lib/string/strchr/: strchrcnt(): Add function

Signed-off-by: Alejandro Colomar <alx@kernel.org>

lib/string/strchr/strchrcnt.c

@@ -0,0 +1,12 @@
+// SPDX-FileCopyrightText: 2024, Alejandro Colomar <alx@kernel.org>
+// SPDX-License-Identifier: BSD-3-Clause
+
+
+#include <config.h>
+
+#include "string/strchr/strchrcnt.h"
+
+#include <stddef.h>
+
+
+extern inline size_t strchrcnt(const char *s, char c);

lib/string/strchr/strchrcnt.h

@@ -0,0 +1,35 @@
+// SPDX-FileCopyrightText: 2024, Alejandro Colomar <alx@kernel.org>
+// SPDX-License-Identifier: BSD-3-Clause
+
+
+#ifndef SHADOW_INCLUDE_LIB_STRING_STRCHR_STRCHRCNT_H_
+#define SHADOW_INCLUDE_LIB_STRING_STRCHR_STRCHRCNT_H_
+
+
+#include <config.h>
+
+#include <stddef.h>
+
+#include "attr.h"
+#include "string/strcmp/streq.h"
+
+
+ATTR_STRING(1)
+inline size_t strchrcnt(const char *s, char c);
+
+
+inline size_t
+strchrcnt(const char *s, char c)
+{
+	size_t  n = 0;
+
+	for (; !streq(s, ""); s++) {
+		if (*s == c)
+			n++;
+	}
+
+	return n;
+}
+
+
+#endif  // include guard