Allow conditional compilation with GPGME

This makes it possible to omit usage of -lgpgme, just as we can do for
-lcurl and -lcrypto.

Thanks to Rémy Oudompheng for an initial stab at this.

Signed-off-by: Dan McGee <dan@archlinux.org>

3 files changed, 32 insertions, 4 deletions

diff --git a/configure.ac b/configure.ac
index b5fdfff8..738cd7fa 100644
--- a/configure.ac
+++ b/configure.ac
@@ -93,6 +93,11 @@ AC_ARG_WITH(openssl,
 	AS_HELP_STRING([--with-openssl], [use OpenSSL crypto implementations instead of internal routines]),
 	[], [with_openssl=check])
 
+# Help line for using gpgme
+AC_ARG_WITH(gpgme,
+	AS_HELP_STRING([--with-gpgme], [use GPGME for PGP signature verification]),
+	[], [with_gpgme=check])
+
 # Check for useable libcurl
 LIBCURL_CHECK_CONFIG([yes], [7.19.4])
 
@@ -151,8 +156,17 @@ AS_IF([test "x$with_openssl" != "xno"],
 AM_CONDITIONAL([HAVE_LIBSSL], [test "x$ac_cv_lib_ssl_MD5_Final" = "xyes"])
 
 # Check for gpgme
-AC_CHECK_LIB([gpgme], [gpgme_check_version], ,
-	AC_MSG_ERROR([gpgme is needed to compile pacman!]))
+AC_MSG_CHECKING(whether to link with libgpgme)
+AS_IF([test "x$with_gpgme" != "xno"],
+	[AC_MSG_RESULT(yes)
+	AC_CHECK_LIB([gpgme], [gpgme_check_version], ,
+	[if test "x$with_gpgme" != "xcheck"; then
+		AC_MSG_FAILURE([--with-ggpme was given, but -lgpgme was not found])
+	fi],
+	[-lgpgme])
+	with_gpgme=$ac_cv_lib_gpgme_gpgme_check_version],
+	AC_MSG_RESULT(no))
+AM_CONDITIONAL([HAVE_LIBGPGME], [test "x$with_gpgme" = "xyes"])
 
 # Checks for header files.
 AC_CHECK_HEADERS([fcntl.h glob.h libintl.h locale.h mntent.h string.h \
diff --git a/lib/libalpm/Makefile.am b/lib/libalpm/Makefile.am
index 080ac195..b2b6d0d2 100644
--- a/lib/libalpm/Makefile.am
+++ b/lib/libalpm/Makefile.am
@@ -25,7 +25,6 @@ libalpm_la_SOURCES = \
 	alpm.h alpm.c \
 	alpm_list.h alpm_list.c \
 	backup.h backup.c \
-	base64.h base64.c \
 	be_local.c \
 	be_package.c \
 	be_sync.c \
@@ -54,6 +53,11 @@ libalpm_la_SOURCES += \
 	md5.h md5.c
 endif
 
+if HAVE_LIBGPGME
+libalpm_la_SOURCES += \
+	base64.h base64.c
+endif
+
 libalpm_la_LDFLAGS = -no-undefined -version-info $(LIB_VERSION_INFO) @LIBCURL@
 libalpm_la_LIBADD = $(LTLIBINTL)
 
diff --git a/lib/libalpm/signing.c b/lib/libalpm/signing.c
index 867e0a58..a2a6457a 100644
--- a/lib/libalpm/signing.c
+++ b/lib/libalpm/signing.c
@@ -22,17 +22,21 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+
+#if HAVE_LIBGPGME
 #include <locale.h> /* setlocale() */
 #include <gpgme.h>
+#include "base64.h"
+#endif
 
 /* libalpm */
 #include "signing.h"
 #include "package.h"
-#include "base64.h"
 #include "util.h"
 #include "log.h"
 #include "alpm.h"
 
+#if HAVE_LIBGPGME
 #define CHECK_ERR(void) do { \
 		if(err != GPG_ERR_NO_ERROR) { goto error; } \
 	} while(0)
@@ -364,6 +368,12 @@ error:
 	}
 	return ret;
 }
+#else
+int _alpm_gpgme_checksig(const char *path, const char *base64_sig)
+{
+	return -1;
+}
+#endif
 
 /**
  * Determines the necessity of checking for a valid PGP signature