Implement function used to seek within data blocks.

This only implements seeking fully for uncompressed RAR files. Seeking is not
implemented for compressed RAR files and for the other formats (ZIP, TAR, etc.).

1 files changed, 126 insertions, 1 deletions

diff --git a/libarchive/archive_read.c b/libarchive/archive_read.c
index faadbea4..118c10b6 100644
--- a/libarchive/archive_read.c
+++ b/libarchive/archive_read.c
@@ -399,6 +399,8 @@ archive_read_set_callback_data2(struct archive *_a, void *client_data,
 		return ARCHIVE_FATAL;
 	}
 	a->client.dataset[iindex].data = client_data;
+	a->client.dataset[iindex].begin_position = -1;
+	a->client.dataset[iindex].total_size = -1;
 	return ARCHIVE_OK;
 }
 
@@ -427,8 +429,14 @@ archive_read_add_callback_data(struct archive *_a, void *client_data,
 	}
 	a->client.dataset = (struct archive_read_data_node *)p;
 	for (i = a->client.nodes - 1; i > iindex && i > 0; i--)
+	{
 		a->client.dataset[i].data = a->client.dataset[i-1].data;
+		a->client.dataset[i].begin_position = -1;
+		a->client.dataset[i].total_size = -1;
+	}
 	a->client.dataset[iindex].data = client_data;
+	a->client.dataset[iindex].begin_position = -1;
+	a->client.dataset[iindex].total_size = -1;
 	return ARCHIVE_OK;
 }
 
@@ -495,6 +503,9 @@ archive_read_open1(struct archive *_a)
 	filter->code = ARCHIVE_COMPRESSION_NONE;
 	a->filter = filter;
 
+	client_switch_proxy(a->filter, 0);
+	a->client.dataset[0].begin_position = 0;
+
 	/* Build out the input pipeline. */
 	e = choose_filters(a);
 	if (e < ARCHIVE_WARN) {
@@ -641,6 +652,7 @@ _archive_read_next_header2(struct archive *_a, struct archive_entry *entry)
 
 	a->read_data_output_offset = 0;
 	a->read_data_remaining = 0;
+	a->data_start_node = a->client.cursor;
 	/* EOF always wins; otherwise return the worst error. */
 	return (r2 < r1 || r2 == ARCHIVE_EOF) ? r2 : r1;
 }
@@ -838,6 +850,23 @@ archive_read_data_skip(struct archive *_a)
 	return (r);
 }
 
+int64_t
+archive_seek_data(struct archive *_a, int64_t offset, int whence)
+{
+	struct archive_read *a = (struct archive_read *)_a;
+	archive_check_magic(_a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_DATA,
+	    "archive_seek_data_block");
+
+	if (a->format->seek_data == NULL) {
+		archive_set_error(&a->archive, ARCHIVE_ERRNO_PROGRAMMER,
+		    "Internal error: "
+		    "No format_seek_data_block function registered");
+		return (ARCHIVE_FATAL);
+	}
+
+	return (a->format->seek_data)(a, offset, whence);
+}
+
 /*
  * Read the next block of entry data from the archive.
  * This is a zero-copy interface; the client receives a pointer,
@@ -1049,6 +1078,7 @@ __archive_read_register_format(struct archive_read *a,
     int (*read_header)(struct archive_read *, struct archive_entry *),
     int (*read_data)(struct archive_read *, const void **, size_t *, int64_t *),
     int (*read_data_skip)(struct archive_read *),
+    int64_t (*seek_data)(struct archive_read *, int64_t, int),
     int (*cleanup)(struct archive_read *))
 {
 	int i, number_slots;
@@ -1068,6 +1098,7 @@ __archive_read_register_format(struct archive_read *a,
 			a->formats[i].read_header = read_header;
 			a->formats[i].read_data = read_data;
 			a->formats[i].read_data_skip = read_data_skip;
+			a->formats[i].seek_data = seek_data;
 			a->formats[i].cleanup = cleanup;
 			a->formats[i].data = format_data;
 			a->formats[i].name = name;
@@ -1463,12 +1494,106 @@ int64_t
 __archive_read_filter_seek(struct archive_read_filter *filter, int64_t offset, int whence)
 {
 	int64_t r;
+	unsigned int cursor;
 
 	if (filter->closed || filter->fatal)
 		return (ARCHIVE_FATAL);
 	if (filter->seek == NULL)
 		return (ARCHIVE_FAILED);
-	r = filter->seek(filter, offset, whence);
+
+	switch (whence)
+	{
+		case SEEK_CUR:
+			/* Adjust the offset and use SEEK_SET instead */
+			offset += filter->position;			
+		case SEEK_SET:
+			cursor = 0;
+			while (1)
+			{
+				if (filter->archive->client.dataset[cursor].begin_position < 0 ||
+					filter->archive->client.dataset[cursor].total_size < 0 ||
+					filter->archive->client.dataset[cursor].begin_position +
+					filter->archive->client.dataset[cursor].total_size - 1 > offset ||
+					cursor + 1 >= filter->archive->client.nodes)
+					break;
+				r = filter->archive->client.dataset[cursor].begin_position +
+					filter->archive->client.dataset[cursor].total_size;
+				filter->archive->client.dataset[++cursor].begin_position = r;
+			}
+			while (1)
+			{
+				if ((r = client_switch_proxy(filter, cursor)) != (ARCHIVE_OK))
+					return r;
+				if ((r = client_seek_proxy(filter, 0, SEEK_END)) < 0)
+					return r;
+				filter->archive->client.dataset[cursor].total_size = r;
+				if (filter->archive->client.dataset[cursor].begin_position +
+					filter->archive->client.dataset[cursor].total_size - 1 > offset ||
+					cursor + 1 >= filter->archive->client.nodes)
+					break;
+				r = filter->archive->client.dataset[cursor].begin_position +
+					filter->archive->client.dataset[cursor].total_size;
+				filter->archive->client.dataset[++cursor].begin_position = r;
+			}
+			offset -= filter->archive->client.dataset[cursor].begin_position;
+			if (offset < 0)
+				offset = 0;
+			else if (offset > filter->archive->client.dataset[cursor].total_size - 1)
+				offset = filter->archive->client.dataset[cursor].total_size - 1;
+			if ((r = client_seek_proxy(filter, offset, SEEK_SET)) < 0)
+				return r;
+			break;
+
+		case SEEK_END:
+			cursor = 0;
+			while (1)
+			{
+				if (filter->archive->client.dataset[cursor].begin_position < 0 ||
+					filter->archive->client.dataset[cursor].total_size < 0 ||
+					cursor + 1 >= filter->archive->client.nodes)
+					break;
+				r = filter->archive->client.dataset[cursor].begin_position +
+					filter->archive->client.dataset[cursor].total_size;
+				filter->archive->client.dataset[++cursor].begin_position = r;
+			}
+			while (1)
+			{
+				if ((r = client_switch_proxy(filter, cursor)) != (ARCHIVE_OK))
+					return r;
+				if ((r = client_seek_proxy(filter, 0, SEEK_END)) < 0)
+					return r;
+				filter->archive->client.dataset[cursor].total_size = r;
+				r = filter->archive->client.dataset[cursor].begin_position +
+					filter->archive->client.dataset[cursor].total_size;
+				if (cursor + 1 >= filter->archive->client.nodes)
+					break;
+				filter->archive->client.dataset[++cursor].begin_position = r;
+			}
+			while (1)
+			{
+				if (r + offset >=
+					filter->archive->client.dataset[cursor].begin_position)
+					break;
+				offset += filter->archive->client.dataset[cursor].total_size;
+				if (cursor == 0)
+					break;
+				cursor--;
+				r = filter->archive->client.dataset[cursor].begin_position +
+					filter->archive->client.dataset[cursor].total_size;
+			}
+			offset = (r + offset) -
+				filter->archive->client.dataset[cursor].begin_position;
+			if ((r = client_switch_proxy(filter, cursor)) != (ARCHIVE_OK))
+				return r;
+			if ((r = client_seek_proxy(filter, offset, SEEK_SET)) < (ARCHIVE_OK))
+				return r;
+			break;
+
+		default:
+			return (ARCHIVE_FATAL);
+	}
+	r += filter->archive->client.dataset[cursor].begin_position;
+
 	if (r >= 0) {
 		/*
 		 * Ouch.  Clearing the buffer like this hurts, especially