Add lseek() function to IsoFileSource.

libisofs/fs_image.c

@@ -632,6 +632,60 @@ int ifs_read(IsoFileSource *src, void *buf, size_t count)
     return read;
 }
 
+static
+off_t ifs_lseek(IsoFileSource *src, off_t offset, int flag)
+{
+    ImageFileSourceData *data;
+
+    if (src == NULL) {
+        return (off_t)ISO_NULL_POINTER;
+    }
+    if (offset < (off_t)0) {
+        return (off_t)ISO_WRONG_ARG_VALUE;
+    }
+    
+    data = src->data;
+    
+    if (!data->opened) {
+        return (off_t)ISO_FILE_NOT_OPENED;
+    } else if (data->opened != 1) {
+        return (off_t)ISO_FILE_IS_DIR;
+    }
+
+    switch (flag) {
+    case 0: /* SEEK_SET */
+        data->data.offset = offset;
+        break;
+    case 1: /* SEEK_CUR */
+        data->data.offset += offset;
+        break;
+    case 2: /* SEEK_END */
+        /* do this make sense? */
+        data->data.offset = data->info.st_size + offset;
+        break;
+    default:
+        return (off_t)ISO_WRONG_ARG_VALUE;
+    }
+    
+    if (data->data.offset % BLOCK_SIZE != 0) {
+        /* we need to buffer the block */
+        uint32_t block;
+        _ImageFsData *fsdata;
+        
+        if (data->data.offset < data->info.st_size) {
+            int ret;
+            fsdata = data->fs->data;
+            block = data->block + (data->data.offset / BLOCK_SIZE);
+            ret = fsdata->src->read_block(fsdata->src, block, 
+                                          data->data.content);
+            if (ret < 0) {
+                return (off_t)ret;
+            }
+        }
+    }
+    return data->data.offset;
+}
+
 static
 int ifs_readdir(IsoFileSource *src, IsoFileSource **child)
 {
@@ -771,6 +825,7 @@ IsoFileSourceIface ifs_class = {
     ifs_open,
     ifs_close,
     ifs_read,
+    ifs_lseek,
     ifs_readdir,
     ifs_readlink,
     ifs_get_filesystem,

libisofs/fs_local.c

@@ -304,6 +304,52 @@ int lfs_read(IsoFileSource *src, void *buf, size_t count)
     }
 }
 
+static
+off_t lfs_lseek(IsoFileSource *src, off_t offset, int flag)
+{
+    _LocalFsFileSource *data;
+    int whence;
+
+    if (src == NULL) {
+        return (off_t)ISO_NULL_POINTER;
+    }
+    switch (flag) {
+    case 0: 
+        whence = SEEK_SET; break;
+    case 1: 
+        whence = SEEK_CUR; break;
+    case 2: 
+        whence = SEEK_END; break;
+    default: 
+        return (off_t)ISO_WRONG_ARG_VALUE;
+    }
+
+    data = src->data;
+    switch (data->openned) {
+    case 1: /* not dir */
+        {
+            off_t ret;
+            ret = lseek(data->info.fd, offset, whence);
+            if (ret < 0) {
+                /* error on read */
+                switch (errno) {
+                case ESPIPE:
+                    ret = (off_t)ISO_FILE_ERROR;
+                    break;
+                default:
+                    ret = (off_t)ISO_ERROR;
+                    break;
+                }
+            }
+            return ret;
+        }
+    case 2: /* directory */
+        return (off_t)ISO_FILE_IS_DIR;
+    default:
+        return (off_t)ISO_FILE_NOT_OPENED;
+    }
+}
+
 static
 int lfs_readdir(IsoFileSource *src, IsoFileSource **child)
 {
@@ -430,6 +476,7 @@ IsoFileSourceIface lfs_class = {
     lfs_open,
     lfs_close,
     lfs_read,
+    lfs_lseek,
     lfs_readdir,
     lfs_readlink,
     lfs_get_filesystem,

libisofs/fsource.c

@@ -92,6 +92,12 @@ int iso_file_source_read(IsoFileSource *src, void *buf, size_t count)
     return src->class->read(src, buf, count);
 }
 
+inline
+off_t iso_file_source_lseek(IsoFileSource *src, off_t offset, int flag)
+{
+    return src->class->lseek(src, offset, flag);
+}
+
 inline
 int iso_file_source_readdir(IsoFileSource *src, IsoFileSource **child)
 {

libisofs/libisofs.h

@@ -559,6 +559,25 @@ struct IsoFileSource_Iface
      *         ISO_INTERRUPTED
      */
     int (*read)(IsoFileSource *src, void *buf, size_t count);
+    
+    /**
+     * Repositions the offset of the IsoFileSource (must be opened) to the 
+     * given offset according to the value of flag.
+     * 
+     * @param offset
+     *      in bytes 
+     * @param flag
+     *      0 The offset is set to offset bytes (SEEK_SET)
+     *      1 The offset is set to its current location plus offset bytes 
+     *        (SEEK_CUR)
+     *      2 The offset is set to the size of the file plus offset bytes 
+     *        (SEEK_END).
+     * @return
+     *      Absolute offset posistion on the file, or < 0 on error. Cast the
+     *      returning value to int to get a valid libisofs error.
+     * @since 0.6.4
+     */
+    off_t (*lseek)(IsoFileSource *src, off_t offset, int flag);
 
     /**
      * Read a directory. 
@@ -3216,6 +3235,25 @@ int iso_file_source_close(IsoFileSource *src);
  */
 int iso_file_source_read(IsoFileSource *src, void *buf, size_t count);
 
+/**
+ * Repositions the offset of the given IsoFileSource (must be opened) to the 
+ * given offset according to the value of flag.
+ * 
+ * @param offset
+ *      in bytes 
+ * @param flag
+ *      0 The offset is set to offset bytes (SEEK_SET)
+ *      1 The offset is set to its current location plus offset bytes 
+ *        (SEEK_CUR)
+ *      2 The offset is set to the size of the file plus offset bytes 
+ *        (SEEK_END).
+ * @return
+ *      Absolute offset posistion on the file, or < 0 on error. Cast the
+ *      returning value to int to get a valid libisofs error.
+ * @since 0.6.4
+ */
+off_t iso_file_source_lseek(IsoFileSource *src, off_t offset, int flag);
+
 /**
  * Read a directory. 
  *