On 2019-10-09, Michael Kerrisk (man-pages) <mtk.manpages@xxxxxxxxx> wrote: > Hello Aleksa, > > You write "5.FOO" in these patches. When do you expect these changes to > land in the kernel? Probably 5.6 (I'd hope for 5.5, but I don't know how the v14 review will go). I'm not too sure though, and the magic-link changes (plus O_EMPTYPATH) will probably land after openat2(2) since there is some remaining work to do. > On 10/3/19 4:55 PM, Aleksa Sarai wrote: > > Some of the wording around empty paths in path_resolution(7) also needed > > to be reworked since it's now legal (if you pass O_EMPTYPATH). > > > > Signed-off-by: Aleksa Sarai <cyphar@xxxxxxxxxx> > > --- > > man2/open.2 | 42 +++++++++++++++++++++++++++++++++++++++++- > > man7/path_resolution.7 | 17 ++++++++++++++++- > > 2 files changed, 57 insertions(+), 2 deletions(-) > > > > diff --git a/man2/open.2 b/man2/open.2 > > index b0f485b41589..7217fe056e5e 100644 > > --- a/man2/open.2 > > +++ b/man2/open.2 > > @@ -48,7 +48,7 @@ > > .\" FIXME . Apr 08: The next POSIX revision has O_EXEC, O_SEARCH, and > > .\" O_TTYINIT. Eventually these may need to be documented. --mtk > > .\" > > -.TH OPEN 2 2018-04-30 "Linux" "Linux Programmer's Manual" > > +.TH OPEN 2 2019-10-03 "Linux" "Linux Programmer's Manual" > > No need to update the timestamp. I have scripts that handle this > automatically. > > > .SH NAME > > open, openat, creat \- open and possibly create a file > > .SH SYNOPSIS > > @@ -421,6 +421,21 @@ was followed by a call to > > .BR fdatasync (2)). > > .IR "See NOTES below" . > > .TP > > +.BR O_EMPTYPATH " (since Linux 5.FOO)" > > +If \fIpathname\fP is an empty string, re-open the the file descriptor given as > > In general, I prefer the general form > > .I pathname > > over \fIpathname\fP. > > If you would be willing to cahnge that, it would save me a little work. > (And likewise throughout the rest of the patch.) > > > +the \fIdirfd\fP argument to > > +.BR openat (2). > > +This can be used with both ordinary (file and directory) and \fBO_PATH\fP file > > +descriptors, but cannot be used with > > +.BR AT_FDCWD > > +(or as an argument to plain > > +.BR open (2).) When re-opening an \fBO_PATH\fP file descriptor, the same "link > > There's a formatting problem here which can be fixed by inserting a > newline before "When". > > > +mode" restrictions apply as with re-opening through > > +.BR proc (5) > > +(see > > +.BR path_resolution "(7) and " symlink (7) > > +for more details.) > > +.TP > > .B O_EXCL > > Ensure that this call creates the file: > > if this flag is specified in conjunction with > > @@ -668,6 +683,13 @@ with > > (or via procfs using > > .BR AT_SYMLINK_FOLLOW ) > > even if the file is not a directory. > > +You can even "re-open" (or upgrade) an > > +.BR O_PATH > > +file descriptor by using > > +.BR O_EMPTYPATH > > +(see the section for > > +.BR O_EMPTYPATH > > +for more details.) > > .IP * > > Passing the file descriptor to another process via a UNIX domain socket > > (see > > @@ -958,6 +980,15 @@ is not allowed. > > (See also > > .BR path_resolution (7).) > > .TP > > +.B EBADF > > +.I pathname > > +was an empty string (and > > +.B O_EMPTYPATH > > +was passed) with > > +.BR open (2) > > +(instead of > > +.BR openat (2).) > > +.TP > > .B EDQUOT > > Where > > .B O_CREAT > > @@ -1203,6 +1234,15 @@ The following additional errors can occur for > > .I dirfd > > is not a valid file descriptor. > > .TP > > +.B EBADF > > +.I pathname > > +was an empty string (and > > +.B O_EMPTYPATH > > +was passed), but the provided > > +.I dirfd > > +was an invalid file descriptor (or was > > +.BR AT_FDCWD .) > > +.TP > > .B ENOTDIR > > .I pathname > > is a relative pathname and > > diff --git a/man7/path_resolution.7 b/man7/path_resolution.7 > > index 46f25ec4cdfa..85dd354e9a93 100644 > > --- a/man7/path_resolution.7 > > +++ b/man7/path_resolution.7 > > @@ -22,7 +22,7 @@ > > .\" the source, must acknowledge the copyright and authors of this work. > > .\" %%%LICENSE_END > > .\" > > -.TH PATH_RESOLUTION 7 2017-11-26 "Linux" "Linux Programmer's Manual" > > +.TH PATH_RESOLUTION 7 2019-10-03 "Linux" "Linux Programmer's Manual" > > .SH NAME > > path_resolution \- how a pathname is resolved to a file > > .SH DESCRIPTION > > @@ -198,6 +198,21 @@ successfully. > > Linux returns > > .B ENOENT > > in this case. > > +.PP > > +As of Linux 5.FOO, an empty path argument can be used to indicate the "re-open" > > +an existing file descriptor if > > +.B O_EMPTYPATH > > +is passed as a flag argument to > > +.BR openat (2), > > +with the > > +.I dfd > > +argument indicating which file descriptor to "re-open". This is approximately > > +equivalent to opening > > +.I /proc/self/fd/$fd > > .IR /proc/self/fd/$fd , > > > +where > > +.I $fd > > +is the open file descriptor to be "re-opened". > > + > > No blank line here. > > > .SS Permissions > > The permission bits of a file consist of three groups of three bits; see > > .BR chmod (1) Will fix all of the above -- thanks! -- Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH <https://www.cyphar.com/>
Attachment:
signature.asc
Description: PGP signature
