scripts: always use double quotes and curly braces

Command line:
shellcheck -s sh -i SC2248,SC2250 -o quote-safe-variables,require-variable-braces $(git ls-files "*.sh")

(There will be two complaints about wanting to double-quote
${CFLAGS_C99}, but it's constructing a command-line, so ignore those
warnings.)

Explanation:
- Prefer double quoting even when variables don't contain special
  characters.
  https://www.shellcheck.net/wiki/SC2248

- Prefer putting braces around variable references even when not
  strictly required.
  https://github.com/koalaman/shellcheck/wiki/SC2250

Reported by:	shellcheck 0.9.0

libcperciva/POSIX/posix-cflags-filter.sh

@@ -9,15 +9,15 @@ if [ -z "${CC}" ]; then
 	exit 1
 fi
 if ! [ "${PATH}" = "$1" ]; then
-	echo "WARNING: POSIX violation: $SHELL's command -p resets \$PATH" 1>&2
+	echo "WARNING: POSIX violation: ${SHELL}'s command -p resets \$PATH" 1>&2
 	PATH=$1
 fi
 
 # Find directory of this script and the source files
 D=$(dirname "$0")
 
-if ! ${CC} -O2 "$D/posix-cflags-filter.c" 2>/dev/null; then
-	if ${CC} "$D/posix-cflags-filter.c" 2>/dev/null; then
+if ! ${CC} -O2 "${D}/posix-cflags-filter.c" 2>/dev/null; then
+	if ${CC} "${D}/posix-cflags-filter.c" 2>/dev/null; then
 		echo 'CFLAGS_FILTERED=""'
 		echo 'for OPT in $CFLAGS; do'
 		echo '	if [ "$OPT" = "-O2" ]; then'

libcperciva/POSIX/posix-cflags.sh

@@ -8,15 +8,15 @@ if [ -z "${CC}" ]; then
 	exit 1
 fi
 if ! [ "${PATH}" = "$1" ]; then
-	echo "WARNING: POSIX violation: $SHELL's command -p resets \$PATH" 1>&2
+	echo "WARNING: POSIX violation: ${SHELL}'s command -p resets \$PATH" 1>&2
 	PATH=$1
 fi
 
 # Find directory of this script and the source files
 D=$(dirname "$0")
 
 # Check if we can compile & run a binary.
-if ! ${CC} ${CFLAGS} "$D/posix-trivial.c" 2>/dev/null; then
+if ! ${CC} ${CFLAGS} "${D}/posix-trivial.c" 2>/dev/null; then
 	echo "WARNING: failed to compile posix-trivial.c" 1>&2
 else
 	# If the user hasn't disabled runtime checks...
@@ -31,28 +31,28 @@ else
 fi
 
