download_and_compile.sh: add core file support to run_fgfs_debug.sh

Usage of run_fgfs_debug.sh is slightly changed: you now need to put a
'--' argument before all arguments that you want to pass to fgfs. For
instance:

  ./run_fgfs_debug.sh -- --aircraft=ufo --airport=PMDY

There is also a new option: -c, alias --core-file. This option allows
one to start gdb from an existing fgfs core dump, with appropriate
LD_LIBRARY_PATH setting and --directory options; in this case, don't
specify any fgfs argument (the fgfs arguments used when the core file
was produced have been recorded therein). Example:

  ./run_fgfs_debug.sh -c /path/to/core

All this is documented with './run_fgfs_debug.sh --help'.

download_and_compile.sh

@@ -1500,7 +1500,7 @@ if _elementIn "FGFS" "${WHATTOBUILD[@]}" || \
             ../../flightgear 2>&1 | _logOutput
     fi
 
-    if [[ `uname` == 'OpenBSD' ]]; then
+    if [[ "$(uname)" == 'OpenBSD' ]]; then
       # _make will end up running fgrcc, which was built with our zlib, so we
       # need to set LD_LIBRARY_PATH, otherwise things will fail because the
       # system zlib is too old.
@@ -1519,7 +1519,7 @@ if _elementIn "FGFS" "${WHATTOBUILD[@]}" || \
   common="${common}cd \"\$(dirname \"\$0\")\"\n"
   common="${common}cd '$SUB_INSTALL_DIR/$FGFS_INSTALL_DIR/bin'\n"
 
-  if [[ `uname` == 'OpenBSD' ]]; then
+  if [[ "$(uname)" == 'OpenBSD' ]]; then
     # Force use of our zlib.
     paths="$paths:../../$ZLIB_INSTALL_DIR/lib"
     # OpenBSD's base gdb is too old; `pkg_add egdb` gives one that we can use.
@@ -1536,8 +1536,63 @@ if _elementIn "FGFS" "${WHATTOBUILD[@]}" || \
   chmod 755 $SCRIPT
 
   SCRIPT=run_fgfs_debug.sh
-  echo -en "$common" > $SCRIPT
-  echo "$gdb --directory='$CBD/flightgear/src' --args ./fgfs --fg-root=\"\$PWD/../fgdata\" \"\$@\"" >> $SCRIPT
+  cat >"$SCRIPT" <<EndOfScriptText
+#! /bin/sh
+
+PROGNAME=\$(basename "\$0")
+GETOPT=getopt
+
+USAGE="\$PROGNAME [OPTION...] [-- FGFS_ARG...]
+Run FlightGear under GDB.
+
+Note the need for a '--' argument before all fgfs arguments. Examples:
+
+  ./run_fgfs_debug.sh -- --aircraft=ufo --airport=PMDY
+  ./run_fgfs_debug.sh -c /path/to/core
+
+Options:
+  -c, --core-file=FILE   instruct GDB to examine FILE as a core dump (no need
+                         for the '--' and fgfs arguments in this case)
+      --help             display this help message and exit"
+
+CORE_FILE=
+
+if [ "\$(uname)" = "OpenBSD" ]; then
+    GETOPT=gnugetopt
+fi
+TEMP=\$("\$GETOPT" -o '+c:' --longoptions 'core-file:,help' -n "\$PROGNAME" -- "\$@")
+
+case \$? in
+    0) : ;;
+    1) echo "\$USAGE" >&2; exit 1 ;;
+    *) exit 1 ;;
+esac
+
+eval set -- "\$TEMP"
+
+while true; do
+  case "\$1" in
+    -c|--core-file) CORE_FILE="\$2"; shift 2 ;;
+    --help) echo "\$USAGE"; exit 0 ;;
+    --) shift; break ;;
+    *) echo "\$PROGNAME: unexpected option '\$1'; please report a bug." >&2
+       exit 1 ;;
+  esac
+done
+
+cd "\$(dirname "\$0")/$SUB_INSTALL_DIR/$FGFS_INSTALL_DIR/bin"
+${set_ld_library_path}
+
+if [ -z "\$CORE_FILE" ]; then
+  gdb --directory="$INSTALL_DIR_SIMGEAR" \\
+      --directory="$INSTALL_DIR_FGFS" \\
+      --args ./fgfs --fg-root="$INSTALL_DIR_FGFS/fgdata" "\$@"
+else
+  gdb --directory="$INSTALL_DIR_SIMGEAR" \\
+      --directory="$INSTALL_DIR_FGFS" \\
+      --core="\$CORE_FILE" ./fgfs
+fi
+EndOfScriptText
   chmod 755 $SCRIPT
 
   # Useful for debugging library problems.