MORE INFORMATION
The time and date stamps can be removed from the built image without
removing relevant information (code and data) using the /RAWDATA switch
available in the DUMPBIN utility. Any file compare utility can then be used
on the DUMPBIN output as follows:
DUMPBIN /RAWDATA MyApp.EXE > first.txt
If Myapp.exe is built again at a different time, then use DUMPBIN as
follows:
DUMPBIN /RAWDATA MyApp.EXE > second.txt
You can now compare first.txt and second.txt using a file compare utility
like:
FC /B first.txt second.txt
Run DUMPBIN in the resident directory of the image. The above procedure
applies to the Release build only because the Debug build records the time
and date stamp on the images (irrespective of /Zi or /Z7) and DUMPBIN does
not remove this information. If the predefined macros __DATE__ and __TIME__
are used in the source, the time and date stamp recorded in the images will
not be removed by DUMPBIN for the Release build. Under these circumstances,
you may use the /DISASM switch. However, the /DISASM switch removes the
time and date stamp, as well as the initialized data. This means that you
will not get a true image compare.
NOTE: There is no guarantee that Visual C++ will generate the same binary
image when building the same source files on successive builds. However,
you are guaranteed that the EXE (or DLL) will behave in precisely the same
manner under execution, all other things being equal. Compile and link
options and link order play a role in whether two binary images will
compare equally.
If you follow the procedures outlined above and the two images compare
equally, then the images are the same. If the two images do not compare
equally, then there is still uncertainty as to whether the images are the
same or not.
The resource section of the executable contains date/time stamps. In the
resource section of the executable, there is a header for each type of
resource (for example, string table, dialog, icon). Each of these headers
contains a date/time stamp.
Use the Microsoft Portable Executable and Common Object File Format
Specification from the MSDN Library to alter the date/time stamps so that
they won't be a factor in the comparison or ignore the resources section in
the comparison.
To identify the section containing the differences, run the WinDiff utility
shipped with Visual C++:
WINDIFF first.txt second.txt
The section containing the differences will start with a line similar to
the following (although the number may be different):
RAW DATA #5
Then, compare this with the output from the following:
dumpbin /headers MyApp.exe
You should find a header that starts with the following:
SECTION HEADER #5
.rsrc name
Because the section number matches the section with the differences in the
raw data (in this example, the section number is 5), then the differences
occur in the section named ".rsrc". This is the name of the resource
section.
The Export Directory Table has a date/time stamp as well. This is typically
located in the .rdata section (Visual C++ 4.2 and later) or the .edata
section (earlier than Visual C++ 4.2). This table exists only if you export
symbols from the PE image.
The Import Directory Table also has a date/time stamp. This is typically
located in the .idata section. One of these tables exists for each DLL to
which the image refers. This date/time stamp is zero unless the image is
bound. Once the image is bound, the date/time stamp is set to the date/time
stamp of the DLL from where the symbols are imported.
Once again, please refer to the Microsoft Portable Executable and Common
Object File Format Specification in the MSDN Library for information on how
to locate the date/time information in an image.