Libguestfs - Feb 2015 - Re: [PATCH] ./run: Use 'prepend' function to build paths.

Add a bash function 'prepend' for intelligently prepending elements to
paths.  eg:

  prepend PYTHONPATH "/foo"

would set PYTHONPATH to "/foo" or
"/foo:<previous-contents-of-PYTHONPATH>"

Tested by:

(1) Building and testing libguestfs twice: first without libguestfs
installed as a system library, and then with it installed.

(2) Examining the output of './run printenv' by hand and comparing
environment variables to the expected values.
---
 run.in | 103 +++++++++++++++++++++++++++++++++++------------------------------
 1 file changed, 55 insertions(+), 48 deletions(-)

diff --git a/run.in b/run.in
index bf7ea1b..46b47c3 100755
--- a/run.in
+++ b/run.in
@@ -43,6 +43,13 @@ if [ "$1" = "--test" ]; then
     shift
 fi
 
+# Function to intelligently prepend a path to an environment variable.
+# See http://stackoverflow.com/a/9631350
+prepend()
+{
+    eval $1="$2\${$1:+:\$$1}"
+}
+
 # Source and build directories (absolute paths so this works from any
 # directory).
 s="$(cd @abs_srcdir@ && pwd)"
@@ -74,33 +81,55 @@ fi
 
 # Set the PATH to contain all the libguestfs binaries.  There are a
 # lot of binaries, so a lot of path entries.
-PATH="$b/align:$b/builder:$b/cat:$b/customize:$b/df:$b/diff:$b/edit:$b/erlang:$b/fish:$b/format:$b/fuse:$b/inspector:$b/make-fs:$b/p2v:$b/rescue:$b/resize:$b/sparsify:$b/sysprep:$b/test-tool:$b/tools:$b/v2v:$PATH"
+prepend PATH "$b/align"
+prepend PATH "$b/builder"
+prepend PATH "$b/cat"
+prepend PATH "$b/customize"
+prepend PATH "$b/df"
+prepend PATH "$b/diff"
+prepend PATH "$b/edit"
+prepend PATH "$b/erlang"
+prepend PATH "$b/fish"
+prepend PATH "$b/format"
+prepend PATH "$b/fuse"
+prepend PATH "$b/inspector"
+prepend PATH "$b/make-fs"
+prepend PATH "$b/p2v"
+prepend PATH "$b/rescue"
+prepend PATH "$b/resize"
+prepend PATH "$b/sparsify"
+prepend PATH "$b/sysprep"
+prepend PATH "$b/test-tool"
+prepend PATH "$b/tools"
+prepend PATH "$b/v2v"
 export PATH
 
 # Set LD_LIBRARY_PATH and DYLD_LIBRARY_PATH to contain library.
-build_libs_path="$b/src/.libs:$b/java/.libs:$b/gobject/.libs"
-export
LD_LIBRARY_PATH="$build_libs_path${LD_LIBRARY_PATH:+:}$LD_LIBRARY_PATH"
-export
DYLD_LIBRARY_PATH="$build_libs_path${DYLD_LIBRARY_PATH:+:}$DYLD_LIBRARY_PATH"
+prepend LD_LIBRARY_PATH "$b/gobject/.libs"
+prepend LD_LIBRARY_PATH "$b/java/.libs"
+prepend LD_LIBRARY_PATH "$b/src/.libs"
+prepend DYLD_LIBRARY_PATH "$b/gobject/.libs"
+prepend DYLD_LIBRARY_PATH "$b/java/.libs"
+prepend DYLD_LIBRARY_PATH "$b/src/.libs"
+export LD_LIBRARY_PATH
+export DYLD_LIBRARY_PATH
 
 # Make virt-builder use the local website copy to avoid hitting
 # the network all the time.
 if [ -z "$XDG_CONFIG_DIRS" ]; then
-    XDG_CONFIG_DIRS="$b/builder/test-website"
+    prepend XDG_CONFIG_DIRS "$b/builder/test-website"
     export XDG_CONFIG_DIRS
 fi
 
 # virt-p2v-make-* data directory.
 if [ -z "$VIRT_P2V_DATA_DIR" ]; then
-    VIRT_P2V_DATA_DIR="$b/p2v"
+    prepend VIRT_P2V_DATA_DIR "$b/p2v"
     export VIRT_P2V_DATA_DIR
 fi
 
 # For Perl.
-if [ -z "$PERL5LIB" ]; then
-    PERL5LIB="$b/perl/blib/lib:$b/perl/blib/arch"
-else
-    PERL5LIB="$b/perl/blib/lib:$b/perl/blib/arch:$PERL5LIB"
-fi
+prepend PERL5LIB "$b/perl/blib/arch"
+prepend PERL5LIB "$b/perl/blib/lib"
 export PERL5LIB
 
