zlib Changelog

What's new in zlib 1.2.6

Feb 1, 2012
  • gzread() can now read a file that is being written concurrently
  • gzgetc() is now a macro for increased speed
  • Added a 'T' option to gzopen() for transparent writing (no compression)
  • Added deflatePending() to return the amount of pending output
  • Allow deflateSetDictionary() and inflateSetDictionary() at any time in raw mode
  • deflatePrime() can now insert bits in the middle of the stream
  • ./configure now creates a configure.log file with all of the results
  • Added a ./configure --solo option to compile zlib with no dependency on any libraries
  • Fixed a problem with large file support macros
  • Fixed a bug in contrib/puff
  • Many portability improvements

New in zlib 1.2.5 (Jun 10, 2010)

  • fixes bugs in gzseek() and gzeof() that were present in version 1.2.4 (

New in zlib 1.2.3 (Oct 23, 2008)

  • Eliminate a potential security vulnerability when decoding invalid compressed data
  • Eliminate a potential security vulnerability when decoding specially crafted compressed data
  • Fix a bug when decompressing dynamic blocks with no distance codes
  • Fix crc check bug in gzread() after gzungetc()
  • Do not return an error when using gzread() on an empty file