[PATCH v3 6/6] cfgfile: add support for empty value string

[Allain Legacy <allain.legacy@windriver.com>]

This commit adds support to the cfgfile library for parsing a key=value
line that has no value string specified (e.g., "key=").  This can be used
to override a configuration attribute that has a default value or default
list of values to set it back to an undefined value to disable
functionality.

Signed-off-by: Allain Legacy <allain.legacy@windriver.com>
---
 lib/librte_cfgfile/rte_cfgfile.c                | 23 ++++++++++++------
 lib/librte_cfgfile/rte_cfgfile.h                |  6 +++++
 test/test/test_cfgfile.c                        | 32 +++++++++++++++++++++++++
 test/test/test_cfgfiles/etc/empty_key_value.ini |  2 +-
 4 files changed, 55 insertions(+), 8 deletions(-)

diff --git a/lib/librte_cfgfile/rte_cfgfile.c b/lib/librte_cfgfile/rte_cfgfile.c
index 4ef7decb3..b54a523d2 100644
--- a/lib/librte_cfgfile/rte_cfgfile.c
+++ b/lib/librte_cfgfile/rte_cfgfile.c
@@ -258,12 +258,21 @@ rte_cfgfile_load_with_params(const char *filename, int flags,
 
 			struct rte_cfgfile_section *sect =
 				cfg->sections[curr_section];
-			char *split[2];
-			if (rte_strsplit(buffer, sizeof(buffer), split, 2, '=')
-				!= 2) {
-				printf("Error at line %d - cannot split "
-					"string\n", lineno);
-				goto error1;
+			int n;
+			char *split[2] = {NULL};
+			n = rte_strsplit(buffer, sizeof(buffer), split, 2, '=');
+			if (flags & CFG_FLAG_EMPTY_VALUES) {
+				if ((n < 1) || (n > 2)) {
+					printf("Error at line %d - cannot split string, n=%d\n",
+					       lineno, n);
+					goto error1;
+				}
+			} else {
+				if (n != 2) {
+					printf("Error at line %d - cannot split string, n=%d\n",
+					       lineno, n);
+					goto error1;
+				}
 			}
 
 			curr_entry++;
@@ -293,7 +302,7 @@ rte_cfgfile_load_with_params(const char *filename, int flags,
 			snprintf(entry->name, sizeof(entry->name), "%s",
 				split[0]);
 			snprintf(entry->value, sizeof(entry->value), "%s",
-				split[1]);
+				 split[1] ? split[1] : "");
 			_strip(entry->name, strnlen(entry->name,
 				sizeof(entry->name)));
 			_strip(entry->value, strnlen(entry->value,
diff --git a/lib/librte_cfgfile/rte_cfgfile.h b/lib/librte_cfgfile/rte_cfgfile.h
index a7cd3944e..b06f55d56 100644
--- a/lib/librte_cfgfile/rte_cfgfile.h
+++ b/lib/librte_cfgfile/rte_cfgfile.h
@@ -78,6 +78,12 @@ struct rte_cfgfile_parameters {
  * section.  These entries can be accessed in the "GLOBAL" section.
  */
 #define CFG_FLAG_GLOBAL_SECTION (1 << 0)
+
+/**
+ * Indicates that file supports key value entries where the value can be zero
+ * length (e.g., "key=").
+ */
+#define CFG_FLAG_EMPTY_VALUES (1 << 1)
 /**@} */
 
 /** Defines the default comment character used for parsing config files. */
diff --git a/test/test/test_cfgfile.c b/test/test/test_cfgfile.c
index 0478de59e..4559f8688 100644
--- a/test/test/test_cfgfile.c
+++ b/test/test/test_cfgfile.c
@@ -193,6 +193,35 @@ test_cfgfile_invalid_key_value_pair(void)
 }
 
 static int
+test_cfgfile_empty_key_value_pair(void)
+{
+	struct rte_cfgfile *cfgfile;
+	const char *value;
+	int ret;
+
+	cfgfile = rte_cfgfile_load(CFG_FILES_ETC "/empty_key_value.ini",
+				   CFG_FLAG_EMPTY_VALUES);
+	TEST_ASSERT_NOT_NULL(cfgfile, "Failed to parse empty_key_value.ini");
+
+	ret = rte_cfgfile_num_sections(cfgfile, NULL, 0);
+	TEST_ASSERT(ret == 1, "Unexpected number of sections: %d", ret);
+
+	ret = rte_cfgfile_has_section(cfgfile, "section1");
+	TEST_ASSERT(ret, "section1 missing");
+
+	ret = rte_cfgfile_section_num_entries(cfgfile, "section1");
+	TEST_ASSERT(ret == 1, "section1 unexpected number of entries: %d", ret);
+
+	value = rte_cfgfile_get_entry(cfgfile, "section1", "key");
+	TEST_ASSERT(strlen(value) == 0, "key unexpected value: %s", value);
+
+	ret = rte_cfgfile_close(cfgfile);
+	TEST_ASSERT_SUCCESS(ret, "Failed to close cfgfile");
+
+	return 0;
+}
+
+static int
 test_cfgfile_missing_section(void)
 {
 	struct rte_cfgfile *cfgfile;
@@ -272,6 +301,9 @@ test_cfgfile(void)
 	if (test_cfgfile_invalid_key_value_pair())
 		return -1;
 
+	if (test_cfgfile_empty_key_value_pair())
+		return -1;
+
 	if (test_cfgfile_missing_section())
 		return -1;
 
diff --git a/test/test/test_cfgfiles/etc/empty_key_value.ini b/test/test/test_cfgfiles/etc/empty_key_value.ini
index 8f203ce3e..53284467b 100644
--- a/test/test/test_cfgfiles/etc/empty_key_value.ini
+++ b/test/test/test_cfgfiles/etc/empty_key_value.ini
@@ -1,3 +1,3 @@
 [section1]
 ; this is section 1
-invalid=
+key=
-- 
2.12.1