tools/nolibc/string: split the string functions into string.h

The string manipulation functions (mem*, str*) are now found in
string.h. The file depends on almost nothing and will be
usable from other includes if needed. Maybe more functions could
be added.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

1 files changed, 107 insertions, 0 deletions

diff --git a/tools/include/nolibc/string.h b/tools/include/nolibc/string.h
new file mode 100644
index 000000000000..8a23cda2d450
--- /dev/null
+++ b/tools/include/nolibc/string.h
@@ -0,0 +1,107 @@
+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+/*
+ * string function definitions for NOLIBC
+ * Copyright (C) 2017-2021 Willy Tarreau <w@1wt.eu>
+ */
+
+#ifndef _NOLIBC_STRING_H
+#define _NOLIBC_STRING_H
+
+#include "std.h"
+
+/*
+ * As much as possible, please keep functions alphabetically sorted.
+ */
+
+static __attribute__((unused))
+int memcmp(const void *s1, const void *s2, size_t n)
+{
+	size_t ofs = 0;
+	char c1 = 0;
+
+	while (ofs < n && !(c1 = ((char *)s1)[ofs] - ((char *)s2)[ofs])) {
+		ofs++;
+	}
+	return c1;
+}
+
+static __attribute__((unused))
+void *memmove(void *dst, const void *src, size_t len)
+{
+	ssize_t pos = (dst <= src) ? -1 : (long)len;
+	void *ret = dst;
+
+	while (len--) {
+		pos += (dst <= src) ? 1 : -1;
+		((char *)dst)[pos] = ((char *)src)[pos];
+	}
+	return ret;
+}
+
+/* must be exported, as it's used by libgcc on ARM */
+__attribute__((weak,unused))
+void *memcpy(void *dst, const void *src, size_t len)
+{
+	return memmove(dst, src, len);
+}
+
+static __attribute__((unused))
+void *memset(void *dst, int b, size_t len)
+{
+	char *p = dst;
+
+	while (len--)
+		*(p++) = b;
+	return dst;
+}
+
+static __attribute__((unused))
+char *strchr(const char *s, int c)
+{
+	while (*s) {
+		if (*s == (char)c)
+			return (char *)s;
+		s++;
+	}
+	return NULL;
+}
+
+static __attribute__((unused))
+char *strcpy(char *dst, const char *src)
+{
+	char *ret = dst;
+
+	while ((*dst++ = *src++));
+	return ret;
+}
+
+/* this function is only used with arguments that are not constants */
+static __attribute__((unused))
+size_t nolibc_strlen(const char *str)
+{
+	size_t len;
+
+	for (len = 0; str[len]; len++);
+	return len;
+}
+
+#define strlen(str) ({                          \
+	__builtin_constant_p((str)) ?           \
+		__builtin_strlen((str)) :       \
+		nolibc_strlen((str));           \
+})
+
+static __attribute__((unused))
+char *strrchr(const char *s, int c)
+{
+	const char *ret = NULL;
+
+	while (*s) {
+		if (*s == (char)c)
+			ret = s;
+		s++;
+	}
+	return (char *)ret;
+}
+
+#endif /* _NOLIBC_STRING_H */