 FIRST=YES
-if ! ${CC} ${CFLAGS} -D_POSIX_C_SOURCE=200809L "$D/posix-msg_nosignal.c" 2>/dev/null; then
-	[ ${FIRST} = "NO" ] && printf " "; FIRST=NO
+if ! ${CC} ${CFLAGS} -D_POSIX_C_SOURCE=200809L "${D}/posix-msg_nosignal.c" 2>/dev/null; then
+	[ "${FIRST}" = "NO" ] && printf " "; FIRST=NO
 	printf %s "-DPOSIXFAIL_MSG_NOSIGNAL"
 	echo "WARNING: POSIX violation: <sys/socket.h> not defining MSG_NOSIGNAL" 1>&2
 fi
-if ! ${CC} ${CFLAGS} -D_POSIX_C_SOURCE=200809L "$D/posix-clock_realtime.c" 2>/dev/null; then
-	[ ${FIRST} = "NO" ] && printf " "; FIRST=NO
+if ! ${CC} ${CFLAGS} -D_POSIX_C_SOURCE=200809L "${D}/posix-clock_realtime.c" 2>/dev/null; then
+	[ "${FIRST}" = "NO" ] && printf " "; FIRST=NO
 	printf %s "-DPOSIXFAIL_CLOCK_REALTIME"
 	echo "WARNING: POSIX violation: <time.h> not defining CLOCK_REALTIME" 1>&2
 fi
-if ! ${CC} ${CFLAGS} -D_POSIX_C_SOURCE=200809L -D_XOPEN_SOURCE=700 "$D/posix-inet-addrstrlen.c" 2>/dev/null; then
-	[ ${FIRST} = "NO" ] && printf " "; FIRST=NO
+if ! ${CC} ${CFLAGS} -D_POSIX_C_SOURCE=200809L -D_XOPEN_SOURCE=700 "${D}/posix-inet-addrstrlen.c" 2>/dev/null; then
+	[ "${FIRST}" = "NO" ] && printf " "; FIRST=NO
 	printf %s "-DPOSIXFAIL_INET_ADDRSTRLEN"
 	echo "WARNING: POSIX violation: <netinet/in.h> not defining INET_ADDRSTRLEN" 1>&2
 fi
-if ! ${CC} ${CFLAGS} -D_POSIX_C_SOURCE=200809L -D_XOPEN_SOURCE=700 "$D/posix-inet6-addrstrlen.c" 2>/dev/null; then
-	[ ${FIRST} = "NO" ] && printf " "; FIRST=NO
+if ! ${CC} ${CFLAGS} -D_POSIX_C_SOURCE=200809L -D_XOPEN_SOURCE=700 "${D}/posix-inet6-addrstrlen.c" 2>/dev/null; then
+	[ "${FIRST}" = "NO" ] && printf " "; FIRST=NO
 	printf %s "-DPOSIXFAIL_INET6_ADDRSTRLEN"
 	echo "WARNING: POSIX violation: <netinet/in.h> not defining INET6_ADDRSTRLEN" 1>&2
 fi
-if ! ${CC} ${CFLAGS} -D_POSIX_C_SOURCE=200809L "$D/posix-clock_gettime.c" 2>/dev/null; then
-	[ ${FIRST} = "NO" ] && printf " "; FIRST=NO
+if ! ${CC} ${CFLAGS} -D_POSIX_C_SOURCE=200809L "${D}/posix-clock_gettime.c" 2>/dev/null; then
+	[ "${FIRST}" = "NO" ] && printf " "; FIRST=NO
 	printf %s "-DPOSIXFAIL_CLOCK_GETTIME"
 	echo "WARNING: POSIX violation: <time.h> not declaring clock_gettime()" 1>&2
 elif [ "${DISABLE_POSIX_RUNTIME_CHECKS:-0}" -ne "0" ]; then
@@ -68,30 +68,30 @@ else
 	# calling process.  The "( ./x 2>y ) 2>y" captures both types of error
 	# message.
 	if ! ( ./a.out 2>/dev/null ) 2>/dev/null ; then
-		[ ${FIRST} = "NO" ] && printf " "; FIRST=NO
+		[ "${FIRST}" = "NO" ] && printf " "; FIRST=NO
 		printf %s "-DPOSIXFAIL_CLOCK_GETTIME"
 		echo "WARNING: POSIX violation: clock_gettime() is not linkable" 1>&2
 	fi
 fi
-if ! ${CC} ${CFLAGS} -D_POSIX_C_SOURCE=200809L -D_XOPEN_SOURCE=700 "$D/posix-stat-st_mtim.c" 2>/dev/null; then
-	[ ${FIRST} = "NO" ] && printf " "; FIRST=NO
+if ! ${CC} ${CFLAGS} -D_POSIX_C_SOURCE=200809L -D_XOPEN_SOURCE=700 "${D}/posix-stat-st_mtim.c" 2>/dev/null; then
+	[ "${FIRST}" = "NO" ] && printf " "; FIRST=NO
 	printf %s "-DPOSIXFAIL_STAT_ST_MTIM"
 	echo "WARNING: POSIX violation: struct stat does not contain st_mtim" 1>&2
 fi
 CFLAGS_C99=""
-if ! ${CC} ${CFLAGS} -D_POSIX_C_SOURCE=200809L "$D/posix-restrict.c" 2>/dev/null; then
+if ! ${CC} ${CFLAGS} -D_POSIX_C_SOURCE=200809L "${D}/posix-restrict.c" 2>/dev/null; then
 	echo "WARNING: POSIX violation: ${CC} does not accept the 'restrict' keyword" 1>&2
-	if ${CC} ${CFLAGS} -D_POSIX_C_SOURCE=200809L -std=c99 "$D/posix-restrict.c" 2>/dev/null; then
-		[ ${FIRST} = "NO" ] && printf " "; FIRST=NO
+	if ${CC} ${CFLAGS} -D_POSIX_C_SOURCE=200809L -std=c99 "${D}/posix-restrict.c" 2>/dev/null; then
+		[ "${FIRST}" = "NO" ] && printf " "; FIRST=NO
 		printf %s "-std=c99"
 		CFLAGS_C99="-std=c99"
 	fi
 fi
-if ! ${CC} ${CFLAGS} ${CFLAGS_C99} -D_POSIX_C_SOURCE=200809L -DARGNAME="" "$D/posix-abstract-declarator.c" 2>/dev/null; then
+if ! ${CC} ${CFLAGS} ${CFLAGS_C99} -D_POSIX_C_SOURCE=200809L -DARGNAME="" "${D}/posix-abstract-declarator.c" 2>/dev/null; then
 	echo "WARNING: POSIX violation: ${CC} does not accept qualifiers in an abstract declarator" 1>&2
 	# Test compile with -DPOSIXFAIL_ABSTRACT_DECLARATOR
-	if ${CC} ${CFLAGS} ${CFLAGS_C99} -D_POSIX_C_SOURCE=200809L -DPOSIXFAIL_ABSTRACT_DECLARATOR "$D/posix-abstract-declarator.c" 2>/dev/null; then
-		[ ${FIRST} = "NO" ] && printf " "; FIRST=NO
+	if ${CC} ${CFLAGS} ${CFLAGS_C99} -D_POSIX_C_SOURCE=200809L -DPOSIXFAIL_ABSTRACT_DECLARATOR "${D}/posix-abstract-declarator.c" 2>/dev/null; then
+		[ "${FIRST}" = "NO" ] && printf " "; FIRST=NO
 		printf %s "-DPOSIXFAIL_ABSTRACT_DECLARATOR"
 	fi
 fi

libcperciva/POSIX/posix-l.sh

@@ -8,7 +8,7 @@ if [ -z "${CC}" ]; then
 	exit 1
 fi
 if ! [ "${PATH}" = "$1" ]; then
-	echo "WARNING: POSIX violation: $SHELL's command -p resets \$PATH" 1>&2
+	echo "WARNING: POSIX violation: ${SHELL}'s command -p resets \$PATH" 1>&2
 	PATH=$1
 fi
 
@@ -17,8 +17,8 @@ D=$(dirname "$0")
 
 FIRST=YES
 for LIB in rt xnet; do
-	if ${CC} ${CFLAGS} -l${LIB} "$D/posix-trivial.c" 2>/dev/null; then
-		if [ ${FIRST} = "NO" ]; then
+	if ${CC} ${CFLAGS} -l"${LIB}" "${D}/posix-trivial.c" 2>/dev/null; then
+		if [ "${FIRST}" = "NO" ]; then
 			printf " ";
 		fi
 		printf "%s" "-l${LIB}";

libcperciva/apisupport/Build/apisupport.sh

@@ -1,7 +1,7 @@
 # Should be sourced by `command -p sh path/to/apisupport.sh "$PATH"` from
 # within a Makefile.
 if ! [ "${PATH}" = "$1" ]; then
-	echo "WARNING: POSIX violation: $SHELL's command -p resets \$PATH" 1>&2
+	echo "WARNING: POSIX violation: ${SHELL}'s command -p resets \$PATH" 1>&2
 	PATH=$1
 fi
 
@@ -34,17 +34,17 @@ feature() {
 
 	# Check if we can compile this feature (and any required arguments).
 	printf "Checking if compiler supports %s %s feature..."		\
-	    "$PLATFORM" "$FEATURE" 1>&2
+	    "${PLATFORM}" "${FEATURE}" 1>&2
 	for API_CFLAGS in "$@"; do
 		if ${CC} ${CPPFLAGS} ${CFLAGS} ${CFLAGS_HARDCODED}	\
 		    ${API_CFLAGS} "${feature_filename}" ${LDADD_EXTRA}	\
-		    ${EXTRALIB}	2>>${outcc}; then
+		    ${EXTRALIB}	2>>"${outcc}"; then
 			rm -f a.out
 			break;
 		fi
 		API_CFLAGS=NOTSUPPORTED;
 	done
-	case $API_CFLAGS in
+	case ${API_CFLAGS} in
 	NOTSUPPORTED)
 		echo " no" 1>&2
 		;;
@@ -53,7 +53,7 @@ feature() {
 		echo "#define APISUPPORT_${PLATFORM}_${FEATURE} 1"
 		;;
 	*)
-		echo " yes, via $API_CFLAGS" 1>&2
+		echo " yes, via ${API_CFLAGS}" 1>&2
 		echo "#define APISUPPORT_${PLATFORM}_${FEATURE} 1"
 		echo "#ifdef apisupport_dummy"
 		echo "export CFLAGS_${PLATFORM}_${FEATURE}=\"${API_CFLAGS}\""

libcperciva/cpusupport/Build/cpusupport.sh

@@ -1,7 +1,7 @@
 # Should be sourced by `command -p sh path/to/cpusupport.sh "$PATH"` from
 # within a Makefile.
 if ! [ "${PATH}" = "$1" ]; then
-	echo "WARNING: POSIX violation: $SHELL's command -p resets \$PATH" 1>&2
+	echo "WARNING: POSIX violation: ${SHELL}'s command -p resets \$PATH" 1>&2
 	PATH=$1
 fi
 
@@ -33,16 +33,16 @@ feature() {
 
 	# Check if we can compile this feature (and any required arguments).
 	printf "Checking if compiler supports %s %s feature..."		\
-	    "$ARCH" "$FEATURE" 1>&2
+	    "${ARCH}" "${FEATURE}" 1>&2
 	for CPU_CFLAGS in "$@"; do
 		if ${CC} ${CPPFLAGS} ${CFLAGS} ${CFLAGS_HARDCODED}	\
-		    ${CPU_CFLAGS} "${feature_filename}" 2>>${outcc}; then
+		    ${CPU_CFLAGS} "${feature_filename}" 2>>"${outcc}"; then
 			rm -f a.out
 			break;
 		fi
 		CPU_CFLAGS=NOTSUPPORTED;
 	done
-	case $CPU_CFLAGS in
+	case ${CPU_CFLAGS} in
 	NOTSUPPORTED)
 		echo " no" 1>&2
 		;;
@@ -51,7 +51,7 @@ feature() {
 		echo "#define CPUSUPPORT_${ARCH}_${FEATURE} 1"
 		;;
 	*)
-		echo " yes, via $CPU_CFLAGS" 1>&2
+		echo " yes, via ${CPU_CFLAGS}" 1>&2
 		echo "#define CPUSUPPORT_${ARCH}_${FEATURE} 1"
 		echo "#ifdef cpusupport_dummy"
 		echo "export CFLAGS_${ARCH}_${FEATURE}=\"${CPU_CFLAGS}\""

release-tools/metabuild.sh

@@ -9,7 +9,7 @@ CFLAGS_HARDCODED=$3
 OUT=Makefile
 
 # Check environment
-if [ -z "$CPP" ]; then
+if [ -z "${CPP}" ]; then
 	echo "Need CPP environment variable."
 	exit 1
 fi
@@ -43,17 +43,17 @@ fi
 
 copyvar() {
 	var=$1
-	if [ -n "$(${MAKEBSD} -v "$var")" ]; then
-		printf "%s=" "$var" >> $OUT
-		${MAKEBSD} -v "$var" >> $OUT
+	if [ -n "$(${MAKEBSD} -v "${var}")" ]; then
+		printf "%s=" "${var}" >> "${OUT}"
+		${MAKEBSD} -v "${var}" >> "${OUT}"
 	fi
 }
 
 addvar_lib() {
 	var=$1
-	varval=$(${MAKEBSD} -v "$var")
+	varval=$(${MAKEBSD} -v "${var}")
 	if [ -n "${varval}" ]; then
-		printf "%s=lib%s.a\n" "$var" "${varval}" >> $OUT
+		printf "%s=lib%s.a\n" "${var}" "${varval}" >> "${OUT}"
 	fi
 }
 
@@ -74,7 +74,7 @@ add_makefile_prog() {
 	fi
 
 	# Add the (adjusted) Makefile.prog to the Makefile, and clean up
-	cat prog.tmp >> $OUT
+	cat prog.tmp >> "${OUT}"
 	rm prog.tmp
 }
 
@@ -84,7 +84,7 @@ get_cpusupport_cflags() {
 	str=$(grep 'CPUSUPPORT CFLAGS:' "${src}" | cut -f 2- -d :)
 	# ${str} must be unquoted.
 	for X in ${str}; do
-		printf " \${CFLAGS_%s}" "$X"
+		printf " \${CFLAGS_%s}" "${X}"
 	done | sed 's/^ //'
 }
 
@@ -94,7 +94,7 @@ get_apisupport_cflags() {
 	str=$(grep 'APISUPPORT CFLAGS:' "${src}" | cut -f 2- -d :)
 	# ${str} must be unquoted.
 	for X in ${str}; do
-		printf " \${CFLAGS_%s}" "$X"
+		printf " \${CFLAGS_%s}" "${X}"
 	done | sed 's/^ //'
 }
 
@@ -111,7 +111,7 @@ add_object_files() {
 	OUT_CC_MID="-I${SUBDIR_DEPTH} \${IDIRS} \${CPPFLAGS} \${CFLAGS}"
 
