X-Git-Url: https://wimlib.net/git/?a=blobdiff_plain;f=src%2Fextract.c;h=cd1dd2c1ca0ebb319066db5c02c5fcacff3ba84b;hb=1e99a9de97d9e244496aec79bc3cc8506886b507;hp=d3df861fb6ba5cef0a27c3998f8c0e51088d0b46;hpb=43f92ce30b2398d1823e34e39ff248de521d015c;p=wimlib

diff --git a/src/extract.c b/src/extract.c
index d3df861f..cd1dd2c1 100644
--- a/src/extract.c
+++ b/src/extract.c
@@ -6,7 +6,7 @@
  */
 
 /*
- * Copyright (C) 2012-2016 Eric Biggers
+ * Copyright (C) 2012-2018 Eric Biggers
  *
  * This file is free software; you can redistribute it and/or modify it under
  * the terms of the GNU Lesser General Public License as published by the Free
@@ -63,6 +63,7 @@
 #include "wimlib/unix_data.h"
 #include "wimlib/wim.h"
 #include "wimlib/win32.h" /* for realpath() equivalent */
+#include "wimlib/xattr.h"
 #include "wimlib/xml.h"
 
 #define WIMLIB_EXTRACT_FLAG_FROM_PIPE   0x80000000
@@ -141,6 +142,70 @@ end_file_metadata_phase(struct apply_ctx *ctx)
 	return end_file_phase(ctx, WIMLIB_PROGRESS_MSG_EXTRACT_METADATA);
 }
 
+/* Are all bytes in the specified buffer zero? */
+static bool
+is_all_zeroes(const u8 *p, const size_t size)
+{
+	const u8 * const end = p + size;
+
+	for (; (uintptr_t)p % WORDBYTES && p != end; p++)
+		if (*p)
+			return false;
+
+	for (; end - p >= WORDBYTES; p += WORDBYTES)
+		if (*(const machine_word_t *)p)
+			return false;
+
+	for (; p != end; p++)
+		if (*p)
+			return false;
+
+	return true;
+}
+
+/*
+ * Sparse regions should be detected at the granularity of the filesystem block
+ * size.  For now just assume 4096 bytes, which is the default block size on
+ * NTFS and most Linux filesystems.
+ */
+#define SPARSE_UNIT 4096
+
+/*
+ * Detect whether the specified buffer begins with a region of all zero bytes.
+ * Return %true if a zero region was found or %false if a nonzero region was
+ * found, and sets *len_ret to the length of the region.  This operates at a
+ * granularity of SPARSE_UNIT bytes, meaning that to extend a zero region, there
+ * must be SPARSE_UNIT zero bytes with no interruption, but to extend a nonzero
+ * region, just one nonzero byte in the next SPARSE_UNIT bytes is sufficient.
+ *
+ * Note: besides compression, the WIM format doesn't yet have a way to
+ * efficiently represent zero regions, so that's why we need to detect them
+ * ourselves.  Things will still fall apart badly on extremely large sparse
+ * files, but this is a start...
+ */
+bool
+detect_sparse_region(const void *data, size_t size, size_t *len_ret)
+{
+	const void *p = data;
+	const void * const end = data + size;
+	size_t len = 0;
+	bool zeroes = false;
+
+	while (p != end) {
+		size_t n = min(end - p, SPARSE_UNIT);
+		bool z = is_all_zeroes(p, n);
+
+		if (len != 0 && z != zeroes)
+			break;
+		zeroes = z;
+		len += n;
+		p += n;
+	}
+
+	*len_ret = len;
+	return zeroes;
+}
+
 #define PWM_FOUND_WIM_HDR (-1)
 
 /* Read the header for a blob in a pipable WIM.  If @pwm_hdr_ret is not NULL,
@@ -1160,6 +1225,8 @@ inode_tally_features(const struct wim_inode *inode,
 		features->unix_data++;
 	if (inode_has_object_id(inode))
 		features->object_ids++;
+	if (inode_has_xattrs(inode))
+		features->xattrs++;
 }
 
 /* Tally features necessary to extract a dentry and the corresponding inode.  */
@@ -1297,19 +1364,32 @@ do_feature_check(const struct wim_features *required_features,
 		WARNING("Ignoring Windows NT security descriptors of %lu files",
 			required_features->security_descriptors);
 
-	/* UNIX data.  */
-	if ((extract_flags & WIMLIB_EXTRACT_FLAG_UNIX_DATA) &&
-	    required_features->unix_data && !supported_features->unix_data)
+	/* Standard UNIX metadata */
+	if (required_features->unix_data &&
+	    (!supported_features->unix_data ||
+	     !(extract_flags & WIMLIB_EXTRACT_FLAG_UNIX_DATA)))
 	{
-		ERROR("Extraction backend does not support UNIX data!");
-		return WIMLIB_ERR_UNSUPPORTED;
+		if (extract_flags & WIMLIB_EXTRACT_FLAG_UNIX_DATA) {
+			ERROR("Requested UNIX metadata extraction, but "
+			      "extraction backend does not support it!");
+			return WIMLIB_ERR_UNSUPPORTED;
+		}
+		WARNING("Ignoring UNIX metadata (uid/gid/mode/rdev) of %lu files%"TS,
+			required_features->unix_data,
+			(supported_features->unix_data ?
+			 T("\n          (use --unix-data mode to extract these)") : T("")));
 	}
 
-	if (required_features->unix_data &&
-	    !(extract_flags & WIMLIB_EXTRACT_FLAG_UNIX_DATA))
+	/* Extended attributes */
+	if (required_features->xattrs &&
+	    (!supported_features->xattrs ||
+	     (supported_features->unix_data &&
+	      !(extract_flags & WIMLIB_EXTRACT_FLAG_UNIX_DATA))))
 	{
-		WARNING("Ignoring UNIX metadata of %lu files",
-			required_features->unix_data);
+		WARNING("Ignoring extended attributes of %lu files%"TS,
+			required_features->xattrs,
+			(supported_features->xattrs ?
+			 T("\n          (use --unix-data mode to extract these)") : T("")));
 	}
 
 	/* Object IDs.  */