Imported Upstream version 1.2.7

[platform/upstream/harfbuzz.git] / src / hb-blob.h

diff --git a/src/hb-blob.h b/src/hb-blob.h
index 1a93baa..ef3fc98 100644 (file)
--- a/src/hb-blob.h
+++ b/src/hb-blob.h
@@ -36,6 +36,25 @@
 HB_BEGIN_DECLS
 
 
+/*
+ * Note re various memory-modes:
+ *
+ * - In no case shall the HarfBuzz client modify memory
+ *   that is passed to HarfBuzz in a blob.  If there is
+ *   any such possibility, MODE_DUPLICATE should be used
+ *   such that HarfBuzz makes a copy immediately,
+ *
+ * - Use MODE_READONLY otherse, unless you really really
+ *   really know what you are doing,
+ *
+ * - MODE_WRITABLE is appropriate if you really made a
+ *   copy of data solely for the purpose of passing to
+ *   HarfBuzz and doing that just once (no reuse!),
+ *
+ * - If the font is mmap()ed, it's ok to use
+ *   READONLY_MAY_MAKE_WRITABLE, however, using that mode
+ *   correctly is very tricky.  Use MODE_READONLY instead.
+ */
 typedef enum {
   HB_MEMORY_MODE_DUPLICATE,
   HB_MEMORY_MODE_READONLY,
@@ -45,28 +64,34 @@ typedef enum {
 
 typedef struct hb_blob_t hb_blob_t;
 
-hb_blob_t *
+HB_EXTERN hb_blob_t *
 hb_blob_create (const char        *data,
                unsigned int       length,
                hb_memory_mode_t   mode,
                void              *user_data,
                hb_destroy_func_t  destroy);
 
-hb_blob_t *
+/* Always creates with MEMORY_MODE_READONLY.
+ * Even if the parent blob is writable, we don't
+ * want the user of the sub-blob to be able to
+ * modify the parent data as that data may be
+ * shared among multiple sub-blobs.
+ */
+HB_EXTERN hb_blob_t *
 hb_blob_create_sub_blob (hb_blob_t    *parent,
                         unsigned int  offset,
                         unsigned int  length);
 
-hb_blob_t *
+HB_EXTERN hb_blob_t *
 hb_blob_get_empty (void);
 
-hb_blob_t *
+HB_EXTERN hb_blob_t *
 hb_blob_reference (hb_blob_t *blob);
 
-void
+HB_EXTERN void
 hb_blob_destroy (hb_blob_t *blob);
 
-hb_bool_t
+HB_EXTERN hb_bool_t
 hb_blob_set_user_data (hb_blob_t          *blob,
                       hb_user_data_key_t *key,
                       void *              data,
@@ -74,25 +99,25 @@ hb_blob_set_user_data (hb_blob_t          *blob,
                       hb_bool_t           replace);
 
 
-void *
+HB_EXTERN void *
 hb_blob_get_user_data (hb_blob_t          *blob,
                       hb_user_data_key_t *key);
 
 
-void
+HB_EXTERN void
 hb_blob_make_immutable (hb_blob_t *blob);
 
-hb_bool_t
+HB_EXTERN hb_bool_t
 hb_blob_is_immutable (hb_blob_t *blob);
 
 
-unsigned int
+HB_EXTERN unsigned int
 hb_blob_get_length (hb_blob_t *blob);
 
-const char *
+HB_EXTERN const char *
 hb_blob_get_data (hb_blob_t *blob, unsigned int *length);
 
-char *
+HB_EXTERN char *
 hb_blob_get_data_writable (hb_blob_t *blob, unsigned int *length);