tools: make SDB descriptor generator script less fragile wrt git commands. Also add header.

tools/sdb_desc_gen.tcl

-# Tcl script to automatically generate the SDB synthesis descriptor.
-#
-# Must be added to your top-level Manifest.py like this:
-#
-# syn_post_project_cmd = "$(TCL_INTERPRETER) [this_tcl_script] " +
-#                         syn_tool + " $(PROJECT_FILE)"
-#
-# Notes:
-#
-# 1. $(TCL_INTERPRETER) and $(PROJECT_FILE) will be automatically
-#    resolved inside the Makefile generated by hdlmake.
-# 2. syn_tool is a Manifest.py variable, it should already be in your
-#    tol-level Manifest.py.
-# 3. [this_tcl_script] should be replaced by the full path to
-#    this Tcl script. Relative paths should be with respect to
-#    the location of the top-level Manifest.py.
-# 4. Mind the spaces inside the quotes, before and after syn_tool.
+##-------------------------------------------------------------------------------
+## CERN BE-CO-HT
+## General Cores
+## https://www.ohwr.org/projects/general-cores
+##-------------------------------------------------------------------------------
+##
+## Tcl script to automatically generate the SDB synthesis descriptor.
+##
+## Must be added to your top-level Manifest.py like this:
+##
+## syn_post_project_cmd = "$(TCL_INTERPRETER) [this_tcl_script] " +
+##                         syn_tool + " $(PROJECT_FILE)"
+##
+## notes:
+##
+## 1. $(TCL_INTERPRETER) and $(PROJECT_FILE) will be automatically
+##    resolved inside the Makefile generated by hdlmake.
+## 2. syn_tool is a Manifest.py variable, it should already be in your
+##    tol-level Manifest.py.
+## 3. [this_tcl_script] should be replaced by the full path to
+##    this Tcl script. Relative paths should be with respect to
+##    the location of the top-level Manifest.py.
+## 4. Mind the spaces inside the quotes, before and after syn_tool.
+##
+##-------------------------------------------------------------------------------
+## Copyright CERN 2018
+##-------------------------------------------------------------------------------
+## This Source Code Form is subject to the terms of the Mozilla Public License,
+## version 2.0. If a copy of the MPL was not distributed with this file, You can
+## obtain one at https://mozilla.org/MPL/2.0/.
+##-------------------------------------------------------------------------------
 
 # get current time
 set time_now [clock seconds]
@@ -92,13 +106,21 @@ if {$syn_tool == "ise"} {
     # For now we hard-code, since anyway ISE is end-of-life at version 14.7.
     set inf_tool_version [format "%08d" "147"]
 }
+
 set inf_tool_name [string toupper $syn_tool]
-set inf_commit_id [exec git log -1 --format=%H]
 set inf_date [clock format $time_now -format "%A, %B %d %Y"]
 set inf_date_ymd [clock format $time_now -format "%Y%m%d"]
-set inf_user [exec git config user.name]
-# next line could break if git remote is not called "origin"
-set inf_repo_url [exec git remote get-url origin]
+
+# Git commands below have fallbacks in case something goes wrong.
+if { [catch { set inf_user [exec git config --get user.name] }] } {
+    set inf_user "unknown user"
+}
+if { [catch { set inf_commit_id [exec git log -1 --format=%H] }] } {
+    set inf_commit_id "unknown commit"
+}
+if { [catch { set inf_repo_url [exec git config --get remote.origin.url] }] } {
+    set inf_repo_url "unknown url"
+}
 
 #-------------------------------------------------------------------------------
 # STEP 5/7: Generate the output file