On 02/07/2011 04:43 AM, Alon Levy wrote:
On Mon, Feb 07, 2011 at 09:53:44AM +0100, Markus Armbruster wrote:I haven't been able to follow the evolution of this series, my apologies if I'm missing things already discussed.Alon Levy<al...@redhat.com> writes:Example usage: EnumTable foo_enum_table[] = { {"bar", 1}, {"buz", 2}, {NULL, 0}, }; DEFINE_PROP_ENUM("foo", State, foo, 1, foo_enum_table) When using qemu -device foodev,? it will appear as: foodev.foo=bar/buz Signed-off-by: Alon Levy<al...@redhat.com> --- hw/qdev-properties.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++ hw/qdev.h | 15 ++++++++++++ 2 files changed, 75 insertions(+), 0 deletions(-) diff --git a/hw/qdev-properties.c b/hw/qdev-properties.c index a493087..3157721 100644 --- a/hw/qdev-properties.c +++ b/hw/qdev-properties.c @@ -63,6 +63,66 @@ PropertyInfo qdev_prop_bit = { .print = print_bit, }; +/* --- Enumeration --- */ +/* Example usage: +EnumTable foo_enum_table[] = { + {"bar", 1}, + {"buz", 2}, + {NULL, 0}, +}; +DEFINE_PROP_ENUM("foo", State, foo, 1, foo_enum_table), + */ +static int parse_enum(DeviceState *dev, Property *prop, const char *str) +{ + uint8_t *ptr = qdev_get_prop_ptr(dev, prop);uint8_t is inconsistent with print_enum() and DEFINE_PROP_ENUM(), which both use uint32_t.Thanks, fixing.+ EnumTable *option = (EnumTable*)prop->data;Please don't cast from void * to pointer type (this isn't C++).Will fix for all references.Not thrilled about the "void *data", to be honest. Smells like premature generality to me.I did put it in there because I didn't think a "EnumTable *enum" variable would have been acceptable (added baggage just used by a single property type), and I didn't find any other place to add it. I guess I should just do a: typedef struct EnumProperty { Property base; EnumTable *table; } EnumProperty; But then because we define the properties in a Property[] array this won't work. Maybe turn that into a Property* array? In summary I guess data is a terrible name, but it was least amount of change. Happy to take suggestions.+ + while (option->name != NULL) { + if (!strncmp(str, option->name, strlen(option->name))) {Why strncmp() and not straight strcmp()?I guess no reason except "strncmp is more secure" but irrelevant here since option->name is from the source, I'll fix.+ *ptr = option->value; + return 0; + } + option++; + } + return -EINVAL; +} + +static int print_enum(DeviceState *dev, Property *prop, char *dest, size_t len) +{ + uint32_t *p = qdev_get_prop_ptr(dev, prop); + EnumTable *option = (EnumTable*)prop->data; + while (option->name != NULL) { + if (*p == option->value) { + return snprintf(dest, len, "%s", option->name); + } + option++; + } + return 0;Bug: must dest[0] = 0 when returning 0.will just return snprintf(dest, len, "<enum %d>", option->value)+} + +static int print_enum_options(DeviceInfo *info, Property *prop, char *dest, size_t len) +{ + int ret = 0; + EnumTable *option = (EnumTable*)prop->data;Please don't cast from void * to pointer type (this isn't C++).fixing.+ while (option->name != NULL) { + ret += snprintf(dest + ret, len - ret, "%s", option->name); + if (option[1].name != NULL) { + ret += snprintf(dest + ret, len - ret, "/"); + } + option++; + } + return ret; +} + +PropertyInfo qdev_prop_enum = { + .name = "enum", + .type = PROP_TYPE_ENUM, + .size = sizeof(uint32_t), + .parse = parse_enum, + .print = print_enum, + .print_options = print_enum_options, +}; + /* --- 8bit integer --- */ static int parse_uint8(DeviceState *dev, Property *prop, const char *str) diff --git a/hw/qdev.h b/hw/qdev.h index 3d9acd7..3701d83 100644 --- a/hw/qdev.h +++ b/hw/qdev.h @@ -102,6 +102,7 @@ enum PropertyType { PROP_TYPE_VLAN, PROP_TYPE_PTR, PROP_TYPE_BIT, + PROP_TYPE_ENUM, }; struct PropertyInfo { @@ -121,6 +122,11 @@ typedef struct GlobalProperty { QTAILQ_ENTRY(GlobalProperty) next; } GlobalProperty; +typedef struct EnumTable { + const char *name; + uint32_t value; +} EnumTable; + /*** Board API. This should go away once we have a machine config file. ***/ DeviceState *qdev_create(BusState *bus, const char *name); @@ -235,6 +241,7 @@ extern PropertyInfo qdev_prop_drive; extern PropertyInfo qdev_prop_netdev; extern PropertyInfo qdev_prop_vlan; extern PropertyInfo qdev_prop_pci_devfn; +extern PropertyInfo qdev_prop_enum; #define DEFINE_PROP(_name, _state, _field, _prop, _type) { \ .name = (_name), \ @@ -257,6 +264,14 @@ extern PropertyInfo qdev_prop_pci_devfn; + type_check(uint32_t,typeof_field(_state, _field)), \ .defval = (bool[]) { (_defval) }, \ } +#define DEFINE_PROP_ENUM(_name, _state, _field, _defval, _options) { \ + .name = (_name), \ + .info =&(qdev_prop_enum), \ + .offset = offsetof(_state, _field) \ + + type_check(uint32_t,typeof_field(_state, _field)), \ + .defval = (uint32_t[]) { (_defval) }, \ + .data = (void*)(_options), \Please don't cast from pointer type to void * (this isn't C++). If someone accidentally passes an integral argument for _options (forgotten operator&), the cast suppresses the warning.fixing.+ } #define DEFINE_PROP_UINT8(_n, _s, _f, _d) \ DEFINE_PROP_DEFAULT(_n, _s, _f, _d, qdev_prop_uint8, uint8_t)Okay, let's examine how your enumeration properties work. An enumeration property describes a uint32_t field of the state object. Differences to ordinary properties defined with DEFINE_PROP_UINT32: * info is qdev_prop_enum instead of qdev_prop_uint32. Differences between the two: - parse, print: symbolic names vs. numbers - name, print_options: only for -device DRIVER,\? (and name's use there isn't particularly helpful)Why do you say that? this is being used by libvirt to get the names of the supported backends for the ccid-card-emulated device.
This is wrong.Libvirt should query this information through QMP. This is my main concern with enums. If there isn't a useful introspection interface, libvirt is going to do dumb things like query help output.
This has been a nightmare historically and I'm not inclined to repeat it. Regards, Anthony Liguori
