From 79fb6ac7a5acc4178b66314c573aeada1d387ed9 Mon Sep 17 00:00:00 2001
From: Denys Vlasenko <vda.linux@googlemail.com>
Date: Fri, 13 Jul 2018 20:30:02 +0200
Subject: [PATCH] cp: optional --reflink support

function                                             old     new   delta
cp_main                                              428     512     +84
copy_file                                           1676    1742     +66

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
---
 coreutils/cp.c    | 24 ++++++++++++++++++++++++
 include/libbb.h   |  3 +++
 libbb/copy_file.c | 19 +++++++++++++++++++
 3 files changed, 46 insertions(+)

diff --git a/coreutils/cp.c b/coreutils/cp.c
index 455bffbba..b623aaf33 100644
--- a/coreutils/cp.c
+++ b/coreutils/cp.c
@@ -24,6 +24,11 @@
 //config:	help
 //config:	Enable long options.
 //config:	Also add support for --parents option.
+//config:
+//config:config FEATURE_CP_REFLINK
+//config:	bool "Enable --reflink[=auto]
+//config:	default y
+//config:	depends on FEATURE_CP_LONG_OPTIONS
 
 //applet:IF_CP(APPLET_NOEXEC(cp, cp, BB_DIR_BIN, BB_SUID_DROP, cp))
 /* NOEXEC despite cases when it can be a "runner" (cp -r LARGE_DIR NEW_DIR) */
@@ -72,10 +77,14 @@ int cp_main(int argc, char **argv)
 #if ENABLE_FEATURE_CP_LONG_OPTIONS
 		/*OPT_rmdest  = FILEUTILS_RMDEST = 1 << FILEUTILS_CP_OPTNUM */
 		OPT_parents = 1 << (FILEUTILS_CP_OPTNUM+1),
+		OPT_reflink = 1 << (FILEUTILS_CP_OPTNUM+2),
 #endif
 	};
 
 #if ENABLE_FEATURE_CP_LONG_OPTIONS
+# if ENABLE_FEATURE_CP_REFLINK
+	char *reflink = NULL;
+# endif
 	flags = getopt32long(argv, "^"
 		FILEUTILS_CP_OPTSTR
 		"\0"
@@ -99,7 +108,22 @@ int cp_main(int argc, char **argv)
 		"update\0"         No_argument "u"
 		"remove-destination\0" No_argument "\xff"
 		"parents\0"        No_argument "\xfe"
+# if ENABLE_FEATURE_CP_REFLINK
+		"reflink\0"        Optional_argument "\xfd"
+		, &reflink
+# endif
 	);
+# if ENABLE_FEATURE_CP_REFLINK
+	BUILD_BUG_ON(OPT_reflink != FILEUTILS_REFLINK);
+	if (flags & FILEUTILS_REFLINK) {
+		if (!reflink)
+			flags |= FILEUTILS_REFLINK_ALWAYS;
+		else if (strcmp(reflink, "always") == 0)
+			flags |= FILEUTILS_REFLINK_ALWAYS;
+		else if (strcmp(reflink, "auto") != 0)
+			bb_show_usage();
+	}
+# endif
 #else
 	flags = getopt32(argv, "^"
 		FILEUTILS_CP_OPTSTR
diff --git a/include/libbb.h b/include/libbb.h
index d4ba031df..94caba2bb 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -410,6 +410,9 @@ enum {	/* cp.c, mv.c, install.c depend on these values. CAREFUL when changing th
 	FILEUTILS_PRESERVE_SECURITY_CONTEXT = 1 << 15, /* -c */
 #endif
 	FILEUTILS_RMDEST          = 1 << (16 - !ENABLE_SELINUX), /* --remove-destination */
+	/* bit 17 skipped for "cp --parents" */
+	FILEUTILS_REFLINK         = 1 << (18 - !ENABLE_SELINUX), /* cp --reflink=auto */
+	FILEUTILS_REFLINK_ALWAYS  = 1 << (19 - !ENABLE_SELINUX), /* cp --reflink[=always] */
 	/*
 	 * Hole. cp may have some bits set here,
 	 * they should not affect remove_file()/copy_file()
diff --git a/libbb/copy_file.c b/libbb/copy_file.c
index 1b8befd65..98bd4fe72 100644
--- a/libbb/copy_file.c
+++ b/libbb/copy_file.c
@@ -339,9 +339,28 @@ int FAST_FUNC copy_file(const char *source, const char *dest, int flags)
 				freecon(con);
 			}
 		}
+#endif
+#if ENABLE_FEATURE_CP_REFLINK
+# undef BTRFS_IOCTL_MAGIC
+# define BTRFS_IOCTL_MAGIC 0x94
+# undef BTRFS_IOC_CLONE
+# define BTRFS_IOC_CLONE _IOW (BTRFS_IOCTL_MAGIC, 9, int)
+		if (flags & FILEUTILS_REFLINK) {
+			retval = ioctl(dst_fd, BTRFS_IOC_CLONE, src_fd);
+			if (retval == 0)
+				goto do_close;
+			/* reflink did not work */
+			if (flags & FILEUTILS_REFLINK_ALWAYS) {
+				bb_perror_msg("failed to clone '%s' from '%s'", dest, source);
+				goto do_close;
+			}
+			/* fall through to standard copy */
+			retval = 0;
+		}
 #endif
 		if (bb_copyfd_eof(src_fd, dst_fd) == -1)
 			retval = -1;
+ IF_FEATURE_CP_REFLINK(do_close:)
 		/* Careful with writing... */
 		if (close(dst_fd) < 0) {
 			bb_perror_msg("error writing to '%s'", dest);