Message-ID: <467BA0FA.4050100@gsi.go.jp> Date: Fri, 22 Jun 2007 19:14:18 +0900 From: Yuki Hatanaka User-Agent: Thunderbird 1.5.0.10 (Windows/20070221) To: igsmail@igscb.jpl.nasa.gov Subject: [IGSMAIL-5615]: A harmful bug in CRX2RNX was found and fixed References: <46666F6A.60300@gsi.go.jp> <46675DE0.5070008@gsi.go.jp> <46695855.3050301@gsi.go.jp> In-Reply-To: <46695855.3050301@gsi.go.jp> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: owner-igsmail Precedence: bulk ****************************************************************************** IGS Electronic Mail 22 Jun 03:14:29 PDT 2007 Message Number 5615 ****************************************************************************** Author: Yuki Hatanaka Dear colleagues, A harmful bug was found in the RINEX uncompression program CRX2RNX. The bug resides only in the crx2rnx.c versions 4.0.0-4.0.2. Since rnx2crx.c is free from this bug, the Compact RINEX files just compressed with RNX2CRX of these versions are not affected (unless re-compressed after uncompression). I'm sorry for the trouble the bug may cause. All the package files in the GSI's FTP server was replaced with bug fixed ones with updating the version of software from 4.0.2 to 4.0.3: ftp://terras.gsi.go.jp/software/RNXCMP_4.0.3/ The followings are the detailes about the bug. Reported problem: CRX2RNX version 4.0.2 produced corrupted RINEX files when being applied to some of Compact RINEX files of 1 Hz sampling, although an old version (2.4.3) of CRX2RNX uncompressed the same file correctly. The cause: In process of uncompress of a data arc, value of some specific intermediate variables may drift in a randome-walk-like manner and may overflow eventually and corrupt the recovered output of RINEX files. The drift was caused by omission of carrying numbers in a intermediate process. The higher the sampling rate is, the more likely an overflow may take place, hence. Solution: Drift and overflow of the intermediate variable was prevented by adding process of carrying numbers. new version 4.0.3 is created. Finally, I would thank Mark Schenewerk for reporting the problem and providing a sample file, which was helpful to identify the cause of the bug. Best Regards, Yuki ---------------------------------------------------- Yuki Hatanaka, Ph.D, Geographical Survey Institute e-mail : hata@gsi.go.jp ---------------------------------------------------