[gparted] Use pkg-config Autoconf check for libparted version first (#740004)

[Curtis Gedak <gedakc src gnome org>]

commit 9c7cb6f4965349a2fec0ec16056beff6b8c5d3ce
Author: Mike Fleetwood <mike fleetwood googlemail com>
Date:   Thu Nov 13 20:53:54 2014 +0000

    Use pkg-config Autoconf check for libparted version first (#740004)
    
    Currently ./configure links and runs a program to query the libparted
    library version, which is used to determine the availability of some
    features.  This makes cross-compiling harder because the compile host
    has to fake a virtual installation target in which to run the check.
    Because of this, pkg-config based Autoconf checks are preferred.
    
    Switch to using a pkg-config based Autoconf check first to determine the
    version of libparted, falling back to the previous method for older
    distributions which don't provide a pkg-config file for libparted.
    
    Also small comment tidy-up elsewhere.
    
    Bug 740004 - use pkg-config to check for version of libparted

 configure.ac |   50 +++++++++++++++++++++++++++++++++-----------------
 1 files changed, 33 insertions(+), 17 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 37025b0..e1709bc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -43,14 +43,31 @@ AC_CHECK_LIB([dl], [dlopen], [], AC_MSG_ERROR([*** libdl not found.]))
 AC_CHECK_LIB([parted], [ped_device_read], [], AC_MSG_ERROR([*** libparted not found.]))
 
 
-dnl Check for minimum required libparted version
+dnl Check for minimum required libparted version.
+dnl 1) Check using pkg-config.
+dnl    (Older distros tend to not provide pkg-config information for libparted).
+dnl 2) Check by linking and running a program to report libparted version directly.
 LIBPARTED_REQUIRED_VERSION='1.7.1'
-AC_MSG_CHECKING([for libparted >= $LIBPARTED_REQUIRED_VERSION])
+AC_MSG_CHECKING([for libparted >= $LIBPARTED_REQUIRED_VERSION (querying pkg-config)])
 LIBPARTED_REQUIRED_INT=`echo "$LIBPARTED_REQUIRED_VERSION" |
        $AWK -F. '{print $1 * 10000 + $2 * 100 + $3}'`
-AC_RUN_IFELSE(
-       [AC_LANG_SOURCE(
-               [[
+dnl 1) Check using pkg-config.
+PKG_CHECK_EXISTS(
+       [libparted],
+       [LIBPARTED_FOUND_VERSION=`$PKG_CONFIG --modversion libparted`
+        LIBPARTED_FOUND_INT=`echo "$LIBPARTED_FOUND_VERSION" |
+               $AWK -F. '{print $1 * 10000 + $2 * 100 + $3}'`
+        AC_MSG_RESULT([$LIBPARTED_FOUND_VERSION])
+        test "$LIBPARTED_FOUND_INT" -ge "$LIBPARTED_REQUIRED_INT" ||
+               AC_MSG_ERROR([*** libparted too old.  Require libparted >= $LIBPARTED_REQUIRED_VERSION but 
only found libparted $LIBPARTED_FOUND_VERSION.])
+       ],
+       [AC_MSG_RESULT([not found])
+        dnl 2) Check by linking and running a program to report libparted version
+        dnl    directly.
+        AC_MSG_CHECKING([for libparted >= $LIBPARTED_REQUIRED_VERSION (querying libparted)])
+        AC_RUN_IFELSE(
+               [AC_LANG_SOURCE(
+                       [[
 #include <stdio.h>
 #include <stdlib.h>
 #include <parted/parted.h>
@@ -66,16 +83,17 @@ int main()
        printf("%s\n", version);
        return EXIT_SUCCESS;
 }
-               ]]
-       )],
-       dnl Run test program again to cache libparted version.
-       [LIBPARTED_FOUND_VERSION=`./conftest$EXEEXT`
-        LIBPARTED_FOUND_INT=`echo "$LIBPARTED_FOUND_VERSION" |
-               $AWK -F. '{print $1 * 10000 + $2 * 100 + $3}'`
-        test "$LIBPARTED_FOUND_INT" -ge "$LIBPARTED_REQUIRED_INT" ||
-               AC_MSG_ERROR([*** libparted too old.  Require libparted >= $LIBPARTED_REQUIRED_VERSION but 
only found libparted $LIBPARTED_FOUND_VERSION.])
-       ],
-       [AC_MSG_ERROR([*** Error querying libparted version.  Check config.log for details.])]
+                       ]]
+               )],
+               dnl Run test program again to cache libparted version.
+               [LIBPARTED_FOUND_VERSION=`./conftest$EXEEXT`
+                LIBPARTED_FOUND_INT=`echo "$LIBPARTED_FOUND_VERSION" |
+                       $AWK -F. '{print $1 * 10000 + $2 * 100 + $3}'`
+                test "$LIBPARTED_FOUND_INT" -ge "$LIBPARTED_REQUIRED_INT" ||
+                       AC_MSG_ERROR([*** libparted too old.  Require libparted >= 
$LIBPARTED_REQUIRED_VERSION but only found libparted $LIBPARTED_FOUND_VERSION.])
+               ],
+               [AC_MSG_ERROR([*** Error querying libparted version.  Check config.log for details.])]
+       )]
 )
 
 
@@ -106,8 +124,6 @@ dnl NOTE:
 dnl For AC_CHECK_LIB the default action-if-found ($3) includes extending
 dnl LIBS with the newly found library ($1) thus:
 dnl     LIBS="-l$1 $LIBS"
-dnl If default action-if-found is overridden, LIBS is not extended when
-dnl the library is found.
 dnl
 dnl As the default action-if-found is overridden, LIBS isn't extended so
 dnl saving and restoring LIBS isn't required.