Demonstrate "dist-of-git-commit" message

It is certainly possible to do that in a cleaner way with less code,
but at least this works.

4 files changed, 155 insertions, 62 deletions

diff --git a/git-buildmsg/Makefile-files b/git-buildmsg/Makefile-files
index ad5bcc5..e639d56 100644
--- a/git-buildmsg/Makefile-files
+++ b/git-buildmsg/Makefile-files
@@ -15,3 +15,44 @@ git-buildmsg/git-buildmsg-test.c: git-buildmsg/git-buildmsg
 	mkdir -p git-buildmsg
 	sh git-buildmsg/git-buildmsg --example --srcdir "$(top_srcdir)" \
 		--output git-buildmsg/git-buildmsg-test.c
+
+BUILT_SOURCES += git-buildmsg.stamp
+GIT_BUILDMSG_CMD = $(SHELL) "git-buildmsg/git-buildmsg" --error-if-no-git
+GIT_BUILDMSG_H = git-buildmsg.h
+CLEANFILES += $(GIT_BUILDMSG_H)
+git-buildmsg.stamp: git-buildmsg/git-buildmsg
+	if env GIT_DIR="$(top_srcdir)/.git" $(GIT_BUILDMSG_CMD) -s "$(top_srcdir)" -o "$(GIT_BUILDMSG_H)"; then \
+		if test -s "$(srcdir)/$(GIT_BUILDMSG_H)"; then \
+			if diff "$(srcdir)/$(GIT_BUILDMSG_H)" "$(GIT_BUILDMSG_H)"; then \
+				echo "New $(GIT_BUILDMSG_H) does not differ from $(srcdir)/$(GIT_BUILDMSG_H)"; \
+				exit 0; \
+			else \
+				echo "Error: $(srcdir)/$(GIT_BUILDMSG_H) and $(GIT_BUILDMSG_H) differ."; \
+				echo "       You probably want to remove the former."; \
+				exit 1; \
+			fi; \
+		fi; \
+	else \
+		if test -s "$(srcdir)/$(GIT_BUILDMSG_H)"; then \
+			echo "Not a git worktree."; \
+			echo "Keep using the $(GIT_BUILDMSG_H) from $(top_srcdir)"; \
+			rm -f "$(GIT_BUILDMSG_H)"; \
+			exit 0; \
+		else \
+			echo "Warning: $(GIT_BUILDMSG_H) without git workdir."; \
+			exit 0; \
+		fi; \
+	fi
+
+TESTS += print-buildmsg
+bin_PROGRAMS += print-buildmsg
+check_PROGRAMS += print-buildmsg
+print_buildmsg_SOURCES = git-buildmsg/print-buildmsg.c
+print_buildmsg_SOURCES += $(GIT_BUILDMSG_H)
+
+dist-hook:
+	if test -e "$(GIT_BUILDMSG_H)"; then \
+		$(SED) -e 's|^#undef GIT_IS_DIST.*|#define GIT_IS_DIST 1|' \
+			"$(GIT_BUILDMSG_H)" > "$(GIT_BUILDMSG_H).new"; \
+		mv -f "$(GIT_BUILDMSG_H).new" "$(GIT_BUILDMSG_H)"; \
+	fi
diff --git a/git-buildmsg/README.git-buildmsg b/git-buildmsg/README.git-buildmsg
index c95f5e7..dc9a7cd 100644
--- a/git-buildmsg/README.git-buildmsg
+++ b/git-buildmsg/README.git-buildmsg
@@ -7,12 +7,12 @@ EXTRA_DIST += git-buildmsg
 ---[ END top-level Makefile.am ]---
 
 ---[ BEGIN Makefile.am where information is needed ]---
-BUILT_SOURCES += git-buildmsgstamp
+BUILT_SOURCES += git-buildmsg.stamp
 GIT_BUILDMSG_CMD = $(SHELL) "$(top_srcdir)/git-buildmsg"
 GIT_BUILDMSG_H = git-buildmsg.h
 CLEANFILES += $(GIT_BUILDMSG_H)
-git_version.stamp:
-	env GIT_DIR="$(top_srcdir)/.git" $(GIT_VERSION_CMD) -s "$(top_srcdir)" -o "$(GIT_BUILDMSG_H)"
+git-buildmsg.stamp:
+	env GIT_DIR="$(top_srcdir)/.git" $(GIT_BUILDMSG_CMD) -s "$(top_srcdir)" -o "$(GIT_BUILDMSG_H)"
 	@if test -s "$(srcdir)/$(GIT_BUILDMSG_H)"; then \
 		if cmp "$(srcdir)/$(GIT_BUILDMSG_H)" "$(GIT_BUILDMSG_H)"; then :; \
 		else \
@@ -24,7 +24,7 @@ git_version.stamp:
 
 bin_PROGRAMS += foo
 foo_SOURCES = foo.c
-ndist_foo_SOURCES = $(GIT_BUILDMSG_H)
+nodist_foo_SOURCES = $(GIT_BUILDMSG_H)
 ---[ END Makefile.am where information is needed ]---
 
 
diff --git a/git-buildmsg/git-buildmsg.in b/git-buildmsg/git-buildmsg.in
index 7cb53dd..1f7d5ea 100644
--- a/git-buildmsg/git-buildmsg.in
+++ b/git-buildmsg/git-buildmsg.in
@@ -48,11 +48,12 @@ working_dir="$(pwd)"
 # Who am I?
 self="$(basename "$0")"
 
