libc: add string operations for libc

CMakeLists.txt

@@ -4,7 +4,7 @@ cmake_minimum_required(VERSION 3.14.0)
 
 project(gaybsd VERSION 0.1.0 LANGUAGES C ASM)
 set(CMAKE_C_STANDARD 11)
-set(CMAKE_C_EXTENSIONS OFF)
+set(CMAKE_C_EXTENSIONS ON)
 
 if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME)
     set_property(GLOBAL PROPERTY USE_FOLDERS ON)
@@ -33,11 +33,21 @@ set(CMAKE_LINKER_FLAGS "${CMAKE_LINKER_FLAGS} -nodefaultlibs -static --whole-arc
 set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -nostdlib -nodefaultlibs -static")
 
 set(GAY_INCLUDE_DIRS
-    ${CMAKE_CURRENT_SOURCE_DIR}/include
-    ${CMAKE_CURRENT_SOURCE_DIR}/arch/${ARCH}/include
-    ${CMAKE_CURRENT_BINARY_DIR}/include
+    "${CMAKE_SOURCE_DIR}/include"
+    "${CMAKE_SOURCE_DIR}/arch/${ARCH}/include"
+    "${CMAKE_BINARY_DIR}/include"
 )
 
+set(GAY_DEFINITIONS
+    "_GAY_SOURCE=202109L"
+)
+set(GAY_KERNEL_DEFINITIONS
+    "__KERNEL__"
+    ${GAY_DEFINITIONS}
+)
+
+include("lib/lib.cmake")
+
 add_subdirectory("boot")
 
 add_executable(gaybsd_image.elf)

include/string.h

@@ -0,0 +1,102 @@
+/* See the end of this file for copyright and license terms. */
+
+#pragma once
+
+#include <gay/types.h>
+
+/**
+ * @brief Copy `n` bytes from `src` to `dest`.
+ *
+ * @param dest The destination
+ * @param src The source
+ * @param n The amount of bytes to copy
+ * @returns A pointer to `dest`
+ */
+void *memcpy(void *dest, const void *src, size_t n);
+
+/**
+ * @brief Starting from `ptr`, fill `n` bytes with the constant byte `c`.
+ *
+ * @param ptr The start of the memory region
+ * @param c The byte to fill with
+ * @param n The amount of bytes to write
+ * @returns A pointer to `ptr`
+ */
+void *memset(void *ptr, int c, size_t n);
+
+/**
+ * @brief Copy a memory area.
+ * The two areas may overlap since the individual bytes are copied to a
+ * temporary array first.
+ *
+ * @param dest The destination address
+ * @param src The source address
+ * @param n The amount of bytes to copy
+ * @return a pointer to dest
+ */
+void *memmove(void *dest, const void *src, size_t n);
+
+/**
+ * @brief Compare the two strings `s1` and `s2`.
+ *
+ * @param s1 The first string
+ * @param s2 The second string
+ * @returns `0` if both strings are equal, a positive value f `s1` is greater
+ *	than `s2`, and a negative value if `s1` is less than `s2`
+ */
+int strcmp(const char *s1, const char *s2);
+
+/**
+ * @brief Copy a `NUL` terminated string from `src` to `dest`.
+ *
+ * @param dest The destination to copy to.  The memory region must be able to
+ *	hold the entire string plus one byte for the terminator.
+ * @param src The original string to copy from
+ * @returns A pointer to the destination string
+ */
+char *strcpy(char *dest, const char *src);
+
+/**
+ * @brief Copy a `NUL` terminated string from `src` to `dest`, but at most `n` characters.
+ * Note that this may cause `dest` to miss a `NUL` terminator.
+ *
+ * @param dest The destination to copy to.  The memory region must be able to
+ *	hold the entire string plus one byte for the terminator.
+ * @param src The original string to copy from
+ * @param n The amount of characters to copy at most
+ * @returns A pointer to the destination string
+ */
+char *strncpy(char *dest, const char *src, size_t n);
+
+/**
+ * @brief Compute the length of the `NUL` terminated string `s`.
+ *
+ * @param s The string
+ * @returns The length of `s` without the `NUL` terminator
+ */
+size_t strlen(const char *s);
+
+#if _POSIX_C_SOURCE >= 200809L || _GAY_SOURCE >= 202109L
+/**
+ * @brief Compute the length of the `NUL` terminated string `s`, but at most `maxlen` bytes.
+ *
+ * @param s The string
+ * @param maxlen Maximum bytes after which to return
+ * @returns The length of `s` without the `NUL` terminator, but at most `maxlen`
+ */
+size_t strnlen(const char *s, size_t maxlen);
+#endif
+
+/*
+ * This file is part of GayBSD.
+ * Copyright (c) 2021 fef <owo@fef.moe>.
+ *
+ * GayBSD is nonviolent software: you may only use, redistribute, and/or
+ * modify it under the terms of the Cooperative Nonviolent Public License
+ * (CNPL) as found in the LICENSE file in the source code root directory
+ * or at <https://git.pixie.town/thufie/npl-builder>; either version 7
+ * of the license, or (at your option) any later version.
+ *
+ * GayBSD comes with ABSOLUTELY NO WARRANTY, to the extent
+ * permitted by applicable law.  See the CNPL for details.
+ */

