[file-roller] libarchive: correctly extract sparse files

[Paolo Bacchilega <paobac src gnome org>]

commit 1149ff864d45da217d952dfbd0a45f5832f7b3bc
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Sun Dec 13 14:31:47 2015 +0100

    libarchive: correctly extract sparse files
    
    [bug #747091]

 src/fr-archive-libarchive.c |   60 ++++++++++++++++++++++++++++++++++++++++---
 1 files changed, 56 insertions(+), 4 deletions(-)
---
diff --git a/src/fr-archive-libarchive.c b/src/fr-archive-libarchive.c
index 9e84475..dbe48bf 100644
--- a/src/fr-archive-libarchive.c
+++ b/src/fr-archive-libarchive.c
@@ -443,6 +443,9 @@ fr_archive_libarchive_list (FrArchive           *archive,
 /* -- extract -- */
 
 
+#define NULL_BUFFER_SIZE (16 * 1024)
+
+
 typedef struct {
        LoadData    parent;
        GList      *file_list;
@@ -455,6 +458,7 @@ typedef struct {
        int         n_files_to_extract;
        GHashTable *usernames;
        GHashTable *groupnames;
+       char       *null_buffer;
 } ExtractData;
 
 
@@ -467,6 +471,7 @@ extract_data_free (ExtractData *extract_data)
        g_hash_table_unref (extract_data->files_to_extract);
        g_hash_table_unref (extract_data->usernames);
        g_hash_table_unref (extract_data->groupnames);
+       g_free (extract_data->null_buffer);
        load_data_free (LOAD_DATA (extract_data));
 }
 
@@ -564,6 +569,37 @@ restore_original_file_attributes (GHashTable    *created_files,
 }
 
 
+static gboolean
+_g_output_stream_add_padding (ExtractData    *extract_data,
+                             GOutputStream  *ostream,
+                             gssize          target_offset,
+                             gssize          actual_offset,
+                             GCancellable   *cancellable,
+                             GError        **error)
+{
+       gboolean success = TRUE;
+       gsize    count;
+       gsize    bytes_written;
+
+       if (extract_data->null_buffer == NULL)
+               extract_data->null_buffer = g_malloc0 (NULL_BUFFER_SIZE);
+
+       while (target_offset > actual_offset) {
+               count = NULL_BUFFER_SIZE;
+               if (target_offset < actual_offset + NULL_BUFFER_SIZE)
+                       count = target_offset - actual_offset;
+
+               success = g_output_stream_write_all (ostream, extract_data->null_buffer, count, 
&bytes_written, cancellable, error);
+               if (! success)
+                       break;
+
+               actual_offset += bytes_written;
+       }
+
+       return success;
+}
+
+
 static void
 extract_archive_thread (GSimpleAsyncResult *result,
                        GObject            *object,
@@ -599,7 +635,7 @@ extract_archive_thread (GSimpleAsyncResult *result,
                GOutputStream *ostream;
                const void    *buffer;
                size_t         buffer_size;
-               int64_t        offset;
+               int64_t        target_offset, actual_offset;
                GError        *local_error = NULL;
                __LA_MODE_T    filetype;
 
@@ -788,11 +824,27 @@ extract_archive_thread (GSimpleAsyncResult *result,
                                if (ostream == NULL)
                                        break;
 
-                               while ((r = archive_read_data_block (a, &buffer, &buffer_size, &offset)) == 
ARCHIVE_OK) {
-                                       if (g_output_stream_write (ostream, buffer, buffer_size, cancellable, 
&load_data->error) == -1)
+                               actual_offset = 0;
+                               while ((r = archive_read_data_block (a, &buffer, &buffer_size, 
&target_offset)) == ARCHIVE_OK) {
+                                       gsize bytes_written;
+
+                                       if (target_offset > actual_offset) {
+                                               if (! _g_output_stream_add_padding (extract_data, ostream, 
target_offset, actual_offset, cancellable, &load_data->error))
+                                                       break;
+                                               actual_offset = target_offset;
+                                               fr_archive_progress_set_completed_bytes (load_data->archive, 
actual_offset);
+                                       }
+
+                                       if (! g_output_stream_write_all (ostream, buffer, buffer_size, 
&bytes_written, cancellable, &load_data->error))
                                                break;
-                                       fr_archive_progress_inc_completed_bytes (load_data->archive, 
buffer_size);
+
+                                       actual_offset += bytes_written;
+                                       fr_archive_progress_set_completed_bytes (load_data->archive, 
actual_offset);
                                }
+
+                               if ((r == ARCHIVE_EOF) && (target_offset > actual_offset))
+                                       _g_output_stream_add_padding (extract_data, ostream, target_offset, 
actual_offset, cancellable, &load_data->error);
+
                                _g_object_unref (ostream);
 
                                if (r != ARCHIVE_EOF)