IsoStream version 3 with cmp_ino(),

new API call iso_stream_cmp_ino() for proper comparison of filtered streams

libisofs/filters/external.c

@@ -594,8 +594,13 @@ IsoStream *extf_get_input_stream(IsoStream *stream, int flag)
 }
 
 
+static
+int extf_cmp_ino(IsoStream *s1, IsoStream *s2);
+/* Function is defined after definition of extf_stream_class */
+
+
 IsoStreamIface extf_stream_class = {
-    2,
+    3,
     "extf",
     extf_stream_open,
     extf_stream_close,
@@ -605,10 +610,28 @@ IsoStreamIface extf_stream_class = {
     extf_stream_get_id,
     extf_stream_free,
     extf_update_size,
-    extf_get_input_stream
+    extf_get_input_stream,
+    extf_cmp_ino
 };
 
 
+static
+int extf_cmp_ino(IsoStream *s1, IsoStream *s2)
+{
+    ExternalFilterStreamData *data1, *data2;
+
+    if (s1->class != &extf_stream_class || s2->class != &extf_stream_class)
+        return iso_stream_cmp_ino(s1, s2, 1);
+    data1 = (ExternalFilterStreamData*) s1->data;
+    data2 = (ExternalFilterStreamData*) s2->data;
+    if (data1->cmd != data2->cmd)
+        return (data1->cmd < data2->cmd ? -1 : 1);
+    return iso_stream_cmp_ino(data1->orig, data2->orig, 0);
+}
+
+
+/* ------------------------------------------------------------------------- */
+
 static
 void extf_filter_free(FilterContext *filter)
 {

libisofs/filters/gzip.c

@@ -521,8 +521,12 @@ IsoStream *gzip_get_input_stream(IsoStream *stream, int flag)
 }
 
 
+static
+int gzip_cmp_ino(IsoStream *s1, IsoStream *s2);
+
+
 IsoStreamIface gzip_stream_compress_class = {
-    2,
+    3,
     "gzip",
     gzip_stream_open,
     gzip_stream_close,
@@ -532,12 +536,13 @@ IsoStreamIface gzip_stream_compress_class = {
     gzip_stream_get_id,
     gzip_stream_free,
     gzip_update_size,
-    gzip_get_input_stream
+    gzip_get_input_stream,
+    gzip_cmp_ino
 };
 
 
 IsoStreamIface gzip_stream_uncompress_class = {
-    2,
+    3,
     "pizg",
     gzip_stream_open,
     gzip_stream_close,
@@ -547,10 +552,25 @@ IsoStreamIface gzip_stream_uncompress_class = {
     gzip_stream_get_id,
     gzip_stream_free,
     gzip_update_size,
-    gzip_get_input_stream
+    gzip_get_input_stream,
+    gzip_cmp_ino
 };
 
     
+static
+int gzip_cmp_ino(IsoStream *s1, IsoStream *s2)
+{
+    if (s1->class != s2->class || (s1->class != &gzip_stream_compress_class &&
+                                   s2->class != &gzip_stream_compress_class))
+        return iso_stream_cmp_ino(s1, s2, 1);
+    return iso_stream_cmp_ino(iso_stream_get_input_stream(s1, 0),
+                              iso_stream_get_input_stream(s2, 0), 0);
+}   
+
+
+/* ------------------------------------------------------------------------- */
+
+
 static
 void gzip_filter_free(FilterContext *filter)
 {

libisofs/filters/zisofs.c

@@ -775,8 +775,12 @@ IsoStream *ziso_get_input_stream(IsoStream *stream, int flag)
 }
 
 
+static
+int ziso_cmp_ino(IsoStream *s1, IsoStream *s2);
+
+
 IsoStreamIface ziso_stream_compress_class = {
-    2,
+    3,
     "ziso",
     ziso_stream_open,
     ziso_stream_close,
@@ -786,12 +790,13 @@ IsoStreamIface ziso_stream_compress_class = {
     ziso_stream_get_id,
     ziso_stream_free,
     ziso_update_size,
-    ziso_get_input_stream
+    ziso_get_input_stream,
+    ziso_cmp_ino
 };
 
