string_copying.7: Reimplement stpecpy()

This implementation resembles more strtcpy(), so the differences are
more visible.  Also, it has no -1's, so it's a bit easier to implement
correctly.

Signed-off-by: Alejandro Colomar <alx@kernel.org>

1 files changed, 9 insertions, 8 deletions

diff --git a/man7/string_copying.7 b/man7/string_copying.7
index d79812a6a..0b1562e4c 100644
--- a/man7/string_copying.7
+++ b/man7/string_copying.7
@@ -734,19 +734,20 @@ ssize_t
 char *
 .IR stpecpy "(char *dst, char end[0], const char *restrict src)"
 {
-    char *p;
+    bool    trunc;
+    size_t  dsize, dlen, slen;
 \&
-    if (dst == NULL)
-        return NULL;
     if (dst == end)
         return end;
+    if (dst == NULL)
+        return NULL;
 \&
-    p = memccpy(dst, src, \[aq]\e0\[aq], end \- dst);
-    if (p != NULL)
-        return p \- 1;
+    dsize = end \- dst;
+    slen = strnlen(src, dsize);
+    trunc = (slen == dsize);
+    dlen = slen \- trunc;
 \&
-    /* truncation detected */
-    return stpcpy(end\-1, "");
+    return stpcpy(mempcpy(dst, src, dlen), "") + trunc;
 }
 .\" ----- SEE ALSO :: -------------------------------------------------/
 .SH SEE ALSO