From 72634b98b9d78dbebec868b3e6fd0d5227162343 Mon Sep 17 00:00:00 2001
From: Stephen Heumann <heumann1@illinois.edu>
Date: Thu, 20 Nov 2014 23:12:01 -0600
Subject: [PATCH] In redirection operations, map fds 0/1/2 to 1/2/3 so they
 work as stdin/stdout/stderr, preserving compatibility with Unix shell
 scripts.

Also do a similar mapping for fds passed to "read -u" and "test -t".
---
 coreutils/test.c     | 14 ++++++++++++--
 shell/hush.c         | 24 ++++++++++++++++++------
 shell/shell.common.c |  5 +++++
 3 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/coreutils/test.c b/coreutils/test.c
index 4dc36e8a9..7ffd8132b 100644
--- a/coreutils/test.c
+++ b/coreutils/test.c
@@ -782,8 +782,18 @@ static number_t primary(enum token n)
 			unnest_msg_and_return(args[0][0] == '\0', ("<primary"));
 		if (n == STRNZ)
 			unnest_msg_and_return(args[0][0] != '\0', ("<primary"));
-		if (n == FILTT)
-			unnest_msg_and_return(isatty(getn(*args)), ("<primary: isatty(%s)", *args));
+		if (n == FILTT) {
+			/* Map fds for stdin/stdout/stderr from the Unix fds to GNO ones.
+			 * Existing GNO /bin/test doesn't map fds here, but we prioritize 
+			 * compatibility with Unix scripts and do the remapping.
+			 */
+			number_t fd = getn(*args);
+#ifdef __GNO__
+			if (fd >= 0 && fd <= 2)
+				fd++;
+#endif
+			unnest_msg_and_return(isatty(fd), ("<primary: isatty(%s)", *args));
+		}
 		unnest_msg_and_return(filstat(*args, n), ("<primary: filstat(%s)", *args));
 	}
 
diff --git a/shell/hush.c b/shell/hush.c
index b7b132452..5ede47299 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -495,11 +495,11 @@ static const struct {
 	signed char default_fd;
 	char descrip[3];
 } redir_table[] = {
-	{ O_RDONLY,                  0, "<"  },
-	{ O_CREAT|O_TRUNC|O_WRONLY,  1, ">"  },
-	{ O_CREAT|O_APPEND|O_WRONLY, 1, ">>" },
-	{ O_CREAT|O_RDWR,            1, "<>" },
-	{ O_RDONLY,                  0, "<<" },
+	{ O_RDONLY,                  STDIN_FILENO, "<"  },
+	{ O_CREAT|O_TRUNC|O_WRONLY,  STDOUT_FILENO, ">"  },
+	{ O_CREAT|O_APPEND|O_WRONLY, STDOUT_FILENO, ">>" },
+	{ O_CREAT|O_RDWR,            STDOUT_FILENO, "<>" },
+	{ O_RDONLY,                  STDIN_FILENO, "<<" },
 /* Should not be needed. Bogus default_fd helps in debugging */
 /*	{ O_RDONLY,                 77, "<<" }, */
 };
@@ -3603,7 +3603,15 @@ static int parse_redirect(struct parse_context *ctx,
 	/* redir->next = NULL; */
 	/* redir->rd_filename = NULL; */
 	redir->rd_type = style;
-	redir->rd_fd = (fd == -1) ? redir_table[style].default_fd : fd;
+	
+	/* On GNO, we map fd 0/1/2 in scripts to stdin/stdout/stderr 
+	 * to preserve compatibility with Unix shell scripts. */
+	redir->rd_fd = (fd == -1) ? redir_table[style].default_fd : 
+#ifndef __GNO__
+								fd;
+#else
+								(fd < 3 ? fd + 1 : fd);
+#endif
 
 	debug_printf_parse(("redirect type %d %s\n", redir->rd_fd,
 				redir_table[style].descrip));
@@ -3613,6 +3621,10 @@ static int parse_redirect(struct parse_context *ctx,
 		/* Erik had a check here that the file descriptor in question
 		 * is legit; I postpone that to "run time"
 		 * A "-" representation of "close me" shows up as a -3 here */
+#ifdef __GNO__
+		if (redir->rd_dup >= 0 && redir->rd_dup <= 2)
+			redir->rd_dup++;
+#endif
 		debug_printf_parse(("duplicating redirect '%d>&%d'\n",
 				redir->rd_fd, redir->rd_dup));
 	} else {
diff --git a/shell/shell.common.c b/shell/shell.common.c
index 16cb397d0..b75a9685d 100644
--- a/shell/shell.common.c
+++ b/shell/shell.common.c
@@ -127,6 +127,11 @@ shell_builtin_read(void FAST_FUNC (*setvar)(const char *name, const char *val),
 		fd = bb_strtou(opt_u, NULL, 10);
 		if (fd < 0 || errno)
 			return "invalid file descriptor";
+#ifdef __GNO__
+		/* Map Unix standard stdin/stdout/stderr fds to GNO ones */
+		if (fd < 3)
+			fd++;
+#endif
 	}
 
 	if (opt_p && isatty(fd)) {