BuildSystem: Search for Python/C API when possibly needed only.

The Python/C API is used only if the Test Framework was enabled in Asterisk
'make menuselect'. The Test Framework is available only if the Developer Mode
was enabled in Asterisk './configure --enable-dev-mode'. And that Python/C API
is used only if the PJProject was found and not disabled in Asterisk; the user
did not go for './configure --without-pjproject'.

Furthermore, because version 2 of that Python/C API is required (currently) and
because some platforms do not offer a generic version 2, the script searches
for 2.7 explicitly as well.

To avoid version mismatch between the Python/C API and the Python environment,
the script searches for the latter in the same versions, in the same the order
as well. Because this Python/C API is just for (some) Asterisk contributors,
the script also goes for the Python 3 environment as a last resort for all
other Asterisk users. This allows 'make full' even on minimal installations of
Ubuntu 18.04 LTS and newer.

Because the Python/C API is Asterisk contributor specific, the Python packages
are removed from the script './contrib/scripts/install_prereq' as this script
is intended for Asterisk users. Asterisk contributors have to install much more
packages in any case, like:
sudo apt install autoconf automake git git-review python2.7-dev

ASTERISK-28824
ASTERISK-27717

Change-Id: Id46d357e18869f64dcc217b8fdba821b63eeb876

configure

@@ -6829,8 +6829,10 @@ $as_echo "no" >&6; }
 fi
 
 
-# Extract the first word of "python", so it can be a program name with args.
-set dummy python; ac_word=$2
+for ac_prog in python2.7 python2 python python3
+do
+  # Extract the first word of "$ac_prog", so it can be a program name with args.
+set dummy $ac_prog; ac_word=$2
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
 $as_echo_n "checking for $ac_word... " >&6; }
 if ${ac_cv_path_PYTHON+:} false; then :
@@ -6856,7 +6858,6 @@ done
   done
 IFS=$as_save_IFS
 
-  test -z "$ac_cv_path_PYTHON" && ac_cv_path_PYTHON=":"
   ;;
 esac
 fi
@@ -6870,6 +6871,10 @@ $as_echo "no" >&6; }
 fi
 
 
+  test -n "$PYTHON" && break
+done
+test -n "$PYTHON" || PYTHON=":"
+
 # Extract the first word of "find", so it can be a program name with args.
 set dummy find; ac_word=$2
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
@@ -25981,10 +25986,187 @@ fi
 
 
    fi
+
+   if test "x$PBX_PJPROJECT" = "x1" ; then
+      if test "x${AST_DEVMODE}" = "xyes" ; then
+
+
+
+   if test "x${PBX_PYTHONDEV}" != "x1" -a "${USE_PYTHONDEV}" != "no"; then
+
+pkg_failed=no
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for PYTHONDEV" >&5
+$as_echo_n "checking for PYTHONDEV... " >&6; }
+
+if test -n "$PYTHONDEV_CFLAGS"; then
+    pkg_cv_PYTHONDEV_CFLAGS="$PYTHONDEV_CFLAGS"
+ elif test -n "$PKG_CONFIG"; then
+    if test -n "$PKG_CONFIG" && \
+    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"python-2.7\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "python-2.7") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; then
+  pkg_cv_PYTHONDEV_CFLAGS=`$PKG_CONFIG --cflags "python-2.7" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes
+else
+  pkg_failed=yes
+fi
+ else
+    pkg_failed=untried
+fi
+if test -n "$PYTHONDEV_LIBS"; then
+    pkg_cv_PYTHONDEV_LIBS="$PYTHONDEV_LIBS"
+ elif test -n "$PKG_CONFIG"; then
+    if test -n "$PKG_CONFIG" && \
+    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"python-2.7\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "python-2.7") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; then
+  pkg_cv_PYTHONDEV_LIBS=`$PKG_CONFIG --libs "python-2.7" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes
+else
+  pkg_failed=yes
+fi
+ else
+    pkg_failed=untried
 fi
 
 
 
+if test $pkg_failed = yes; then
+   	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+
+if $PKG_CONFIG --atleast-pkgconfig-version 0.20; then
+        _pkg_short_errors_supported=yes
+else
+        _pkg_short_errors_supported=no
+fi
+        if test $_pkg_short_errors_supported = yes; then
+	        PYTHONDEV_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "python-2.7" 2>&1`
+        else
+	        PYTHONDEV_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "python-2.7" 2>&1`
+        fi
+	# Put the nasty error message in config.log where it belongs
+	echo "$PYTHONDEV_PKG_ERRORS" >&5
+
+
+            PBX_PYTHONDEV=0
+
+
+elif test $pkg_failed = untried; then
+     	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+
+            PBX_PYTHONDEV=0
+
+
+else
+	PYTHONDEV_CFLAGS=$pkg_cv_PYTHONDEV_CFLAGS
+	PYTHONDEV_LIBS=$pkg_cv_PYTHONDEV_LIBS
+        { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+
+            PBX_PYTHONDEV=1
+            PYTHONDEV_INCLUDE=$(echo ${PYTHONDEV_CFLAGS} | $SED -e "s|-std=c99||g")
+            PYTHONDEV_LIB="$PYTHONDEV_LIBS"
+
+$as_echo "#define HAVE_PYTHONDEV 1" >>confdefs.h
+
+
+fi
+   fi
+
+
+   if test "x${PBX_PYTHONDEV}" != "x1" -a "${USE_PYTHONDEV}" != "no"; then
+
+pkg_failed=no
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for PYTHONDEV" >&5
+$as_echo_n "checking for PYTHONDEV... " >&6; }
+
+if test -n "$PYTHONDEV_CFLAGS"; then
+    pkg_cv_PYTHONDEV_CFLAGS="$PYTHONDEV_CFLAGS"
+ elif test -n "$PKG_CONFIG"; then
+    if test -n "$PKG_CONFIG" && \
+    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"python2\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "python2") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; then
+  pkg_cv_PYTHONDEV_CFLAGS=`$PKG_CONFIG --cflags "python2" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes
+else
+  pkg_failed=yes
+fi
+ else
+    pkg_failed=untried
+fi
+if test -n "$PYTHONDEV_LIBS"; then
+    pkg_cv_PYTHONDEV_LIBS="$PYTHONDEV_LIBS"
+ elif test -n "$PKG_CONFIG"; then
+    if test -n "$PKG_CONFIG" && \
+    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"python2\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "python2") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; then
+  pkg_cv_PYTHONDEV_LIBS=`$PKG_CONFIG --libs "python2" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes
+else
+  pkg_failed=yes
+fi
+ else
+    pkg_failed=untried
+fi
+
+
+
+if test $pkg_failed = yes; then
+   	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+
+if $PKG_CONFIG --atleast-pkgconfig-version 0.20; then
+        _pkg_short_errors_supported=yes
+else
+        _pkg_short_errors_supported=no
+fi
+        if test $_pkg_short_errors_supported = yes; then
+	        PYTHONDEV_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "python2" 2>&1`
+        else
+	        PYTHONDEV_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "python2" 2>&1`
+        fi
+	# Put the nasty error message in config.log where it belongs
+	echo "$PYTHONDEV_PKG_ERRORS" >&5
+
+
+            PBX_PYTHONDEV=0
+
+
+elif test $pkg_failed = untried; then
+     	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+
+            PBX_PYTHONDEV=0
+
+
+else
+	PYTHONDEV_CFLAGS=$pkg_cv_PYTHONDEV_CFLAGS
+	PYTHONDEV_LIBS=$pkg_cv_PYTHONDEV_LIBS
+        { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+
+            PBX_PYTHONDEV=1
+            PYTHONDEV_INCLUDE=$(echo ${PYTHONDEV_CFLAGS} | $SED -e "s|-std=c99||g")
+            PYTHONDEV_LIB="$PYTHONDEV_LIBS"
+
+$as_echo "#define HAVE_PYTHONDEV 1" >>confdefs.h
+
+
+fi
+   fi
+
 
    if test "x${PBX_PYTHONDEV}" != "x1" -a "${USE_PYTHONDEV}" != "no"; then
 
@@ -26073,6 +26255,16 @@ $as_echo "#define HAVE_PYTHONDEV 1" >>confdefs.h
 fi
    fi
 