 
 IsoStreamIface ziso_stream_uncompress_class = {
-    2,
+    3,
     "osiz",
     ziso_stream_open,
     ziso_stream_close,
@@ -801,10 +806,25 @@ IsoStreamIface ziso_stream_uncompress_class = {
     ziso_stream_get_id,
     ziso_stream_free,
     ziso_update_size,
-    ziso_get_input_stream
+    ziso_get_input_stream,
+    ziso_cmp_ino
 };
 
 
+static
+int ziso_cmp_ino(IsoStream *s1, IsoStream *s2)
+{
+    if (s1->class != s2->class || (s1->class != &ziso_stream_compress_class &&
+                                   s2->class != &ziso_stream_uncompress_class))
+        iso_stream_cmp_ino(s1, s2, 1);
+    return iso_stream_cmp_ino(iso_stream_get_input_stream(s1, 0),
+                              iso_stream_get_input_stream(s2, 0), 0);
+}
+
+
+/* ------------------------------------------------------------------------- */
+
+
 static
 void ziso_filter_free(FilterContext *filter)
 {

libisofs/libisofs.h

@@ -759,7 +759,10 @@ typedef struct IsoStream_Iface IsoStreamIface;
 extern ino_t serial_id;
 
 /**
- * Interface definition for IsoStream methods.
+ * Interface definition for IsoStream methods. It is public to allow
+ * implementation of own stream types.
+ * The methods defined here typically make use of stream.data which points
+ * to the individual state data of stream instances.
  * 
  * @since 0.6.4
  */
@@ -773,6 +776,8 @@ struct IsoStream_Iface
      *    update_size() added.
      * Version 2 (since 0.6.18)
      *    get_input_stream() added. A filter stream must have version 2.
+     * Version 3 (since 0.6.20)
+     *    compare() added. A filter stream should have version 3.
      */
     int version;
 
@@ -856,7 +861,6 @@ struct IsoStream_Iface
     void (*free)(IsoStream *stream);
 
     /**
-     * Present if .version is 1 or higher:
      * Updates the size of the IsoStream with the current size of the
      * underlying source. After calling this, get_size() will return
      * the new size. This should never be called after
@@ -869,12 +873,13 @@ struct IsoStream_Iface
      *     1 if ok, < 0 on error (has to be a valid libisofs error code)
      *
      * @since 0.6.8
+     * Present if .version is 1 or higher.
      */
     int (*update_size)(IsoStream *stream);
 
     /**
-     * Present if .version is 2 or higher:
      * Obtains the eventual input stream of a filter stream.
+     *
      * @param stream
      *     The eventual filter stream to be inquired.
      * @param flag
@@ -884,9 +889,45 @@ struct IsoStream_Iface
      *     No extra reference to the stream is taken by this call.
      *
      * @since 0.6.18
+     * Present if .version is 2 or higher.
      */
     IsoStream *(*get_input_stream)(IsoStream *stream, int flag);
 
