The first led to an endless loop because of a missing "$feof"-check, the second caused the rare mentioned errors when encoding failed for some reason in larger files, especially when Unfortunately my "function" for encoding base64 on-the-fly from 2007 had 2 errors! However, this does make the assumption that the encoded data really is MIME-formatted without that assurance it is necessary to accept that the base64 data won't be so conveniently arranged. What that means is that each line can be decoded independently of the others, and the decoded chunks can then be concatenated together or written out sequentially. Obviously the last chunk will probably be shorter, but encoding it is still independent of the rest.Ĭonversely, each 76-character MIME-formatted line (not counting the trailing CRLF) contains exactly enough data for 57 bytes of output without needing to retain leftover bits that need prepending to the next line. Just read a chunk, encode it, write it out, and go on to the next chunk. There is no need to retain left-over symbols (either six- or eight-bit) from one chunk to the next. So if you read from the input file in chunks of 8151 (=57*143) bytes you will get (up to) 8151 eight-bit symbols, which encode as exactly 10868 six-bit symbols, which then wrap to exactly 143 MIME-formatted lines. Finally, PHP's default buffer size is 8192 bytes - enough for 143 MIME lines' worth of input.
Reading 57 eight-bit symbols provides exactly enough data for a complete MIME-formatted line. 76 characters is enough for 19 quadruples of six-bit symbols thus representing 19 triples of eight-bit symbols.
BASE64 XML DECODE PLUS
MIME additionally enforces a line length of 76 characters plus the CRLF.
Reading the input file in chunks that are a multiple of three bytes in length results in a chunk that can be encoded independently of the rest of the input file.
BASE64 XML DECODE ARCHIVE
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