BuildSystem: Write my own disk image perm updater

If user's bash does not have bultin stat, updating image perms was
terribly slow. This patch adds a simple c program that does the job
without exec overhead

.gitignore

@@ -3,3 +3,4 @@
 build/
 base/
 script/fakeroot-context
+tools/update-image-perms

script/build.sh

@@ -42,9 +42,17 @@ build_toolchain () {
 	$BANAN_TOOLCHAIN_DIR/build.sh
 }
 
+build_tools() {
+	perm_tool="$BANAN_TOOLS_DIR/update-image-perms"
+	if [ ! -f "$perm_tool" ] || [ "$perm_tool" -ot "$perm_tool.c" ]; then
+		gcc -O2 -Wall -Wextra -Werror -o "$perm_tool" "$perm_tool.c" || exit 1
+	fi
+}
+
 create_image () {
 	build_target all
 	build_target install
+	build_tools
 	$BANAN_SCRIPT_DIR/image.sh "$1"
 }
 

script/config.sh

@@ -19,6 +19,8 @@ export BANAN_BUILD_DIR="$BANAN_ROOT_DIR/build"
 
 export BANAN_PORT_DIR="$BANAN_ROOT_DIR/ports"
 
+export BANAN_TOOLS_DIR="$BANAN_ROOT_DIR/tools"
+
 export BANAN_SYSROOT="$BANAN_BUILD_DIR/sysroot"
 
 export BANAN_FAKEROOT="$BANAN_BUILD_DIR/fakeroot-context"

script/image.sh

@@ -20,57 +20,38 @@ if [ -z $BANAN_BUILD_DIR ]; then
 	exit 1
 fi
 
-if [ "$1" == "full" ] || [ ! -f $BANAN_DISK_IMAGE_PATH ]; then
+if [ "$1" == "full" ] || [ ! -f "$BANAN_DISK_IMAGE_PATH" ]; then
-	$BANAN_SCRIPT_DIR/image-create.sh || exit 1
+	"$BANAN_SCRIPT_DIR/image-create.sh" || exit 1
 fi
 
 set -u
 
 MOUNT_DIR="$BANAN_BUILD_DIR/mount"
-mkdir -p $MOUNT_DIR
+mkdir -p "$MOUNT_DIR"
 
-LOOP_DEV="$(sudo losetup --show -Pf $BANAN_DISK_IMAGE_PATH || exit 1)"
+LOOP_DEV="$(sudo losetup --show -Pf "$BANAN_DISK_IMAGE_PATH" || exit 1)"
 ROOT_PARTITION="${LOOP_DEV}p2"
-if [ ! -b $ROOT_PARTITION ]; then
+if [ ! -b "$ROOT_PARTITION" ]; then
 	echo "Failed to probe partitions for banan disk image." >&2
-	sudo losetup -d $LOOP_DEV
+	sudo losetup -d "$LOOP_DEV"
 	exit 1
 fi
 
-if sudo mount $ROOT_PARTITION $MOUNT_DIR; then
+if sudo mount "$ROOT_PARTITION" "$MOUNT_DIR"; then
 	if (($BANAN_INITRD)); then
-		fakeroot -i $BANAN_FAKEROOT tar -C $BANAN_SYSROOT -cf $BANAN_SYSROOT.initrd .
+		fakeroot -i "$BANAN_FAKEROOT" tar -C "$BANAN_SYSROOT" -cf "$BANAN_SYSROOT.initrd" .
 
-		sudo mkdir -p $MOUNT_DIR/boot
+		sudo mkdir -p "$MOUNT_DIR/boot"
-		sudo cp $BANAN_BUILD_DIR/kernel/banan-os.kernel $MOUNT_DIR/boot/banan-os.kernel
+		sudo cp "$BANAN_BUILD_DIR/kernel/banan-os.kernel" "$MOUNT_DIR/boot/banan-os.kernel"
-		sudo mv $BANAN_SYSROOT.initrd $MOUNT_DIR/boot/banan-os.initrd
+		sudo mv "$BANAN_SYSROOT.initrd" "$MOUNT_DIR/boot/banan-os.initrd"
 	else
-		sudo rsync -rulHpt $BANAN_SYSROOT/ $MOUNT_DIR
+		sudo rsync -rulHpt "$BANAN_SYSROOT/" "$MOUNT_DIR"
 
