Re: POSIXfy readlink() call
On Mon, May 11, 2009 at 04:23:52PM -0400, John Baldwin wrote: On Monday 11 May 2009 2:58:14 pm Kostik Belousov wrote: On Mon, May 11, 2009 at 02:46:14PM -0400, John Baldwin wrote: On Monday 11 May 2009 2:33:09 pm Kostik Belousov wrote: On Mon, May 11, 2009 at 02:05:07PM -0400, John Baldwin wrote: On Friday 28 September 2007 10:39:56 pm Ighighi wrote: ^ Yes, I had this stuck in the back of my head from when it first appeared. The POXIX prototype for readlink(2) is: ssize_t readlink(const char *restrict path, char *restrict buf, size_t bufsize); It can't simply be corrected as it would change the ABI and thus requires a new system call, etc. However, do you really expect a symlink to be longer than 2^31 on a 64-bit machine? Yes, I agree that this is ABI change. Meantime, r176215 | ru | 2008-02-12 22:09:04 +0200 (Tue, 12 Feb 2008) | 5 lines Change readlink(2)'s return type and type of the last argument to match POSIX. Prodded by: Alexey Lyashkov I tried to convince ru@ that ABI breakage is not good, but has not succeeded. Ugh, is this only in HEAD? If so, I will back it out for 8.0. If this made it into a release then this is a far bigger mess. Oh, good, this is only in 8. I will fix this ASAP. I can just add the new syscall I guess. You need to symver the syscalls. It requires some ugly games with our syscall stubs, because gnu ld only honor .symver in the same object where the symbol is defined. I did prototyped this some time ago, by including a file with appropriate .symver from all stubs. So, after thinking about this out loud some more, it seems the ABI breakage would only be for 64-bit platforms that passed a -ve value as the buffer size. However, doing so would already either panic due to triggering an assertion, or result in otherwise undefined behavior and that making the new parameter unsigned actually results in the same undefined behavior in the non-panic case. For the record. I also suggest (re-)reading a thread http://lists.freebsd.org/pipermail/freebsd-current/2008-February/thread.html#83314 that resulted from the original commit where I try to make it clear that a scary ABI breakage Konstantin mentions is pure artificial. Cheers, -- Ruslan Ermilov r...@freebsd.org FreeBSD committer ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to freebsd-hackers-unsubscr...@freebsd.org
Re: POSIXfy readlink() call
On Friday 28 September 2007 10:39:56 pm Ighighi wrote: The POXIX prototype for readlink(2) is: ssize_t readlink(const char *restrict path, char *restrict buf, size_t bufsize); It can't simply be corrected as it would change the ABI and thus requires a new system call, etc. However, do you really expect a symlink to be longer than 2^31 on a 64-bit machine? -- John Baldwin ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to freebsd-hackers-unsubscr...@freebsd.org
Re: POSIXfy readlink() call
On Mon, May 11, 2009 at 02:05:07PM -0400, John Baldwin wrote: On Friday 28 September 2007 10:39:56 pm Ighighi wrote: ^ The POXIX prototype for readlink(2) is: ssize_t readlink(const char *restrict path, char *restrict buf, size_t bufsize); It can't simply be corrected as it would change the ABI and thus requires a new system call, etc. However, do you really expect a symlink to be longer than 2^31 on a 64-bit machine? Yes, I agree that this is ABI change. Meantime, r176215 | ru | 2008-02-12 22:09:04 +0200 (Tue, 12 Feb 2008) | 5 lines Change readlink(2)'s return type and type of the last argument to match POSIX. Prodded by: Alexey Lyashkov I tried to convince ru@ that ABI breakage is not good, but has not succeeded. pgpsYZ4PZioal.pgp Description: PGP signature
Re: POSIXfy readlink() call
On Monday 11 May 2009 2:33:09 pm Kostik Belousov wrote: On Mon, May 11, 2009 at 02:05:07PM -0400, John Baldwin wrote: On Friday 28 September 2007 10:39:56 pm Ighighi wrote: ^ Yes, I had this stuck in the back of my head from when it first appeared. The POXIX prototype for readlink(2) is: ssize_t readlink(const char *restrict path, char *restrict buf, size_t bufsize); It can't simply be corrected as it would change the ABI and thus requires a new system call, etc. However, do you really expect a symlink to be longer than 2^31 on a 64-bit machine? Yes, I agree that this is ABI change. Meantime, r176215 | ru | 2008-02-12 22:09:04 +0200 (Tue, 12 Feb 2008) | 5 lines Change readlink(2)'s return type and type of the last argument to match POSIX. Prodded by: Alexey Lyashkov I tried to convince ru@ that ABI breakage is not good, but has not succeeded. Ugh, is this only in HEAD? If so, I will back it out for 8.0. If this made it into a release then this is a far bigger mess. Oh, good, this is only in 8. I will fix this ASAP. I can just add the new syscall I guess. -- John Baldwin ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to freebsd-hackers-unsubscr...@freebsd.org
