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From: | Peter Lieven |
Subject: | Re: [Qemu-devel] [PATCH V2 5/8] block/qcow2: read and write the compress format extension |
Date: | Thu, 13 Jul 2017 17:00:39 +0200 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 |
Am 13.07.2017 um 16:58 schrieb Daniel P. Berrange:
On Thu, Jul 13, 2017 at 04:18:13PM +0200, Peter Lieven wrote:Okay, so it has to be a mix of QAPI parsing and manual parameter checking, right?Yeah. It does feel like a valid RFE for QAPI to add a permitted range to 'int' types though, which would simplify the code in future.I currently have the following: options = qemu_opts_to_qdict(opts, NULL); qdict_extract_subqdict(options, &compressopts, "compress."); v = qobject_input_visitor_new_keyval(QOBJECT(compressopts)); visit_start_struct(v, NULL, NULL, 0, &local_err); if (local_err) { ret= -EINVAL; goto finish; } visit_type_Qcow2Compress_members(v, &compress, &local_err); if (local_err) { ret= -EINVAL; goto finish; } visit_end_struct(v, NULL); visit_free(v); QDECREF(compressopts); QDECREF(options)Looks good.And I have the following 2 questions: a) I have to specifiy compress.format and compress.level otherwise I will get an error. How can I fix that the settings are optional?Put an '*' as the first character of any field name if it should be optional.b) If I just specify a compress.format can I default the compress.level to 0 without an error?I believe you'd get compress.level as 0 automatically for an 'int' type.
I still face the issue that I now always have to specify a compress.format. I tried to solve it like this: int compress_format = -1; uint8_t compress_level = 0; if (qemu_opt_find(opts, BLOCK_OPT_COMPRESS_FORMAT) || qemu_opt_find(opts, BLOCK_OPT_COMPRESS_LEVEL)) { QDict *options, *compressopts = NULL; Qcow2Compress compress; Visitor *v; options = qemu_opts_to_qdict(opts, NULL); qdict_extract_subqdict(options, &compressopts, "compress."); v = qobject_input_visitor_new_keyval(QOBJECT(compressopts)); visit_start_struct(v, NULL, NULL, 0, &local_err); if (local_err) { error_propagate(errp, local_err); ret = -EINVAL; goto finish; } visit_type_Qcow2Compress_members(v, &compress, &local_err); if (local_err) { error_propagate(errp, local_err); ret = -EINVAL; goto finish; } visit_end_struct(v, NULL); visit_free(v); QDECREF(compressopts); QDECREF(options); compress_format = compress.format; compress_level = compress.level; if (compress_format == QCOW2_COMPRESS_FORMAT_ZLIB && compress_level > 9) { error_setg(errp, "Compress level %" PRIu8 " is not supported for" " format '%s'", compress_level, qemu_opt_get(opts, BLOCK_OPT_COMPRESS_FORMAT)); ret = -EINVAL; goto finish; } } Maybe there is a better option? Peter
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