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2015-10-16util - add automated ID generation utilityJeff Cody1-0/+37
Multiple sub-systems in QEMU may find it useful to generate IDs for objects that a user may reference via QMP or HMP. This patch presents a standardized way to do it, so that automatic ID generation follows the same rules. This patch enforces the following rules when generating an ID: 1.) Guarantee no collisions with a user-specified ID 2.) Identify the sub-system the ID belongs to 3.) Guarantee of uniqueness 4.) Spoiling predictability, to avoid creating an assumption of object ordering and parsing (i.e., we don't want users to think they can guess the next ID based on prior behavior). The scheme for this is as follows (no spaces): # subsys D RR Reserved char --| | | | Subsystem String ----| | | Unique number (64-bit) --| | Two-digit random number ---| For example, a generated node-name for the block sub-system may look like this: #block076 The caller of id_generate() is responsible for freeing the generated node name string with g_free(). Reviewed-by: John Snow <jsnow@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Signed-off-by: Jeff Cody <jcody@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-10-03util: Emancipate id_wellformed() from QemuOptsMarkus Armbruster1-0/+28
IDs have long spread beyond QemuOpts: not everything with an ID necessarily goes through QemuOpts. Commit 9aebf3b is about such a case: block layer names are meant to be well-formed IDs, but some of them don't go through QemuOpts, and thus weren't checked. The commit fixed that the straightforward way: rename the internal QemuOpts helper id_wellformed() to qemu_opts_id_wellformed() and give it external linkage. Instead of using it directly in block.c, the commit adds wrapper bdrv_is_valid_name(), probably to hide the connection to QemuOpts. Go one logical step further: emancipate IDs from QemuOpts. Rename the function back to id_wellformed(), and put it in another file. While there, clean up its value to bool. Peel off the bdrv_is_valid_name() wrapper. [Replaced stray return 0 with return false to match bool returns used elsewhere in id_wellformed(). --Stefan] Signed-off-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>