We're using Apache 2.0.43, with apr-util built from within the Apache
tree. We recently (around the time we upgraded to 2.0.43) found a
problem where apr-util stopped building the expat it contains (which is
the expat we want to use) if the build was started from a symlinked
directory. The problem is that in configure, the attempt to determine
if the expat_include_dir is inside apr-util contains one canonicalized
path, and one path accessed via a symlink.
The relevant if/else block looks like this in my srclib/apr-util
directory:
if test "$expat_include_dir" = "xml/expat/lib" -o "$expat_include_dir" =
"xml/expat-cvs/lib"; then
...
else
if test "$expat_include_dir" = "$srcdir/xml/expat/include" -o
"$expat_include_dir" = "$srcdir/xml/expat/lib"; then
...
The second one is the one should test true in the context that we are
using this. It was working for some people and not others; bread crumbs
turned up the fact that the two dirs were the same, but wouldn't test
the same with a string compare because expat_include_dir started with a
path to a symlink. Using the canonicalized version of srcdir (available
as abs_srcdir, at least in configure) fixed the problem.
We start by invoking httpd's general configure script with something
like the following (/home/ed/src is a symlink to /opt/src and
/home/ed/target is a symlink to /opt/target in this example -- the paths
have been simplified), run from within
/home/ed/src/tmp/httpd-2.0.43
taken from config.status in that directory:
# ./configure --with-mpm=prefork
--bindir=/home/ed/target/bin
--sbindir=/home/ed/target/bin
--includedir=/home/ed/target/include
--libdir=/home/ed/target/lib/apache
--libexecdir=/home/ed/target/lib/apache
--mandir=/home/ed/target/docs/man
--datadir=/home/ed/target/bin
--sysconfdir=/home/ed/target/conf/apache-20
--localstatedir=/home/ed/target/bin/var
--enable-modules=all
--enable-ssl
--disable-auth-digest
--enable-dav
--enable-rewrite
--enable-proxy
--enable-so
--enable-static-support
--with-berkeley-db=/home/ed/target/bin/BerkeleyDB-40/include:/home/ed/target/lib/BerkeleyDB-40
--with-expat=/home/ed/src/tmp/httpd-2.0.43/srclib/apr-util/xml/expat
--prefix=/home/ed/target/bin
Note that all the options start with the symlink, rather than the
canonical path. Also note the inclusion of --with-expat ... This then
generates a configure call within srclib/apr-util which looks like this
(taken from config.status in apr-util):
# /opt/src/tmp/httpd-2.0.43/srclib/apr-util/configure
--with-mpm=prefork
--bindir=/home/ed/target/bin
--sbindir=/home/ed/target/bin
--includedir=/home/ed/target/include
--libdir=/home/ed/target/lib/apache
--libexecdir=/home/ed/target/lib/apache
--mandir=/home/ed/target/docs/man
--datadir=/home/ed/target/bin
--sysconfdir=/home/ed/target/conf/apache-20
--localstatedir=/home/ed/target/bin/var
--enable-modules=all --enable-ssl --disable-auth-digest --enable-dav
--enable-rewrite --enable-proxy --enable-so --enable-static-support
--with-berkeley-db=/home/ed/target/bin/BerkeleyDB-40/include:/home/ed/target/lib/BerkeleyDB-40
--with-expat=/home/ed/src/tmp/httpd-2.0.43/srclib/apr-util/xml/expat
--prefix=/home/ed/target/bin
--cache-file=/opt/src/tmp/httpd-2.0.43/./config.cache
--srcdir=/opt/src/tmp/httpd-2.0.43/srclib/apr-util
--with-apr=../apr
--prefix=/home/ed/target/bin
--exec-prefix=/home/ed/target/bin
--libdir=/home/ed/target/lib/apache
--includedir=/home/ed/target/include
--bindir=/home/ed/target/bin
Apparently, for some reason Apache managed to canonicalize some of the
tokens, but not all of them. This is on a linux RH 7.3 box, so pwd does
not canonicalize a symlinked path when /bin/sh is the shell; /bin/pwd is
required for that.
The attached patch resolves the issue I was seeing, through insisting on
proper canonicalization when testing paths known only as strings.
This may be new since Apache 2.0.42 (we just switched to 2.0.43); it's
also arguable that a better solution is making the canonicalization
correct and consistent in Apache's configure script. I'm not sure that
using /bin/pwd is portable; and another solution was to run Apache's
configure with --srcdir pointing to the full path as our build system
knows it (using the symlink). But after doing this debugging, I figured
better path canonicalization might be of general interest.
thanks --
Ed
--- configure.in.orig Thu Dec 12 18:22:25 2002
+++ configure.in Thu Dec 12 18:22:35 2002
@@ -22,8 +22,8 @@
dnl # and which files are to be configured.
dnl Absolute source/build directory
-abs_srcdir=`(cd $srcdir && pwd)`
-abs_builddir=`pwd`
+abs_srcdir=`(cd $srcdir && /bin/pwd)`
+abs_builddir=`/bin/pwd`
if test "$abs_builddir" != "$abs_srcdir"; then
USE_VPATH=1
--- build/apu-conf.m4.orig Thu Dec 12 18:21:58 2002
+++ build/apu-conf.m4 Thu Dec 12 18:22:10 2002
@@ -19,7 +19,7 @@
dnl make APR_BUILD_DIR an absolute directory (we'll need it in the
dnl sub-projects in some cases)
- APR_BUILD_DIR="`cd $APR_BUILD_DIR && pwd`"
+ APR_BUILD_DIR="`cd $APR_BUILD_DIR && /bin/pwd`"
APR_INCLUDES="`$apr_config --includes`"
APR_LIBS="`$apr_config --link-libtool --libs`"
@@ -569,7 +569,7 @@
elif test "$withval" = "no"; then
AC_MSG_ERROR([Expat cannot be disabled (at this time)])
else
- abs_expatdir="`cd $withval && pwd`"
+ abs_expatdir="`cd $withval && /bin/pwd`"
APU_TEST_EXPAT($abs_expatdir, $withval)
if test -z "$expat_include_dir"; then
AC_MSG_ERROR([Expat was not found (or recognized) in \"$withval\"])
@@ -614,7 +614,7 @@
APR_XML_SUBDIRS="`echo $bundled_subdir | sed -e 's%xml/%%'`"
APR_ADDTO(APRUTIL_EXPORT_LIBS, [$expat_libtool])
else
-if test "$expat_include_dir" = "$srcdir/xml/expat/include" -o
"$expat_include_dir" = "$srcdir/xml/expat/lib"; then
+if test "$expat_include_dir" = "$abs_srcdir/xml/expat/include" -o
"$expat_include_dir" = "$abs_srcdir/xml/expat/lib"; then
dnl This is a bit of a hack. This only works because we know that
dnl we are working with the bundled version of the software.
bundled_subdir="xml/expat"
