commit 0b4b49387cce8358783a493004b77c1603b34b5c
author Eric Blake <eblake@redhat.com> Tue Feb 09 14:27:16 2016 -0700
committer Michael Roth <mdroth@linux.vnet.ibm.com> Thu Feb 25 09:48:50 2016 -0600
tree debae516d511132c0a7155aa62148c26615666af
parent 774ae4254d3910f1c94ad6ed44d14cbea0e6a2f2

qga: Support enum names in guest-file-seek

Magic constants are a pain to use, especially when we run the
risk that our choice of '1' for QGA_SEEK_CUR might differ from
the host or guest's choice of SEEK_CUR.  Better is to use an
enum value, via a qapi alternate type for back-compatibility.

With this,
 {"command":"guest-file-seek", "arguments":{"handle":1,
  "offset":0, "whence":"cur"}}
becomes a synonym for the older
 {"command":"guest-file-seek", "arguments":{"handle":1,
  "offset":0, "whence":1}}

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

qga/qapi-schema.json

diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
index 01c9ee4..c21f308 100644
--- a/qga/qapi-schema.json
+++ b/qga/qapi-schema.json
@@ -314,6 +314,34 @@
   'data': { 'position': 'int', 'eof': 'bool' } }
 
 ##
+# @QGASeek:
+#
+# Symbolic names for use in @guest-file-seek
+#
+# @set: Set to the specified offset (same effect as 'whence':0)
+# @cur: Add offset to the current location (same effect as 'whence':1)
+# @end: Add offset to the end of the file (same effect as 'whence':2)
+#
+# Since: 2.6
+##
+{ 'enum': 'QGASeek', 'data': [ 'set', 'cur', 'end' ] }
+
+##
+# @GuestFileWhence:
+#
+# Controls the meaning of offset to @guest-file-seek.
+#
+# @value: Integral value (0 for set, 1 for cur, 2 for end), available
+#         for historical reasons, and might differ from the host's or
+#         guest's SEEK_* values (since: 0.15)
+# @name: Symbolic name, and preferred interface
+#
+# Since: 2.6
+##
+{ 'alternate': 'GuestFileWhence',
+  'data': { 'value': 'int', 'name': 'QGASeek' } }
+
+##
 # @guest-file-seek:
 #
 # Seek to a position in the file, as with fseek(), and return the
@@ -324,14 +352,15 @@
 #
 # @offset: bytes to skip over in the file stream
 #
-# @whence: 0 for SEEK_SET, 1 for SEEK_CUR, or 2 for SEEK_END
+# @whence: Symbolic or numeric code for interpreting offset
 #
 # Returns: @GuestFileSeek on success.
 #
 # Since: 0.15.0
 ##
 { 'command': 'guest-file-seek',
-  'data':    { 'handle': 'int', 'offset': 'int', 'whence': 'int' },
+  'data':    { 'handle': 'int', 'offset': 'int',
+               'whence': 'GuestFileWhence' },
   'returns': 'GuestFileSeek' }
 
 ##