[PATCH] newlib: riscv: Remove undefined behavior in strlen()

Pointer arithmetic overflow is undefined behavior, so use a signed type
to avoid it.

Signed-off-by: Eric Salem <[email protected]>
---
While strlen() has worked this way since the beginning, it's better to
not depend on compilers not changing the behavior when optimizing. Clang
will take advantage of this:
https://releases.llvm.org/20.1.0/tools/clang/docs/ReleaseNotes.html#potentially-breaking-changes

 newlib/libc/machine/riscv/strlen.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/newlib/libc/machine/riscv/strlen.c b/newlib/libc/machine/riscv/strlen.c
index 9f1be1b0e70e..8ab5ce53737a 100644
--- a/newlib/libc/machine/riscv/strlen.c
+++ b/newlib/libc/machine/riscv/strlen.c
@@ -9,6 +9,7 @@
    http://www.opensource.org/licenses.
 */
 
+#include <sys/types.h>
 #include <string.h>
 #include <stdint.h>
 #include "rv_string.h"
@@ -38,7 +39,9 @@ size_t strlen(const char *str)
   asm volatile ("" : "+r"(ps)); /* prevent "optimization" */
 
   str = (const char *)ps;
-  size_t ret = str - start, sp = sizeof (*ps);
+
+  size_t ret = str - start;
+  ssize_t sp = sizeof (*ps);
 
   #if __riscv_zbb
     psval = ~__LIBC_RISCV_ZBB_ORC_B(psval);
-- 
2.49.0