-# Defaults
+# Default settings
 ifndef_symbol="GIT_BUILDMSG_H"
 outfile="-"
 print_example=false
 srcdir="$(pwd)"
+error_if_no_git=false
 
 # Help messages
 USAGE="[<option>...]"
@@ -62,7 +63,9 @@ LONG_USAGE="\
 
   -x --example          Print complete example program.
   -o --output FILENAME  Set output file name.
-  -s --srcdir DIRNAME   Set source tree dir name."
+  -s --srcdir DIRNAME   Set source tree dir name.
+
+  -e --error-if-no-git  Abort with exitcode!=0 if git worktree not found."
 
 # Parse command line parameter, affecting defaults
 while [ "x$1" != "x" ]
@@ -74,11 +77,8 @@ do
         -o|--output)
             if shift; then
                 outfile="$1"
-                if [ "x$outfile" = "x-" ]; then
-                    : # keep default ifndef_symbol
-                else
+                [ "x$outfile" = "x-" ] || \
                     ifndef_symbol=`basename "$outfile" | $SED 's|\.|_|g; s|[^A-Za-z0-9_]||g' | tr a-z A-Z`
-                fi
             else
                 echo "$self: Fatal: \"$1\" option requires parameter." >&2
                 exit 1
@@ -90,25 +90,24 @@ do
 	    ;;
         -h|--help)
             echo "Usage: ${self} $USAGE"
-	    if test "x$LONG_USAGE" = "x"; then :;
-	    else
-		echo "$LONG_USAGE"
-	    fi
+	    [ -n "$LONG_USAGE" ] && echo "$LONG_USAGE"
             exit
             ;;
 	-s|--srcdir)
 	    if shift; then
-		if test -d "$1"; then
-		    srcdir="$1"
-		else
-		    echo "$self: Fatal: \"$1\" not a directory."
+		srcdir="$1"
+		[ -d "$srcdir" ] || {
+		    echo "$self: Fatal: \"$1\" not a directory." >&2
 		    exit 1
-		fi
+		}
 	    else
 		echo "$self: Fatal: \"$1\" option requires directory parameter."
 		exit 1
 	    fi
 	    ;;
+	-e|--error-if-no-git)
+	    error_if_no_git=:
+	    ;;
         *)
             echo "$self: Fatal: Invalid command line paramenter: \"$1\"" >&2
             exit 1
@@ -118,29 +117,21 @@ do
 done
 
 # If not printing to stdout, redirect stdout to output file
+outfile_exists=false
 rename_new_output=false
 if [ "x$outfile" = "x-" ]
 then
     : # keep using stdout
 else
+    if [ -e "$outfile" ]; then
+	outfile_exists=:
+    fi
     exec 1> "${outfile}.new"
 fi
 
 # Done with creating output files, so we can change to source dir
 cd "$srcdir"
 
-# Write program header
-cat<<EOF
-/*
- * Basic versioning gathered from the git repository.
- * Automatically generated by ${self}.
- */
-
-#ifndef ${ifndef_symbol}
-#define ${ifndef_symbol} 1
-
-EOF
-
 # Detect git tools (should work with old and new git versions)
 git_found=yes
 for git_tool in git-symbolic-ref git-rev-parse git-diff-files git-diff-index
@@ -148,41 +139,78 @@ do
     [ x`which $git_tool 2>/dev/null` = "x" ] && { git_found=no; break; }
 done
 
-# Determine and write git specific defines
+# Determine data about git tree
+is_git_worktree=no
 if [ "x$git_found" = "xyes" ]; then
     if [ -e "$GIT_DIR/index" ]; then
-        echo "/* This is a git repository */"
-        echo "#define GIT_USED 1"
-        echo ""
+	is_git_worktree="yes"
 
-        # Commit SHA-ID
-        git_shaid=`git-rev-parse HEAD | $SED -n 's/^\(.\{8\}\).*/\1/p'`
-        echo "/* Git SHA ID of last commit */"
-        echo "#define GIT_SHAID \"${git_shaid}..\""
-        echo ""
+        # Commit ID
+        git_commitid=`git-rev-parse HEAD | $SED -n 's/^\(.\{8\}\).*/\1/p'` || \
+	    { echo "Error running git-rev-parse HEAD" >&2; exit 1; }
 
         # Branch
-        git_branch=`git-symbolic-ref HEAD | $SED -n 's|^refs/heads/||p'`
-        echo "/* Branch this tree is on */"
-        echo "#define GIT_BRANCH \"$git_branch\""
-        echo ""
+        git_branch=`git-symbolic-ref HEAD | $SED -n 's|^refs/heads/||p'` || \
+	    { echo "Error running git-symbolic-ref HEAD" >&2; exit 1; }
 
