git: 70164d957eb2 - main - Fix truncation when ssize_t is larger than MAX_INT

The branch main has been updated by imp:

URL: https://cgit.FreeBSD.org/src/commit/?id=70164d957eb2d1147e0b52a4b1da45f64be8af8e

commit 70164d957eb2d1147e0b52a4b1da45f64be8af8e
Author:     Alfonso <gfunni234@gmail.com>
AuthorDate: 2021-07-24 16:52:31 +0000
Commit:     Warner Losh <imp@FreeBSD.org>
CommitDate: 2023-02-05 04:14:14 +0000

    Fix truncation when ssize_t is larger than MAX_INT
    
    Casting to int truncates size on some platforms, resulting swab not
    copying all the data. Cast len to size_t to avoid right shifting a
    signed value: we know here it's > 0, so we can safely cast it w/o losing
    precision.
    
    In addition, be more careful with signedness of char pointers and
    temporaries. Downgrade tmp from unsigned long to unsigned char since
    we're only reading and writing characters.
    
    Reviewed by: imp
    Pull Request: https://github.com/freebsd/freebsd-src/pull/516
---
 lib/libc/string/swab.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/lib/libc/string/swab.c b/lib/libc/string/swab.c
index 1a30ce813784..724ee48ea0c7 100644
--- a/lib/libc/string/swab.c
+++ b/lib/libc/string/swab.c
@@ -43,15 +43,16 @@ __FBSDID("$FreeBSD$");
 void
 swab(const void * __restrict from, void * __restrict to, ssize_t len)
 {
-	unsigned long temp;
-	int n;
-	char *fp, *tp;
+	unsigned char temp;
+	size_t n;
+	const unsigned char *fp;
+	unsigned char *tp;
 
 	if (len <= 0)
 		return;
-	n = len >> 1;
-	fp = (char *)from;
-	tp = (char *)to;
+	n  = (size_t)len >> 1;
+	fp = (const unsigned char *)from;
+	tp = (unsigned char *)to;
 #define	STEP	temp = *fp++,*tp++ = *fp++,*tp++ = temp
 	/* round to multiple of 8 */
 	for (; n & 0x7; --n)