Revert "lib: string: Fix strlcpy return value", fix callers

Both the Linux kernel and libbsd agree that strlcpy() should always
return strlen(src) and not include the NUL termination. The incorrect
U-Boot implementation makes it impossible to check the return value for
truncation, and breaks code written with the usual implementation in
mind (for example, fdtdec_add_reserved_memory() was subtly broken).

I reviewed all callers of strlcpy() and strlcat() and fixed them
according to my understanding of the intended function.

This reverts commit d3358ecc54 and adds
related fixes.

Fixes: d3358ecc54 ("lib: string: Fix strlcpy return value")
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Sean Anderson <sean.anderson@seco.com>

board/amlogic/vim3/vim3.c

@@ -104,8 +104,8 @@ int meson_ft_board_setup(void *blob, struct bd_info *bd)
 		}
 
 		/* Update PHY names (mandatory to disable USB3.0) */
-		len = strlcpy(data, "usb2-phy0", 32);
-		len += strlcpy(&data[len], "usb2-phy1", 32 - len);
+		len = strlcpy(data, "usb2-phy0", 32) + 1;
+		len += strlcpy(&data[len], "usb2-phy1", 32 - len) + 1;
 		ret = fdt_setprop(blob, node, "phy-names", data, len);
 		if (ret < 0) {
 			printf("vim3: failed to update usb phy names property (%d)\n", ret);
@@ -132,7 +132,7 @@ int meson_ft_board_setup(void *blob, struct bd_info *bd)
 		}
 
 		/* Enable PCIe */
-		len = strlcpy(data, "okay", 32);
+		len = strlcpy(data, "okay", 32) + 1;
 		ret = fdt_setprop(blob, node, "status", data, len);
 		if (ret < 0) {
 			printf("vim3: failed to enable pcie node (%d)\n", ret);

drivers/fastboot/fb_getvar.c

@@ -183,7 +183,7 @@ static void __maybe_unused getvar_has_slot(char *part_name, char *response)
 
 	/* part_name_wslot = part_name + "_a" */
 	len = strlcpy(part_name_wslot, part_name, PART_NAME_LEN - 3);
-	if (len > PART_NAME_LEN - 3)
+	if (len >= PART_NAME_LEN - 3)
 		goto fail;
 	strcat(part_name_wslot, "_a");
 

lib/string.c

@@ -116,20 +116,18 @@ char * strncpy(char * dest,const char *src,size_t count)
  * of course, the buffer size is zero). It does not pad
  * out the result like strncpy() does.
  *
- * Return: the number of bytes copied
+ * Return: strlen(src)
  */
 size_t strlcpy(char *dest, const char *src, size_t size)
 {
-	if (size) {
-		size_t srclen = strlen(src);
-		size_t len = (srclen >= size) ? size - 1 : srclen;
+	size_t ret = strlen(src);
 
+	if (size) {
+		size_t len = (ret >= size) ? size - 1 : ret;
 		memcpy(dest, src, len);
 		dest[len] = '\0';
-		return len + 1;
 	}
-
-	return 0;
+	return ret;
 }
 #endif
 
@@ -191,6 +189,8 @@ char * strncat(char *dest, const char *src, size_t count)
  * Compatible with *BSD: the result is always a valid NUL-terminated string that
  * fits in the buffer (unless, of course, the buffer size is zero). It does not
  * write past @size like strncat() does.
+ *
+ * Return: min(strlen(dest), size) + strlen(src)
  */
 size_t strlcat(char *dest, const char *src, size_t size)
 {

test/lib/strlcat.c

@@ -43,11 +43,11 @@ static int do_test_strlcat(struct unit_test_state *uts, int line, size_t align1,
 		s2[i] = 32 + 23 * i % (127 - 32);
 	s2[len2 - 1] = '\0';
 
-	expected = len2 < n ? min(len1 + len2 - 1, n) : n;
+	expected = min(strlen(s2), n) + strlen(s1);
 	actual = strlcat(s2, s1, n);
 	if (expected != actual) {
 		ut_failf(uts, __FILE__, line, __func__,
-			 "strlcat(s2, s1, 2) == len2 < n ? min(len1 + len2, n) : n",
+			 "strlcat(s2, s1, n) == min(len2, n) + len1",
 			 "Expected %#zx (%zd), got %#zx (%zd)",
 			 expected, expected, actual, actual);
 		return CMD_RET_FAILURE;