tee(1): use idiomatic write loop

tee(1) handles partial writes correctly, but the more idiomatic write
loop is shorter and easier to audit than this heterodox approach.

ok millert@

diff --git a/usr.bin/tee/tee.c b/usr.bin/tee/tee.c
index f0cd6f2..826aeaa 100644 (file)
--- a/usr.bin/tee/tee.c
+++ b/usr.bin/tee/tee.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: tee.c,v 1.12 2017/07/11 13:14:59 bluhm Exp $  */
+/*     $OpenBSD: tee.c,v 1.13 2021/11/21 16:15:43 cheloha Exp $        */
 /*     $NetBSD: tee.c,v 1.5 1994/12/09 01:43:39 jtc Exp $      */
 
 /*
@@ -68,7 +68,6 @@ main(int argc, char *argv[])
        struct list *p;
        int fd;
        ssize_t n, rval, wval;
-       char *bp;
        int append, ch, exitval;
        char buf[8192];
 
@@ -112,16 +111,14 @@ main(int argc, char *argv[])
 
        while ((rval = read(STDIN_FILENO, buf, sizeof(buf))) > 0) {
                SLIST_FOREACH(p, &head, next) {
-                       n = rval;
-                       bp = buf;
-                       do {
-                               if ((wval = write(p->fd, bp, n)) == -1) {
+                       for (n = 0; n < rval; n += wval) {
+                               wval = write(p->fd, buf + n, rval - n);
+                               if (wval == -1) {
                                        warn("%s", p->name);
                                        exitval = 1;
                                        break;
                                }
-                               bp += wval;
-                       } while (n -= wval);
+                       }
                }
        }
        if (rval == -1) {