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add and "f" flag to fopen that makes sure we are opening a plain file,

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so that there is no chance to block.
This commit is contained in:
christos 2000-01-15 01:11:45 +00:00
parent b41faac27c
commit fc1a83184b
3 changed files with 51 additions and 14 deletions
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28
lib/libc/stdio/flags.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: flags.c,v 1.11 1999/09/20 04:39:27 lukem Exp $ */
/* $NetBSD: flags.c,v 1.12 2000/01/15 01:11:45 christos Exp $ */
/*-
* Copyright (c) 1990, 1993
@ -41,7 +41,7 @@
#if 0
static char sccsid[] = "@(#)flags.c 8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: flags.c,v 1.11 1999/09/20 04:39:27 lukem Exp $");
__RCSID("$NetBSD: flags.c,v 1.12 2000/01/15 01:11:45 christos Exp $");
#endif
#endif /* LIBC_SCCS and not lint */
@ -91,11 +91,25 @@ __sflags(mode, optr)
return (0);
}
/* [rwa]\+ or [rwa]b\+ means read and write */
if (*mode == '+' || (*mode == 'b' && mode[1] == '+')) {
ret = __SRW;
m = O_RDWR;
}
/*
* [rwa]\+ or [rwa]b\+ means read and write
* f means open only plain files.
*/
for (; *mode; mode++)
switch (*mode) {
case '+':
ret = __SRW;
m = O_RDWR;
break;
case 'f':
o |= O_NONBLOCK;
break;
case 'b':
break;
default: /* We could produce a warning here */
break;
}
*optr = m | o;
return (ret);
}

13
lib/libc/stdio/fopen.3
View File

@ -1,4 +1,4 @@
.\" $NetBSD: fopen.3,v 1.9 1999/01/12 15:27:28 kleink Exp $
.\" $NetBSD: fopen.3,v 1.10 2000/01/15 01:11:45 christos Exp $
.\"
.\" Copyright (c) 1990, 1991, 1993
.\" The Regents of the University of California. All rights reserved.
@ -87,12 +87,18 @@ The file is created if it does not exist.
.Pp
The
.Fa mode
string can also include the letter ``b'' either as a third character or
string can also include the letter ``b'' either as a last character or
as a character between the characters in any of the two-character strings
described above.
This is strictly for compatibility with
.St -ansiC
and has no effect; the ``b'' is ignored.
In addition the letter ``f'' in the mode string restricts fopen to plain
files; if the file opened is not a plain file,
.Fn fopen
will fail. This is a non
.St -ansiC
extension.
.Pp
Any created files will have mode
.Pf \\*q Dv S_IRUSR
@ -189,6 +195,9 @@ provided to
or
.Fn freopen
was invalid.
.It Bq Er EFTYPE
The file is not a plain file and the character ``f'' is specified
in the mode.
.El
.Pp
The

24
lib/libc/stdio/fopen.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: fopen.c,v 1.8 1999/09/20 04:39:27 lukem Exp $ */
/* $NetBSD: fopen.c,v 1.9 2000/01/15 01:11:45 christos Exp $ */
/*-
* Copyright (c) 1990, 1993
@ -41,7 +41,7 @@
#if 0
static char sccsid[] = "@(#)fopen.c 8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: fopen.c,v 1.8 1999/09/20 04:39:27 lukem Exp $");
__RCSID("$NetBSD: fopen.c,v 1.9 2000/01/15 01:11:45 christos Exp $");
#endif
#endif /* LIBC_SCCS and not lint */
@ -49,6 +49,7 @@ __RCSID("$NetBSD: fopen.c,v 1.8 1999/09/20 04:39:27 lukem Exp $");
#include <sys/stat.h>
#include <assert.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include "local.h"
@ -67,9 +68,19 @@ fopen(file, mode)
return (NULL);
if ((fp = __sfp()) == NULL)
return (NULL);
if ((f = open(file, oflags, DEFFILEMODE)) < 0) {
fp->_flags = 0; /* release */
return (NULL);
if ((f = open(file, oflags, DEFFILEMODE)) < 0)
goto release;
if (oflags & O_NONBLOCK) {
struct stat st;
if (fstat(f, &st) == -1) {
close(f);
goto release;
}
if (!S_ISREG(st.st_mode)) {
errno = EFTYPE;
close(f);
goto release;
}
}
fp->_file = f;
fp->_flags = flags;
@ -90,4 +101,7 @@ fopen(file, mode)
if (oflags & O_APPEND)
(void) __sseek((void *)fp, (fpos_t)0, SEEK_END);
return (fp);
release:
fp->_flags = 0; /* release */
return (NULL);
}