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Having RPM Use a Different Build Area

While RPM's build root requires a certain amount of spec file and make file tweaking in order to get it working properly, directing RPM to perform the build in a different directory is a snap. The hardest part is to create the directories RPM will use during the build process.

Setting up a Build Area

RPM's build area consists of five directories in the top-level:

  1. The BUILD directory is where the software is unpacked and built.

  2. The RPMS directory is where the newly created binary package files are written.

  3. The SOURCES directory contains the original sources, patches, and icon files.

  4. The SPECS directory contains the spec files for each package to be built.

  5. The SRPMS directory is where the newly created source package files are written.

The description of the RPMS directory above, is missing one key point. Since the binary package files are specific to an architecture, the directory actually contains one or more subdirectories, one for each architecture. It is in these subdirectories that RPM will write the binary package files.

Let's start by creating the directories. We can even do it with one command:
% pwd
% mkdir mybuild\
?  mybuild/BUILD\
?  mybuild/RPMS\
?  mybuild/RPMS/i386\
?  mybuild/SOURCES\
?  mybuild/SPECS\
?  mybuild/SRPMS\

That's all there is to it. You may have noticed that we created a subdirectory to RPMS called i386 — This is the architecture-specific subdirectory for Intel x86-based systems, which is our example build system.

The next step in getting RPM to use a different build area is telling RPM where the new build area is. And it's almost as easy as creating the build area itself.

Directing RPM to Use the New Build Area

All that's required to get RPM to start using the new build area is to define an alternate value for topdir in an rpmrc file. For the non-root user, this means putting the following line in a file called .rpmrc, located in your home directory:
topdir: <path>
By replacing <path> with the path to the new build area's top-level directory, RPM will attempt to use it the next time a build is performed. Using our newly created build area as an example, we'll set topdir to /home/ed/mybuild:
topdir: /home/ed/mybuild

That's all there is to it. Now it's time to try a build.

Performing a Build in a New Build Area

In the following example, a non-root user attempts to build the cdplayer package in a personal build area. If the user has modified rpmrc file entries to change the default build area, the command used to start the build is just like the one used by a root user. Otherwise, the --buildroot option will need to be used:
% cd /home/ed/mybuild/SPECS
% rpm -ba --buildroot /home/ed/mybuildroot cdplayer-1.0.spec
* Package: cdplayer
+ umask 022
Executing: %prep
+ cd /home/ed/mybuild/BUILD
+ cd /home/ed/mybuild/BUILD
+ rm -rf cdplayer-1.0
+ gzip -dc /home/ed/mybuild/SOURCES/cdplayer-1.0.tgz
+ tar -xvvf -
drwxrwxr-x root/users        0 Aug 20 20:58 1996 cdplayer-1.0/
-rw-r--r-- root/users    17982 Nov 10 01:10 1995 cdplayer-1.0/COPYING
+ cd /home/ed/mybuild/BUILD/cdplayer-1.0
+ chmod -R a+rX,g-w,o-w .
+ exit 0
Executing: %build
+ cd /home/ed/mybuild/BUILD
+ cd cdplayer-1.0
+ make
gcc -Wall -O2  -c -I/usr/include/ncurses  cdp.c 
Executing: %install
+ cd /home/ed/mybuild/BUILD
+ make ROOT=/home/ed/mybuildroot/cdplayer install
install -m 755 -o 0 -g 0 -d /home/ed/mybuildroot/cdplayer/usr/local/bin/
install: /home/ed/mybuildroot/cdplayer: Operation not permitted
install: /home/ed/mybuildroot/cdplayer/usr: Operation not permitted
install: /home/ed/mybuildroot/cdplayer/usr/local: Operation not permitted
install: /home/ed/mybuildroot/cdplayer/usr/local/bin: Operation not
install: /home/ed/mybuildroot/cdplayer/usr/local/bin/: Operation not
make: *** [install] Error 1
Bad exit status

Things started off pretty well — The %prep section of the spec file unpacked the sources into the new build area, as did the %build section. The build was proceeding normally in the user-specified build area, and root access was not required. In the %install section, however, things started to fall apart. What happened?

Take a look at that install command. The two options, "-o 0" and "-g 0", dictate that the directories to be created in the build root are to be owned by the root account. Since the user performing this build did not have root access, the install failed, and rightly so.

OK, let's remove the offending options and see where that gets us. Here's the install section of the make file after our modifications:
install: cdp cdp.1.Z
	install -m 755 -d $(ROOT)/usr/local/bin/
	install -m 755 cdp $(ROOT)/usr/local/bin/cdp
	rm -f $(ROOT)/usr/local/bin/cdplay
	ln -s ./cdp $(ROOT)/usr/local/bin/cdplay
	install -m 755 -d $(ROOT)/usr/local/man/man1/
	install -m 755 cdp.1 $(ROOT)/usr/local/man/man1/cdp.1
We'll spare you from having to read through another build, but this time it completed successfully. Now, let's put our sysadmin hat on and install the newly built package:
# rpm -ivh cdplayer-1.0-1.i386.rpm
cdplayer       ##################################################
Well, that was easy enough. Let's take a look at some of the files and make sure everything looks OK. We know there are some files installed in /usr/local/bin, so let's check those:
# ls -al /usr/local/bin
-rwxr-xr-x   1 ed       ed          40739 Sep 13 20:16 cdp*
lrwxrwxrwx   1 ed       ed             47 Sep 13 20:34 cdplay -> ./cdp*

Looks pretty good… Wait a minute! What's up with the owner and group? The answer is simple: User ed ran the build, which executed the make file, which ran install, which created the files. Since ed created the files, they are owned by him.

This brings up an interesting point. Software must be installed with very specific file ownership and permissions. But a non-root user can't create files that are owned by anyone other than his or herself. What is a non-root user to do?