         # Any uncommitted changes we should know about?
         # Or technically: Are the working tree or index dirty?
+	git_dirty_tree=yes
         if git-diff-files --quiet && git-diff-index --cached --quiet HEAD; then
-            echo "/* SHA-ID uniquely defines the state of this code */"
-            echo "#undef GIT_UNCOMMITTED"
-        else
-            echo "/* Local changes might be breaking things */"
-            echo "#define GIT_UNCOMMITTED 1"
+	    git_dirty_tree=no
         fi
-    else
-        echo "/* This is not a git repository */"
-        echo "#undef GIT_USED"
     fi
-else
+fi
+
+# Write program header
+cat<<EOF
+/*
+ * Basic versioning gathered from the git repository.
+ * Automatically generated by ${self}.
+ */
+
+#ifndef ${ifndef_symbol}
+#define ${ifndef_symbol} 1
+
+/* whether this header file is from a dist tarball */
+#undef GIT_IS_DIST
+
+EOF
+
+# Write git specific defines
+if [ "x$git_found" = "xno" ]; then
     echo "/* git is not installed */"
-    echo "#undef GIT_USED"
+    echo "#undef GIT_IS_GIT_WORKTREE"
+elif [ "x$is_git_worktree" = "xno" ]; then
+    echo "/* This is not a git repository */"
+    echo "#undef GIT_IS_GIT_WORKTREE"
+else
+    echo "/* This is a git repository */"
+    echo "#define GIT_IS_GIT_WORKTREE 1"
+    echo ""
+    if [ "x$is_git_worktree" = "xyes" ]; then
+	echo "/* Git ID of last commit */"
+	echo "#define GIT_COMMIT_ID \"${git_commitid}..\""
+	echo ""
+
+	echo "/* Branch this tree is on */"
+	echo "#define GIT_BRANCH \"$git_branch\""
+	echo ""
+
+	if [ "x$git_dirty_tree" = "xyes" ]; then
+	    echo "/* Commit ID uniquely defines the state of this code */"
+	    echo "#undef GIT_DIRTY_WORKTREE"
+	else
+	    echo "/* Local changes might be breaking things */"
+	    echo "#define GIT_DIRTY_WORKTREE 1"
+	fi
+    else
+	echo "/* Git ID of last commit */"
+	echo "#undef GIT_COMMIT_ID"
+	echo ""
+	echo "/* Branch this tree is on */"
+	echo "#undef GIT_BRANCH"
+    fi
 fi
 
 # Define a few immediately useful message strings
@@ -193,21 +221,28 @@ cat<<EOF
  * forms a proper sentence.
  */
 
-#ifdef GIT_USED
+#ifdef GIT_IS_DIST
+# define GIT_DIST_MSG "dist of "
+#else
+# define GIT_DIST_MSG ""
+#endif
+
+#ifdef GIT_IS_GIT_WORKTREE
 
-# ifdef GIT_UNCOMMITTED
-#  define GIT_WITH_WITHOUT_UNCOMMITTED " + changes"
+# ifdef GIT_DIRTY_WORKTREE
+#  define GIT_CHANGE_MSG " + changes"
 # else
-#  define GIT_WITH_WITHOUT_UNCOMMITTED ""
-# endif /* GIT_UNCOMMITTED */
+#  define GIT_CHANGE_MSG ""
+# endif /* GIT_DIRTY_WORKTREE */
 
 # define GIT_MESSAGE \\
+        GIT_DIST_MSG \\
         "git branch " GIT_BRANCH ", " \\
-        "commit " GIT_SHAID GIT_WITH_WITHOUT_UNCOMMITTED
+        "commit " GIT_COMMIT_ID GIT_CHANGE_MSG
 
 #else
-# define GIT_MESSAGE "non-git sources"
-#endif /* GIT_USED */
+# define GIT_MESSAGE GIT_DIST_MSG "non-git sources"
+#endif /* GIT_IS_GIT_WORKTREE */
 
 #endif /* ${ifndef_symbol} */
 EOF
@@ -250,8 +285,14 @@ then
             mv -f "$outfile.new" "$outfile"
         fi
     else
+        echo "$self: Output is new file, creating $outfile" >&2
         mv -f "$outfile.new" "$outfile"
     fi
 fi
 
+if "$error_if_no_git" && [ "x$is_git_worktree" = "xno" ]; then
+    echo "$self: No git worktree found. Aborting with error, as requested." >&2
+    exit 2
+fi
+
 # THE END.
diff --git a/git-buildmsg/print-buildmsg.c b/git-buildmsg/print-buildmsg.c
new file mode 100644
index 0000000..c5f4e84
--- /dev/null
+++ b/git-buildmsg/print-buildmsg.c
@@ -0,0 +1,11 @@
+#include <stdio.h>
+#include <string.h>
+#include "git-buildmsg.h"
+
+int main(int argc, char *argv[])
+{
+  const char *const lastslash = strrchr(argv[0], '/');
+  const char *const self = (lastslash)?(lastslash+1):(argv[0]);
+  printf("%s: %s\n", self, GIT_MESSAGE);
+  return 0;
+}