Add capability to check for capabilities

This adds and API to check a device for specific capabilities,
when need be.

Signed-off-by: Linus Walleij <triad@df.lth.se>

2 files changed, 65 insertions, 1 deletions

diff --git a/src/libmtp.c b/src/libmtp.c
index 46edab7..24382cd 100644
--- a/src/libmtp.c
+++ b/src/libmtp.c
@@ -3919,6 +3919,45 @@ int LIBMTP_Get_Supported_Filetypes(LIBMTP_mtpdevice_t *device, uint16_t ** const
 }
 
 /**
+ * This function checks if the device has some specific capabilities, in
+ * order to avoid calling APIs that may disturb the device.
+ *
+ * @param device a pointer to the device to check the capability on.
+ * @param cap the capability to check.
+ * @return 0 if not supported, any other value means the device has the
+ * requested capability.
+ */
+int LIBMTP_Check_Capability(LIBMTP_mtpdevice_t *device, LIBMTP_devicecap_t cap)
+{
+  switch (cap) {
+  case LIBMTP_DEVICECAP_GetPartialObject:
+    return (ptp_operation_issupported(device->params,
+				      PTP_OC_GetPartialObject) ||
+	    ptp_operation_issupported(device->params,
+				      PTP_OC_ANDROID_GetPartialObject64));
+  case LIBMTP_DEVICECAP_SendPartialObject:
+    return ptp_operation_issupported(device->params,
+				     PTP_OC_ANDROID_SendPartialObject);
+  case LIBMTP_DEVICECAP_EditObjects:
+    return (ptp_operation_issupported(device->params,
+				      PTP_OC_ANDROID_TruncateObject) &&
+	    ptp_operation_issupported(device->params,
+				      PTP_OC_ANDROID_BeginEditObject) &&
+	    ptp_operation_issupported(device->params,
+				      PTP_OC_ANDROID_EndEditObject));
+  /*
+   * Handle other capabilities here, this is also a good place to
+   * blacklist some advanced operations on specific devices if need
+   * be.
+   */
+
+  default:
+    break;
+  }
+  return 0;
+}
+
+/**
  * This function updates all the storage id's of a device and their
  * properties, then creates a linked list and puts the list head into
  * the device struct. It also optionally sorts this list. If you want
diff --git a/src/libmtp.h.in b/src/libmtp.h.in
index 9c1c73f..7a9001e 100644
--- a/src/libmtp.h.in
+++ b/src/libmtp.h.in
@@ -2,7 +2,7 @@
  * \file libmtp.h
  * Interface to the Media Transfer Protocol library.
  *
- * Copyright (C) 2005-2012 Linus Walleij <triad@df.lth.se>
+ * Copyright (C) 2005-2013 Linus Walleij <triad@df.lth.se>
  * Copyright (C) 2005-2008 Richard A. Low <richard@wentnet.com>
  * Copyright (C) 2007 Ted Bullock <tbullock@canada.com>
  * Copyright (C) 2008 Florent Mertens <flomertens@gmail.com>
@@ -403,6 +403,30 @@ typedef enum {
 } LIBMTP_datatype_t;
 
 /**
+ * These are device capabilities
+ */
+typedef enum {
+  /**
+   * This capability tells whether you can call the funcion getting
+   * partial objects, @see LIBMTP_GetPartialObject()
+   */
+  LIBMTP_DEVICECAP_GetPartialObject,
+  /**
+   * This capability tells whether you can call the function sending
+   * partial objects. @see LIBMTP_SendPartialObject()
+   */
+  LIBMTP_DEVICECAP_SendPartialObject,
+  /**
+   * This capability tells whether you can call the functions editing
+   * objects in-place on a device.
+   * @see LIBMTP_BeginEditObject()
+   * @see LIBMTP_EndEditObject()
+   * @see LIBMTP_TruncateObject()
+   */
+  LIBMTP_DEVICECAP_EditObjects,
+} LIBMTP_devicecap_t;
+
+/**
  * These are the numbered error codes. You can also
  * get string representations for errors.
  */
@@ -825,6 +849,7 @@ int LIBMTP_Get_Batterylevel(LIBMTP_mtpdevice_t *,
 int LIBMTP_Get_Secure_Time(LIBMTP_mtpdevice_t *, char ** const);
 int LIBMTP_Get_Device_Certificate(LIBMTP_mtpdevice_t *, char ** const);
 int LIBMTP_Get_Supported_Filetypes(LIBMTP_mtpdevice_t *, uint16_t ** const, uint16_t * const);
+int LIBMTP_Check_Capability(LIBMTP_mtpdevice_t *, LIBMTP_devicecap_t);
 LIBMTP_error_t *LIBMTP_Get_Errorstack(LIBMTP_mtpdevice_t*);
 void LIBMTP_Clear_Errorstack(LIBMTP_mtpdevice_t*);
 void LIBMTP_Dump_Errorstack(LIBMTP_mtpdevice_t*);