 # Enable Perl valgrinding.
@@ -112,52 +141,38 @@ export PERL_DESTRUCT_LEVEL=2
 
 # For Python.
 export PYTHON=@PYTHON@
-if [ -z "$PYTHONPATH" ]; then
-    PYTHONPATH="$s/python:$b/python:$b/python/.libs"
-else
-    PYTHONPATH="$s/python:$b/python:$b/python/.libs:$PYTHONPATH"
-fi
+prepend PYTHONPATH "$b/python/.libs"
+prepend PYTHONPATH "$b/python"
+prepend PYTHONPATH "$s/python"
 export PYTHONPATH
 
 # For Ruby.
 export RUBY=@RUBY@
 export RAKE=@RAKE@
-if [ -z "$RUBYLIB" ]; then
-    RUBYLIB="$b/ruby/lib:$b/ruby/ext/guestfs"
-else
-    RUBYLIB="$b/ruby/lib:$b/ruby/ext/guestfs:$RUBYLIB"
-fi
+prepend RUBYLIB "$b/ruby/ext/guestfs"
+prepend RUBYLIB "$b/ruby/lib"
 export RUBYLIB
-export
LD_LIBRARY_PATH="$b/ruby/ext/guestfs${LD_LIBRARY_PATH:+:}$LD_LIBRARY_PATH"
-export
DYLD_LIBRARY_PATH="$b/ruby/ext/guestfs${DYLD_LIBRARY_PATH:+:}$DYLD_LIBRARY_PATH"
+prepend LD_LIBRARY_PATH "$b/ruby/ext/guestfs"
+prepend DYLD_LIBRARY_PATH "$b/ruby/ext/guestfs"
 
 # For OCaml.
-if [ -z "$CAML_LD_LIBRARY_PATH" ]; then
-    CAML_LD_LIBRARY_PATH="$b/ocaml"
-else
-    CAML_LD_LIBRARY_PATH="$b/ocaml:$CAML_LD_LIBRARY_PATH"
-fi
+prepend CAML_LD_LIBRARY_PATH "$b/ocaml"
 export CAML_LD_LIBRARY_PATH
 
 # For Java.
 export JAVA_EXE=@JAVA_EXE@
-if [ -z "$CLASSPATH" ]; then
-    CLASSPATH="$b/java:$b/java/t:$b/java/libguestfs-@VERSION@.jar"
-else
-   
CLASSPATH="$b/java:$b/java/t:$b/java/libguestfs-@VERSION@.jar:$CLASSPATH"
-fi
+prepend CLASSPATH "$b/java/libguestfs-@VERSION@.jar"
+prepend CLASSPATH "$b/java/t"
+prepend CLASSPATH "$b/java"
 export CLASSPATH
 
 # For Erlang (note $PATH is adjusted above to include erl-guestfs).
-if [ -z "$ERL_LIBS" ]; then
-    ERL_LIBS="$b/erlang"
-else
-    ERL_LIBS="$b/erlang:$ERL_LIBS"
-fi
+prepend ERL_LIBS "$b/erlang"
 export ERL_LIBS
 
 # For Lua.
 export LUA=@LUA@
+# Can't use 'prepend' here because Lua paths use semicolons.
 if [ -z "$LUA_CPATH" ]; then
     LUA_CPATH="$b/lua/?.so"
 else
@@ -167,11 +182,7 @@ export LUA_CPATH
 
 # For golang.
 export GOLANG=@GOLANG@
-if [ -z "$GOPATH" ]; then
-    GOPATH="$b/golang"
-else
-    GOPATH="$b/golang:$GOPATH"
-fi
+prepend GOPATH "$b/golang"
 export GOPATH
 if [ -z "$CGO_CFLAGS" ]; then
     CGO_CFLAGS="-I$s/src"
@@ -188,11 +199,7 @@ export CGO_LDFLAGS
 
 # For GObject, Javascript and friends.
 export GJS=@GJS@
-if [ -z "$GI_TYPELIB_PATH" ]; then
-    GI_TYPELIB_PATH="$b/gobject"
-else
-    GI_TYPELIB_PATH="$b/gobject:$GI_TYPELIB_PATH"
-fi
+prepend GI_TYPELIB_PATH "$b/gobject"
 export GI_TYPELIB_PATH
 # Be friendly to valgrind (https://live.gnome.org/Valgrind)
 export G_SLICE=always-malloc
-- 
2.1.0

