1 files changed, 20 insertions, 10 deletions
diff --git a/mesalib/bin/extract_git_sha1 b/mesalib/bin/extract_git_sha1
index cf3006f8f..828387016 100644
--- a/mesalib/bin/extract_git_sha1
+++ b/mesalib/bin/extract_git_sha1
@@ -1,10 +1,20 @@
-#!/bin/sh
-touch src/mesa/main/git_sha1.h
-if which git > /dev/null; then
-    # Extract the 7-digit "short" SHA1 for the current HEAD, convert
-    # it to a string, and wrap it in a #define.  This is used in
-    # src/mesa/main/version.c to put the GIT SHA1 in the GL_VERSION string.
-    git log -n 1 --oneline |\
-	sed 's/^\([^ ]*\) .*/#define MESA_GIT_SHA1 "git-\1"/' \
-	> src/mesa/main/git_sha1.h
-fi
+#!/bin/sh
+if [ ! -f src/mesa/main/git_sha1.h ]; then
+	touch src/mesa/main/git_sha1.h
+fi
+
+if [ ! -d .git ]; then
+	exit
+fi
+
+if which git > /dev/null; then
+    # Extract the 7-digit "short" SHA1 for the current HEAD, convert
+    # it to a string, and wrap it in a #define.  This is used in
+    # src/mesa/main/version.c to put the GIT SHA1 in the GL_VERSION string.
+    git log -n 1 --oneline |\
+	sed 's/^\([^ ]*\) .*/#define MESA_GIT_SHA1 "git-\1"/' \
+	> src/mesa/main/git_sha1.h.tmp
+    if ! cmp -s src/mesa/main/git_sha1.h.tmp src/mesa/main/git_sha1.h; then
+    	mv src/mesa/main/git_sha1.h.tmp src/mesa/main/git_sha1.h
+    fi
+fi