lib: utils: implement internal strlcpy function

The strlcpy() function has only recently become available in glibc.
To ensure compatibility with legacy libc versions, this commit
implements an internal version of strlcpy().

The function has been adapted from the FreeBSD implementation to
fit our needs.

Signed-off-by: Arnaud Pouliquen <[email protected]>
(cherry picked from commit c7c85bcfeb4f2c1be772efea8a889aa796d1a7c1)

Upstream PR: OpenAMP/open-amp#620

Signed-off-by: Tomi Fontanilles <[email protected]>

lib/include/internal/string.h

@@ -0,0 +1,10 @@
+/*
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright (c) 2024, STMicroelectronics
+ *
+ */
+
+#include <string.h>
+
+size_t strlcpy(char *dest, const char *src, size_t size);

lib/utils/CMakeLists.txt

@@ -0,0 +1 @@
+collect (PROJECT_LIB_SOURCES string.c)

lib/utils/string.c

@@ -0,0 +1,53 @@
+/*
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright (c) 2024, STMicroelectronics
+ *
+ */
+
+#include <internal/string.h>
+
+/**
+ * @internal
+ *
+ * @brief Copies a string to a destination buffer with size limitation and returns the length of
+ *        the source string.
+ *
+ * This function copies up to `size - 1` characters from the source string `src`
+ * to the destination buffer `dest`, ensuring that the destination buffer is
+ * null-terminated. The function returns the length of the source string `src`.
+ * If the length of `src` is greater than or equal to `size`, the destination
+ * buffer will be truncated.
+ *
+ * @param dst Destination buffer where the string will be copied.
+ * @param src Source string to be copied.
+ * @param size Size of the destination buffer.
+ * @return The length of the source string `src`.
+ *
+ * @note If the size of the destination buffer is 0, the function does not copy any characters and
+ *       the destination buffer is not null-terminated.
+ * @note The function ensures that the destination buffer is always null-terminated if `size` is
+ *       greater than 0.
+ * @note: this code is inspired from the strlcpy.c file from freeBSD .
+ */
+
+size_t
+strlcpy(char *dst, const char *src, size_t size)
+{
+	size_t nleft = size;
+
+	/* Copy as many bytes as will fit. */
+	if (nleft != 0) {
+		while (--nleft != 0) {
+			*dst = *src++;
+			if (*dst++ == '\0')
+				break;
+		}
+	}
+
+	/* Not enough room in dst, add NUL and traverse rest of src. */
+	if (nleft == 0 && size != 0)
+		*dst = '\0';		/* NUL-terminate dst */
+
+	return strlen(src);
+}

open-amp/lib/CMakeLists.txt

@@ -10,6 +10,7 @@ collect (PROJECT_LIB_SOURCES version.c)
 add_subdirectory (virtio)
 add_subdirectory (rpmsg)
 add_subdirectory (remoteproc)
+add_subdirectory (utils)
 if (WITH_VIRTIO_MMIO_DRV)
 add_subdirectory (virtio_mmio)
 endif (WITH_VIRTIO_MMIO_DRV)
@@ -23,6 +24,7 @@ set (OPENAMP_LIB open_amp)
 
 configure_file(version.h.in ${PROJECT_BINARY_DIR}/include/generated/openamp/version_def.h)
 collect (PROJECT_INC_DIRS " ${PROJECT_BINARY_DIR}/include/generated/openamp")
+collect (PROJECT_INC_DIRS " ${PROJECT_BINARY_DIR}/include/internal")
 
 if (NOT CMAKE_INSTALL_LIBDIR)
 	set (CMAKE_INSTALL_LIBDIR "lib")