[PATCH] Clean up: Makefiles: Improve support for out-of-tree builds

[Michael Witten]

The following patch should be applied after all the other patches
that I've submitted recently.

I suspect that this whole patch series will result in some debate,
and so I intend to make adjustments as issues are brought to light,
and then submit a consolidated, refreshed series that includes
all of these patches in a more coherent format.

Sincerely,
Michael Witten

To apply this patch, save this email to a file:

  /path/to/email

and then apply it:

  git am --scissors /path/to/email

Here is the scissors-line across which git will cut in order to
throw away the text above it.

8<----8<----8<----8<----8<----8<----8<----8<----8<----8<----8<----8<----8<----

There's a lot going on here that makes it difficult to support
out-of-tree builds entirely, but this commit goes a long way:

    This commit allows for the out-of-tree building
    of the binaries for Dropbear and for the built-in
    `libtom{crypto,math}' dependencies.

That's basically all users of Dropbear care about.

Overall, the key is to ensure that `make' is given good values
for the `VPATH' and `srcdir' variables, and then also to use
`$(srcdir)' where appropriate.

Setting `VPATH' and `scrdir' is as easy as ensuring that the
`configure' script is told about the various makefiles, and
then including places in those makefiles to be so configured.

The irritating part is ensuring that `$(srcdir)' is used
appropriately; the only place where this is really a problem
is in the makefiles for `libtommath', which were not written
in a way that supports out-of-tree building in general (while
it does work to build the binaries, it doesn't work to build
the ancillary files, such as the documentation).

Configure needs to know about the following files (which, at
the moment, simply provide for a working `clean' target):

  libtommath/etc/makefile
  libtommath/pics/makefile

This is achieved by adding them to `configure.ac' as files
that need to be configured; unfortunately, this seems to
require those files to end with a `.in' extension.

To keep the naming consistent, this commit renames each of
those files to `Makefile.in'.

At this point, neither of those files has been edited to include
a place for `configure' to insert a value for `VPATH' or `srcdir';
there are 2 reasons for this:

  * `git' will better be able to determine that a file has been
    renamed if it has not been modified at the same time.

  * The `clean' targets in them work without modification, and
    the rest of their targets are not useful to the main purpose
    of this commit: To make it possible to perform out-of-tree
    building of the *binaries*.

So, why not just copy those files into the out-of-tree build
directory without modifying those names or telling `configure'
about them? Well, because it's probably useful to prepare the
way for a possible future commit that does get the rest of the
targets working; then it will just be a matter of modifying
those files to do the right thing.
---
 configure.ac                              | 3 ++-
 libtomcrypt/Makefile.in                   | 4 ++--
 libtommath/Makefile.in                    | 7 ++++---
 libtommath/etc/{makefile => Makefile.in}  | 0
 libtommath/pics/{makefile => Makefile.in} | 0
 5 files changed, 8 insertions(+), 6 deletions(-)
 rename libtommath/etc/{makefile => Makefile.in} (100%)
 rename libtommath/pics/{makefile => Makefile.in} (100%)

diff --git a/configure.ac b/configure.ac
index 8be542a..0467d7e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -828,6 +828,7 @@ AS_MKDIR_P(libtomcrypt/src/modes/ecb)
 AS_MKDIR_P(libtomcrypt/src/modes/ofb)
 AS_MKDIR_P(libtomcrypt/src/modes/f8)
 AS_MKDIR_P(libtomcrypt/src/modes/lrw)
+AS_MKDIR_P(libtomcrypt/src/modes/xts)
 AS_MKDIR_P(libtomcrypt/src/pk/asn1/der/bit)
 AS_MKDIR_P(libtomcrypt/src/pk/asn1/der/boolean)
 AS_MKDIR_P(libtomcrypt/src/pk/asn1/der/choice)
@@ -848,7 +849,7 @@ AS_MKDIR_P(libtomcrypt/src/pk/katja)
 AS_MKDIR_P(libtomcrypt/src/pk/pkcs1)
 AS_MKDIR_P(libtomcrypt/src/pk/rsa)
 AS_MKDIR_P(libtomcrypt/src/prngs)
-LIBTOM_FILES="libtomcrypt/Makefile libtommath/Makefile"
+LIBTOM_FILES="libtomcrypt/Makefile libtommath/Makefile libtommath/etc/Makefile libtommath/pics/Makefile"
 fi
 AC_CONFIG_HEADER(config.h)
 AC_CONFIG_FILES(Makefile $LIBTOM_FILES)
diff --git a/libtomcrypt/Makefile.in b/libtomcrypt/Makefile.in
index d8f9a6d..e42b03e 100644
--- a/libtomcrypt/Makefile.in
+++ b/libtomcrypt/Makefile.in
@@ -8,8 +8,8 @@ VERSION=1.17
 
 PLATFORM := $(shell uname | sed -e 's/_.*//')
 
-
-srcdir=.
+VPATH=@srcdir@
+srcdir=@srcdir@
 
 # Compiler and Linker Names
 #CC=gcc
diff --git a/libtommath/Makefile.in b/libtommath/Makefile.in
index 2fec4ce..1f0280c 100644
--- a/libtommath/Makefile.in
+++ b/libtommath/Makefile.in
@@ -2,7 +2,8 @@
 #
 #Tom St Denis
 
-srcdir=.
+VPATH=@srcdir@
+srcdir=@srcdir@
 
 # So that libtommath can include Dropbear headers for options and m_burn()
 CFLAGS += -I$(srcdir) -I../libtomcrypt/src/headers/ -I$(srcdir)/../libtomcrypt/src/headers/ -I../ -I$(srcdir)/../
@@ -17,7 +18,7 @@ endif
 ifneq ($V,1)
 	@echo "   * ${CC} $@"
 endif
-	${silent} ${CC} -c ${CFLAGS} $*.c -o $@
+	${silent} ${CC} -c ${CFLAGS} $(filter %.c,$^) -o $@
 
 #default files to install
 ifndef LIBNAME
@@ -26,7 +27,7 @@ endif
 
 coverage: LIBNAME:=-Wl,--whole-archive $(LIBNAME)  -Wl,--no-whole-archive
 
-include makefile.include
+include $(srcdir)/makefile.include
 
 LCOV_ARGS=--directory .
 
diff --git a/libtommath/etc/makefile b/libtommath/etc/Makefile.in
similarity index 100%
rename from libtommath/etc/makefile
rename to libtommath/etc/Makefile.in
diff --git a/libtommath/pics/makefile b/libtommath/pics/Makefile.in
similarity index 100%
rename from libtommath/pics/makefile
rename to libtommath/pics/Makefile.in
-- 
2.10.0