Re: [Qemu-devel] [PATCH 2/3] qmp: qmp_send_key(): accept key codes in hex

[Markus Armbruster <armbru@redhat.com>]

Luiz Capitulino <lcapitulino@redhat.com> writes:

> Before the qapi conversion, the sendkey command could be used to
> send key codes in hex directly to the guest. In HMP, this would
> be like:
>
>  (qemu) sendkey 0xdc
>
> However, the qapi conversion broke this, as it only supports sending
> QKeyCode values to the guest. That's a regression.

Let me elaborate, to make sure I got it.

Before the QAPI conversion, sendkey used get_keycode() to convert key
substrings to integer key codes.  Source code:

    static int get_keycode(const char *key)
    {
        const KeyDef *p;
        char *endp;
        int ret;

        for(p = key_defs; p->name != NULL; p++) {
            if (!strcmp(key, p->name))
                return p->keycode;
        }
        if (strstart(key, "0x", NULL)) {
            ret = strtoul(key, &endp, 0);
            if (*endp == '\0' && ret >= 0x01 && ret <= 0xff)
                return ret;
        }
        return -1;
    }

If @key is a recognized key name, return its (positive) code.
Else, if @key is a hexadecimal number between 1 and 0xff, return the
number.
Else, return -1.

Since the QAPI conversion, it uses index_from_key():

    int index_from_key(const char *key)
    {
        int i, keycode;
        char *endp;

        for (i = 0; QKeyCode_lookup[i] != NULL; i++) {
            if (!strcmp(key, QKeyCode_lookup[i])) {
                break;
            }
        }

        if (strstart(key, "0x", NULL)) {
            keycode = strtoul(key, &endp, 0);
            if (*endp == '\0' && keycode >= 0x01 && keycode <= 0xff) {
                for (i = 0; i < Q_KEY_CODE_MAX; i++) {
                    if (keycode == key_defs[i]) {
                        break;
                    }
                }
            }
        }

        /* Return Q_KEY_CODE_MAX if the key is invalid */
        return i;
    }

If @key is a recognized key name, return its (positive) code.
Else, if @key is a hexadecimal number between 1 and 0xff, and a
recognized key with that code exists, return the number.
Else, return -1.

The regression is *not* that the hexadecimal format isn't recognized
anymore, it's that numbers that don't have a key definition are now
rejected.

> This commit fixes the problem by adding hex value support down
> the QMP interface, qmp_send_key().
>
> In more detail, this commit:
>
>  1. Adds the KeyValue union. This can represent an hex value or
>     a QKeyCode value
>
>  2. *Changes* the QMP send-key command to take an KeyValue argument
>     instead of a QKeyCode one
>
>  3. Adapt hmp_send_key() to the QMP interface changes
>
> Item 2 is an incompatible change, but as we're in development phase
> (and this command has been merged a few weeks ago) this shouldn't be
> a problem.
>
> Finally, it's not possible to split this commit without breaking the
> build.
>
> Reported-by: Avi Kivity <avi@redhat.com>
> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
> ---
>  hmp.c            | 43 +++++++++++++++++++++++++++++--------------
>  input.c          | 33 +++++++++++++++++++++++++++------
>  qapi-schema.json | 20 +++++++++++++++++---
>  3 files changed, 73 insertions(+), 23 deletions(-)
>
> diff --git a/hmp.c b/hmp.c
> index ba6fbd3..8738dc5 100644
> --- a/hmp.c
> +++ b/hmp.c
> @@ -1109,13 +1109,13 @@ void hmp_closefd(Monitor *mon, const QDict *qdict)
>  void hmp_send_key(Monitor *mon, const QDict *qdict)
>  {
>      const char *keys = qdict_get_str(qdict, "keys");
> -    QKeyCodeList *keylist, *head = NULL, *tmp = NULL;
> +    KeyValueList *keylist, *head = NULL, *tmp = NULL;
>      int has_hold_time = qdict_haskey(qdict, "hold-time");
>      int hold_time = qdict_get_try_int(qdict, "hold-time", -1);
>      Error *err = NULL;
>      char keyname_buf[16];
>      char *separator;
> -    int keyname_len, idx;
> +    int keyname_len;
>  
>      while (1) {
>          separator = strchr(keys, '-');
> @@ -1129,15 +1129,8 @@ void hmp_send_key(Monitor *mon, const QDict *qdict)
>          }
>          keyname_buf[keyname_len] = 0;
>  
> -        idx = index_from_key(keyname_buf);
> -        if (idx == Q_KEY_CODE_MAX) {
> -            monitor_printf(mon, "invalid parameter: %s\n", keyname_buf);
> -            break;
> -        }
> -
>          keylist = g_malloc0(sizeof(*keylist));
> -        keylist->value = idx;
> -        keylist->next = NULL;
> +        keylist->value = g_malloc0(sizeof(*keylist->value));
>  
>          if (!head) {
>              head = keylist;
> @@ -1147,17 +1140,39 @@ void hmp_send_key(Monitor *mon, const QDict *qdict)
>          }
>          tmp = keylist;
>  
> +        if (strstart(keyname_buf, "0x", NULL)) {
> +            char *endp;
> +            int value = strtoul(keyname_buf, &endp, 0);
> +            if (*endp != '\0') {
> +                goto err_out;
> +            }
> +            keylist->value->kind = KEY_VALUE_KIND_NUMBER;
> +            keylist->value->number = value;
> +        } else {
> +            int idx = index_from_key(keyname_buf);
> +            if (idx == Q_KEY_CODE_MAX) {
> +                goto err_out;
> +            }
> +            keylist->value->kind = KEY_VALUE_KIND_QCODE;
> +            keylist->value->qcode = idx;
> +        }
> +

TL;DR: this differs unnecessarily from the pre-QAPI code, which makes
the fix less obvious than it could be.  But I think it should work, and
unbreaking autotest quickly is more important than making this patch
perfect, so I'm *not* asking for a respin because of that.

