Refactor build_tools/build_detect_version

.gitignore

@@ -19,5 +19,4 @@ sst_dump
 util/build_version.cc
 build_tools/VALGRIND_LOGS/
 coverage/COVERAGE_REPORT
-util/build_version.cc.tmp
 .gdbhistory

build_tools/build_detect_version

@@ -5,38 +5,18 @@
 # is then built as a regular source file as part of the compilation process.
 # One can run "strings executable_filename | grep _build_" to find the version of
 # the source that we used to build the executable file.
-#
 
-# create git version file
-VFILE=$PWD/util/build_version.cc.tmp
-trap "rm $VFILE" EXIT
+OUTFILE="$PWD/util/build_version.cc"
 
-# check to see if git is in the path
-which git > /dev/null
-
-if [ "$?" = 0 ]; then
-  env -i git rev-parse HEAD 2>&1 |
-  awk '
-  BEGIN {
-    print "#include \"build_version.h\"\n"
-  }
-  { print "const char* rocksdb_build_git_sha = \"rocksdb_build_git_sha:" $0"\";" }
-  ' >  ${VFILE}
-else
-  echo "git not found" |
-  awk '
-    BEGIN {
-      print "#include \"build_version.h\""
-    }
-    { print "const char* rocksdb_build_git_sha = \"rocksdb_build_git_sha:git not found\";" }
-    ' > ${VFILE}
+GIT_SHA=""
+if command -v git >/dev/null 2>&1; then
+    GIT_SHA=$(git rev-parse HEAD 2>/dev/null)
 fi
 
-echo "const char* rocksdb_build_git_datetime = \"rocksdb_build_git_datetime:$(date)\";" >> ${VFILE}
-echo "const char* rocksdb_build_compile_date = __DATE__;" >> ${VFILE}
-echo "const char* rocksdb_build_compile_time = __TIME__;" >> ${VFILE}
-
-OUTFILE=$PWD/util/build_version.cc
-if [ ! -e $OUTFILE ] || ! cmp -s $VFILE $OUTFILE; then
-    cp $VFILE $OUTFILE
-fi
+cat > "${OUTFILE}" <<EOF
+#include "build_version.h"
+const char* rocksdb_build_git_sha = "rocksdb_build_git_sha:${GIT_SHA}";
+const char* rocksdb_build_git_datetime = "rocksdb_build_git_datetime:$(date)";
+const char* rocksdb_build_compile_date = __DATE__;
+const char* rocksdb_build_compile_time = __TIME__;
+EOF