[dpdk-dev] [PATCH v4 3/5] kvargs: add get by key function

[Xueming Li <xuemingl@nvidia.com>]

Adds a new function to get value of a specific key from kvargs list.

Signed-off-by: Xueming Li <xuemingl@nvidia.com>
Reviewed-by: Gaetan Rivet <grive@u256.net>
---
 lib/librte_kvargs/rte_kvargs.c | 20 ++++++++++++++++++++
 lib/librte_kvargs/rte_kvargs.h | 21 +++++++++++++++++++++
 lib/librte_kvargs/version.map  |  3 +++
 3 files changed, 44 insertions(+)

diff --git a/lib/librte_kvargs/rte_kvargs.c b/lib/librte_kvargs/rte_kvargs.c
index ffae8914cf..40e7670ab3 100644
--- a/lib/librte_kvargs/rte_kvargs.c
+++ b/lib/librte_kvargs/rte_kvargs.c
@@ -203,6 +203,26 @@ rte_kvargs_free(struct rte_kvargs *kvlist)
 	free(kvlist);
 }
 
+/* Lookup a value in an rte_kvargs list by its key. */
+const char *
+rte_kvargs_get(const struct rte_kvargs *kvlist, const char *key)
+{
+	unsigned int i;
+
+	if (!kvlist)
+		return NULL;
+	for (i = 0; i < kvlist->count; ++i) {
+		/* Allows key to be NULL. */
+		if (!key && !kvlist->pairs[i].key)
+			return kvlist->pairs[i].value;
+		if (!key || !kvlist->pairs[i].key)
+			continue;
+		if (!strcmp(kvlist->pairs[i].key, key))
+			return kvlist->pairs[i].value;
+	}
+	return NULL;
+}
+
 /*
  * Parse the arguments "key=value,key=value,..." string and return
  * an allocated structure that contains a key/value list. Also
diff --git a/lib/librte_kvargs/rte_kvargs.h b/lib/librte_kvargs/rte_kvargs.h
index eff598e08b..cb3ea99850 100644
--- a/lib/librte_kvargs/rte_kvargs.h
+++ b/lib/librte_kvargs/rte_kvargs.h
@@ -114,6 +114,27 @@ struct rte_kvargs *rte_kvargs_parse_delim(const char *args,
  */
 void rte_kvargs_free(struct rte_kvargs *kvlist);
 
+/**
+ * Get the value associated with a given key.
+ *
+ * If the key is NULL, the first value from the list is returned.
+ * If multiple key matches, the value of the first one is returned.
+ *
+ * The memory returned is allocated as part of the rte_kvargs structure,
+ * it must never be modified.
+ *
+ * @param kvlist
+ *   A list of rte_kvargs pair of 'key=value'.
+ * @param key
+ *   The matching key.
+
+ * @return
+ *   NULL if no key matches the input, a value associated with a matching
+ *   key otherwise.
+ */
+__rte_experimental
+const char *rte_kvargs_get(const struct rte_kvargs *kvlist, const char *key);
+
 /**
  * Call a handler function for each key/value matching the key
  *
diff --git a/lib/librte_kvargs/version.map b/lib/librte_kvargs/version.map
index ed375bf4a3..fb9bed4f93 100644
--- a/lib/librte_kvargs/version.map
+++ b/lib/librte_kvargs/version.map
@@ -15,4 +15,7 @@ EXPERIMENTAL {
 	rte_kvargs_parse_delim;
 	rte_kvargs_strcmp;
 
+	# added in 21.05
+	rte_kvargs_get;
+
 };
-- 
2.25.1