shadow/libmisc/ttytype.c
Alejandro Colomar 5da8388fc6 ttytype(): Fix race
The intention of the code is just to not report an error message when
'typefile' doesn't exist.  If we call access(2) and then fopen(2),
there's a race.  It's not a huge problem, and the worst thing that can
happen is reporting an error when the file has been removed after
access(2).  It's not a problem, but we can fix the race and at the same
time clarify the intention of not warning about ENOENT and also remove
one syscall.  Seems like a win-win.

Suggested-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-02-09 10:03:03 -06:00

66 lines
1.2 KiB
C

/*
* SPDX-FileCopyrightText: 1989 - 1994, Julianne Frances Haugh
* SPDX-FileCopyrightText: 1996 - 1997, Marek Michałkiewicz
* SPDX-FileCopyrightText: 2003 - 2005, Tomasz Kłoczko
* SPDX-FileCopyrightText: 2008 - 2010, Nicolas François
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <config.h>
#ident "$Id$"
#include <stdio.h>
#include "prototypes.h"
#include "defines.h"
#include "getdef.h"
/*
* ttytype - set ttytype from port to terminal type mapping database
*/
void ttytype (const char *line)
{
FILE *fp;
char buf[BUFSIZ];
const char *typefile;
char *cp;
char type[1024] = "";
char port[1024];
if (getenv ("TERM") != NULL) {
return;
}
typefile = getdef_str ("TTYTYPE_FILE");
if (NULL == typefile) {
return;
}
fp = fopen (typefile, "r");
if (NULL == fp) {
if (errno != ENOENT)
perror (typefile);
return;
}
while (fgets (buf, sizeof buf, fp) == buf) {
if (buf[0] == '#') {
continue;
}
cp = strchr (buf, '\n');
if (NULL != cp) {
*cp = '\0';
}
if ( (sscanf (buf, "%1023s %1023s", type, port) == 2)
&& (strcmp (line, port) == 0)) {
break;
}
}
if ((feof (fp) == 0) && (ferror (fp) == 0) && (type[0] != '\0')) {
addenv ("TERM", type);
}
(void) fclose (fp);
}