 	# Generate build instructions for each object
-	for F in $OBJ; do
+	for F in ${OBJ}; do
 		S=$(${MAKEBSD} source-"${F}")
 		CF_MANUAL=$(${MAKEBSD} -v CFLAGS."$(basename "${S}")")
 		CF_CPUSUPPORT=$(get_cpusupport_cflags "${S}")
@@ -132,12 +132,12 @@ add_object_files() {
 		# Print the build instructions
 		echo "	${OUT_CC_BEGIN} ${OUT_CC_MID} ${CF} -c ${S} -o ${F}" |
 		    tr -s ' '
-	done >> $OUT
+	done >> "${OUT}"
 }
 
 # Add header and variables
-echo '.POSIX:' > $OUT
-echo '# AUTOGENERATED FILE, DO NOT EDIT' >> $OUT
+echo '.POSIX:' > "${OUT}"
+echo '# AUTOGENERATED FILE, DO NOT EDIT' >> "${OUT}"
 if [ -n "$(${MAKEBSD} -v LIB)" ]; then
 	addvar_lib LIB
 else
@@ -147,24 +147,24 @@ copyvar MAN1
 
 # SRCS is trickier to handle, as we need to remove any -config.h from the list.
 if [ -n "$(${MAKEBSD} -v SRCS)" ]; then
-	printf "SRCS=" >> $OUT
+	printf "SRCS=" >> "${OUT}"
 	${MAKEBSD} -v SRCS |				\
 	    sed -e 's| apisupport-config.h||' |		\
-	    sed -e 's| cpusupport-config.h||' >> $OUT
+	    sed -e 's| cpusupport-config.h||' >> "${OUT}"
 fi
 copyvar IDIRS
 copyvar LDADD_REQ
 copyvar SUBDIR_DEPTH
-printf "RELATIVE_DIR=%s\n" "$D" >> $OUT
+printf "RELATIVE_DIR=%s\n" "${D}" >> "${OUT}"
 
 # Add all, install, clean, $PROG
 if [ -n "$(${MAKEBSD} -v LIB)" ]; then
-	cat "${SUBDIR_DEPTH}/release-tools/Makefile.lib" >> $OUT
+	cat "${SUBDIR_DEPTH}/release-tools/Makefile.lib" >> "${OUT}"
 elif [ -n "$(${MAKEBSD} -v SRCS)" ]; then
 	copyvar LIBALL
 	add_makefile_prog
 else
-	printf "\nall:\n\ttrue\n\nclean:\n\ttrue\n" >> $OUT
+	printf "\nall:\n\ttrue\n\nclean:\n\ttrue\n" >> "${OUT}"
 fi
 
 # Add all object files (if applicable)
@@ -174,33 +174,33 @@ fi
 
 # Add test (if applicable)
 if grep -q "^test:" Makefile.BSD ; then
-	printf "\n" >> $OUT
+	printf "\n" >> "${OUT}"
 	awk '/^test:/, /^$/' Makefile.BSD |			\
-	    awk '$1' >> $OUT
+	    awk '$1' >> "${OUT}"
 fi
 
 # Add perftest (if applicable)
 if grep -q "^perftest:" Makefile.BSD ; then
-	printf "\n" >> $OUT
+	printf "\n" >> "${OUT}"
 	awk '/^perftest:/, /^$/' Makefile.BSD |			\
-	    awk '$1' >> $OUT
+	    awk '$1' >> "${OUT}"
 fi
 
 # Add all_extra (if applicable)
 if grep -q "^all_extra:" Makefile.BSD ; then
-	printf "\n" >> $OUT
+	printf "\n" >> "${OUT}"
 	awk '/^all_extra:/, /^$/' Makefile.BSD |		\
-	    awk '$1' >> $OUT
+	    awk '$1' >> "${OUT}"
 	sed -e 's/${MAKE} ${PROG}/${MAKE} ${PROG} all_extra/'	\
 	    Makefile > Makefile.new
 	mv Makefile.new Makefile
 fi
 
 # Add clean_extra (if applicable)
 if grep -q "^clean_extra:" Makefile.BSD ; then
-	printf "\n" >> $OUT
+	printf "\n" >> "${OUT}"
 	awk '/^clean_extra:/, /^$/' Makefile.BSD |		\
-	    awk '$1' >> $OUT
+	    awk '$1' >> "${OUT}"
 	awk '/^clean:/ {print $0 "\tclean_extra";next}{print}'	\
 	    Makefile > Makefile.new
 	mv Makefile.new Makefile