From: Eric Biggers <ebiggers3@gmail.com>
Date: Sun, 27 Apr 2014 05:03:51 +0000 (-0500)
Subject: Handle inconsistent uncompressed resources in same way as WIMGAPI
X-Git-Tag: v1.7.0~260
X-Git-Url: https://wimlib.net/git/?p=wimlib;a=commitdiff_plain;h=b24275706ca80ffd423fbb91557199f7289191ac

Handle inconsistent uncompressed resources in same way as WIMGAPI
---

diff --git a/src/lookup_table.c b/src/lookup_table.c
index 2cca979c..1058bf26 100644
--- a/src/lookup_table.c
+++ b/src/lookup_table.c
@@ -684,9 +684,27 @@ read_wim_lookup_table(WIMStruct *wim)
 		if (!(reshdr.flags & (WIM_RESHDR_FLAG_PACKED_STREAMS |
 				      WIM_RESHDR_FLAG_COMPRESSED))) {
 			if (reshdr.uncompressed_size != reshdr.size_in_wim) {
-				ERROR("Invalid resource entry!");
-				ret = WIMLIB_ERR_INVALID_LOOKUP_TABLE_ENTRY;
-				goto err;
+				/* So ... This is an uncompressed resource, but
+				 * its uncompressed size is NOT the same as its
+				 * "compressed" size (size_in_wim).  What to do
+				 * with it?
+				 *
+				 * Based on a simple test, WIMGAPI seems to
+				 * handle this as follows:
+				 *
+				 * if (size_in_wim > uncompressed_size) {
+				 *	Ignore uncompressed_size; use
+				 *	size_in_wim instead.
+				 * } else {
+				 *	Honor uncompressed_size, but treat the
+				 *	part of the file data above size_in_wim
+				 *	as all zeros.
+				 * }
+				 *
+				 * So we will do the same.
+				 */
+				if (reshdr.size_in_wim > reshdr.uncompressed_size)
+					reshdr.uncompressed_size = reshdr.size_in_wim;
 			}
 		}
 
diff --git a/src/resource.c b/src/resource.c
index b45db597..b5db1452 100644
--- a/src/resource.c
+++ b/src/resource.c
@@ -562,6 +562,28 @@ read_error:
 	goto out_free_memory;
 }
 
+static int
+fill_zeroes(u64 size, consume_data_callback_t cb, void *cb_ctx)
+{
+	if (unlikely(size)) {
+		u8 buf[min(size, BUFFER_SIZE)];
+
+		memset(buf, 0, sizeof(buf));
+
+		do {
+			size_t len;
+			int ret;
+
+			len = min(size, BUFFER_SIZE);
+			ret = cb(buf, len, cb_ctx);
+			if (ret)
+				return ret;
+			size -= len;
+		} while (size);
+	}
+	return 0;
+}
+
 /* Read raw data from a file descriptor at the specified offset, feeding the
  * data it in chunks into the specified callback function.  */
 static int
@@ -654,11 +676,37 @@ read_partial_wim_resource(const struct wim_resource_spec *rspec,
 		return read_compressed_wim_resource(rspec, &range, 1,
 						    cb, cb_ctx);
 	} else {
-		return read_raw_file_data(&rspec->wim->in_fd,
-					  rspec->offset_in_wim + offset,
-					  size,
-					  cb,
-					  cb_ctx);
+		/* Reading uncompressed resource.  For completeness, handle the
+		 * weird case where size_in_wim < uncompressed_size.  */
+
+		u64 read_size;
+		u64 zeroes_size;
+		int ret;
+
+		if (likely(offset + size <= rspec->size_in_wim) ||
+		    rspec->is_pipable)
+		{
+			read_size = size;
+			zeroes_size = 0;
+		} else {
+			if (offset >= rspec->size_in_wim) {
+				read_size = 0;
+				zeroes_size = size;
+			} else {
+				read_size = rspec->size_in_wim - offset;
+				zeroes_size = offset + size - rspec->size_in_wim;
+			}
+		}
+
+		ret = read_raw_file_data(&rspec->wim->in_fd,
+					 rspec->offset_in_wim + offset,
+					 read_size,
+					 cb,
+					 cb_ctx);
+		if (ret)
+			return ret;
+
+		return fill_zeroes(zeroes_size, cb, cb_ctx);
 	}
 }