Strings starting with "0x" are interpreted differently than before the
QAPI conversion.

Before:

    If @key is a recognized key name, use its (positive) code.
    Else, if @key is a hexadecimal number between 1 and 0xff, use the
    number.
    Else, error.

After:

    If @key starts with "0x"
        If @key is a number, use it (range check is done later)
        Else, error
    Else
        If it's a recognized key name, use its (positive) code
        Else, error.

Makes a difference only if key names starting with "0x" exist.  None
exist now, and such names aren't likely to appear in the future.

Aside: codes starting with a digit do exist, and that's why we can do
only hexadecimal numeric keys.

The use of strtoul() here is sloppy, but it's no worse as before, in
index_from_key():

* Numbers overflowing int are silently truncated, as before.

* Numbers outside 0x01..0xff (possibly after truncation) are still
  flagged as error, in qmp_send_key() below.

>          if (!separator) {
>              break;
>          }
>          keys = separator + 1;
>      }
>  
> -    if (idx != Q_KEY_CODE_MAX) {
> -        qmp_send_key(head, has_hold_time, hold_time, &err);
> -    }
> +    qmp_send_key(head, has_hold_time, hold_time, &err);
>      hmp_handle_error(mon, &err);
> -    qapi_free_QKeyCodeList(head);
> +
> +out:
> +    qapi_free_KeyValueList(head);
> +    return;
> +
> +err_out:
> +    monitor_printf(mon, "invalid parameter: %s\n", keyname_buf);
> +    goto out;

Jumping forward and backward like that is a bit ugly, but let's unbreak
autotest.

>  }
>  
>  void hmp_screen_dump(Monitor *mon, const QDict *qdict)
> diff --git a/input.c b/input.c
> index 32c6057..76ade64 100644
> --- a/input.c
> +++ b/input.c
> @@ -228,6 +228,23 @@ static int *keycodes;
>  static int keycodes_size;
>  static QEMUTimer *key_timer;
>  
> +static int keycode_from_keyvalue(const KeyValue *value)
> +{
> +    if (value->kind == KEY_VALUE_KIND_QCODE) {
> +        return key_defs[value->qcode];
> +    } else {
> +        assert(value->kind == KEY_VALUE_KIND_NUMBER);
> +        return value->number;
> +    }
> +}
> +
> +static void free_keycodes(void)
> +{
> +    g_free(keycodes);
> +    keycodes = NULL;
> +    keycodes_size = 0;
> +}
> +
>  static void release_keys(void *opaque)
>  {
>      int i;
> @@ -239,16 +256,14 @@ static void release_keys(void *opaque)
>          kbd_put_keycode(keycodes[i]| 0x80);
>      }
>  
> -    g_free(keycodes);
> -    keycodes = NULL;
> -    keycodes_size = 0;
> +    free_keycodes();
>  }
>  
> -void qmp_send_key(QKeyCodeList *keys, bool has_hold_time, int64_t hold_time,
> +void qmp_send_key(KeyValueList *keys, bool has_hold_time, int64_t hold_time,
>                    Error **errp)
>  {
>      int keycode;
> -    QKeyCodeList *p;
> +    KeyValueList *p;
>  
>      if (!key_timer) {
>          key_timer = qemu_new_timer_ns(vm_clock, release_keys, NULL);
> @@ -265,7 +280,13 @@ void qmp_send_key(QKeyCodeList *keys, bool has_hold_time, int64_t hold_time,
>  
>      for (p = keys; p != NULL; p = p->next) {
>          /* key down events */
> -        keycode = key_defs[p->value];
> +        keycode = keycode_from_keyvalue(p->value);
> +        if (keycode < 0x01 || keycode > 0xff) {
> +            error_setg(errp, "invalid hex keycode 0x%x\n", keycode);
> +            free_keycodes();
> +            return;
> +        }
> +
>          if (keycode & 0x80) {
>              kbd_put_keycode(0xe0);
>          }
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 14e4419..02135cc 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -2588,12 +2588,26 @@
>               'lf', 'help', 'meta_l', 'meta_r', 'compose' ] }
>  
>  ##
> +# @KeyValue
> +#
> +# Represents a keyboard key.
> +# 

Trailing whitespace, could be fixed up on merge if we care.

> +# Since: 1.3.0
> +##
> +{ 'union': 'KeyValue',
> +  'data': {
> +    'number': 'int',
> +    'qcode': 'QKeyCode' } }
> +
> +##
>  # @send-key:
>  #
>  # Send keys to guest.
>  #
> -# @keys: key sequence. 'keys' is the name of the key. Use a JSON array to
> -#        press several keys simultaneously.
> +# @keys: An array of @KeyValue elements. All @KeyValues in this array are
> +#        simultaneously sent to the guest. A @KeyValue.number value is sent
> +#        directly to the guest, while @KeyValue.qcode must be a valid
> +#        @QKeyCode value
>  #
>  # @hold-time: #optional time to delay key up events, milliseconds. Defaults
>  #             to 100
> @@ -2605,7 +2619,7 @@
>  #
>  ##
>  { 'command': 'send-key',
> -  'data': { 'keys': ['QKeyCode'], '*hold-time': 'int' } }
> +  'data': { 'keys': ['KeyValue'], '*hold-time': 'int' } }
>  
>  ##
>  # @screendump: