Author: jilles
Date: Fri Nov 30 23:51:33 2012
New Revision: 243731
URL: http://svnweb.freebsd.org/changeset/base/243731
Log:
libc: Allow setting close-on-exec in fopen/freopen/fdopen.
This commit adds a new mode option 'e' that must follow any 'b', '+' and/or
'x' options. C11 is clear about the 'x' needing to follow 'b' and/or '+' and
that is what we implement; therefore, require a strict position for 'e' as
well.
For freopen() with a non-NULL path argument and fopen(), the close-on-exec
flag is set iff the 'e' mode option is specified. For freopen() with a NULL
path argument and fdopen(), the close-on-exec flag is turned on if the 'e'
mode option is specified and remains unchanged otherwise.
Although the same behaviour for fopen() can be obtained by open(O_CLOEXEC)
and fdopen(), this needlessly complicates the calling code.
Apart from the ordering requirement, the new option matches glibc.
PR: kern/169320
Modified:
head/lib/libc/stdio/fdopen.c
head/lib/libc/stdio/flags.c
head/lib/libc/stdio/fopen.3
head/lib/libc/stdio/freopen.c
Modified: head/lib/libc/stdio/fdopen.c
==============================================================================
--- head/lib/libc/stdio/fdopen.c Fri Nov 30 23:50:07 2012
(r243730)
+++ head/lib/libc/stdio/fdopen.c Fri Nov 30 23:51:33 2012
(r243731)
@@ -80,6 +80,12 @@ fdopen(fd, mode)
if ((fp = __sfp()) == NULL)
return (NULL);
+
+ if ((oflags & O_CLOEXEC) && _fcntl(fd, F_SETFD, FD_CLOEXEC) == -1) {
+ fp->_flags = 0;
+ return (NULL);
+ }
+
fp->_flags = flags;
/*
* If opened for appending, but underlying descriptor does not have
Modified: head/lib/libc/stdio/flags.c
==============================================================================
--- head/lib/libc/stdio/flags.c Fri Nov 30 23:50:07 2012 (r243730)
+++ head/lib/libc/stdio/flags.c Fri Nov 30 23:51:33 2012 (r243731)
@@ -97,6 +97,7 @@ __sflags(mode, optr)
/* 'x' means exclusive (fail if the file exists) */
if (*mode == 'x') {
+ mode++;
if (m == O_RDONLY) {
errno = EINVAL;
return (0);
@@ -104,6 +105,10 @@ __sflags(mode, optr)
o |= O_EXCL;
}
+ /* set close-on-exec */
+ if (*mode == 'e')
+ o |= O_CLOEXEC;
+
*optr = m | o;
return (ret);
}
Modified: head/lib/libc/stdio/fopen.3
==============================================================================
--- head/lib/libc/stdio/fopen.3 Fri Nov 30 23:50:07 2012 (r243730)
+++ head/lib/libc/stdio/fopen.3 Fri Nov 30 23:51:33 2012 (r243731)
@@ -32,7 +32,7 @@
.\" @(#)fopen.3 8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
-.Dd October 17, 2011
+.Dd November 30, 2012
.Dt FOPEN 3
.Os
.Sh NAME
@@ -97,6 +97,14 @@ or
causes the
.Fn fopen
call to fail if the file already exists.
+An optional
+.Dq Li e
+following the above
+causes the
+.Fn fopen
+call to set the
+.Dv FD_CLOEXEC
+flag on the underlying file descriptor.
.Pp
The
.Fa mode
@@ -144,6 +152,11 @@ of the stream must be compatible with th
The
.Dq Li x
mode option is ignored.
+If the
+.Dq Li e
+mode option is present, the
+.Dv FD_CLOEXEC
+flag is set, otherwise it remains unchanged.
When the stream is closed via
.Xr fclose 3 ,
.Fa fildes
@@ -277,3 +290,7 @@ The
function
conforms to
.St -p1003.1-88 .
+The
+.Dq Li e
+mode option does not conform to any standard
+but is also supported by glibc.
Modified: head/lib/libc/stdio/freopen.c
==============================================================================
--- head/lib/libc/stdio/freopen.c Fri Nov 30 23:50:07 2012
(r243730)
+++ head/lib/libc/stdio/freopen.c Fri Nov 30 23:51:33 2012
(r243731)
@@ -118,6 +118,8 @@ freopen(file, mode, fp)
(void) ftruncate(fp->_file, (off_t)0);
if (!(oflags & O_APPEND))
(void) _sseek(fp, (fpos_t)0, SEEK_SET);
+ if (oflags & O_CLOEXEC)
+ (void) _fcntl(fp->_file, F_SETFD, FD_CLOEXEC);
f = fp->_file;
isopen = 0;
wantfd = -1;
@@ -194,7 +196,8 @@ finish:
* assume stderr is always fd STDERR_FILENO, even if being freopen'd.
*/
if (wantfd >= 0) {
- if (_dup2(f, wantfd) >= 0) {
+ if ((oflags & O_CLOEXEC ? _fcntl(f, F_DUP2FD_CLOEXEC, wantfd) :
+ _dup2(f, wantfd)) >= 0) {
(void)_close(f);
f = wantfd;
} else
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