+    /* ts A90511 */
+    /**
+     * Compare two streams whether they are based on the same input and will
+     * produce the same output. If in any doubt, then this comparison should
+     * indicate no match. A match might allow hardlinking of IsoFile objects.
+     * This function has to establish an equivalence and order relation: 
+     *   A = A, if A = B then B = A, if A = B and B = C then A = C,
+     *   if A < B then not B < A, if A < B and B < C then A < C
+     *
+     * A function s1.(*cmp_ino)() must only accept stream s2 if function
+     * s2.(*cmp_ino)() would accept s1. Best is to accept only the own stream
+     * type or to have the same function for a family of similar stream types.
+     *
+     * If the function cannot accept one of the given stream types, then
+     * the decision must be delegated to
+     *    iso_stream_cmp_ino(s1, s2, 1);
+     * This is also appropriate if one has reason to implement stream.cmp_ino()
+     * without special comparison algorithm.
+     * With filter streams the decision whether the underlying chains of
+     * streams match should be delegated to
+     *    iso_stream_cmp_ino(iso_stream_get_input_stream(s1, 0),
+     *                       iso_stream_get_input_stream(s2, 0), 0);
+     *
+     * @param s1
+     *     The first stream to compare. Expect foreign stream types.
+     * @param s2
+     *     The second stream to compare. Expect foreign stream types.
+     * @return
+     *     -1 if s1 is smaller s2 , 0 if s1 matches s2 , 1 if s1 is larger s2
+     *
+     * @since 0.6.20
+     * Present if .version is 3 or higher.
+     */
+    int (*cmp_ino)(IsoStream *s1, IsoStream *s2);
+
 };
 
 /**
@@ -4162,6 +4203,26 @@ void iso_stream_get_id(IsoStream *stream, unsigned int *fs_id, dev_t *dev_id,
  */
 char *iso_stream_get_source_path(IsoStream *stream, int flag);
 
+/* ts A90502 */
+/**
+ * Compare two streams whether they are based on the same input and will
+ * produce the same output. If in any doubt, then this comparison will
+ * indicate no match.
+ *
+ * @param s1
+ *     The first stream to compare.
+ * @param s2
+ *     The second stream to compare.
+ * @return
+ *     -1 if s1 is smaller s2 , 0 if s1 matches s2 , 1 if s1 is larger s2
+ * @param flag
+ *     bit0= do not use s1->class->compare() even if available
+ *           (e.g. because iso_stream_cmp_ino(0 is called as fallback
+ *            from said stream->class->compare())
+ *
+ * @since 0.6.20
+ */
+int iso_stream_cmp_ino(IsoStream *s1, IsoStream *s2, int flag);
 
 /* --------------------------------- AAIP --------------------------------- */
 

libisofs/stream.c

@@ -728,10 +728,11 @@ int iso_stream_set_image_ino(IsoStream *stream, ino_t ino, int flag)
    return 0;
 }
 
-/* ts A90502 */
-/* The former core of iso_file_src_cmp() */
+/* ts A90511 */
+/* API */ 
 int iso_stream_cmp_ino(IsoStream *s1, IsoStream *s2, int flag)
 {
+    int ret;
     unsigned int fs_id1, fs_id2;
     dev_t dev_id1, dev_id2;
     ino_t ino_id1, ino_id2;
@@ -741,9 +742,19 @@ int iso_stream_cmp_ino(IsoStream *s1, IsoStream *s2, int flag)
     static int report_counter = 0;
     static int debug = 1;
 
-    if (s1 == s2) {
+    if (s1 == s2)
         return 0;
+    if (s1 == NULL)
+        return -1;
+    if (s2 == NULL)
+        return 1;
+
+    if (s1->class->version >= 3 && !(flag & 1)) {
+       /* Filters may have smarter methods to compare themselves with others */
+       ret = s1->class->cmp_ino(s1, s2);
+       return ret;
     }
+
     iso_stream_get_id(s1, &fs_id1, &dev_id1, &ino_id1);
     iso_stream_get_id(s2, &fs_id2, &dev_id2, &ino_id2);
     if (fs_id1 < fs_id2) {

libisofs/stream.h

@@ -82,8 +82,5 @@ int iso_stream_get_src_zf(IsoStream *stream, int *header_size_div4,
  */
 int iso_stream_set_image_ino(IsoStream *stream, ino_t ino, int flag);
 
-/* ts A90502 */
-/* The former core of iso_file_src_cmp() */
-int iso_stream_cmp_ino(IsoStream *s1, IsoStream *s2, int flag);
 
 #endif /*STREAM_H_*/