From 6deecb26de80907cfbd4dfb78205261a9217ab92 Mon Sep 17 00:00:00 2001
From: Andrea Mazzoleni <amadvance@gmail.com>
Date: Sat, 28 Sep 2013 15:33:56 +0200
Subject: [PATCH] Detects the case of physical offsets not reported beucase the
 file doesn't have one.

---
 HISTORY      |  7 +++++++
 configure.ac |  2 +-
 mingw.c      |  9 ++++++---
 portable.h   | 16 ++++++++++++++++
 scan.c       |  2 +-
 unix.c       | 10 +++++-----
 6 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/HISTORY b/HISTORY
index 3720ce55..fff25da1 100644
--- a/HISTORY
+++ b/HISTORY
@@ -1,6 +1,13 @@
 SnapRAID HISTORY
 ================
 
+4.2 2013/9
+==========
+ * Fixed the wrong warning about physical offsets not supported caused
+   by files not having a real offset because too small.
+   For example, in NTFS it's possible to store such files in the MFT.
+   It's just a cosmetic change, and not a functional one.
+
 4.1 2013/9
 ==========
  * If the underline filesystem doesn't support the FIEMAP command,
diff --git a/configure.ac b/configure.ac
index 8d622376..859b7b98 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,6 +1,6 @@
 dnl Process this file with autoconf to produce a configure script.
 AC_PREREQ([2.65])
-AC_INIT([snapraid], [4.1], [], [], [http://snapraid.sourceforge.net])
+AC_INIT([snapraid], [4.2], [], [], [http://snapraid.sourceforge.net])
 AM_INIT_AUTOMAKE([foreign no-dependencies -Wall])
 AC_CONFIG_SRCDIR([snapraid.c])
 AC_CONFIG_HEADER([config.h])
diff --git a/mingw.c b/mingw.c
index 7057ee11..4ccc6a1e 100644
--- a/mingw.c
+++ b/mingw.c
@@ -1130,7 +1130,10 @@ int filephy(const char* file, struct stat* st, uint64_t* physical)
 		} else if (error == ERROR_HANDLE_EOF) {
 			/* if the file is small, it can be stored in the Master File Table (MFT) */
 			/* and then it doesn't have a physical address */
-			rpb->ExtentCount = 0;
+			/* In such case we report a specific fake address, to report this special condition */
+			/* that it's different from the 0 offset reported by the underline file system */
+			rpb->ExtentCount = 1;
+			rpb->Extents[0].Lcn.QuadPart = FILEPHY_WITHOUT_OFFSET;
 		} else {
 			windows_errno(error);
 			CloseHandle(h);
@@ -1141,9 +1144,9 @@ int filephy(const char* file, struct stat* st, uint64_t* physical)
 	CloseHandle(h);
 
 	if (rpb->ExtentCount < 1)
-		*physical = 0;
+		*physical = FILEPHY_UNREPORTED_OFFSET;
 	else
-		*physical = rpb->Extents[0].Lcn.QuadPart;
+		*physical = rpb->Extents[0].Lcn.QuadPart + FILEPHY_REAL_OFFSET;
 
 	return 0;
 }
diff --git a/portable.h b/portable.h
index 4922d2f0..ccaa34fa 100644
--- a/portable.h
+++ b/portable.h
@@ -187,6 +187,22 @@ static inline int hardlink(const char* a, const char* b)
  */
 int devuuid(uint64_t device, char* uuid, size_t size);
 
+/**
+ * Special value returned when the file doesn't have a real offset.
+ * For example, because it's stored in the NTFS MFT.
+ */
+#define FILEPHY_WITHOUT_OFFSET 0
+
+/**
+ * Special value returned when the filesystem doesn't report any offset for unknown reason.
+ */
+#define FILEPHY_UNREPORTED_OFFSET 1
+
+/**
+ * Value indicating real offsets. All offsets greater or equal at this one are real.
+ */
+#define FILEPHY_REAL_OFFSET 2
+
 /**
  * Get the physcal address of the specified file.
  * This is expected to be just a hint and not necessarely correct or unique.
diff --git a/scan.c b/scan.c
index 8b17ddda..4b1d961d 100644
--- a/scan.c
+++ b/scan.c
@@ -974,7 +974,7 @@ void state_scan(struct snapraid_state* state, int output)
 
 			/* if the file is not empty, count duplicate physical offsets */
 			if (state->opt.force_order == SORT_PHYSICAL && file->size != 0) {
-				if (phy_count > 0 && file->physical == phy_last)
+				if (phy_count > 0 && file->physical == phy_last && phy_last != FILEPHY_WITHOUT_OFFSET)
 					++phy_dup;
 				phy_last = file->physical;
 				++phy_count;
diff --git a/unix.c b/unix.c
index a775b9da..f6c646a1 100644
--- a/unix.c
+++ b/unix.c
@@ -149,7 +149,7 @@ int filephy(const char* path, struct stat* st, uint64_t* physical)
 	fm.fiemap.fm_extent_count = 1; /* we are interested only at the first block */
 
 	if (ioctl(f, FS_IOC_FIEMAP, &fm) != -1) {
-		*physical = fm.fiemap.fm_extents[0].fe_physical;
+		*physical = fm.fiemap.fm_extents[0].fe_physical + FILEPHY_REAL_OFFSET;
 		if (close(f) == -1)
 			return -1;
 		return 0;
@@ -157,7 +157,7 @@ int filephy(const char* path, struct stat* st, uint64_t* physical)
 
 	/* if empty, FIBMAP doesn't work */
 	if (st->st_size == 0) {
-		*physical = 0;
+		*physical = FILEPHY_WITHOUT_OFFSET;
 		if (close(f) == -1)
 			return -1;
 		return 0;
@@ -168,7 +168,7 @@ int filephy(const char* path, struct stat* st, uint64_t* physical)
 	/* in exfat it always returns 0, that it's anyway better than the fake inodes */
 	blknum = 0; /* first block */
 	if (ioctl(f, FIBMAP, &blknum) != -1) {
-		*physical = blknum;
+		*physical = blknum + FILEPHY_REAL_OFFSET;
 		if (close(f) == -1)
 			return -1;
 		return 0;
@@ -177,13 +177,13 @@ int filephy(const char* path, struct stat* st, uint64_t* physical)
 	/* otherwise don't use anything, and keep the existing order */
 	/* at now this should happen only for vfat */
 	/* and it's surely better than using fake inodes */
-	*physical = 0;
+	*physical = FILEPHY_UNREPORTED_OFFSET;
 	if (close(f) == -1)
 		return -1;
 #else
 	/* In a generic Unix use a dummy value for all the files */
 	/* We don't want to risk to use the inode without knowing if it really improves performance */
-	*physical = 0;
+	*physical = FILEPHY_UNREPORTED_OFFSET;
 
 	(void)path; /* not used here */
 	(void)st;