 filename)) (t nil)))) |