-		fakeroot -i $BANAN_FAKEROOT find $BANAN_SYSROOT -printf './%P|%U|%G|%04m\n' >$BANAN_BUILD_DIR/sysroot-perms.txt
+		fakeroot -i "$BANAN_FAKEROOT" find "$BANAN_SYSROOT" -printf '%P|%U|%G|%04m\n' >"$BANAN_BUILD_DIR/sysroot-perms.txt"
-		sudo bash -c "
+		sudo "$BANAN_TOOLS_DIR/update-image-perms" "$MOUNT_DIR" "$BANAN_BUILD_DIR/sysroot-perms.txt"
-			if enable stat &>/dev/null; then
-				while IFS='|' read -r path uid gid mode; do
-					full=\"$MOUNT_DIR/\$path\"
-					stat \"\$full\"
-					if [[ \${STAT[uid]} != \$uid ]] || [[ \${STAT[gid]} != \$gid ]] || [[ \${STAT[perms]} != \$mode ]]; then
-						chown -h \"\$uid:\$gid\" \"\$full\"
-						test ! -h \"\$full\" && chmod \"\$mode\" \"\$full\"
-					fi
-				done <$BANAN_BUILD_DIR/sysroot-perms.txt
-			else
-				while IFS='|' read -r path uid gid mode; do
-					full=\"$MOUNT_DIR/\$path\"
-					if [[ \$(stat -c '%u %g %a' \"\$full\") != \"\$uid \$gid \$mode\" ]]; then
-						chown -h \"\$uid:\$gid\" \"\$full\"
-						test ! -h \"\$full\" && chmod \"\$mode\" \"\$full\"
-					fi
-				done <$BANAN_BUILD_DIR/sysroot-perms.txt
-			fi
-		"
 	fi
 
-	sudo umount $MOUNT_DIR
+	sudo umount "$MOUNT_DIR"
 fi
 
-sudo losetup -d $LOOP_DEV
+sudo losetup -d "$LOOP_DEV"

tools/update-image-perms.c

@@ -0,0 +1,60 @@
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+int main(int argc, char** argv)
+{
+	if (argc != 3)
+	{
+		fprintf(stderr, "usage: %s MOUNT_POINT PERMS_FILE\n", argv[0]);
+		return 1;
+	}
+
+	int mount_fd = open(argv[1], O_RDONLY | O_DIRECTORY);
+	if (mount_fd == -1)
+	{
+		fprintf(stderr, "could not open %s: %s\n", argv[1], strerror(errno));
+		return 1;
+	}
+
+	FILE* perm_fp = fopen(argv[2], "r");
+	if (perm_fp == NULL)
+	{
+		fprintf(stderr, "could not open %s: %s\n", argv[2], strerror(errno));
+		return 1;
+	}
+
+	char buffer[1024];
+	while (fgets(buffer, sizeof(buffer), perm_fp))
+	{
+		char path[PATH_MAX];
+		uid_t uid;
+		gid_t gid;
+		mode_t mode;
+
+		if (sscanf(buffer, "%[^|\n]|%d|%d|%o\n", path, &uid, &gid, &mode) != 4)
+			continue;
+
+		struct stat st;
+		if (fstatat(mount_fd, path, &st, AT_SYMLINK_NOFOLLOW) != 0)
+			continue;
+
+		if (st.st_uid != uid || st.st_gid != gid)
+			if (fchownat(mount_fd, path, uid, gid, AT_SYMLINK_NOFOLLOW) != 0)
+				fprintf(stderr, "fchownat: %s: %s\n", path, strerror(errno));
+
+		const mode_t mode_mask = S_ISUID | S_ISGID | S_ISVTX | 0777;
+		if (mode != (st.st_mode & mode_mask))
+			if (fchmodat(mount_fd, path, mode, AT_SYMLINK_NOFOLLOW) != 0)
+				fprintf(stderr, "fchmodat: %s: %s\n", path, strerror(errno));
+	}
+
+	fclose(perm_fp);
+	close(mount_fd);
+
+	return 0;
+}