libc: Fix time() and implement gmtime() #21
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functions/time/gmtime.c
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| * Original Author: Adapted from tzcode maintained by Arthur David Olson. | ||
| * | ||
| * This file is part of the Public Domain C Library (PDCLib). | ||
| * Permission is granted to use, modify, and / or redistribute at will. |
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This section is no longer true; copying from newlib is also problematic as it conflicts with the pdclib license and it's not clearly marked as such.
The file in newlib is actually problematic in itself because it doesn't have explicit copyright headers, but mentions a couple of contributors and external sources. Strictly speaking we'd have to add https://www.sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;a=blob;f=COPYING.NEWLIB and also ship it with each release of an nxdk app - this feels overkill to me.
I guess we could say that some of these algorithms are fact and non-copyrightable (as are the constants), but it still feels "bad".
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Well, there even is a pointer in the comments to a github page that describe the algorithm. Being what it is (converting seconds since 1970 to day/month/etc) I don't think there are so many ways to do it.
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| #ifndef REGTEST | |||
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| #include <xboxkrnl/xboxkrnl.h> | |||
| #define NT_EPOCH_TIME_OFFSET ((LONGLONG)(369 * 365 + 89) * 24 * 3600 * 10000000) | |||
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I'm surprised this works (does it?). 3600 * 10000000 is more than 32-bit. I'd assume this has to be 3600LL * 10000000LL etc. (I keep forgetting about C int promotion rules, so maybe it's already fine?)
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It works. That's from ntfs-3g ntfstime.h. The compiler uses the first type that fits. Better explained there: https://stackoverflow.com/questions/13134956/what-is-the-reason-for-explicitly-declaring-l-or-ul-for-long-values.
The offset between win32 and unix epochs wasn't taken care of, resulting in a wrong value. Added the correct offset from ntfs3g.
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Provide a working gmtime() implementation instead of the NULL-returning pdclib stub.
Not resetting last seen '\n' offset after flushing the buffer (which resets the buffer index to 0) can lead to a situation where that offset has a higher value the the current buffer index, overflowing (unsigned) stream->bufidx = bufidx - offset and then doing a memmove of a gigantic size.
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This includes the other changes now, none of which follow prefix style or have anything to do with this. Other than that I think the changes made the PR fine. I was hoping someone else would also review / merge this. |
I messed up. Here is a clean branch with only the intended changes: #24 |
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Oh! I see. Default branch for PR. I'm closing this PR. |
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