The last route took any image whose id or address contained "cover", so
images/discover-ch1.png listed before images/cover.jpg won, and
recovery-map.png alone became the cover. A name now says cover only with
it as a word of its own: words break at anything not a letter or digit
and where a lower case letter meets a capital, so CoverImage and
Book_COVER still do. An image named cover outright comes first, then
manifest order. It is still a guess.
The guide's cover page took its first image, which can be a logo. Where
the page has several, the one whose file name, alt, id or class says
cover is taken; where none does, the first is, with a note saying how
many there were.
Each member was read no further than MAX_COVER, but nothing bounded how
many: two hundred cover-named images of 16 MiB took seven seconds to
inflate and left two hundred notes. One search now reads at most eight
members and stops with one note.
A percent-escape takes two hex digits and nothing else. from_str_radix
also takes a sign, so a%+fb decoded to a, 0x0f, b.
bookmeta: Cover::guessed says the file left the choice open — a Kindle
book's first image record, or an EPUB image picked because its name says
cover — so a caller with a register to ask can prefer that. A cover the
file names is never a guess. Cover::extension matches bibfetch's.
bibfetch: Open Library answers 403 to more than a hundred covers by ISBN
in five minutes from one address. That is now Error::Limited, not
Unreachable: the other form of the ISBN is not asked, the cover id still
is, since those are not limited, and the CLI exits 75. Covers asked by
ISBN are kept three seconds apart across the process (Covers::pace), which
stays under the limit however long a run goes. A deadline too long to add
to the clock no longer panics; it is no deadline.
bindings: fetch_cover and search_title for Python, and catena.Limited,
which fetch_identifier raises too when a register refuses for being asked
too often.
corpus-core: exit 75, a service refused for now.
The cover is the first image reached by EPUB 3's cover-image property,
EPUB 2's <meta name="cover"> (by id, or by address where a converter wrote
one), the guide's cover page and the first <img> or SVG <image> on it, and
last any manifest image whose id or address says cover. A route that names
something unusable leaves a note and the next is asked.
Addresses are resolved against the document they are written in, with the
fragment off and percent-escapes undone; one that climbs out of the archive
or carries a scheme is not followed. Every member is read through a bound,
checked against the size the archive declares and enforced on the read
itself, so an understated entry stops at the cap too.
The media type is read off the bytes, now WebP as well, and a manifest that
disagrees is a note; bytes that are not an image are no cover. MAX_COVER
(16 MiB) is the cap for both formats, so a Kindle cover record larger than
that is left out as well.
When a MOBI or AZW3 file names no cover (no EXTH 201 or 202), the cover is
the record at the first image index if it is a JPEG, PNG or GIF, and
nothing otherwise, as calibre does (metadata/mobi.py:524-532). The walk to
the next image is gone: a later record may be an inline illustration, and
kindlegen puts a font or RESC record first.
EXTH 121 is no longer read, which also stops a stale KF8 boundary below
first_image from hiding the cover.
EXTH 113 is an ASIN only when it is ten letters and digits; a UUID goes
under uuid, as the EPUB reader files it, and anything else under other.
With no EXTH 201 or 202, the first record from the first image index that
is a JPEG, PNG or GIF is the cover, stopping at the KF8 boundary (EXTH 121).
A Kindle book's title, authors, publisher, description, ISBN, ASIN,
subjects, date and language come from the EXTH block, with the full name,
the Palm database name and the header's locale as fallbacks. The cover
image (EXTH 201, or the thumbnail) is returned as Metadata::cover with its
media type; it stays out of the JSON record. Every offset is bounds-checked:
a damaged header gives an empty record with a note, a broken EXTH block
keeps what came before the break, and an encrypted book is still read and
noted as drm.
Metadata gains description, which the EPUB reader now fills from
dc:description as well.
Fixtures are a story and cover written for the tests (CC0), converted with
calibre to MOBI 6 and AZW3, plus no-EXTH, DRM-flagged and truncated copies.
funkpower