string: add spdk_str_chomp() function

Add a helper function to remove trailing newlines.

Change-Id: I8b1a2bf3d70ef17e0bc7e74429ac955c68cb6bcf
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-on: https://review.gerrithub.io/370592
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>

include/spdk/string.h

@@ -89,6 +89,16 @@ char *spdk_strsepq(char **stringp, const char *delim);
  */
 char *spdk_str_trim(char *s);
 
+/**
+ * Remove trailing newlines from the end of a string in place.
+ *
+ * Any sequence of trailing \r and \n characters is removed from the end of the string.
+ *
+ * \param s String to remove newline from.
+ * \return Number of characters removed.
+ */
+size_t spdk_str_chomp(char *s);
+
 /**
  * Copy a string into a fixed-size buffer, padding extra bytes with a specific character.
  *

lib/util/string.c

@@ -307,3 +307,22 @@ spdk_parse_ip_addr(char *ip, char **host, char **port)
 
 	return 0;
 }
+
+size_t
+spdk_str_chomp(char *s)
+{
+	size_t len = strlen(s);
+	size_t removed = 0;
+
+	while (len > 0) {
+		if (s[len - 1] != '\r' && s[len - 1] != '\n') {
+			break;
+		}
+
+		s[len - 1] = '\0';
+		len--;
+		removed++;
+	}
+
+	return removed;
+}

test/unit/lib/util/string.c/string_ut.c

@@ -95,6 +95,47 @@ test_parse_ip_addr(void)
 	CU_ASSERT_EQUAL(port, NULL);
 }
 
+static void
+test_str_chomp(void)
+{
+	char s[1024];
+
+	/* One \n newline */
+	snprintf(s, sizeof(s), "%s", "hello world\n");
+	CU_ASSERT(spdk_str_chomp(s) == 1);
+	CU_ASSERT(strcmp(s, "hello world") == 0);
+
+	/* One \r\n newline */
+	snprintf(s, sizeof(s), "%s", "hello world\r\n");
+	CU_ASSERT(spdk_str_chomp(s) == 2);
+	CU_ASSERT(strcmp(s, "hello world") == 0);
+
+	/* No newlines */
+	snprintf(s, sizeof(s), "%s", "hello world");
+	CU_ASSERT(spdk_str_chomp(s) == 0);
+	CU_ASSERT(strcmp(s, "hello world") == 0);
+
+	/* Two newlines */
+	snprintf(s, sizeof(s), "%s", "hello world\n\n");
+	CU_ASSERT(spdk_str_chomp(s) == 2);
+	CU_ASSERT(strcmp(s, "hello world") == 0);
+
+	/* Empty string */
+	snprintf(s, sizeof(s), "%s", "");
+	CU_ASSERT(spdk_str_chomp(s) == 0);
+	CU_ASSERT(strcmp(s, "") == 0);
+
+	/* One-character string with only \n */
+	snprintf(s, sizeof(s), "%s", "\n");
+	CU_ASSERT(spdk_str_chomp(s) == 1);
+	CU_ASSERT(strcmp(s, "") == 0);
+
+	/* One-character string without a newline */
+	snprintf(s, sizeof(s), "%s", "a");
+	CU_ASSERT(spdk_str_chomp(s) == 0);
+	CU_ASSERT(strcmp(s, "a") == 0);
+}
+
 int
 main(int argc, char **argv)
 {
@@ -112,7 +153,8 @@ main(int argc, char **argv)
 	}
 
 	if (
-		CU_add_test(suite, "test_parse_ip_addr", test_parse_ip_addr) == NULL) {
+		CU_add_test(suite, "test_parse_ip_addr", test_parse_ip_addr) == NULL ||
+		CU_add_test(suite, "test_str_chomp", test_str_chomp) == NULL) {
 		CU_cleanup_registry();
 		return CU_get_error();
 	}