NetBSD Problem Report #55551

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Date: Sat,  8 Aug 2020 14:39:37 +0000 (UTC)
From: soumendra@tamu.edu
Reply-To: soumendra@tamu.edu
To: gnats-bugs@NetBSD.org
Subject: [PATCH] script(1): Minor modification to tcgetattr error handling.
X-Send-Pr-Version: www-1.0

>Number:         55551
>Category:       bin
>Synopsis:       [PATCH] script(1): Minor modification to tcgetattr error handling.
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Aug 08 14:40:00 +0000 2020
>Last-Modified:  Sat Aug 08 16:05:01 +0000 2020
>Originator:     Soumendra Ganguly
>Release:        9.0
>Organization:
Texas A&M University
>Environment:
NetBSD localhost 9.0 NetBSD 9.0 (GENERIC) #0: Fri Feb 14 00:06:28 UTC 2020  mkrepro@mkrepro.NetBSD.org:/usr/src/sys/arch/amd64/compile/GENERIC amd64
>Description:
Upon more testing, it was found that the way tcgetattr is called in script(1), it cannot fail with errno == EBADF under normal circumstances (*): script(1) of course does not close its own stdin/stdout voluntarily mid execution.

(*) The only way I was able to force an EBADF was by using
[ p close(1) ] in gdb. Therefore, the EBADF error handling is not removed by this patch, it is only changed to errno != ENOTTY.

>How-To-Repeat:
There is no problem. Only minor restructuring is being done.
>Fix:
--- src/usr.bin/script/script.c	2020-08-08 04:42:52.154774132 -0500
+++ script.c	2020-08-08 04:58:28.624464431 -0500
@@ -158,16 +158,10 @@

 	if (tcgetattr(STDIN_FILENO, &tt) == -1 ||
 	    ioctl(STDIN_FILENO, TIOCGWINSZ, &win) == -1) {
-		switch (errno) {
-		case ENOTTY:
-			if (openpty(&master, &slave, NULL, NULL, NULL) == -1)
-				err(EXIT_FAILURE, "openpty");
-			break;
-		case EBADF:
-			err(EXIT_FAILURE, "%d not valid fd", STDIN_FILENO);
-		default: /* errno == EFAULT or EINVAL for ioctl. Not reached in practice. */
-			err(EXIT_FAILURE, "ioctl");
-		}
+		if (errno != ENOTTY) /* For debugger. */
+			err(EXIT_FAILURE, "tcgetattr/ioctl");
+		if (openpty(&master, &slave, NULL, NULL, NULL) == -1)
+			err(EXIT_FAILURE, "openpty");
 	} else {
 		if (openpty(&master, &slave, NULL, &tt, &win) == -1)
 			err(EXIT_FAILURE, "openpty");
@@ -383,9 +377,8 @@
 	struct termios traw;

 	if (tcgetattr(STDOUT_FILENO, &tt) == -1) {
-		if (errno == EBADF)
-			err(EXIT_FAILURE, "%d not valid fd", STDOUT_FILENO);
-		/* errno == ENOTTY */
+		if (errno != ENOTTY) /* For debugger. */
+			err(EXIT_FAILURE, "tcgetattr");
 		return;
 	}
 	isterm = 1;

>Audit-Trail:
From: "Christos Zoulas" <christos@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/55551 CVS commit: src/usr.bin/script
Date: Sat, 8 Aug 2020 12:01:35 -0400

 Module Name:	src
 Committed By:	christos
 Date:		Sat Aug  8 16:01:35 UTC 2020

 Modified Files:
 	src/usr.bin/script: script.c

 Log Message:
 PR/55551 Soumendra Ganguly: Simplify tcgetattr error handling.


 To generate a diff of this commit:
 cvs rdiff -u -r1.25 -r1.26 src/usr.bin/script/script.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

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