Date: Thu, 12 Jan 2012 22:07:58 -0500 From: Eitan Adler <lists@eitanadler.com> To: Kostik Belousov <kostikbel@gmail.com> Cc: jilles@freebsd.org, FreeBSD Hackers <freebsd-hackers@freebsd.org>, Colin Percival <cperciva@freebsd.org> Subject: Re: dup3 syscall - atomic set O_CLOEXEC with dup2 Message-ID: <CAF6rxgn5uddFb4LOGb0E_OOpVMiFavOVHwnrKF7cFHb6tfrPjw@mail.gmail.com> In-Reply-To: <CAF6rxgne7M9xBb-mM1xsjPy3r-O%2BO%2BMzuYrsweG849V83MX3mA@mail.gmail.com> References: <CAF6rxg=EjkwFbXQt3i2Nnz6_dcZtdek-2YdqyZnAdVPxVaWR_Q@mail.gmail.com> <20120112100840.GV31224@deviant.kiev.zoral.com.ua> <CAF6rxgne7M9xBb-mM1xsjPy3r-O%2BO%2BMzuYrsweG849V83MX3mA@mail.gmail.com>
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Okay - here is version 2 (compile and run tested)
Index: sys/kern/kern_descrip.c
===================================================================
--- sys/kern/kern_descrip.c (revision 229830)
+++ sys/kern/kern_descrip.c (working copy)
@@ -110,6 +110,7 @@
/* Flags for do_dup() */
#define DUP_FIXED 0x1 /* Force fixed allocation */
#define DUP_FCNTL 0x2 /* fcntl()-style errors */
+#define DUP_CLOEXEC 0x4 /* Enable O_CLOEXEC on the new fs */
static int do_dup(struct thread *td, int flags, int old, int new,
register_t *retval);
@@ -307,7 +308,36 @@
return (0);
}
+struct dup3_args {
+ u_int from;
+ u_int to;
+ int flags;
+};
+
/*
+ * Duplicate a file descriptor and allow for O_CLOEXEC
+ */
+
+int
+sys_dup3(struct thread * td, struct dup3_args * uap) {
+ int dupflags;
+
+ if (uap->from == uap->to)
+ return (EINVAL);
+
+ if (uap->flags & ~O_CLOEXEC)
+ return (EINVAL);
+
+ dupflags = DUP_FIXED;
+ if (uap->flags & O_CLOEXEC)
+ dupflags |= DUP_CLOEXEC;
+
+ return (do_dup(td, dupflags, (int)uap->from, (int)uap->to,
+ td->td_retval));
+ return (0);
+}
+
+/*
* Duplicate a file descriptor to a particular value.
*
* Note: keep in mind that a potential race condition exists when closing
@@ -912,6 +942,9 @@
fdp->fd_lastfile = new;
*retval = new;
+ if (flags & DUP_CLOEXEC)
+ fdp->fd_ofileflags[new] |= UF_EXCLOSE;
+
/*
* If we dup'd over a valid file, we now own the reference to it
* and must dispose of it using closef() semantics (as if a
Index: sys/kern/syscalls.master
===================================================================
--- sys/kern/syscalls.master (revision 229830)
+++ sys/kern/syscalls.master (working copy)
@@ -951,5 +951,6 @@
off_t offset, off_t len); }
531 AUE_NULL STD { int posix_fadvise(int fd, off_t offset, \
off_t len, int advice); }
+532 AUE_NULL STD { int dup3(u_int from, u_int to, int flags); }
; Please copy any additions and changes to the following compatability tables:
; sys/compat/freebsd32/syscalls.master
Index: sys/compat/freebsd32/syscalls.master
===================================================================
--- sys/compat/freebsd32/syscalls.master (revision 229830)
+++ sys/compat/freebsd32/syscalls.master (working copy)
@@ -997,3 +997,4 @@
uint32_t offset1, uint32_t offset2,\
uint32_t len1, uint32_t len2, \
int advice); }
+532 AUE_NULL STD { int dup3(u_int from, u_int to, int flags); }
Index: lib/libc/sys/Symbol.map
===================================================================
--- lib/libc/sys/Symbol.map (revision 229830)
+++ lib/libc/sys/Symbol.map (working copy)
@@ -383,6 +383,7 @@
FBSD_1.3 {
posix_fadvise;
+ dup3;
};
FBSDprivate_1.0 {
--
Eitan Adler
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