cfgfile: support configurable comment character

The current cfgfile comment character is hardcoded to ';'.  This commit a
new API to allow the user to specify which comment character to use while
parsing the file.

This is to ease adoption by applications that have an existing
configuration file which may use a different comment character.  For
instance, an application may already have a configuration file that uses
the '#' as the comment character.

The approach of using a new API with an extensible parameters structure was
used rather than simply adding a new argument to the existing API to allow
for additional arguments to be introduced in the future.

Signed-off-by: Allain Legacy <allain.legacy@windriver.com>
Acked-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>

lib/librte_cfgfile/rte_cfgfile.c

@@ -35,6 +35,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
+#include <rte_common.h>
 #include <rte_string_fns.h>
 
 #include "rte_cfgfile.h"
@@ -58,6 +59,25 @@ struct rte_cfgfile {
  * for new entries do we add in */
 #define CFG_ALLOC_ENTRY_BATCH 16
 
+/**
+ * Default cfgfile load parameters.
+ */
+static const struct rte_cfgfile_parameters default_cfgfile_params = {
+	.comment_character = CFG_DEFAULT_COMMENT_CHARACTER,
+};
+
+/**
+ * Defines the list of acceptable comment characters supported by this
+ * library.
+ */
+static const char valid_comment_chars[] = {
+	'!',
+	'#',
+	'%',
+	';',
+	'@'
+};
+
 static unsigned
 _strip(char *str, unsigned len)
 {
@@ -85,8 +105,44 @@ _strip(char *str, unsigned len)
 	return newlen;
 }
 
+static int
+rte_cfgfile_check_params(const struct rte_cfgfile_parameters *params)
+{
+	unsigned int valid_comment;
+	unsigned int i;
+
+	if (!params) {
+		printf("Error - missing cfgfile parameters\n");
+		return -EINVAL;
+	}
+
+	valid_comment = 0;
+	for (i = 0; i < RTE_DIM(valid_comment_chars); i++) {
+		if (params->comment_character == valid_comment_chars[i]) {
+			valid_comment = 1;
+			break;
+		}
+	}
+
+	if (valid_comment == 0)	{
+		printf("Error - invalid comment characters %c\n",
+		       params->comment_character);
+		return -ENOTSUP;
+	}
+
+	return 0;
+}
+
 struct rte_cfgfile *
 rte_cfgfile_load(const char *filename, int flags)
+{
+	return rte_cfgfile_load_with_params(filename, flags,
+					    &default_cfgfile_params);
+}
+
+struct rte_cfgfile *
+rte_cfgfile_load_with_params(const char *filename, int flags,
+			     const struct rte_cfgfile_parameters *params)
 {
 	int allocated_sections = CFG_ALLOC_SECTION_BATCH;
 	int allocated_entries = 0;
@@ -96,6 +152,9 @@ rte_cfgfile_load(const char *filename, int flags)
 	int lineno = 0;
 	struct rte_cfgfile *cfg = NULL;
 
+	if (rte_cfgfile_check_params(params))
+		return NULL;
+
 	FILE *f = fopen(filename, "r");
 	if (f == NULL)
 		return NULL;
@@ -132,7 +191,7 @@ rte_cfgfile_load(const char *filename, int flags)
 					"Check if line too long\n", lineno);
 			goto error1;
 		}
-		pos = memchr(buffer, ';', sizeof(buffer));
+		pos = memchr(buffer, params->comment_character, sizeof(buffer));
 		if (pos != NULL) {
 			*pos = '\0';
 			len = pos -  buffer;

lib/librte_cfgfile/rte_cfgfile.h

@@ -66,6 +66,12 @@ struct rte_cfgfile_entry {
 	char value[CFG_VALUE_LEN]; /**< Value */
 };
 
+/** Configuration file operation optional arguments */
+struct rte_cfgfile_parameters {
+	/** Config file comment character; one of '!', '#', '%', ';', '@' */
+	char comment_character;
+};
+
 /**@{ cfgfile load operation flags */
 enum {
 	/**
@@ -77,6 +83,9 @@ enum {
 };
 /**@} */
 