+         # The PJProject offers a C extension to Python. That wrapper is used by the
+         # Asterisk Test Framework, which requires Asterisk to be in Developer Mode.
+         # However, the used wrapper (called 'PJSUA Python') is deprecated and was not
+         # ported from Python 2.7 to Python 3.x. This is confirmed; it simply does not
+         # build. For more see <http://www.pjsip.org/trac/wiki/Python_SIP_Tutorial>.
+         # Therefore, the C libraries for Python 3 are of no help in Asterisk:
+         #AST_PKG_CONFIG_CHECK([PYTHONDEV], [python3])
+      fi
+   fi
+fi
 
 
 if test "x${PBX_POPT}" != "x1" -a "${USE_POPT}" != "no"; then

configure.ac

@@ -263,7 +263,7 @@ AC_PATH_PROG([CAT], [cat], :)
 AC_PATH_PROG([CUT], [cut], :)
 AC_PATH_PROG([FLEX], [flex], :)
 AC_PATH_PROG([GREP], [grep], :)
-AC_PATH_PROG([PYTHON], [python], :)
+AC_PATH_PROGS([PYTHON], [python2.7 python2 python python3], :)
 AC_PATH_PROG([FIND], [find], :)
 AC_PATH_PROG([BASENAME], [basename], :)
 AC_PATH_PROG([DIRNAME], [dirname], :)
@@ -2458,11 +2458,24 @@ if test "$USE_PJPROJECT" != "no" ; then
       AST_EXT_LIB_CHECK([PJSIP_AUTH_CLT_DEINIT], [pjsip], [pjsip_auth_clt_deinit], [pjsip.h], [$PJPROJECT_LIB], [$PJPROJECT_CFLAGS])
       AST_EXT_LIB_CHECK([PJSIP_TSX_LAYER_FIND_TSX2], [pjsip], [pjsip_tsx_layer_find_tsx2], [pjsip.h], [$PJPROJECT_LIB], [$PJPROJECT_CFLAGS])
    fi
-fi
 
-AC_SUBST([PYTHONDEV_LIB])
-AC_SUBST([PYTHONDEV_INCLUDE])
-AST_PKG_CONFIG_CHECK([PYTHONDEV], [python])
+   if test "x$PBX_PJPROJECT" = "x1" ; then
+      if test "x${AST_DEVMODE}" = "xyes" ; then
+         AC_SUBST([PYTHONDEV_LIB])
+         AC_SUBST([PYTHONDEV_INCLUDE])
+         AST_PKG_CONFIG_CHECK([PYTHONDEV], [python-2.7])
+         AST_PKG_CONFIG_CHECK([PYTHONDEV], [python2])
+         AST_PKG_CONFIG_CHECK([PYTHONDEV], [python])
+         # The PJProject offers a C extension to Python. That wrapper is used by the
+         # Asterisk Test Framework, which requires Asterisk to be in Developer Mode.
+         # However, the used wrapper (called 'PJSUA Python') is deprecated and was not
+         # ported from Python 2.7 to Python 3.x. This is confirmed; it simply does not
+         # build. For more see <http://www.pjsip.org/trac/wiki/Python_SIP_Tutorial>.
+         # Therefore, the C libraries for Python 3 are of no help in Asterisk:
+         #AST_PKG_CONFIG_CHECK([PYTHONDEV], [python3])
+      fi
+   fi
+fi
 
 AST_EXT_LIB_CHECK([POPT], [popt], [poptStrerror], [popt.h])
 

contrib/scripts/install_prereq

@@ -32,7 +32,7 @@ PACKAGES_DEBIAN="$PACKAGES_DEBIAN libcodec2-dev libfftw3-dev libsndfile1-dev lib
 # Asterisk: for the unpackaged below:
 PACKAGES_DEBIAN="$PACKAGES_DEBIAN wget subversion"
 # Asterisk: for ./configure --with-pjproject-bundled:
-PACKAGES_DEBIAN="$PACKAGES_DEBIAN bzip2 patch python-dev"
+PACKAGES_DEBIAN="$PACKAGES_DEBIAN bzip2 patch"
 
 # Basic build system:
 PACKAGES_RH="make gcc gcc-c++ pkgconfig"
@@ -48,7 +48,7 @@ PACKAGES_RH="$PACKAGES_RH codec2-devel fftw-devel libsndfile-devel unbound-devel
 # Asterisk: for the unpackaged below:
 PACKAGES_RH="$PACKAGES_RH wget subversion"
 # Asterisk: for ./configure --with-pjproject-bundled:
-PACKAGES_RH="$PACKAGES_RH bzip2 patch python-devel"
+PACKAGES_RH="$PACKAGES_RH bzip2 patch"
 
