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feat: resolve
unzip using package.json browser field (#50)
* feat: resolve unzip using package.json browser field * chore: complete shim implementation * feat: resolve fs-extra as empty for browser
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,156 @@ | ||
| /* eslint-disable consistent-return */ | ||
| const { Z_SYNC_FLUSH, Inflate } = require('pako') | ||
|
|
||
| // browserify-zlib, which is the zlib shim used by default in webpacked code, | ||
| // does not properly uncompress bgzf chunks that contain more than | ||
| // one bgzf block, so export an unzip function that uses pako directly | ||
| // if we are running in a browser. | ||
| async function unzip(inputData) { | ||
| try { | ||
| let strm | ||
| let pos = 0 | ||
| let i = 0 | ||
| const chunks = [] | ||
| let inflator | ||
| do { | ||
| const remainingInput = inputData.slice(pos) | ||
| inflator = new Inflate() | ||
| ;({ strm } = inflator) | ||
| inflator.push(remainingInput, Z_SYNC_FLUSH) | ||
| if (inflator.err) throw new Error(inflator.msg) | ||
|
|
||
| pos += strm.next_in | ||
| chunks[i] = Buffer.from(inflator.result) | ||
| i += 1 | ||
| } while (strm.avail_in) | ||
|
|
||
| const result = Buffer.concat(chunks) | ||
| return result | ||
| } catch (e) { | ||
| if (e.message.match(/incorrect header check/)) { | ||
| throw new Error( | ||
| 'problem decompressing block: incorrect gzip header check', | ||
| ) | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // similar to pakounzip, except it does extra counting | ||
| // to return the positions of compressed and decompressed | ||
| // data offsets | ||
| async function unzipChunk(inputData) { | ||
| try { | ||
| let strm | ||
| let cpos = 0 | ||
| let dpos = 0 | ||
| const blocks = [] | ||
| const cpositions = [] | ||
| const dpositions = [] | ||
| do { | ||
| const remainingInput = inputData.slice(cpos) | ||
| const inflator = new Inflate() | ||
| // @ts-ignore | ||
| ;({ strm } = inflator) | ||
| // @ts-ignore | ||
| inflator.push(remainingInput, Z_SYNC_FLUSH) | ||
| if (inflator.err) throw new Error(inflator.msg) | ||
|
|
||
| // @ts-ignore | ||
| const buffer = Buffer.from(inflator.result) | ||
| blocks.push(buffer) | ||
|
|
||
| cpositions.push(cpos) | ||
| dpositions.push(dpos) | ||
|
|
||
| cpos += strm.next_in | ||
| dpos += buffer.length | ||
| } while (strm.avail_in) | ||
|
|
||
| const buffer = Buffer.concat(blocks) | ||
| return { buffer, cpositions, dpositions } | ||
| } catch (e) { | ||
| if (e.message.match(/incorrect header check/)) { | ||
| throw new Error( | ||
| 'problem decompressing block: incorrect gzip header check', | ||
| ) | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // similar to unzipChunk above but slices (0,minv.dataPosition) and (maxv.dataPosition,end) off | ||
| async function unzipChunkSlice(inputData, chunk) { | ||
| try { | ||
| let strm | ||
| let cpos = chunk.minv.blockPosition | ||
| let dpos = chunk.minv.dataPosition | ||
| const decompressedBlocks = [] | ||
| const cpositions = [] | ||
| const dpositions = [] | ||
| do { | ||
| const remainingInput = inputData.slice(cpos - chunk.minv.blockPosition) | ||
| const inflator = new Inflate() | ||
| // @ts-ignore | ||
| ;({ strm } = inflator) | ||
| // @ts-ignore | ||
| inflator.push(remainingInput, Z_SYNC_FLUSH) | ||
| if (inflator.err) throw new Error(inflator.msg) | ||
|
|
||
| // @ts-ignore | ||
| const buffer = Buffer.from(inflator.result) | ||
| decompressedBlocks.push(buffer) | ||
| let len = buffer.length | ||
|
|
||
| cpositions.push(cpos) | ||
| dpositions.push(dpos) | ||
| if (decompressedBlocks.length === 1 && chunk.minv.dataPosition) { | ||
| // this is the first chunk, trim it | ||
| decompressedBlocks[0] = decompressedBlocks[0].slice( | ||
| chunk.minv.dataPosition, | ||
| ) | ||
| len = decompressedBlocks[0].length | ||
| } | ||
| const origCpos = cpos | ||
| cpos += strm.next_in | ||
| dpos += len | ||
|
|
||
| if (origCpos >= chunk.maxv.blockPosition) { | ||
| // this is the last chunk, trim it and stop decompressing | ||
| // note if it is the same block is minv it subtracts that already | ||
| // trimmed part of the slice length | ||
|
|
||
| decompressedBlocks[decompressedBlocks.length - 1] = decompressedBlocks[ | ||
| decompressedBlocks.length - 1 | ||
| ].slice( | ||
| 0, | ||
| chunk.maxv.blockPosition === chunk.minv.blockPosition | ||
| ? chunk.maxv.dataPosition - chunk.minv.dataPosition + 1 | ||
| : chunk.maxv.dataPosition + 1, | ||
| ) | ||
|
|
||
| cpositions.push(cpos) | ||
| dpositions.push(dpos) | ||
| break | ||
| } | ||
| } while (strm.avail_in) | ||
|
|
||
| const buffer = Buffer.concat(decompressedBlocks) | ||
| return { buffer, cpositions, dpositions } | ||
| } catch (e) { | ||
| if (e.message.match(/incorrect header check/)) { | ||
| throw new Error( | ||
| 'problem decompressing block: incorrect gzip header check', | ||
| ) | ||
| } | ||
| throw e | ||
| } | ||
| } | ||
|
|
||
| module.exports = { | ||
| unzip, | ||
| unzipChunk, | ||
| unzipChunkSlice, | ||
| pakoUnzip: unzip, | ||
| nodeUnzip: () => { | ||
| throw new Error('nodeUnzip not implemented.') | ||
| }, | ||
| } |
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