+/** Defines the default comment character used for parsing config files. */
+#define CFG_DEFAULT_COMMENT_CHARACTER ';'
+
 /**
 * Open config file
 *
@@ -89,6 +98,22 @@ enum {
 */
 struct rte_cfgfile *rte_cfgfile_load(const char *filename, int flags);
 
+/**
+ * Open config file with specified optional parameters.
+ *
+ * @param filename
+ *   Config file name
+ * @param flags
+ *   Config file flags
+ * @param params
+ *   Additional configuration attributes.  Must be configured with desired
+ *   values prior to invoking this API.
+ * @return
+ *   Handle to configuration file on success, NULL otherwise
+ */
+struct rte_cfgfile *rte_cfgfile_load_with_params(const char *filename,
+	int flags, const struct rte_cfgfile_parameters *params);
+
 /**
 * Get number of sections in config file
 *

lib/librte_cfgfile/rte_cfgfile_version.map

@@ -20,3 +20,10 @@ DPDK_16.04 {
 	rte_cfgfile_section_entries_by_index;
 
 } DPDK_2.0;
+
+DPDK_17.05 {
+    global:
+
+    rte_cfgfile_load_with_params;
+
+} DPDK_16.04;

test/test/test_cfgfile.c

@@ -129,6 +129,30 @@ test_cfgfile_sample1(void)
 	return 0;
 }
 
+static int
+test_cfgfile_sample2(void)
+{
+	struct rte_cfgfile_parameters params;
+	struct rte_cfgfile *cfgfile;
+	int ret;
+
+	/* override comment character */
+	memset(&params, 0, sizeof(params));
+	params.comment_character = '#';
+
+	cfgfile = rte_cfgfile_load_with_params(CFG_FILES_ETC "/sample2.ini", 0,
+					       &params);
+	TEST_ASSERT_NOT_NULL(cfgfile, "Failed to parse sample2.ini");
+
+	ret = _test_cfgfile_sample(cfgfile);
+	TEST_ASSERT_SUCCESS(ret, "Failed to validate sample file: %d", ret);
+
+	ret = rte_cfgfile_close(cfgfile);
+	TEST_ASSERT_SUCCESS(ret, "Failed to close cfgfile");
+
+	return 0;
+}
+
 static int
 test_cfgfile_invalid_section_header(void)
 {
@@ -140,6 +164,23 @@ test_cfgfile_invalid_section_header(void)
 	return 0;
 }
 
+static int
+test_cfgfile_invalid_comment(void)
+{
+	struct rte_cfgfile_parameters params;
+	struct rte_cfgfile *cfgfile;
+
+	/* override comment character with an invalid one */
+	memset(&params, 0, sizeof(params));
+	params.comment_character = '$';
+
+	cfgfile = rte_cfgfile_load_with_params(CFG_FILES_ETC "/sample2.ini", 0,
+					       &params);
+	TEST_ASSERT_NULL(cfgfile, "Expected failured did not occur");
+
+	return 0;
+}
+
 static int
 test_cfgfile_invalid_key_value_pair(void)
 {
@@ -219,9 +260,15 @@ test_cfgfile(void)
 	if (test_cfgfile_sample1())
 		return -1;
 
+	if (test_cfgfile_sample2())
+		return -1;
+
 	if (test_cfgfile_invalid_section_header())
 		return -1;
 
+	if (test_cfgfile_invalid_comment())
+		return -1;
+
 	if (test_cfgfile_invalid_key_value_pair())
 		return -1;
 

test/test/test_cfgfiles/etc/sample2.ini

@@ -0,0 +1,12 @@
+# this is a global comment
+
+[section1]
+# this is section 1
+key1=value1
+
+[section2]
+# this is section 2
+#key1=value1
+key2=value2
+key3=value3 # this is key3
+ignore-missing-separator