I noticed this the other day:
(qemu) info qom-tree
/machine (pc-i440fx-7.2-machine)
/fw_cfg (fw_cfg_io)
/\x2from@etc\x2facpi\x2frsdp[0] (memory-region)b
/\x2from@etc\x2facpi\x2ftables[0] (memory-region)
/\x2from@etc\x2ftable-loader[0] (memory-region)
/fwcfg.dma[0] (memory-region)
/fwcfg[0] (memory-region)
[...]
It took me a minute to realize that the "\x2" in these property names
are escaped forms of '/'. I.e. the unescaped path components of the
first property path are
machine
fw_cfg
/from@etc/facpi/frsdp[0]
We're embedding paths within paths. Ugh!
The escaping happens in memory_region_init():
static bool memory_region_need_escape(char c)
{
return c == '/' || c == '[' || c == '\\' || c == ']';
}
static char *memory_region_escape_name(const char *name)
{
const char *p;
char *escaped, *q;
uint8_t c;
size_t bytes = 0;
for (p = name; *p; p++) {
bytes += memory_region_need_escape(*p) ? 4 : 1;
}
if (bytes == p - name) {
return g_memdup(name, bytes + 1);
}
escaped = g_malloc(bytes + 1);
for (p = name, q = escaped; *p; p++) {
c = *p;
if (unlikely(memory_region_need_escape(c))) {
*q++ = '\\';
*q++ = 'x';
*q++ = "0123456789abcdef"[c >> 4];
c = "0123456789abcdef"[c & 15];
}
*q++ = c;
}
*q = 0;
return escaped;
}
static void memory_region_do_init(MemoryRegion *mr,
Object *owner,
const char *name,
uint64_t size)
{
mr->size = int128_make64(size);
if (size == UINT64_MAX) {
mr->size = int128_2_64();
}
mr->name = g_strdup(name);
mr->owner = owner;
mr->ram_block = NULL;
if (name) {
char *escaped_name = memory_region_escape_name(name);
char *name_array = g_strdup_printf("%s[*]", escaped_name);
if (!owner) {
owner = container_get(qdev_get_machine(), "/unattached");
}
object_property_add_child(owner, name_array, OBJECT(mr));
object_unref(OBJECT(mr));
g_free(name_array);
g_free(escaped_name);
}
}
void memory_region_init(MemoryRegion *mr,
Object *owner,
const char *name,
uint64_t size)
{
object_initialize(mr, sizeof(*mr), TYPE_MEMORY_REGION);
memory_region_do_init(mr, owner, name, size);
}
Goes back to
commit b4fefef9d52003b6d09866501275a9a57995c6b0
Author: Peter Crosthwaite <peter.crosthwa...@xilinx.com>
Date: Thu Jun 5 23:15:52 2014 -0700
memory: MemoryRegion: QOMify
QOMify memory regions as an Object. The former init() and destroy()
routines become instance_init() and instance_finalize() resp.
memory_region_init() is re-implemented to be:
object_initialize() + set fields
memory_region_destroy() is re-implemented to call unparent().
Signed-off-by: Peter Crosthwaite <peter.crosthwa...@xilinx.com>
[Add newly-created MR as child, unparent on destruction. - Paolo]
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
No mention of the escapery.
Questions:
1. Do we really want to embed slash-separated paths into slash-separated
paths?
2. As far as I can tell, object.c does not guard against "funny"
characters such as '/' in path components. Should it? For what it's
worth, the kernel doesn't permit '/' in filenames.
3. Should the escapery live in object.c instead of memory.c?