On Friday 13 February 2015 10:16:34 Richard W.M. Jones
wrote:
> Add a bash function 'prepend' for intelligently prepending elements
to
> paths.  eg:
> 
>   prepend PYTHONPATH "/foo"
> 
> would set PYTHONPATH to "/foo" or
"/foo:<previous-contents-of-PYTHONPATH>"
> 
> Tested by:
> 
> (1) Building and testing libguestfs twice: first without libguestfs
> installed as a system library, and then with it installed.
> 
> (2) Examining the output of './run printenv' by hand and comparing
> environment variables to the expected values.
> ---
Nice idea, thanks for it.
>  # Set LD_LIBRARY_PATH and DYLD_LIBRARY_PATH to contain library.
> -build_libs_path="$b/src/.libs:$b/java/.libs:$b/gobject/.libs"
> -export
LD_LIBRARY_PATH="$build_libs_path${LD_LIBRARY_PATH:+:}$LD_LIBRARY_PATH"
> -export
DYLD_LIBRARY_PATH="$build_libs_path${DYLD_LIBRARY_PATH:+:}$DYLD_LIBRARY_PATH"
> +prepend LD_LIBRARY_PATH "$b/gobject/.libs"
> +prepend LD_LIBRARY_PATH "$b/java/.libs"
> +prepend LD_LIBRARY_PATH "$b/src/.libs"
> +prepend DYLD_LIBRARY_PATH "$b/gobject/.libs"
> +prepend DYLD_LIBRARY_PATH "$b/java/.libs"
> +prepend DYLD_LIBRARY_PATH "$b/src/.libs"
> +export LD_LIBRARY_PATH
> +export DYLD_LIBRARY_PATH
I'd still leave the build_libs_path variable, so we don't duplicate
its content twice.
>  # virt-p2v-make-* data directory.
>  if [ -z "$VIRT_P2V_DATA_DIR" ]; then
> -    VIRT_P2V_DATA_DIR="$b/p2v"
> +    prepend VIRT_P2V_DATA_DIR "$b/p2v"
>      export VIRT_P2V_DATA_DIR
>  fi
Is prepend needed here? After all, it is just a single directory.
>  # For Lua.
>  export LUA=@LUA@
> +# Can't use 'prepend' here because Lua paths use semicolons.
>  if [ -z "$LUA_CPATH" ]; then
>      LUA_CPATH="$b/lua/?.so"
>  else
I guess using a second helper like:

  prepend_semicolon()
  {
    eval $1="$2\${$1:+;\$$1}"
  }

could help?

-- 
Pino Toscano

On Fri, Feb 13, 2015 at 11:35:15AM +0100, Pino Toscano
wrote:
> On Friday 13 February 2015 10:16:34 Richard W.M. Jones wrote:
> > Add a bash function 'prepend' for intelligently prepending
elements to
> > paths.  eg:
> > 
> >   prepend PYTHONPATH "/foo"
> > 
> > would set PYTHONPATH to "/foo" or
"/foo:<previous-contents-of-PYTHONPATH>"
> > 
> > Tested by:
> > 
> > (1) Building and testing libguestfs twice: first without libguestfs
> > installed as a system library, and then with it installed.
> > 
> > (2) Examining the output of './run printenv' by hand and
comparing
> > environment variables to the expected values.
> > ---
> 
> Nice idea, thanks for it.
> 
> >  # Set LD_LIBRARY_PATH and DYLD_LIBRARY_PATH to contain library.
> >
-build_libs_path="$b/src/.libs:$b/java/.libs:$b/gobject/.libs"
> > -export
LD_LIBRARY_PATH="$build_libs_path${LD_LIBRARY_PATH:+:}$LD_LIBRARY_PATH"
> > -export
DYLD_LIBRARY_PATH="$build_libs_path${DYLD_LIBRARY_PATH:+:}$DYLD_LIBRARY_PATH"
> > +prepend LD_LIBRARY_PATH "$b/gobject/.libs"
> > +prepend LD_LIBRARY_PATH "$b/java/.libs"
> > +prepend LD_LIBRARY_PATH "$b/src/.libs"
> > +prepend DYLD_LIBRARY_PATH "$b/gobject/.libs"
> > +prepend DYLD_LIBRARY_PATH "$b/java/.libs"
> > +prepend DYLD_LIBRARY_PATH "$b/src/.libs"
> > +export LD_LIBRARY_PATH
> > +export DYLD_LIBRARY_PATH
> 
> I'd still leave the build_libs_path variable, so we don't duplicate
> its content twice.
I considered that, but think this way is clearer, even if there's some
minimal duplication.
> >  # virt-p2v-make-* data directory.
> >  if [ -z "$VIRT_P2V_DATA_DIR" ]; then
> > -    VIRT_P2V_DATA_DIR="$b/p2v"
> > +    prepend VIRT_P2V_DATA_DIR "$b/p2v"
> >      export VIRT_P2V_DATA_DIR
> >  fi
> 
> Is prepend needed here? After all, it is just a single directory.
No it's not -- I removed this hunk.
> >  # For Lua.
> >  export LUA=@LUA@
> > +# Can't use 'prepend' here because Lua paths use
semicolons.
> >  if [ -z "$LUA_CPATH" ]; then
> >      LUA_CPATH="$b/lua/?.so"
> >  else
> 
> I guess using a second helper like:
> 
>   prepend_semicolon()
>   {
>     eval $1="$2\${$1:+;\$$1}"
>   }
> 
> could help?
Actually what's needed is a more general function which could use a
generic separator and also handle appending, thus coping with:

if [ -z "$CGO_CFLAGS" ]; then
    CGO_CFLAGS="-I$s/src"
else
    CGO_CFLAGS="$CGO_CFLAGS -I$s/src"
fi

Anyway, I have pushed this for now, without the P2V data dir hunk.

Thanks,

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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