[PATCH v2 09/23] src: expand docs for guest info array handling
Give an overview of how arrays are handled and represented in
the typed parameters returned by the guest info API.
Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com>
---
src/libvirt-domain.c | 50 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 50 insertions(+)
diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c
index 557efcc0c0..390f54d46e 100644
--- a/src/libvirt-domain.c
+++ b/src/libvirt-domain.c
@@ -13249,6 +13249,56 @@ virDomainSetVcpu(virDomainPtr domain,
* This API requires the VM to run. The caller is responsible for calling
* virTypedParamsFree to free memory returned in @params.
*
+ * In a number of cases the parameters returned are representing
+ * arrays of data items. In these cases multiple VIR_DOMAIN_GUEST_INFO*
+ * constants will need to be concatenated to form a complete typed
+ * parameter key. The design pattern for handling array entries is
+ * as follows
+ *
+ * - VIR_DOMAIN_GUEST_INFO_nnnnn_COUNT
+ *
+ * Defines the upper limit on the number of elements that will
+ * be returned. In some cases the array information may be
+ * sparsely populated, so it is not considered an error if a
+ * given element does not exist. Applications should check for
+ * each possible element upto the declared limit.
+ *
+ * - VIR_DOMAIN_GUEST_INFO_nnnnn_PREFIX
+ *
+ * Defines the prefix to be used to construct the typed parameter
+ * key for an array element, including the trailing '.'. The prefix
+ * must have an array index appended, along with a suffix.
+ *
+ * - VIR_DOMAIN_GUEST_INFO_nnnnn_SUFFIX_mmmmm
+ *
+ * Defines the suffix for accessing a particular data item within
+ * the array element, including the leading '.'. The suffix must
+ * have an array prefix and index prepended.
+ *
+ * As an example, assuming a printf-like formatting approach an
+ * application would construct a key as follows:
+ *
+ * format(VIR_DOMAIN_GUEST_INFO_FS_PREFIX +
+ * "%d" +
+ * VIR_DOMAIN_GUEST_INFO_FS_SUFFIX_NAME,
+ * index)
+ *
+ * Which, when index==3, would result in the key "fs.3.name"
+ *
+ * In some cases there may be nested arrays, in which case the key
+ * is formed by concatenating multiple prefixes and suffixes with
+ * mutliple array indexes. For example:
+ *
+ * format(VIR_DOMAIN_GUEST_INFO_FS_PREFIX +
+ * "%d" +
+ * VIR_DOMAIN_GUEST_INFO_FS_SUFFIX_DISK_PREFIX +
+ * "%d" +
+ * VIR_DOMAIN_GUEST_INFO_FS_SUFFIX_DISK_SUFFIX_SERIAL
+ * fsindex, diskindex)
+ *
+ * Which, when fsindex==3 and diskindex==7, would result in the
+ * key "fs.3.disk.7.serial".
+ *
* Returns 0 on success, -1 on error.
*
* Since: 5.7.0
--
2.48.1