Junio C Hamano 7e71542e8b sha1dc: avoid CPP macro collisions ... In an early part of sha1dc/sha1.c, the code checks the endianness of the target platform by inspecting common CPP macros defined on big-endian boxes, and sets BIGENDIAN macro to 1. If these common CPP macros are not defined, the code declares that the target platform is little endian and does nothing (most notably, it does not #undef its BIGENDIAN macro). The code that does so even has this comment Note that all MSFT platforms are little endian, so none of these will be defined under the MSC compiler. and later, the defined-ness of the BIGENDIAN macro is used to switch the implementation of sha1_load() macro. One thing the code did not anticipate is that somebody might define BIGENDIAN macro in some header it includes to 0 on a little-endian target platform. Because the auto-detection based on common macros do not touch BIGENDIAN macro when it detects a little-endian target, such a definition is still valid and then defined-ness test will say "Ah, BIGENDIAN is defined" and takes the wrong sha1_load(). As this auto-detection logic pretends as if it owns the BIGENDIAN macro by ignoring the setting that may come from the outside and by not explicitly unsetting when it decides that it is working for a little-endian target, solve this problem without breaking that assumption. Namely, we can rename BIGENDIAN this code uses to something much less generic, i.e. SHA1DC_BIGENDIAN. For extra protection, undef the macro on a little-endian target. It is possible to work it around by instead #undef BIGENDIAN in the auto-detection code, but a macro (or include) that happens later in the code can be implemented in terms of BIGENDIAN on Windows and it is possible that the implementation gets upset when it sees the CPP macro undef'ed (instead of set to 0). Renaming the private macro intended to be used only in this file to a less generic name relieves us from having to worry about that kind of breakage. Noticed-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>		2017-03-26 15:34:44 -07:00
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LICENSE.txt
sha1.c	sha1dc: avoid CPP macro collisions	2017-03-26 15:34:44 -07:00
sha1.h	Makefile: add DC_SHA1 knob	2017-03-17 10:40:25 -07:00
ubc_check.c
ubc_check.h