[libgsf] Zip: fix typo for reading certain zip files.

[Morten Welinder <mortenw src gnome org>]

commit e3c6c9118bc4d6ad88bdaa3ec63967638fa4b73b
Author: Morten Welinder <terra gnome org>
Date:   Sun Nov 23 16:52:01 2014 -0500

    Zip: fix typo for reading certain zip files.
    
    This somehow affected xlsx files more than other files.

 ChangeLog            |    2 ++
 gsf/gsf-infile-zip.c |    5 +++--
 gsf/gsf-zip-impl.h   |    1 +
 3 files changed, 6 insertions(+), 2 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index b955088..9dc6c91 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,8 @@
 
        * gsf/gsf-infile-zip.c (zip_dirent_new_in): Fix reading of
        extended field.  csize and usize are swapped in there.
+       (zip_dirent_new_in): Read the right amount of variable data.
+       (zip_read_dirents): Check trailer64 signature.
 
        * gsf/gsf-outfile-zip.c (zip_dirent_write): Fix file mode.
 
diff --git a/gsf/gsf-infile-zip.c b/gsf/gsf-infile-zip.c
index edb5d31..64b94d9 100644
--- a/gsf/gsf-infile-zip.c
+++ b/gsf/gsf-infile-zip.c
@@ -269,7 +269,7 @@ zip_dirent_new_in (GsfInfileZip *zip, gsf_off_t *offset)
        vlen = name_len + extras_len + comment_len;
 
        /* Read variable part */
-       variable = gsf_input_read (zip->source, ZIP_DIRENT_SIZE, NULL);
+       variable = gsf_input_read (zip->source, vlen, NULL);
        if (!variable && vlen > 0)
                return NULL;
        if (FALSE && variable) gsf_mem_dump (variable, vlen);
@@ -426,7 +426,8 @@ zip_read_dirents (GsfInfileZip *zip)
                if (gsf_input_seek (zip->source, zip64_eod_offset, G_SEEK_SET))
                        goto bad;
                data = gsf_input_read (zip->source, ZIP_TRAILER64_SIZE, NULL);
-               if (!data)
+               if (!data ||
+                   GSF_LE_GET_GUINT32 (data) != ZIP_TRAILER64_SIGNATURE)
                        goto bad;
 
                entries = GSF_LE_GET_GUINT64 (data + ZIP_TRAILER64_ENTRIES);
diff --git a/gsf/gsf-zip-impl.h b/gsf/gsf-zip-impl.h
index ab2d71a..29a01d3 100644
--- a/gsf/gsf-zip-impl.h
+++ b/gsf/gsf-zip-impl.h
@@ -55,6 +55,7 @@ G_BEGIN_DECLS
 #define ZIP_ZIP64_LOCATOR_OFFSET       8
 #define ZIP_ZIP64_LOCATOR_DISKS                16
 
+#define ZIP_TRAILER64_SIGNATURE         0x06064b50
 #define ZIP_TRAILER64_SIZE             56  /* or more */
 #define ZIP_TRAILER64_RECSIZE            4
 #define ZIP_TRAILER64_ENCODER          12