block/ssh: Require libssh2 >= 1.2.8.

libssh2 >= 1.2.8 is required to enable this block device (because
that version introduced the libssh2_session_handshake call).

Change the test to use pkg-config exclusively.  If the user requests
--enable-libssh2 and the minimum version is not available, then the
following error is displayed:

  $ ./configure --enable-libssh2

  ERROR: libssh2 >= 1.2.8 required for --enable-libssh2

If --enable-libssh2 is not specified, then the feature is silently
disabled if sufficiently new libssh2 is not available.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 4 insertions, 20 deletions

diff --git a/configure b/configure
index ee2e7e8ad9..8188a7c05f 100755
--- a/configure
+++ b/configure
@@ -2364,35 +2364,19 @@ fi
 
 ##########################################
 # libssh2 probe
+min_libssh2_version=1.2.8
 if test "$libssh2" != "no" ; then
-  cat > $TMPC <<EOF
-#include <stdio.h>
-#include <libssh2.h>
-#include <libssh2_sftp.h>
-int main(void) {
-    LIBSSH2_SESSION *session;
-    session = libssh2_session_init ();
-    (void) libssh2_sftp_init (session);
-    return 0;
-}
-EOF
-
-  if $pkg_config libssh2 --modversion >/dev/null 2>&1; then
+  if $pkg_config --atleast-version=$min_libssh2_version libssh2 >/dev/null 2>&1
+  then
     libssh2_cflags=`$pkg_config libssh2 --cflags`
     libssh2_libs=`$pkg_config libssh2 --libs`
-  else
-    libssh2_cflags=
-    libssh2_libs="-lssh2"
-  fi
-
-  if compile_prog "$libssh2_cflags" "$libssh2_libs" ; then
     libssh2=yes
     libs_tools="$libssh2_libs $libs_tools"
     libs_softmmu="$libssh2_libs $libs_softmmu"
     QEMU_CFLAGS="$QEMU_CFLAGS $libssh2_cflags"
   else
     if test "$libssh2" = "yes" ; then
-      feature_not_found "libssh2"
+      error_exit "libssh2 >= $min_libssh2_version required for --enable-libssh2"
     fi
     libssh2=no
   fi