[REDIR] Replace copyfd by savefd and use dup2 elsewhere

There are two kinds of users to copyfd, those that want to copy an fd to
an exact value and those that want to move an fd to a value >= 10.  The
former can simply use dup2 directly while the latter share a lot of common
code that now constitutes savefd.

1 files changed, 35 insertions, 30 deletions

diff --git a/src/redir.c b/src/redir.c
index aab1585..9e0fae5 100644
--- a/src/redir.c
+++ b/src/redir.c
@@ -138,21 +138,10 @@ redirect(union node *redir, int flags)
 		if (fd == newfd)
 			continue;
 		if (sv && *(p = &sv->renamed[fd]) == EMPTY) {
-			int i = fcntl(fd, F_DUPFD, 10);
-			if (i == -1) {
-				i = errno;
-				if (i != EBADF) {
-					const char *m = strerror(i);
-					close(newfd);
-					sh_error("%d: %s", fd, m);
-					/* NOTREACHED */
-				}
-			} else {
+			int i = savefd(fd);
+
+			if (i >= 0)
 				*p = i;
-				close(fd);
-			}
-		} else {
-			close(fd);
 		}
 #ifdef notyet
 		dupredirect(n, newfd, memory);
@@ -244,6 +233,7 @@ dupredirect(redir, f)
 #endif
 	{
 	int fd = redir->nfile.fd;
+	int err = 0;
 
 #ifdef notyet
 	memory[fd] = 0;
@@ -255,16 +245,24 @@ dupredirect(redir, f)
 				memory[fd] = 1;
 			else
 #endif
-				copyfd(redir->ndup.dupfd, fd);
+				if (dup2(f, fd) < 0) {
+					err = errno;
+					goto err;
+				}
+			return;
 		}
-		return;
-	}
+		f = fd;
+	} else if (dup2(f, fd) < 0)
+		err = errno;
+
+	close(f);
+	if (err < 0)
+		goto err;
 
-	if (f != fd) {
-		copyfd(f, fd);
-		close(f);
-	}
 	return;
+
+err:
+	sh_error("%d: %s", f, strerror(err));
 }
 
 
@@ -327,10 +325,8 @@ popredir(int drop)
 	rp = redirlist;
 	for (i = 0 ; i < 10 ; i++) {
 		if (rp->renamed[i] != EMPTY) {
-			if (!drop) {
-				close(i);
-				copyfd(rp->renamed[i], i);
-			}
+			if (!drop)
+				dup2(rp->renamed[i], i);
 			close(rp->renamed[i]);
 		}
 	}
@@ -372,17 +368,26 @@ clearredir(int drop)
 
 
 /*
- * Copy a file descriptor to be >= to.  Invokes sh_error on error.
+ * Move a file descriptor to > 10.  Invokes sh_error on error unless
+ * the original file dscriptor is not open.
  */
 
 int
-copyfd(int from, int to)
+savefd(int from)
 {
 	int newfd;
+	int err;
+
+	newfd = fcntl(from, F_DUPFD, 10);
+	err = newfd < 0 ? errno : 0;
+	if (err != EBADF) {
+		close(from);
+		if (err)
+			sh_error("%d: %s", from, strerror(err));
+		else
+			fcntl(newfd, F_SETFD, FD_CLOEXEC);
+	}
 
-	newfd = fcntl(from, F_DUPFD, to);
-	if (newfd < 0)
-		sh_error("%d: %s", from, strerror(errno));
 	return newfd;
 }