The Wednesday 14 May 2014 à 23:20:15 (-0400), Jeff Cody wrote : > Currently, node_name is only filled in when done so explicitly by the > user. If no node_name is specified, then the node name field is not > populated. > > If node_names are automatically generated when not specified, that means > that all block job operations can be done by reference to the unique > node_name field. This eliminates ambiguity in filename pathing > (relative filenames, or file descriptors, symlinks, mounts, etc..) that > qemu currently needs to deal with. > > If a node name is specified, then it will not be automatically > generated for that BDS entry. > > If it is automatically generated, it will be prefaced with "__qemu##", > followed by 8 characters of a unique number, followed by 8 random > ASCII characters in the range of 'A-Z'. Some sample generated node-name > strings: > __qemu##00000000IAIYNXXR > __qemu##00000002METXTRBQ > __qemu##00000001FMBORDWG > > The prefix is to aid in identifying it as a qemu-generated name, the > numeric portion is to guarantee uniqueness in a given qemu session, and > the random characters are to further avoid any accidental collisions > with user-specified node-names. > > Signed-off-by: Jeff Cody <jc...@redhat.com> > --- > block.c | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/block.c b/block.c > index c90c71a..81945d3 100644 > --- a/block.c > +++ b/block.c > @@ -838,12 +838,26 @@ static int bdrv_open_flags(BlockDriverState *bs, int > flags) > return open_flags; > } > > +#define GEN_NODE_NAME_PREFIX "__qemu##" > +#define GEN_NODE_NAME_MAX_LEN (sizeof(GEN_NODE_NAME_PREFIX) + 8 + 8) > static void bdrv_assign_node_name(BlockDriverState *bs, > const char *node_name, > Error **errp) > { > + char gen_node_name[GEN_NODE_NAME_MAX_LEN];
The room for the '\0' string termination seems to be missing: char gen_node_name[GEN_NODE_NAME_MAX_LEN + 1]; > + static uint32_t counter; /* simple counter to guarantee uniqueness */ > + > + /* if node_name is NULL, auto-generate a node name */ > if (!node_name) { > - return; > + int len; > + snprintf(gen_node_name, GEN_NODE_NAME_MAX_LEN, > + "%s%08x", GEN_NODE_NAME_PREFIX, counter++); > + len = strlen(gen_node_name); > + while (len < GEN_NODE_NAME_MAX_LEN - 1) { > + gen_node_name[len++] = g_random_int_range('A', 'Z'); > + } Is this code generating only 7 random chars instead of 8 ? > + gen_node_name[GEN_NODE_NAME_MAX_LEN - 1] = '\0'; Could be: gen_node_name[GEN_NODE_NAME_MAX_LEN] = '\0'; if the array is properly declared. > + node_name = gen_node_name; > } > > /* empty string node name is invalid */ > -- > 1.8.3.1 >