100 lines
2.3 KiB
JavaScript
100 lines
2.3 KiB
JavaScript
var mver = 3; // major version
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var ssz = 512; // sector size
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var mssz = 64; // mini sector size
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var nds = 0; // number of directory sectors
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var nfs = 0; // number of FAT sectors
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var nmfs = 0; // number of mini FAT sectors
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var ndfs = 0; // number of DIFAT sectors
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var dir_start = 0; // first directory sector location
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var minifat_start = 0; // first mini FAT sector location
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var difat_start = 0; // first mini FAT sector location
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var ms_cutoff_size = 4096; // mini stream cutoff size
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var minifat_store = 0; // first sector with minifat data
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var minifat_size = 0; // size of minifat data
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var fat_addrs = []; // locations of FAT sectors
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/* [MS-CFB] 2.2 Compound File Header */
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var blob = file.slice(0,512);
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prep_blob(blob);
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var read = ReadShift.bind(blob), chk = CheckField.bind(blob);
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var j = 0, q;
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// header signature 8
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chk(HEADER_SIGNATURE, 'Header Signature: ');
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// clsid 16
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chk(HEADER_CLSID, 'CLSID: ');
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// minor version 2
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read(2);
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// major version 3
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mver = read(2);
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switch(mver) {
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case 3: ssz = 512; break;
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case 4: ssz = 4096; break;
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default: throw "Major Version: Expected 3 or 4 saw " + mver;
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}
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// reprocess header
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var pos = blob.l;
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blob = file.slice(0,ssz);
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prep_blob(blob,pos);
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read = ReadShift.bind(blob);
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chk = CheckField.bind(blob);
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var header = file.slice(0,ssz);
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// Byte Order TODO
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chk('feff', 'Byte Order: ');
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// Sector Shift
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switch((q = read(2))) {
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case 0x09: if(mver !== 3) throw 'MajorVersion/SectorShift Mismatch'; break;
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case 0x0c: if(mver !== 4) throw 'MajorVersion/SectorShift Mismatch'; break;
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default: throw 'Sector Shift: Expected 9 or 12 saw ' + q;
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}
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// Mini Sector Shift
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chk('0600', 'Mini Sector Shift: ');
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// Reserved
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chk('000000000000', 'Mini Sector Shift: ');
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// Number of Directory Sectors
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nds = read(4);
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if(mver === 3 && nds !== 0) throw '# Directory Sectors: Expected 0 saw ' + nds;
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// Number of FAT Sectors
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nfs = read(4);
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// First Directory Sector Location
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dir_start = read(4);
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// Transaction Signature TODO
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read(4);
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// Mini Stream Cutoff Size TODO
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chk('00100000', 'Mini Stream Cutoff Size: ');
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// First Mini FAT Sector Location
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minifat_start = read(4);
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// Number of Mini FAT Sectors
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nmfs = read(4);
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// First DIFAT sector location
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difat_start = read(4);
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// Number of DIFAT Sectors
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ndfs = read(4);
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// Grab FAT Sector Locations
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for(j = 0; blob.l != 512; ) {
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if((q = read(4))>=MAXREGSECT) break;
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fat_addrs[j++] = q;
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}
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