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.NET Forum / Languages / C++ Libraries / June 2004Same code build twice => diff binary
Hi all, I am using Win2k, VS. NET 7.1 (MS development Environment 2003 7.1.3088) and I noticed that by building the exact same code twice the generated binaries are different (not much, but they are). To be sure I tried a simple application like void main(){} and 2 times rebuilding the project gets 2 different binaries. Has anybody any clue why this happens? Could I somehow change a setting or something to remove those diff (I mean from the same code to get identical binaries)? Thanks in advance, Viv > Hi all, > [quoted text clipped - 7 lines] > Could I somehow change a setting or something to remove those diff (I > mean from the same code to get identical binaries)? Re-building a small program, I only see a couple bytes difference around offset 0xe8 in the file. This is a timestamp that the linker puts in the PE header that tells when the image was linked. -cd But I also get the obj different so I thought that this is a compiler option not linker option. Viv >> Hi all, >> [quoted text clipped - 13 lines] > >-cd > But I also get the obj different so I thought that this is a compiler > option not linker option. There may well be timestamps in the .obj files as well, but if so, they don't influence the output of the linker. -cd I found the following article: http://support.microsoft.com/default.aspx?scid=kb;en-us;164151 which tells that indeed the timestamp is the diff, but I couldn't find in VC++ IDE any setting to disable the timepstamp stuff, and I assume this should be somehow doable. Thx, Viv >Hi all, > [quoted text clipped - 10 lines] >Thanks in advance, >Viv > I found the following article: > http://support.microsoft.com/default.aspx?scid=kb;en-us;164151 > which tells that indeed the timestamp is the diff, but I couldn't find > in VC++ IDE any setting to disable the timepstamp stuff, and I assume > this should be somehow doable. I believe that you assume incorrectly. There is no option to suppress the timestamp - it's a required part of the PE header. -cd That is sad :( I am having an update feature in my product, and because of the timestamp it will have to update all the binaries, even though they are identical. >> I found the following article: >> http://support.microsoft.com/default.aspx?scid=kb;en-us;164151 [quoted text clipped - 6 lines] > >-cd Maybe a different way of handling updates is required, not based on binary compares. Cheers Russell > That is sad :( I am having an update feature in my product, and because > of the timestamp it will have to update all the binaries, even though > they are identical. > That is sad :( I am having an update feature in my product, and because > of the timestamp it will have to update all the binaries, even though [quoted text clipped - 10 lines] > > > >-cd Or -- you could use a PE editor and manually change the timestamp to a value of your liking... Already tried that. I have used the editor downloaded from: http://www.softpedia.com/public/cat/5/4/5-4-4.shtml I changed the time stamp and still there are 2 diffs between the exes (initially there were 3 diffs). Viv >> That is sad :( I am having an update feature in my product, and because >> of the timestamp it will have to update all the binaries, even though [quoted text clipped - 13 lines] >Or -- you could use a PE editor and manually change the timestamp to a value of >your liking... Is there a can't you use version numbers to identify binary versions?  SignatureMichael J. Mooney MCP+SB, MCAD, MCSD > That is sad :( I am having an update feature in my product, and because > of the timestamp it will have to update all the binaries, even though [quoted text clipped - 10 lines] > > > >-cd > That is sad :( I am having an update feature in my product, and > because of the timestamp it will have to update all the binaries, > even though they are identical. But that is the point, they are not identical as the two binaries have a different PE information. Why not change the diff program so that it skips over the PE header, in which case it would report no differences in the binaries. Jussi Jumppanen Author of: Zeus for Windows (All new version 3.92 out now) "The C/C++, Cobol, Java, HTML, Python, PHP, Perl programmer's editor" Home Page: http://www.zeusedit.com Any tool I could use for skipping the PE header? As I said I already tried to change the time stamp in the PE header using a PE editor, but still there are 2 diffs between the exes (initially there were 3). Viv >> That is sad :( I am having an update feature in my product, and >> because of the timestamp it will have to update all the binaries, [quoted text clipped - 11 lines] >"The C/C++, Cobol, Java, HTML, Python, PHP, Perl programmer's editor" >Home Page: http://www.zeusedit.com Can't you include a version info resource and check the version number? Andrew > That is sad :( I am having an update feature in my product, and because > of the timestamp it will have to update all the binaries, even though [quoted text clipped - 8 lines] > > > in VC++ IDE any setting to disable the timepstamp stuff, and I assume > > > this should be somehow doable. I could of course, but the problem is like this: I have let's say a binary that uses common code from other libraries, like some header files, so would be hard to know when to change the version number ... There are many developers working on the same header files, so hard to check if something has changed in order to change the version number. >Can't you include a version info resource and check the version number? > [quoted text clipped - 12 lines] >> > > in VC++ IDE any setting to disable the timepstamp stuff, and I assume >> > > this should be somehow doable. In message <2j5dm4FtnmhnU1@uni-berlin.de> of Mon, 14 Jun 2004 12:42:52 in comp.os.ms-windows.programmer.misc, Viviana Vc <vcotirlea@hotmail.com> writes [Poster wants an executable built twice to compare equal. Poster cross-posted to 5 newsgroups and should consider fewer. The same poster started another thread in 9 newsgroups. This is unlikely to be productive. Some knowledgeable people would ignore the posting on that basis. They are a LOT better than corresponding multi-postings.] >I could of course, but the problem is like this: I have let's say a >binary that uses common code from other libraries, like some header >files, so would be hard to know when to change the version number ... >There are many developers working on the same header files, so hard to >check if something has changed in order to change the version number. If you use a project file (Microsoft's term for Makefile) appropriately, your product will be rebuilt if and only if a contributing component changes. Version control systems can help in organising this. Your problem is in a class which is not reasonably soluble with the sort of technique you hope to apply. If I wanted to solve your problem, I would find or write a PE dumper - I can propose no suitable URL - and then compare files with boring things filtered from the comparison. Hopefully, this will work. I usually take the line that files with different dates or sizes are different. This is a fairly conservative approach. It is highly likely that the "same" thing can not be built on my machine and yours or even twice on mine. The same river can not be viewed twice. ;) SignatureWalter Briscoe
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