New API call iso_zisofs_ctrl_susp_z2()

libisofs/filters/zisofs.c

@@ -112,6 +112,11 @@ static double ziso_keep_blocks_free_ratio = ISO_ZISOFS_KBF_RATIO;
  */
 static int ziso_early_bpt_discard = 0;
 
+/* 1 = produce Z2 entries for zisofs2 , 0 = produce ZF for zisofs2
+ * This is used as extern variable in rockridge.c
+ */
+int iso_zisofs2_enable_susp_z2 = 0;
+
 
 static
 int ziso_decide_v2_usage(off_t orig_size)
@@ -1796,3 +1801,12 @@ int iso_stream_zisofs_discard_bpt(IsoStream *stream, int flag)
 #endif /* ! Libisofs_with_zliB */
 
 }
+
+
+/* API */
+int iso_zisofs_ctrl_susp_z2(int enable)
+{
+    if (enable == 0 || enable == 1)
+        iso_zisofs2_enable_susp_z2 = enable;
+    return iso_zisofs2_enable_susp_z2;
+}

libisofs/fs_image.c

@@ -1596,7 +1596,8 @@ int iso_file_source_new_ifs(IsoImageFilesystem *fs, IsoFileSource *parent,
         while ((ret = susp_iter_next(iter, &sue, 0)) > 0) {
 
             /* ignore entries from different version */
-            if (sue->version[0] != 1 && !(SUSP_SIG(sue, 'Z', 'F')))
+            if (sue->version[0] != 1 &&
+                !(SUSP_SIG(sue, 'Z', 'F') || SUSP_SIG(sue, 'Z', '2')))
                 continue;
 
             if (SUSP_SIG(sue, 'P', 'X')) {
@@ -1803,7 +1804,7 @@ if (name != NULL && !namecont) {
 
 #ifdef Libisofs_with_zliB
 
-            } else if (SUSP_SIG(sue, 'Z', 'F')) {
+            } else if (SUSP_SIG(sue, 'Z', 'F') || SUSP_SIG(sue, 'Z', '2')) {
 
                 ret = read_zisofs_ZF(sue, zisofs_alg, &zisofs_hs4,
                                      &zisofs_bsl2, &zisofs_usize, 0);
@@ -1811,7 +1812,9 @@ if (name != NULL && !namecont) {
 invalid_zf:
                     /* notify and continue */
                     ret = iso_rr_msg_submit(fsdata, 13, ISO_WRONG_RR_WARN, ret,
-                                 "Invalid ZF entry");
+                                            SUSP_SIG(sue, 'Z', 'F') ?
+                                            "Invalid ZF entry" :
+                                            "Invalid Z2 entry");
                     zisofs_hs4 = 0;
                     continue;
                 }

libisofs/libisofs.h

@@ -8182,6 +8182,21 @@ int iso_zisofs_set_params(struct iso_zisofs_ctrl *params, int flag);
 int iso_zisofs_get_params(struct iso_zisofs_ctrl *params, int flag);
 
 
+/**
+ * Enable or disable the production and recognition of "Z2" SUSP entries
+ * instead of "ZF" entries for zisofs2 compressed files.
+ * "ZF" with zisofs2 causes unaware Linux kernels to complian like:
+ *   isofs: Unknown ZF compression algorithm: PZ
+ * "Z2" is silently ignored by unaware Linux kernels.
+ * @param enable
+ *      1 = produce and recognize "Z2" , 0 = only "ZF" , -1 = do not change
+ * @return
+ *      1 = enabled , 0 = not enabled
+ * @since 1.5.4
+ */
+int iso_zisofs_ctrl_susp_z2(int enable);
+
+
 /**
  * Check for the given node or for its subtree whether the data file content
  * effectively bears zisofs file headers and eventually mark the outcome

libisofs/libisofs.ver

@@ -370,6 +370,7 @@ iso_write_opts_set_system_area;
 iso_write_opts_set_tail_blocks;
 iso_write_opts_set_untranslated_name_len;
 iso_write_opts_set_will_cancel;
+iso_zisofs_ctrl_susp_z2;
 iso_zisofs_get_params;
 iso_zisofs_get_refcounts;
 iso_zisofs_set_params;

libisofs/rockridge.c

@@ -961,16 +961,22 @@ int zisofs_add_ZF(Ecma119Image *t, struct susp_info *susp, int to_ce,
 {
     unsigned char *ZF = malloc(16);
 
+    /* Intimate friendship with this variable in filters/zisofs.c */
+    extern int iso_zisofs2_enable_susp_z2;
+
     if (ZF == NULL) {
         return ISO_OUT_OF_MEM;
     }
     ZF[0] = 'Z';
     ZF[1] = 'F';
     ZF[2] = (unsigned char) 16;
-    if (algo[0] == 'p' && algo[1] == 'z')
+    if (algo[0] == 'p' && algo[1] == 'z') {
         ZF[3] = (unsigned char) 1;
-    else
+    } else {
         ZF[3] = (unsigned char) 2;
+        if (iso_zisofs2_enable_susp_z2)
+            ZF[1] = '2';
+    }
     ZF[4] = (unsigned char) algo[0];
     ZF[5] = (unsigned char) algo[1];
     ZF[6] = (unsigned char) header_size_div4;

libisofs/rockridge_read.c

@@ -629,9 +629,9 @@ int read_zisofs_ZF(struct susp_sys_user_entry *zf, uint8_t algorithm[2],
     if (zf == NULL) {
         return ISO_NULL_POINTER;
     }
-    if (zf->sig[0] != 'Z' || zf->sig[1] != 'F') {
+    if ((zf->sig[0] != 'Z' || zf->sig[1] != 'F') &&
+        (zf->sig[0] != 'Z' || zf->sig[1] != '2'))
         return ISO_WRONG_ARG_VALUE;
-    }
     if (zf->len_sue[0] != 16) {
         return ISO_WRONG_RR;
     }