GCC has
__TIMESTAMP__
This macro expands to a string constant that describes the date and time of the last modification of the current source file
But if that file does not get modified, the timestamp string doesn't change.
Is there a way to get a string indicating the time at compilation?
Use a -D flag from the command line:
gcc -DCOMPILE_TIME="\"$(date)\"" -c file.c
But if you use any popular build system, file.c won't get rebuilt unless it changes anyway, so it's not that different from __TIMESTAMP__.
Simple question. I am compiling an ada program with gnat. The gcc command ends up looking like gcc -c -Ia -Ibunch -Iof -Iincludes -I- -o /some/object/file.o /some/source/file.adb however the error format consists of just file.adb:line:offset: problem.
Is there any way to get GNAT make or gcc to print the full path to the file in its errors, as specified on the command line? IE: to get /some/source/file.adb:line:offset: problem.
I know that with the -gnatv one could argue that it prints the full path, but I want something significantly less verbose than that.
you need -gnatef option:
-gnatef
Display full source path name in brief error messages.
gcc -gnatef -c %CD%\file.adb
C:\DATA\jff\data\python\stackoverflow\file.adb:1:01: "procedure" expected
https://gcc.gnu.org/onlinedocs/gcc-4.3.6/gnat_ugn_unw/Switches-for-gcc.html
I have been trying to compile openssl 1.0.0g with the following rpath:
$ORIGIN/../lib64
Everytime I readelf -d apps/openssl, I am getting results like the following depending on what escaping variation I tried:
\RIGIN/../lib64
RIGIN/../lib64
ORIGIN/../lib64
I want to setup my rpath without using external tools like chrpath. Is it at all possible? I will basically accept anything that does not involve using external tools like chrpath (though I would already be done with that).
Ideally, I would like to do it by passing options on the command line (any form of -Wl,-rpath,$ORIGIN/../lib64).
I don't mind editing the generated Makefile, which is what I have been trying last. If only I could get it to print a stupid dollar sign!!! I tried modifying LIBRPATH under the BUILDENV= block with no luck. My best results so far:
LIBRPATH=$$'ORIGIN/../lib64 # result: /../lib64
LIBRPATH=$$$$'ORIGIN/../lib64 # result: 12345<pid>/../lib64
I have read various rpath related questions and tried various escaping and quoting tricks but nothing worked so far!
In your makefile try:
-Wl,-rpath,${ORIGIN}/../lib64
I am assuming that the ORIGIN is a shell variable.
EDIT
I have just found an answer to your question (better late then never):
You need to prevent make from interpolating variables, to do that you need to use $$ (double dolar sign):
-Wl,-rpath,'$$ORIGIN/../lib64'
I know that it works because I have tested it with my own application, enjoy :)
I went the chrpath way.
http://enchildfone.wordpress.com/2010/03/23/a-description-of-rpath-origin-ld_library_path-and-portable-linux-binaries/
It is quite complicated to counter shell expansion of `$$ORIGIN`` in openssl. Sooner or later, it gets expanded because of the dollar sign. If you really want to go this way, you can do it. I have found the following to work with openssl 1.0.1g on Linux. In Makefile.shared, look for this line:
DO_GNU_APP=LDFLAGS="$(CFLAGS) -Wl,-rpath,$(LIBRPATH)"
Replace it with the following. This quoting-fu neutralize the expansion of $. The double $$ is the way to get a single dollar sign in makefiles.
DO_GNU_APP=LDFLAGS="$(CFLAGS) -Wl,-rpath,'"'$$'"ORIGIN/../lib64'"
After compiling:
readelf -d apps/openssl | grep RPATH
0x000000000000000f (RPATH) Library rpath: ['$ORIGIN/../lib64']
OK I spent several hours fighting with this same issue and trying all manner of crazy escaping, at one point I was up to eight $ signs, at which point I decided that there must be another way.
In fact, it appears that there is, at least with GNU ld.
Instead of -Wl,-rpath,\\$$$\$\$\$$$\$\\\\$ or some other elder god invoking monstrosity, just do this:
echo '-rpath=$ORIGIN/../lib64' > rpathorigin
./config -Wl,#$(pwd)/rpathorigin ...
I don't see that ld.gold documents the # flag, and I have no idea about, say, lld. But if you are using GCC and it is invoking BFD ld, the above may just work for you.
Of course, the actual path used with origin should be customized as needed, and I have no opinion on ./config vs ./Configure. But using the response file trick seems to entirely sidestep the shell/make escaping nightmare.
I don't mind editing the generated Makefile, which is what I have been trying last...
I'm not sure you can set it with a shell variable and relative path. I don't think ldd expands the $ORIGIN in $ORIGIN/../lib64. In this case, I think you need to use ldconfig to add $ORIGIN/../lib64 to the library search paths. See finding ldd search path on Server Fault for more details.
Since I'm not sure, I'll provide the instructions anyway. You don't need to change the Makefiles. As a matter of fact, I did not have any luck doing so in the past because things get overwritten, and other things like CFLAGS and LDFLAGS get ignored.
Also see Build OpenSSL with RPATH? Your question and the cited question are different question that converge on similar answers (no duplicates between them). But it provides the OpenSSL dev's position on RPATHs. It was a private email, so I shared the relevant details rather than the whole message.
If you manage to embed $ORIGIN/../lib64 in the ELF section and it works, then please report back. Below, I am using /usr/local/ssl/lib for my RPATH. You should substitute $ORIGIN/../lib64 for /usr/local/ssl/lib.
