Setting environment variables and including linking directories in a Makefile

Question

I have a C file that includes a header that itself includes "jni.h". I'm currently compiling the file using the command:

gcc hdfs_test.c -I/HDFS_HOME/hdfs/src/c++/libhdfs -I/usr/lib/jvm/default-java/include -L/HDFS_HOME/hdfs/src/c++/libhdfs -L/HDFS_HOME/build/c++/Linux-i386-32/lib -L/usr/lib/jvm/default-java/jre/lib/i386/server -ljvm -lhdfs -o hdfs_test

to run the resulting .o file, the environment variables for CLASSPATH and JAVAHOME.

Now, I want to use this file in an existing C project where they use make files. The project is Postgresql. In this project Makefiles are used. I want to add the needed instructions to the makefile in the folder where I'm adding the file, so that I can run it with the project.

The current makefile has the following:

subdir = src/backend/storage/smgr
top_builddir = ../../../..
include $(top_builddir)/src/Makefile.global

OBJS = md.o smgr.o smgrtype.o

include $(top_srcdir)/src/backend/common.mk

What should I add to the makefile in order to compile my c file with the project?

Thanks

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* Edit 1 *

I probably should have stated what I was trying to do. So far, I added multiple source files to the postgres SMGR module (source directory). They all worked fine by just adding the fileName.o to the list of OBJS files. For example if I added A.c, I would add A.o to the OBJS list and the file will be compiled and added to the project.

Now the new file that I'm trying to add is hdfs_test.c this is different than the other source files that I added previously. The difference is that it doesn't compile using simple gcc command, but needs the command that I've shown above. I tried to manually generate the .o file manually by adding this to my Makefile:

OBJS = md.o smgr.o smgrtype.o hdfs_FD.o hdfsManager.o smgrWrapper.o hdfs_test.o

include $(top_srcdir)/src/backend/common.mk

hdfs_test.o : hdfs_test.c
        gcc hdfs_test.c -I/HDFS_HOME/hdfs/src/c++/libhdfs -I/usr/lib/jvm/default-java/include -L/HDFS_HOME/hdfs/src/c++/libhdfs -L/HDFS_HOME/build/c++/Linux-i386-32/lib -L/usr/lib/jvm/default-java/jre/lib/i386/server -ljvm -lhdfs -o hdfs_test

When Make, I'm getting the following error:

/usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 0 has invalid symbol index 12

/usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 1 has invalid symbol index 13 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 2 has invalid symbol index 2 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 3 has invalid symbol index 2 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 4 has invalid symbol index 12 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 5 has invalid symbol index 14 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 6 has invalid symbol index 14 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 7 has invalid symbol index 14 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 8 has invalid symbol index 2 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 9 has invalid symbol index 2 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 10 has invalid symbol index 13 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 11 has invalid symbol index 14 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 12 has invalid symbol index 14 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 13 has invalid symbol index 14 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 14 has invalid symbol index 14 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 15 has invalid symbol index 14 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 16 has invalid symbol index 14 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 17 has invalid symbol index 14 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 18 has invalid symbol index 14 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 19 has invalid symbol index 14 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 20 has invalid symbol index 14 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 21 has invalid symbol index 14 /usr/bin/ld: /usr/lib/debug/usr/lib/crt1.o(.debug_info): relocation 22 has invalid symbol index 22 /usr/lib/gcc/i486-linux-gnu/4.4.3/../../../../lib/crt1.o: In function _start': (.text+0x18): undefined reference tomain' collect2: ld returned 1 exit status make: * [tati.o] Error 1

Hope this clarifies things.

Answer 1

Makefiles consisting of multiple files in multiple directories are typically very hard to understand, and rely on lots of black magic to work properly, so showing us just one small file is probably not very meaningful.

That said, I'd start by just adding a new .o file to OBJS, and see what happens. Probably it'll assume that there's a source file of the same basename, and Just Work. The file doesn't give any dependency information, so it will probably auto-generate that without any input from you.

On the other hand, the whole system might be rubbish ....

Answer 2

This really depends on what exactly your code is trying to do, and why role the JVM and C++ play. It might not work at all, even if you get it to build. You should probably discuss the details with the PostgreSQL developers. You might also be better off building your code as a shared library and installing it as an extension.

Answer 3

postgress uses automake build environment from the looks of it.

Your knowledge of just Make seems to be limited, so i would suggest that you read up on the following.:

• GNU make << start here >>,
• GNU autoconf,
• GNU automake,

and do the examples in there and them modify them for your hdfs_test. Once you understand how to do that, you'll be able to answer your question. When you stumble into an issue there, I'll be happy to help you resolve it.