mirror of
https://github.com/fastfetch-cli/fastfetch.git
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Carter Li
67 lines
3.4 KiB
C
67 lines
3.4 KiB
C
#pragma once
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#include "fastfetch.h"
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// Locating an entry inside a zip, which is what both the jar reader and the app label reader need:
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// one looks for `classesN.dex`, the other for the resource table of an APK.
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//
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// The entry is found through the central directory rather than by scanning for its local header,
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// and that is not a micro-optimisation. A local header is preceded by everything that came before
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// it, so scanning costs a pass over all of it, once per lookup: `framework.jar` is 52 MB and its
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// `classes2.dex` starts 9.6 MB in. Measured on the test device, where the sound module resolves
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// seven codes, looking the entries up by scanning was the difference between 30 ms and 2 seconds.
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//
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// The sizes and the compression method are read from the directory rather than from the entry's own
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// local header, which is the more reliable of the two: a local header is allowed to leave its sizes
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// at zero and put them in a data descriptor behind the payload, and an archive writer is free to
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// choose that. Only the local header's two length fields are used, because they are what says where
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// the payload begins -- the local extra field does not have to match the central one.
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// The zip local file header, from APPNOTE.TXT 4.3.7.
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#define FF_ZIP_LOCAL_HEADER_SIZE 30
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#define FF_ZIP_OFF_NAME_LENGTH 26
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#define FF_ZIP_OFF_EXTRA_LENGTH 28
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// The central directory.
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#define FF_ZIP_CENTRAL_MAGIC "PK\x01\x02"
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#define FF_ZIP_CENTRAL_SIZE 46
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#define FF_ZIP_OFF_CENTRAL_METHOD 10
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#define FF_ZIP_OFF_CENTRAL_COMPRESSED_SIZE 20
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#define FF_ZIP_OFF_CENTRAL_UNCOMPRESSED_SIZE 24
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#define FF_ZIP_OFF_CENTRAL_NAME_LENGTH 28
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#define FF_ZIP_OFF_CENTRAL_EXTRA_LENGTH 30
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#define FF_ZIP_OFF_CENTRAL_COMMENT_LENGTH 32
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#define FF_ZIP_OFF_CENTRAL_LOCAL_OFFSET 42
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// The end of central directory record, which points at the directory. It is the last thing in the
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// file, behind a comment of at most 64 KiB, so it is searched for backwards over that much.
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#define FF_ZIP_EOCD_MAGIC "PK\x05\x06"
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#define FF_ZIP_EOCD_SIZE 22
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#define FF_ZIP_EOCD_MAX_COMMENT 0xffffu
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#define FF_ZIP_OFF_EOCD_DIRECTORY_SIZE 12
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#define FF_ZIP_OFF_EOCD_DIRECTORY 16
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// A size or offset of 0xFFFFFFFF means the real one is in a zip64 extra field. AOSP's framework jars
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// and the APKs measured so far are orders of magnitude below that, and carrying the extra field
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// reader for them is not worth it.
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#define FF_ZIP_ZIP64_SENTINEL 0xffffffffu
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#define FF_ZIP_METHOD_STORED 0
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#define FF_ZIP_METHOD_DEFLATED 8
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// One entry, as the archive describes it. `payload` points into the mapping the caller passed in and
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// is not a copy: for a STORED entry it is the file's own bytes, and for a DEFLATED one it is the raw
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// deflate stream, which the caller inflates with `uncompressedSize` as the bound.
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typedef struct FFAndroidZipEntry {
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const uint8_t* payload;
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size_t payloadSize;
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uint32_t uncompressedSize;
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uint16_t method;
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} FFAndroidZipEntry;
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// Resolves `entry` through the archive's central directory, writing where its payload is into
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// `result`. Returns nullptr on success, a static message otherwise -- an archive that is not a zip,
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// a directory that is out of range, an entry that is not there and an entry stored as zip64 are all
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// reported rather than answered with a pointer into nothing.
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[[gnu::nonnull(1, 3, 4), nodiscard]] const char* ffAndroidZipFindEntry(const uint8_t* archive, size_t archiveSize, const char* entry, FFAndroidZipEntry* result);
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