Re: POSIXfy readlink() call
On Mon, May 11, 2009 at 02:46:14PM -0400, John Baldwin wrote: On Monday 11 May 2009 2:33:09 pm Kostik Belousov wrote: On Mon, May 11, 2009 at 02:05:07PM -0400, John Baldwin wrote: On Friday 28 September 2007 10:39:56 pm Ighighi wrote: ^ Yes, I had this stuck in the back of my head from when it first appeared. The POXIX prototype for readlink(2) is: ssize_t readlink(const char *restrict path, char *restrict buf, size_t bufsize); It can't simply be corrected as it would change the ABI and thus requires a new system call, etc. However, do you really expect a symlink to be longer than 2^31 on a 64-bit machine? Yes, I agree that this is ABI change. Meantime, r176215 | ru | 2008-02-12 22:09:04 +0200 (Tue, 12 Feb 2008) | 5 lines Change readlink(2)'s return type and type of the last argument to match POSIX. Prodded by: Alexey Lyashkov I tried to convince ru@ that ABI breakage is not good, but has not succeeded. Ugh, is this only in HEAD? If so, I will back it out for 8.0. If this made it into a release then this is a far bigger mess. Oh, good, this is only in 8. I will fix this ASAP. I can just add the new syscall I guess. You need to symver the syscalls. It requires some ugly games with our syscall stubs, because gnu ld only honor .symver in the same object where the symbol is defined. I did prototyped this some time ago, by including a file with appropriate .symver from all stubs. pgpzuYUSu7iF1.pgp Description: PGP signature
Re: POSIXfy readlink() call
On Monday 11 May 2009 2:58:14 pm Kostik Belousov wrote: On Mon, May 11, 2009 at 02:46:14PM -0400, John Baldwin wrote: On Monday 11 May 2009 2:33:09 pm Kostik Belousov wrote: On Mon, May 11, 2009 at 02:05:07PM -0400, John Baldwin wrote: On Friday 28 September 2007 10:39:56 pm Ighighi wrote: ^ Yes, I had this stuck in the back of my head from when it first appeared. The POXIX prototype for readlink(2) is: ssize_t readlink(const char *restrict path, char *restrict buf, size_t bufsize); It can't simply be corrected as it would change the ABI and thus requires a new system call, etc. However, do you really expect a symlink to be longer than 2^31 on a 64-bit machine? Yes, I agree that this is ABI change. Meantime, r176215 | ru | 2008-02-12 22:09:04 +0200 (Tue, 12 Feb 2008) | 5 lines Change readlink(2)'s return type and type of the last argument to match POSIX. Prodded by: Alexey Lyashkov I tried to convince ru@ that ABI breakage is not good, but has not succeeded. Ugh, is this only in HEAD? If so, I will back it out for 8.0. If this made it into a release then this is a far bigger mess. Oh, good, this is only in 8. I will fix this ASAP. I can just add the new syscall I guess. You need to symver the syscalls. It requires some ugly games with our syscall stubs, because gnu ld only honor .symver in the same object where the symbol is defined. I did prototyped this some time ago, by including a file with appropriate .symver from all stubs. So, after thinking about this out loud some more, it seems the ABI breakage would only be for 64-bit platforms that passed a -ve value as the buffer size. However, doing so would already either panic due to triggering an assertion, or result in otherwise undefined behavior and that making the new parameter unsigned actually results in the same undefined behavior in the non-panic case. -- John Baldwin ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to freebsd-hackers-unsubscr...@freebsd.org
POSIXfy readlink() call
The POXIX prototype for readlink(2) is: ssize_t readlink(const char *restrict path, char *restrict buf, size_t bufsize); See: http://www.opengroup.org/onlinepubs/95399/functions/readlink.html NetBSD already did it: http://netbsd.gw.com/cgi-bin/man-cgi?readlink+2+ It'd be good have it corrected in 7.0. Salutes, Igh. ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to [EMAIL PROTECTED]
