Init implementation of IsoFileSrc.

Ecma119Image, defined for first time in this commit, is the context for image 
written. It keeps the low level objects needed during image written.

IsoFileSrc is the low level object that takes care about the info needed to
write file contents to image. It takes care about reading from Stream in 2K
block chunks. To prevent the same file be written twice to image, we keep in
Ecma119Image a search tree, indexed by the triple key (fs, device, inode) that
uniquelly identifies a source.

src/filesrc.c

@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 2007 Vreixo Formoso
+ * 
+ * This file is part of the libisofs project; you can redistribute it and/or 
+ * modify it under the terms of the GNU General Public License version 2 as 
+ * published by the Free Software Foundation. See COPYING file for details.
+ */
+
+#include "filesrc.h"
+#include "error.h"
+#include "node.h"
+
+#include <stdlib.h>
+#include <search.h>
+
+static
+int comp_iso_file_src(const void *n1, const void *n2)
+{
+    const IsoFileSrc *f1, *f2;
+    f1 = (const IsoFileSrc *)n1;
+    f2 = (const IsoFileSrc *)n2;
+    
+    if (f1->fs_id < f2->fs_id) {
+        return -1;
+    } else if (f1->fs_id > f2->fs_id) {
+        return 1;
+    } else {
+        /* files belong to the same fs */
+        if (f1->dev_id > f2->dev_id) {
+            return -1;
+        } else if (f1->dev_id < f2->dev_id) {
+            return 1;
+        } else {
+            /* files belong to same device in same fs */
+            return f1->ino_id - f2->ino_id;
+        }
+    }
+}
+
+int iso_file_src_create(Ecma119Image *img, IsoFile *file, IsoFileSrc **src)
+{
+    int res;
+    IsoStream *stream;
+    IsoFileSrc *fsrc;
+    unsigned int fs_id;
+    dev_t dev_id;
+    ino_t ino_id;
+    off_t size;
+    
+    if (img == NULL || file == NULL || src == NULL) {
+        return ISO_NULL_POINTER;
+    }
+    
+    stream = file->stream;
+    res = stream->get_id(stream, &fs_id, &dev_id, &ino_id);
+    if (res < 0) {
+        return res;
+    } else if (res == 0) {
+        // TODO this corresponds to Stream that cannot provide a valid id
+        // Not implemented for now
+        return ISO_ERROR;
+    } else {
+        IsoFileSrc *inserted;
+        
+        size = stream->get_size(stream);
+        if (size == (off_t)-1) {
+            return ISO_FILE_ERROR;
+        }
+        
+        fsrc = malloc(sizeof(IsoFileSrc));
+        if (fsrc == NULL) {
+            return ISO_MEM_ERROR;
+        }
+        
+        /* fill key and other atts */
+        fsrc->fs_id = fs_id;
+        fsrc->dev_id = dev_id;
+        fsrc->ino_id = ino_id;
+        fsrc->prev_img = file->msblock ? 1 : 0;
+        fsrc->block = file->msblock;
+        fsrc->size = size;
+        fsrc->sort_weight = file->sort_weight;
+        fsrc->stream = file->stream;
+        
+        /* insert the filesrc in the tree */
+        inserted = tsearch(fsrc, img->file_srcs, comp_iso_file_src);
+        if (inserted == NULL) {
+            free(fsrc);
+            return ISO_MEM_ERROR;
+        } else if (inserted == fsrc) {
+            /* the file was inserted */
+            img->file_count++;
+        } else {
+            /* the file was already on the tree */
+            free(fsrc);
+        }
+        *src = inserted;
+    }
+    return ISO_SUCCESS;
+}
+