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Re: [libvirt] [PATCH v3 6/9] util: virTypedParams{Filter, PickStrings}




On 05/26/2015 09:01 AM, Michal Privoznik wrote:
> From: Pavel Boldin <pboldin mirantis com>
> 
> Add multikey API:
> 
>  * virTypedParamsFilter that returns all the parameters with specified name.
>  * virTypedParamsPickStrings that returns a list with all the values for
>    specified name and string type.
> 
> Signed-off-by: Pavel Boldin <pboldin mirantis com>
> Signed-off-by: Michal Privoznik <mprivozn redhat com>
> ---
>  include/libvirt/libvirt-host.h |  11 ++++
>  src/libvirt_public.syms        |   2 +
>  src/util/virtypedparam.c       | 113 +++++++++++++++++++++++++++++++++++++++++
>  tests/virtypedparamtest.c      |  99 ++++++++++++++++++++++++++++++++++++
>  4 files changed, 225 insertions(+)
> 
> diff --git a/include/libvirt/libvirt-host.h b/include/libvirt/libvirt-host.h
> index 070550b..6767527 100644
> --- a/include/libvirt/libvirt-host.h
> +++ b/include/libvirt/libvirt-host.h
> @@ -249,6 +249,11 @@ virTypedParamsGet       (virTypedParameterPtr params,
>                           int nparams,
>                           const char *name);
>  int
> +virTypedParamsFilter    (virTypedParameterPtr params,
> +                         int nparams,
> +                         const char *name,
> +                         virTypedParameterPtr **ret);
> +int
>  virTypedParamsGetInt    (virTypedParameterPtr params,
>                           int nparams,
>                           const char *name,
> @@ -284,6 +289,12 @@ virTypedParamsGetString (virTypedParameterPtr params,
>                           const char *name,
>                           const char **value);
>  int
> +virTypedParamsPickStrings(virTypedParameterPtr params,
> +                         int nparams,
> +                         const char *name,
> +                         const char ***values,
> +                         size_t *picked);
> +int
>  virTypedParamsAddInt    (virTypedParameterPtr *params,
>                           int *nparams,
>                           int *maxparams,
> diff --git a/src/libvirt_public.syms b/src/libvirt_public.syms
> index 716dd2f..845a0b8 100644
> --- a/src/libvirt_public.syms
> +++ b/src/libvirt_public.syms
> @@ -713,6 +713,8 @@ LIBVIRT_1.2.15 {
>  LIBVIRT_1.2.16 {
>      global:
>          virDomainSetUserPassword;
> +        virTypedParamsFilter;
> +        virTypedParamsPickStrings;
>  } LIBVIRT_1.2.15;

This will need to change since it misses this release...

>  
>  # .... define new API here using predicted next version number ....
> diff --git a/src/util/virtypedparam.c b/src/util/virtypedparam.c
> index e91ca99..d88d4a7 100644
> --- a/src/util/virtypedparam.c
> +++ b/src/util/virtypedparam.c
> @@ -481,6 +481,57 @@ virTypedParamsGet(virTypedParameterPtr params,
>  }
>  
>  
> +/**
> + * virTypedParamsFilter:
> + * @params: array of typed parameters
> + * @nparams: number of parameters in the @params array
> + * @name: name of the parameter to find
> + * @ret: pointer to the returned array
> + *
> + *

Extraneous blank line

> + * Filters @params retaining only the parameters named @name in the
> + * resulting array @ret. Caller should free the @ret array but not
> + * the items since they are pointing to the @params elements.
> + *
> + * Returns amount of elements in @ret on success, -1 on error.
> + */
> +int
> +virTypedParamsFilter(virTypedParameterPtr params,
> +                     int nparams,
> +                     const char *name,
> +                     virTypedParameterPtr **ret)
> +{
> +    size_t i, alloc = 0, n = 0;
> +
> +    virResetLastError();
> +
> +    virCheckNonNullArgGoto(params, error);
> +    virCheckNonNullArgGoto(name, error);
> +    virCheckNonNullArgGoto(ret, error);
> +
> +    *ret = NULL;

Coverity points out:

Event assign_zero: 	Assigning: "*ret" = "NULL".

> +
> +    for (i = 0; i < nparams; i++) {
> +        if (STREQ(params[i].field, name)) {
> +            if (VIR_RESIZE_N(*ret, alloc, n, 1) < 0)


Coverity points out:

"Although "virResizeN" does overwrite "*ret" on some paths, it also
contains at least one feasible path which does not overwrite it."

[True, but that would assume *ret was already large enough (I believe).
On the first pass, there's no way it could return 0.]

> +                goto error;
> +
> +            (*ret)[n] = &params[i];

Coverity points out:

Dereferencing null pointer "*ret".

> +
> +            n++;
> +        }
> +    }

Although it seems it's a false positive, if the *ret = NULL; is removed,
then the error goes away, but that seems to go against your v2 review of
not finding a match to filter and free.  Perplexing, but my latest
Coverity install has a bunch of false positives with similar code.
Another way to avoid the message is a VIR_ALLOC_N(*ret, 1) right after
the *ret = NULL (leading me further down the path of false positive, but
still annoying).
> +
> +    return n;
> +
> + error:
> +    if (ret)
> +        VIR_FREE(*ret);

So should we be freeing this since we don't own it and may not have
RESIZE'd it? Our only caller currently VIR_FREE()'s on both paths.

Looks good in general, but perhaps eblake will have some thoughts on the
Coverity issue...

John
> +    virDispatchError(NULL);
> +    return -1;
> +}
> +
> +
>  #define VIR_TYPED_PARAM_CHECK_TYPE(check_type)                              \
>      do { if (param->type != check_type) {                                   \
>          virReportError(VIR_ERR_INVALID_ARG,                                 \
> @@ -749,6 +800,68 @@ virTypedParamsGetString(virTypedParameterPtr params,
>  
>  
>  /**
> + * virTypedParamsPickStrings:
> + * @params: array of typed parameters
> + * @nparams: number of parameters in the @params array
> + * @name: name of the parameter to find
> + * @values: array of returned values
> + * @picked: pointer to the amount of picked strings.
> + *
> + * Finds all parameters with desired @name within @params and
> + * store their values into @values. The @values array is self
> + * allocated and its length is stored into @picked. When no
> + * longer needed, caller should free the returned array, but not
> + * the items since they are taken from @params array.
> + *
> + * Returns 0 on success, -1 otherwise.
> + */
> +int
> +virTypedParamsPickStrings(virTypedParameterPtr params,
> +                          int nparams,
> +                          const char *name,
> +                          const char ***values,
> +                          size_t *picked)
> +{
> +    size_t i, n;
> +    int nfiltered;
> +    virTypedParameterPtr *filtered = NULL;
> +
> +    virResetLastError();
> +
> +    virCheckNonNullArgGoto(values, error);
> +    virCheckNonNullArgGoto(picked, error);
> +
> +    nfiltered = virTypedParamsFilter(params, nparams, name, &filtered);
> +
> +    if (nfiltered < 0)
> +        goto error;
> +
> +    *values = NULL;
> +
> +    if (nfiltered &&
> +        VIR_ALLOC_N(*values, nfiltered) < 0)
> +        goto error;
> +
> +    for (n = 0, i = 0; i < nfiltered; i++) {
> +        if (filtered[i]->type == VIR_TYPED_PARAM_STRING)
> +            (*values)[n++] = filtered[i]->value.s;
> +    }
> +
> +    *picked = n;
> +
> +    VIR_FREE(filtered);
> +    return 0;
> +
> + error:
> +    if (values)
> +        VIR_FREE(*values);
> +    VIR_FREE(filtered);
> +    virDispatchError(NULL);
> +    return -1;
> +}
> +
> +
> +/**
>   * virTypedParamsAddInt:
>   * @params: pointer to the array of typed parameters
>   * @nparams: number of parameters in the @params array
> diff --git a/tests/virtypedparamtest.c b/tests/virtypedparamtest.c
> index 95e22a7..abdddd5 100644
> --- a/tests/virtypedparamtest.c
> +++ b/tests/virtypedparamtest.c
> @@ -81,6 +81,99 @@ testTypedParamsValidate(const void *opaque)
>      .nparams = PARAMS_SIZE(__VA_ARGS__),
>  
>  static int
> +testTypedParamsFilter(const void *opaque ATTRIBUTE_UNUSED)
> +{
> +    size_t i, nfiltered;
> +    int rv = -1;
> +    virTypedParameter params[] = {
> +        { .field = "bar", .type = VIR_TYPED_PARAM_UINT },
> +        { .field = "foo", .type = VIR_TYPED_PARAM_INT },
> +        { .field = "bar", .type = VIR_TYPED_PARAM_UINT },
> +        { .field = "foo", .type = VIR_TYPED_PARAM_INT },
> +        { .field = "foobar", .type = VIR_TYPED_PARAM_STRING },
> +        { .field = "foo", .type = VIR_TYPED_PARAM_INT }
> +    };
> +    virTypedParameterPtr *filtered = NULL;
> +
> +
> +    nfiltered = virTypedParamsFilter(params, ARRAY_CARDINALITY(params),
> +                                     "foo", &filtered);
> +    if (nfiltered != 3)
> +        goto cleanup;
> +
> +    for (i = 0; i < nfiltered; i++) {
> +        if (filtered[i] != &params[1 + i * 2])
> +            goto cleanup;
> +    }
> +    VIR_FREE(filtered);
> +    filtered = NULL;
> +
> +    nfiltered = virTypedParamsFilter(params, ARRAY_CARDINALITY(params),
> +                                     "bar", &filtered);
> +
> +    if (nfiltered != 2)
> +        goto cleanup;
> +
> +    for (i = 0; i < nfiltered; i++) {
> +        if (filtered[i] != &params[i * 2])
> +            goto cleanup;
> +    }
> +
> +    rv = 0;
> + cleanup:
> +    VIR_FREE(filtered);
> +    return rv;
> +}
> +
> +static int
> +testTypedParamsPickStrings(const void *opaque ATTRIBUTE_UNUSED)
> +{
> +    size_t i, picked;
> +    int rv = -1;
> +    char l = '1';
> +    const char **strings = NULL;
> +
> +    virTypedParameter params[] = {
> +        { .field = "bar", .type = VIR_TYPED_PARAM_STRING,
> +          .value = { .s = (char*)"bar1"} },
> +        { .field = "foo", .type = VIR_TYPED_PARAM_INT },
> +        { .field = "bar", .type = VIR_TYPED_PARAM_STRING,
> +          .value = { .s = (char*)"bar2"} },
> +        { .field = "foo", .type = VIR_TYPED_PARAM_INT },
> +        { .field = "foobar", .type = VIR_TYPED_PARAM_STRING },
> +        { .field = "bar", .type = VIR_TYPED_PARAM_STRING,
> +          .value = { .s = NULL } },
> +        { .field = "foo", .type = VIR_TYPED_PARAM_INT },
> +        { .field = "bar", .type = VIR_TYPED_PARAM_STRING,
> +          .value = { .s = (char*)"bar3"} }
> +    };
> +
> +    if (virTypedParamsPickStrings(params,
> +                                  ARRAY_CARDINALITY(params),
> +                                  "bar",
> +                                  &strings,
> +                                  &picked) < 0)
> +        goto cleanup;
> +
> +    for (i = 0; i < picked; i++) {
> +        if (i == 2) {
> +            if (strings[i] != NULL)
> +                goto cleanup;
> +            continue;
> +        }
> +        if (!STREQLEN(strings[i], "bar", 3))
> +            goto cleanup;
> +        if (strings[i][3] != l++)
> +            goto cleanup;
> +    }
> +
> +    rv = 0;
> + cleanup:
> +    VIR_FREE(strings);
> +    return rv;
> +}
> +
> +static int
>  testTypedParamsValidator(void)
>  {
>      size_t i;
> @@ -159,6 +252,12 @@ mymain(void)
>      if (testTypedParamsValidator() < 0)
>          rv = -1;
>  
> +    if (virtTestRun("Filtering", testTypedParamsFilter, NULL) < 0)
> +        rv = -1;
> +
> +    if (virtTestRun("Picking Strings", testTypedParamsPickStrings, NULL) < 0)
> +        rv = -1;
> +
>      if (rv < 0)
>          return EXIT_FAILURE;
>      return EXIT_SUCCESS;
> 


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