Skip stored data quickly when size is known at beginning even when CRC is at end

diff --git a/libarchive/archive_read_support_format_zip.c b/libarchive/archive_read_support_format_zip.c
index 3f102126b2e18794afd2c384722618b391e61e84..1d232e480baef00f9186ad9c6e357cd33239a33d 100644 (file)
--- a/libarchive/archive_read_support_format_zip.c
+++ b/libarchive/archive_read_support_format_zip.c
@@ -1305,10 +1305,9 @@ zip_read_local_file_header(struct archive_read *a, struct archive_entry *entry,
                    "Truncated ZIP file header");
                return (ARCHIVE_FATAL);
        }
-       process_extra(h, extra_length, zip_entry);
-       zip_read_consume(a, extra_length);
 
        if (zip->have_central_directory) {
+               process_extra(h, extra_length, zip_entry);
                /* If we read the central dir entry, we must have size
                 * information as well, so ignore the length-at-end flag. */
                zip_entry->flags &= ~ZIP_LENGTH_AT_END;
@@ -1350,7 +1349,9 @@ zip_read_local_file_header(struct archive_read *a, struct archive_entry *entry,
                zip_entry->crc32 = local_crc32;
                zip_entry->compressed_size = compressed_size;
                zip_entry->uncompressed_size = uncompressed_size;
+               process_extra(h, extra_length, zip_entry);
        }
+       zip_read_consume(a, extra_length);
 
        /* Populate some additional entry fields: */
        archive_entry_set_mode(entry, zip_entry->mode);
@@ -1798,21 +1799,25 @@ static int
 archive_read_format_zip_read_data_skip(struct archive_read *a)
 {
        struct zip *zip;
+       int64_t bytes_skipped;
 
        zip = (struct zip *)(a->format->data);
+       bytes_skipped = zip_read_consume(a, zip->unconsumed);
+       if (bytes_skipped < 0)
+               return (ARCHIVE_FATAL);
+       zip->unconsumed = 0;
 
        /* If we've already read to end of data, we're done. */
        if (zip->end_of_entry)
                return (ARCHIVE_OK);
 
        /* So we know we're streaming... */
-       if (0 == (zip->entry->flags & ZIP_LENGTH_AT_END)) {
+       if (0 == (zip->entry->flags & ZIP_LENGTH_AT_END)
+           || zip->entry->compressed_size > 0) {
                /* We know the compressed length, so we can just skip. */
-               int64_t bytes_skipped = zip_read_consume(a,
-                   zip->entry_bytes_remaining + zip->unconsumed);
+               bytes_skipped = zip_read_consume(a, zip->entry_bytes_remaining);
                if (bytes_skipped < 0)
                        return (ARCHIVE_FATAL);
-               zip->unconsumed = 0;
                return (ARCHIVE_OK);
        }
 
@@ -1835,7 +1840,6 @@ archive_read_format_zip_read_data_skip(struct archive_read *a)
 #endif
        default: /* Uncompressed or unknown. */
                /* Scan for a PK\007\010 signature. */
-               zip_read_consume(a, zip->unconsumed);
                zip->unconsumed = 0;
                for (;;) {
                        const char *p, *buff;