osmo_escape_str_buf: Always copy, don't return input string pointer

osmo_escape_str_buf() used to have the somewhat odd semantics that
if no escaping was needed, it would return the original pointer without
making any copy to the output buffer.  While this seems like an elegant
optimization, it is a very strange behavior and it works differently
than all of our other *_buf() functions.  Let's unify the API and
turn osmo_escape_str_buf() into a strlcpy() if no escaping is needed.

Change-Id: I3a02bdb27008a73101c2db41ac04248960ed4064

4 files changed, 10 insertions, 31 deletions

diff --git a/include/osmocom/core/utils.h b/include/osmocom/core/utils.h
index 16159d3d..e3728cd0 100644
--- a/include/osmocom/core/utils.h
+++ b/include/osmocom/core/utils.h
@@ -137,7 +137,7 @@ bool osmo_identifier_valid(const char *str);
 bool osmo_separated_identifiers_valid(const char *str, const char *sep_chars);
 
 const char *osmo_escape_str(const char *str, int len);
-const char *osmo_escape_str_buf(const char *str, int in_len, char *buf, size_t bufsize);
+char *osmo_escape_str_buf(const char *str, int in_len, char *buf, size_t bufsize);
 const char *osmo_quote_str(const char *str, int in_len);
 const char *osmo_quote_str_buf(const char *str, int in_len, char *buf, size_t bufsize);
 
diff --git a/src/utils.c b/src/utils.c
index 2d5bcb0e..019e7338 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -538,14 +538,14 @@ bool osmo_identifier_valid(const char *str)
 	return osmo_separated_identifiers_valid(str, NULL);
 }
 
-/*! Return the string with all non-printable characters escaped.
+/*! Return the string with all non-printable characters escapeda, in user-supplied buffer.
  * \param[in] str  A string that may contain any characters.
  * \param[in] len  Pass -1 to print until nul char, or >= 0 to force a length.
  * \param[inout] buf  string buffer to write escaped characters to.
  * \param[in] bufsize  size of \a buf.
- * \returns buf containing an escaped representation, possibly truncated, or str itself.
+ * \returns buf containing an escaped representation, possibly truncated.
  */
-const char *osmo_escape_str_buf(const char *str, int in_len, char *buf, size_t bufsize)
+char *osmo_escape_str_buf(const char *str, int in_len, char *buf, size_t bufsize)
 {
 	int in_pos = 0;
 	int next_unprintable = 0;
@@ -567,9 +567,10 @@ const char *osmo_escape_str_buf(const char *str, int in_len, char *buf, size_t b
 		     && str[next_unprintable] != '\\';
 		     next_unprintable++);
 
-		if (next_unprintable == in_len
-		    && in_pos == 0)
-			return str;
+		if (next_unprintable == in_len && in_pos == 0) {
+			osmo_strlcpy(buf, str, bufsize);
+			return buf;
+		}
 
 		while (in_pos < next_unprintable && out_pos < out_len)
 			out[out_pos++] = str[in_pos++];
@@ -633,25 +634,13 @@ const char *osmo_escape_str(const char *str, int in_len)
  */
 const char *osmo_quote_str_buf(const char *str, int in_len, char *buf, size_t bufsize)
 {
-	const char *res;
 	int l;
 	if (!str)
 		return "NULL";
 	if (bufsize < 3)
 		return "<buf-too-small>";
 	buf[0] = '"';
-	res = osmo_escape_str_buf(str, in_len, buf + 1, bufsize - 2);
-	/* if osmo_escape_str_buf() returned the str itself, we need to copy it to buf to be able to
-	 * quote it. */
-	if (res == str) {
-		/* max_len = bufsize - two quotes - nul term */
-		int max_len = bufsize - 2 - 1;
-		if (in_len >= 0)
-			max_len = OSMO_MIN(in_len, max_len);
-		/* It is not allowed to pass unterminated strings into osmo_strlcpy() :/ */
-		strncpy(buf + 1, str, max_len);
-		buf[1 + max_len] = '\0';
-	}
+	osmo_escape_str_buf(str, in_len, buf + 1, bufsize - 2);
 	l = strlen(buf);
 	buf[l] = '"';
 	buf[l+1] = '\0'; /* both osmo_escape_str_buf() and max_len above ensure room for '\0' */
diff --git a/tests/utils/utils_test.c b/tests/utils/utils_test.c
index d592fe04..711d6e12 100644
--- a/tests/utils/utils_test.c
+++ b/tests/utils/utils_test.c
@@ -545,7 +545,7 @@ static void str_escape_test(void)
 
 	printf("- passthru:\n");
 	res = osmo_escape_str(printable, -1);
-	if (res != printable)
+	if (strcmp(res, printable))
 		printf("NOT passed through! \"%s\"\n", res);
 	else
 		printf("passed through unchanged \"%s\"\n", res);
@@ -560,14 +560,6 @@ static void str_escape_test(void)
 	memset(out_buf, 0x7f, sizeof(out_buf));
 	printf("\"%s\"\n", osmo_escape_str_buf((const char *)in_buf, sizeof(in_buf), out_buf, 10));
 	OSMO_ASSERT(out_buf[10] == 0x7f);
-
-	printf("- passthrough without truncation when no escaping needed:\n");
-	memset(in_buf, 'x', sizeof(in_buf));
-	in_buf[19] = 'E';
-	in_buf[20] = '\0';
-	memset(out_buf, 0x7f, sizeof(out_buf));
-	printf("\"%s\"\n", osmo_escape_str_buf((const char *)in_buf, -1, out_buf, 10));
-	OSMO_ASSERT(out_buf[0] == 0x7f);
 }
 
 static void str_quote_test(void)
diff --git a/tests/utils/utils_test.ok b/tests/utils/utils_test.ok
index 1215ddd1..8fce9f13 100644
--- a/tests/utils/utils_test.ok
+++ b/tests/utils/utils_test.ok
@@ -232,8 +232,6 @@ passed through unchanged "printable"
 ""
 - truncation when too long:
 "\axxxxxxE"
-- passthrough without truncation when no escaping needed:
-"xxxxxxxxxxxxxxxxxxxE"
 
 Testing string quoting
 - all chars from 0 to 255 in batches of 16: