script: Write variables to a FILE

Each variable is NULL terminated inside the file just like the
control stream which saves us from having to flatten it when
writing to the control stream.
Once written, create env pointers to the start of each string
just after the NULL terminator.

This also means that we just need to free two buffers when
dhcpcd exits (FILE buffer and env buffer) rather than each variable
individually.

If open_memstream(3) is not supported by libc then dhcpcd will
write to a file in /tmp instead.

1 files changed, 37 insertions, 16 deletions

diff --git a/configure b/configure
index 4a4920e2..79201c04 100755
--- a/configure
+++ b/configure
@@ -15,6 +15,7 @@ ARC4RANDOM=
 CLOSEFROM=
 RBTREE=
 CONSTTIME_MEMEQUAL=
+OPEN_MEMSTREAM=
 STRLCPY=
 UDEV=
 OS=
@@ -741,29 +742,25 @@ if [ "$ARC4RANDOM_UNIFORM" = no ]; then
 	echo "#include			\"compat/arc4random_uniform.h\"" >>$CONFIG_H
 fi
 
-
-if [ -z "$STRLCPY" ]; then
-	printf "Testing for strlcpy ... "
-	cat <<EOF >_strlcpy.c
-#include <string.h>
+if [ -z "$OPEN_MEMSTREAM" ]; then
+	printf "Testing for open_memstream ... "
+	cat <<EOF >_open_memstream.c
+#include <stdio.h>
 int main(void) {
-	const char s1[] = "foo";
-	char s2[10];
-	strlcpy(s2, s1, sizeof(s2));
+	open_memstream(NULL, NULL);
 	return 0;
 }
 EOF
-	if $XCC _strlcpy.c -o _strlcpy 2>&3; then
-		STRLCPY=yes
+	if $XCC _open_memstream.c -o _open_memstream 2>&3; then
+		OPEN_MEMSTREAM=yes
 	else
-		STRLCPY=no
+		OPEN_MEMSTREAM=no
 	fi
-	echo "$STRLCPY"
-	rm -f _strlcpy.c _strlcpy
+	echo "$OPEN_MEMSTREAM"
+	rm -f _open_memstream.c _open_memstream
 fi
-if [ "$STRLCPY" = no ]; then
-	echo "COMPAT_SRCS+=	compat/strlcpy.c" >>$CONFIG_MK
-	echo "#include			\"compat/strlcpy.h\"" >>$CONFIG_H
+if [ "$OPEN_MEMSTREAM" = yes ]; then
+	echo "#define	HAVE_OPEN_MEMSTREAM" >>$CONFIG_H
 fi
 
 if [ -z "$PIDFILE_LOCK" ]; then
@@ -824,6 +821,30 @@ if [ "$SETPROCTITLE" = yes ]; then
 	echo "#define	HAVE_SETPROCTITLE" >>$CONFIG_H
 fi
 
+if [ -z "$STRLCPY" ]; then
+	printf "Testing for strlcpy ... "
+	cat <<EOF >_strlcpy.c
+#include <string.h>
+int main(void) {
+	const char s1[] = "foo";
+	char s2[10];
+	strlcpy(s2, s1, sizeof(s2));
+	return 0;
+}
+EOF
+	if $XCC _strlcpy.c -o _strlcpy 2>&3; then
+		STRLCPY=yes
+	else
+		STRLCPY=no
+	fi
+	echo "$STRLCPY"
+	rm -f _strlcpy.c _strlcpy
+fi
+if [ "$STRLCPY" = no ]; then
+	echo "COMPAT_SRCS+=	compat/strlcpy.c" >>$CONFIG_MK
+	echo "#include			\"compat/strlcpy.h\"" >>$CONFIG_H
+fi
+
 if [ -z "$STRTOI" ]; then
 	printf "Testing for strtoi ... "
 	cat <<EOF >_strtoi.c