Date: Thu, 12 Jan 2012 10:06:45 +0100 From: Davide Italiano <davide.italiano@gmail.com> To: Eitan Adler <lists@eitanadler.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: <CACYV=-GfH31V_oU_gLWV1SjOLWYDoqW7V5g8kee%2Bwa2P9im2kA@mail.gmail.com> In-Reply-To: <CAF6rxg=EjkwFbXQt3i2Nnz6_dcZtdek-2YdqyZnAdVPxVaWR_Q@mail.gmail.com> References: <CAF6rxg=EjkwFbXQt3i2Nnz6_dcZtdek-2YdqyZnAdVPxVaWR_Q@mail.gmail.com>
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On Thu, Jan 12, 2012 at 6:01 AM, Eitan Adler <lists@eitanadler.com> wrote: > This is an implementation of dup3 for FreeBSD: > man page here (with a FreeBSD patch coming soon): > https://www.kernel.org/doc/man-pages/online/pages/man2/dup.2.html > > Is this implementation correct? If so any objection to adding this as > a supported syscall? > > > 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 +308,39 @@ > return (0); > } > > +#ifndef _SYS_SYSPROTO_H_ > +struct dup3_args { > + u_int from; > + u_int to; > + int flags; > +}; > +#endif > + > /* > + * Duplicate a file descriptor and allow for O_CLOEXEC > + */ > + > +/* ARGSUSED */ > +int > +sys_dup3(struct thread * const td, struct dup3_args * const uap) { > + > + KASSERT(td != NULL, ("%s: td == NULL", __func__)); > + KASSERT(uap != NULL, ("%s: uap == NULL", __func__)); > + > + if (uap->from == uap->to) > + return EINVAL; > + > + if (uap->flags & ~O_CLOEXEC) > + return EINVAL; > + > + const int dupflags = (uap->flags == O_CLOEXEC) ? > DUP_FIXED|DUP_CLOEXEC : DUP_FIXED; > + > + 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 +945,9 @@ > 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); } > > > -- > Eitan Adler > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org" >From what I can see it seems that dup3() is Linux specific and not POSIX, so maybe there are some issues in adding it, but I may be wrong. Davide
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