 # Basic build system:
 PACKAGES_SUSE="make gcc gcc-c++ pkg-config"
@@ -64,7 +64,7 @@ PACKAGES_SUSE="$PACKAGES_SUSE codec2-devel fftw3-devel libsndfile-devel unbound-
 # Asterisk: for the unpackaged below:
 PACKAGES_SUSE="$PACKAGES_SUSE wget subversion"
 # Asterisk: for ./configure --with-pjproject-bundled:
-PACKAGES_SUSE="$PACKAGES_SUSE bzip2 patch python-devel"
+PACKAGES_SUSE="$PACKAGES_SUSE bzip2 patch"
 
 # Basic build system:
 PACKAGES_ARCH="make gcc pkg-config"
@@ -80,7 +80,7 @@ PACKAGES_ARCH="$PACKAGES_ARCH fftw libsndfile unbound"
 # Asterisk: for the unpackaged below:
 PACKAGES_ARCH="$PACKAGES_ARCH wget subversion"
 # Asterisk: for ./configure --with-pjproject-bundled:
-PACKAGES_ARCH="$PACKAGES_ARCH bzip2 patch python2"
+PACKAGES_ARCH="$PACKAGES_ARCH bzip2 patch"
 
 # Basic build system:
 PACKAGES_GENTOO="sys-devel/make sys-devel/gcc dev-util/pkgconfig"
@@ -96,7 +96,7 @@ PACKAGES_GENTOO="$PACKAGES_GENTOO sci-libs/fftw media-libs/libsndfile net-dns/un
 # Asterisk: for the unpackaged below:
 PACKAGES_GENTOO="$PACKAGES_GENTOO net-misc/wget dev-vcs/subversion"
 # Asterisk: for ./configure --with-pjproject-bundled:
-PACKAGES_GENTOO="$PACKAGES_GENTOO app-arch/bzip2 sys-devel/patch dev-lang/python:2.7"
+PACKAGES_GENTOO="$PACKAGES_GENTOO app-arch/bzip2 sys-devel/patch"
 
 # Basic build system:
 PACKAGES_NBSD="gmake pkg-config"
@@ -112,7 +112,7 @@ PACKAGES_NBSD="$PACKAGES_NBSD codec2 fftw libsndfile unbound"
 # Asterisk: for the unpackaged below:
 PACKAGES_NBSD="$PACKAGES_NBSD wget subversion-base"
 # Asterisk: for ./configure --with-pjproject-bundled:
-PACKAGES_NBSD="$PACKAGES_NBSD bzip2 patch python27"
+PACKAGES_NBSD="$PACKAGES_NBSD bzip2 patch"
 
 # Basic build system:
 PACKAGES_OBSD="gmake"
@@ -128,7 +128,7 @@ PACKAGES_OBSD="$PACKAGES_OBSD fftw3 libsndfile"
 # Asterisk: for the unpackaged below:
 PACKAGES_OBSD="$PACKAGES_OBSD wget subversion"
 # Asterisk: for ./configure --with-pjproject-bundled:
-PACKAGES_OBSD="$PACKAGES_OBSD bzip2 python%2"
+PACKAGES_OBSD="$PACKAGES_OBSD bzip2"
 
 # Basic build system:
 PACKAGES_FBSD="gmake pkgconf"
@@ -144,7 +144,7 @@ PACKAGES_FBSD="$PACKAGES_FBSD codec2 fftw3 libsndfile unbound"
 # Asterisk: for the unpackaged below:
 PACKAGES_FBSD="$PACKAGES_FBSD wget subversion"
 # Asterisk: for ./configure --with-pjproject-bundled:
-PACKAGES_FBSD="$PACKAGES_FBSD bzip2 patch python"
+PACKAGES_FBSD="$PACKAGES_FBSD bzip2 patch"
 
 # Basic build system:
 PACKAGES_DBSD="gmake pkgconf"
@@ -160,7 +160,7 @@ PACKAGES_DBSD="$PACKAGES_DBSD codec2 fftw3 libsndfile unbound"
 # Asterisk: for the unpackaged below:
 PACKAGES_DBSD="$PACKAGES_DBSD wget subversion"
 # Asterisk: for ./configure --with-pjproject-bundled:
-PACKAGES_DBSD="$PACKAGES_DBSD bzip2 patch python"
+PACKAGES_DBSD="$PACKAGES_DBSD bzip2 patch"
 
 KVERS=`uname -r`