fmt: handy functions for pointer-length objects (#884)

* fmt: search substring in pointer-length object

* fmt: pl_strstr testcases

* fmt: convert pointer-length hex string to binary

* fmt: buffer string length for improved runtime

* fmt: fix typo

include/re_fmt.h

@@ -39,6 +39,7 @@ uint64_t pl_u64(const struct pl *pl);
 uint64_t pl_x64(const struct pl *pl);
 double   pl_float(const struct pl *pl);
 int      pl_bool(bool *val, const struct pl *pl);
+int      pl_hex(const struct pl *pl, uint8_t *hex, size_t len);
 bool     pl_isset(const struct pl *pl);
 int      pl_strcpy(const struct pl *pl, char *str, size_t size);
 int      pl_strdup(char **dst, const struct pl *src);
@@ -49,6 +50,7 @@ int      pl_cmp(const struct pl *pl1, const struct pl *pl2);
 int      pl_casecmp(const struct pl *pl1, const struct pl *pl2);
 const char *pl_strchr(const struct pl *pl, char c);
 const char *pl_strrchr(const struct pl *pl, char c);
+const char *pl_strstr(const struct pl *pl, const char *str);
 int      pl_trim(struct pl *pl);
 int      pl_ltrim(struct pl *pl);
 int      pl_rtrim(struct pl *pl);

src/fmt/pl.c

@@ -355,6 +355,29 @@ int pl_bool(bool *val, const struct pl *pl)
 }
 
 
+/**
+ * Convert an ASCII hex string as a pointer-length object to binary format
+ *
+ * @param pl  Pointer-length object
+ * @param hex Destination binary buffer
+ * @param len Length of binary buffer
+ *
+ * @return 0 if success, otherwise errorcode
+ */
+int pl_hex(const struct pl *pl, uint8_t *hex, size_t len)
+{
+	if (!pl_isset(pl) || !hex || (pl->l != (2 * len)))
+		return EINVAL;
+
+	for (size_t i = 0; i < pl->l; i += 2) {
+		hex[i/2]  = ch_hex(*(pl->p + i)) << 4;
+		hex[i/2] += ch_hex(*(pl->p + i +1));
+	}
+
+	return 0;
+}
+
+
 /**
  * Check if pointer-length object is set
  *
@@ -655,6 +678,39 @@ const char *pl_strrchr(const struct pl *pl, char c)
 }
 
 
+/**
+ * Locate the first substring in a pointer-length string
+ *
+ * @param pl  Pointer-length string
+ * @param str Substring to locate
+ *
+ * @return Pointer to first char if substring is found, otherwise NULL
+ */
+const char *pl_strstr(const struct pl *pl, const char *str)
+{
+	size_t len = str_len(str);
+
+	/*case pl not set & pl is not long enough*/
+	if (!pl_isset(pl) || pl->l < len)
+		return NULL;
+
+	/*case str is empty or just '\0'*/
+	if (!len)
+		return pl->p;
+
+	for (size_t i = 0; i < pl->l; ++i) {
+		/*case rest of pl is not long enough*/
+		if (pl->l - i < len)
+			return NULL;
+
+		if (!memcmp(pl->p + i, str, len))
+			return pl->p + i;
+	}
+
+	return NULL;
+}
+
+
 /**
  * Trim white space characters at start of pointer-length string
  *

test/fmt.c

@@ -30,6 +30,8 @@ int test_fmt_pl(void)
 	const struct pl pl4  = PL("rattarei4");
 	const char str0[] = "rattarei";
 	const char str1[] = "rattaray";
+	const char str2[] = "foo";
+	const char str3[] = "bar";
 	struct pl pl5, pl6;
 	const struct pl pl7   = PL("hei");
 	const struct pl pl7_  = PL("Hei");
@@ -116,6 +118,20 @@ int test_fmt_pl(void)
 	if (NULL != pl_strrchr(&pl_empty, 'r'))
 		goto out;
 
+	/* pl_strstr() */
+	if (pl.p != pl_strstr(&pl, str0))
+		goto out;
+	if (pl1.p != pl_strstr(&pl1, str2))
+		goto out;
+	if (pl1.p + 3 != pl_strstr(&pl1, str3))
+		goto out;
+	if (NULL != pl_strstr(&pl, str1))
+		goto out;
+	if (pl.p != pl_strstr(&pl, ""))
+		goto out;
+	if (NULL != pl_strstr(&pl1, str0))
+		goto out;
+
 	return 0;
  out:
 	return EINVAL;