OpenSSL supports RPATH's out of the box for BSD targets (but not others). From Configure:
# Unlike other OSes (like Solaris, Linux, Tru64, IRIX) BSD run-time
# linkers (tested OpenBSD, NetBSD and FreeBSD) "demand" RPATH set on
# .so objects. Apparently application RPATH is not global and does
# not apply to .so linked with other .so. Problem manifests itself
# when libssl.so fails to load libcrypto.so. One can argue that we
# should engrave this into Makefile.shared rules or into BSD-* config
# lines above. Meanwhile let's try to be cautious and pass -rpath to
# linker only when --prefix is not /usr.
if ($target =~ /^BSD\-/)
{
$shared_ldflag.=" -Wl,-rpath,\$(LIBRPATH)" if ($prefix !~ m|^/usr[/]*$|);
}
The easiest way to do it for OpenSSL 1.0.2 appears to be add it to linker flags during configuration
./config -Wl,-rpath=/usr/local/ssl/lib
You can also edit Configure line and hard code the rpath. For example, I am working on Debian x86_64. So I opened the file Configure in an editor, copied linux-x86_64, named it linux-x86_64-rpath, and made the following change to add the -rpath option:
"linux-x86_64-rpath", "gcc:-m64 -DL_ENDIAN -O3 -Wall -Wl,-rpath=/usr/local/ssl/lib::
-D_REENTRANT::-Wl,-rpath=/usr/local/ssl/lib -ldl:SIXTY_FOUR_BIT_LONG RC4_CHUNK DES_INT DES_UNROLL:
${x86_64_asm}:elf:dlfcn:linux-shared:-fPIC:-m64:.so.\$(SHLIB_MAJOR).\$(SHLIB_MINOR):::64",
Above, fields 2 and 6 were changed. They correspond to $cflag and $ldflag in OpenSSL's builds system.
Then, Configure with the new configuration:
$ ./Configure linux-x86_64-rpath shared no-ssl2 no-ssl3 no-comp \
--openssldir=/usr/local/ssl enable-ec_nistp_64_gcc_128
Finally, after make, verify the settings stuck:
$ readelf -d ./libssl.so | grep -i rpath
0x000000000000000f (RPATH) Library rpath: [/usr/local/ssl/lib]
$ readelf -d ./libcrypto.so | grep -i rpath
0x000000000000000f (RPATH) Library rpath: [/usr/local/ssl/lib]
$ readelf -d ./apps/openssl | grep -i rpath
0x000000000000000f (RPATH) Library rpath: [/usr/local/ssl/lib]
Once you perform make install, then ldd will produce expected results:
$ ldd /usr/local/ssl/lib/libssl.so
linux-vdso.so.1 => (0x00007ffceff6c000)
libcrypto.so.1.0.0 => /usr/local/ssl/lib/libcrypto.so.1.0.0 (0x00007ff5eff96000)
...
$ ldd /usr/local/ssl/bin/openssl
linux-vdso.so.1 => (0x00007ffc30d3a000)
libssl.so.1.0.0 => /usr/local/ssl/lib/libssl.so.1.0.0 (0x00007f9e8372e000)
libcrypto.so.1.0.0 => /usr/local/ssl/lib/libcrypto.so.1.0.0 (0x00007f9e832c0000)
...
Don't ask me why but this worked for me in OpenSSL 1.1.1i in getting around the $ sign issue:
\$\$\$$ORIGIN
Example:
./Configure linux-x86_64 '-Wl,-rpath,\$\$\$$ORIGIN'
Alternatively, if this command line hack isn't congruent with you, you can always use chrpath after building as others have suggested:
./Configure linux-x86_64 '-Wl,-rpath,XORIGIN'
make depend
make all
chrpath -r "\$ORIGIN" libssl.so
We are using __TIME__ to embed the time of compilation in a binary. Unfortunately, a time without a UTC Offset is meaningless. I don't see an obvious way to get the timezone that the compiler is running in. I suppose I could grab this from the configure script. But is there a better way?
If I do it from a configure script, I'm going to need to put that into a .h or .c file somehow, and do something intelligent if the file is not there.
you can use compiler Flags to pass that externally. Most compiler provide '-D' flag to define #define macros externally. Let's suppose you put the UTC information in an environment variable. Pass that environment variable as -D flag
set $myUTC="-7"
gcc -c mysource.cpp -DUTC=$myUTC
In your mysource.cpp use the macro UTC:
printf("Compiled at %d Offset %d", __TIME__, UTC);
How do I view the output produced by the C pre-processor, prior to its conversion into an object file?
I want to see what the MACRO definitions do to my code.
gcc -E file.c
or
g++ -E file.cpp
will do this for you. The -E switch forces the compiler to stop after the preprocessing phase, spitting all it’s got at the moment to standard output.
Note: Surely you must have some #include directives. The included files get preprocessed, too, so you might get lots of output.
For Visual C++ the switch is /E which spits the preprocessor output to screen.
You can also call the C Preprocessor directly.
cpp infile outfile
Check out man cpp for more info.
For GCC,
gcc -E -dM file.c
or
g++ -E -dM file.cpp
should do the job. -dM, as GNU Preprocessor manual puts it, should generate a list of ‘#define’ directives for all the macros defined during the execution of the preprocessor, including predefined macros.
It depends on the compiler you use.
With GCC, you can specify the -E flag on the command-line to let the compiler produce the pre-processor output.
If using CLion by Jetbrains, you can use the action "clangd: Preprocess current TU"
So hit shift shift and start typing clangd...
Best assign it to a shortcut for simpler reuse in preferences->keymap:
Shout out to marcosbento
PS: TU means 'translation unit' (see here LLVM translation unit)
You can check out my script described here:
http://mosermichael.github.io/cstuff/all/projects/2011/09/16/preprocessor.html
It formats the preprocessor output into a (hopefully) readable html document: lines that are different due to preprocessor are marked in the file.