lib/c/CMakeLists.txt

@@ -0,0 +1,21 @@
+# See the end of this file for copyright and license terms.
+
+add_library(c)
+target_include_directories(c PRIVATE ${GAY_INCLUDE_DIRS})
+target_compile_definitions(c PRIVATE ${GAY_DEFINITIONS})
+
+target_sources(c PRIVATE
+    string.c
+)
+
+# This file is part of GayBSD.
+# Copyright (c) 2021 fef <owo@fef.moe>.
+#
+# GayBSD is nonviolent software: you may only use, redistribute, and/or
+# modify it under the terms of the Cooperative Nonviolent Public License
+# (CNPL) as found in the LICENSE file in the source code root directory
+# or at <https://git.pixie.town/thufie/npl-builder>; either version 7
+# of the license, or (at your option) any later version.
+#
+# GayBSD comes with ABSOLUTELY NO WARRANTY, to the extent
+# permitted by applicable law.  See the CNPL for details.

lib/c/string.c

@@ -0,0 +1,127 @@
+/* See the end of this file for copyright and license terms. */
+
+#include <gay/types.h>
+
+#include <string.h>
+
+int memcmp(const void *s1, const void *s2, size_t n)
+{
+	int delta = 0;
+
+	while (n-- > 0) {
+		/* POSIX explicitly wants a cast to unsigned char */
+		delta = *(const unsigned char *)s1++ - *(const unsigned char *)s2++;
+		if (delta != 0)
+			break;
+	}
+
+	return delta;
+}
+
+void *memcpy(void *dest, const void *src, size_t n)
+{
+	u8 *tmp = (u8 *)dest;
+
+	while (n-- > 0)
+		*tmp++ = *(const u8 *)src++;
+
+	return dest;
+}
+
+void *memset(void *ptr, int c, size_t n)
+{
+	char *tmp = (char *)ptr;
+
+	while (n-- > 0)
+		*tmp++ = (char)c;
+
+	return ptr;
+}
+
+void *memmove(void *dest, const void *src, size_t n)
+{
+	char *tmp = (char *)dest;
+	const char *s = (const char *)src;
+
+	if (dest == src)
+		return dest;
+
+	if (dest < src) {
+		while (n-- != 0)
+			*tmp++ = *s++;
+	} else {
+		tmp += n;
+		s += n;
+		while (n-- != 0)
+			*--tmp = *--s;
+	}
+
+	return dest;
+}
+
+int strcmp(const char *s1, const char *s2)
+{
+	while (*s1 == *s2) {
+		if (*s1++ == '\0' || *s2++ == '\0')
+			break;
+	}
+
+	/* POSIX explicitly wants a cast to unsigned char */
+	return *((const unsigned char *)s1) - *((const unsigned char *)s2);
+}
+
+char *strcpy(char *dest, const char *src)
+{
+	char *tmp = dest;
+
+	while ((*tmp++ = *src++) != '\0');
+		/* nothing */
+
+	return dest;
+}
+
+char *strncpy(char *dest, const char *src, size_t n)
+{
+	char *tmp = dest;
+
+	while (n-- != 0) {
+		if ((*tmp++ = *src++) == '\0')
+			break;
+	}
+
+	return dest;
+}
+
+size_t strlen(const char *s)
+{
+	const char *tmp = s;
+
+	while (*tmp++ != '\0');
+		/* nothing */
+
+	return (size_t)tmp - (size_t)s - 1;
+}
+
+size_t strnlen(const char *s, size_t maxlen)
+{
+	const char *tmp = s;
+
+	while (*tmp++ != '\0' && maxlen-- > 0);
+		/* nothing */
+
+	return (size_t)tmp - (size_t)s - 1;
+}
+
+/*
+ * This file is part of GayBSD.
+ * Copyright (c) 2021 fef <owo@fef.moe>.
+ *
+ * GayBSD is nonviolent software: you may only use, redistribute, and/or
+ * modify it under the terms of the Cooperative Nonviolent Public License
+ * (CNPL) as found in the LICENSE file in the source code root directory
+ * or at <https://git.pixie.town/thufie/npl-builder>; either version 7
+ * of the license, or (at your option) any later version.
+ *
+ * GayBSD comes with ABSOLUTELY NO WARRANTY, to the extent
+ * permitted by applicable law.  See the CNPL for details.
+ */

lib/lib.cmake

@@ -0,0 +1,15 @@
+# See the end of this file for copyright and license terms.
+
+add_subdirectory("${CMAKE_CURRENT_LIST_DIR}/c")
+
+# This file is part of GayBSD.
+# Copyright (c) 2021 fef <owo@fef.moe>.
+#
+# GayBSD is nonviolent software: you may only use, redistribute, and/or
+# modify it under the terms of the Cooperative Nonviolent Public License
+# (CNPL) as found in the LICENSE file in the source code root directory
+# or at <https://git.pixie.town/thufie/npl-builder>; either version 7
+# of the license, or (at your option) any later version.
+#
+# GayBSD comes with ABSOLUTELY NO WARRANTY, to the extent
+# permitted by applicable law.  See the CNPL for details.