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| author | Michael Kerrisk <mtk.manpages@gmail.com> | 2021-08-12 05:01:00 +0200 |
|---|---|---|
| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2021-08-12 05:45:21 +0200 |
| commit | 717c3a7dcf3dcf178af95ce47790f9f31cdabfe0 (patch) | |
| tree | 9383f7bbddb3028da5df2ee4a046a916fc8ed135 | |
| parent | 3c39ce8598454fc44d44f06b8ffc4dccdf2f4304 (diff) | |
| download | man-pages-717c3a7dcf3dcf178af95ce47790f9f31cdabfe0.tar.gz | |
fanotify_mark.2, futimesat.2, mount_setattr.2, statx.2, symlink.2, mkfifo.3: Refer the reader to openat(2) for explanation of why 'dirfd' is useful
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
| -rw-r--r-- | man2/fanotify_mark.2 | 55 | ||||
| -rw-r--r-- | man2/futimesat.2 | 5 | ||||
| -rw-r--r-- | man2/mount_setattr.2 | 5 | ||||
| -rw-r--r-- | man2/statx.2 | 3 | ||||
| -rw-r--r-- | man2/symlink.2 | 5 | ||||
| -rw-r--r-- | man3/mkfifo.3 | 5 |
6 files changed, 78 insertions, 0 deletions
diff --git a/man2/fanotify_mark.2 b/man2/fanotify_mark.2 index 2f2550c725..c0f2d8d9be 100644 --- a/man2/fanotify_mark.2 +++ b/man2/fanotify_mark.2 @@ -358,6 +358,61 @@ has the value then the filesystem object to be marked is determined by interpreting .I pathname relative to the current working directory. +(See +.BR openat (2) +for an explanation of why the +.I dirfd +argument is useful.) +.PP +The +.BR mount_setattr () +system call uses an extensible structure +.RI ( "struct mount_attr" ) +to allow for future extensions. +Any non-flag extensions to +.BR mount_setattr () +will be implemented as new fields appended to the this structure, +with a zero value in a new field resulting in the kernel behaving +as though that extension field was not present. +Therefore, +the caller +.I must +zero-fill this structure on initialization. +See the "Extensibility" subsection under +.B NOTES +for more details. +.PP +The +.I size +argument should usually be specified as +.IR "sizeof(struct mount_attr)" . +However, if the caller is using a kernel that supports an extended +.IR "struct mount_attr" , +but the caller does not intend to make use of these features, +it is possible to pass the size of an earlier +version of the structure together with the extended structure. +This allows the kernel to not copy later parts of the structure +that aren't used anyway. +With each extension that changes the size of +.IR "struct mount_attr" , +the kernel will expose a definition of the form +.BI MOUNT_ATTR_SIZE_VER number\c +\&. +For example, the macro for the size of the initial version of +.I struct mount_attr +is +.BR MOUNT_ATTR_SIZE_VER0 . +.PP +The +.I flags +argument can be used to alter the pathname resolution behavior. +The supported values are: +.TP +.B AT_EMPTY_PATH +If +.I pathname +is the empty string, +change the mount properties on .SH RETURN VALUE On success, .BR fanotify_mark () diff --git a/man2/futimesat.2 b/man2/futimesat.2 index c82e4014c9..bf7de85036 100644 --- a/man2/futimesat.2 +++ b/man2/futimesat.2 @@ -83,6 +83,11 @@ If is absolute, then .I dirfd is ignored. +(See +.BR openat (2) +for an explanation of why the +.I dirfd +argument is useful.) .SH RETURN VALUE On success, .BR futimesat () diff --git a/man2/mount_setattr.2 b/man2/mount_setattr.2 index 24cd363824..0739624cc1 100644 --- a/man2/mount_setattr.2 +++ b/man2/mount_setattr.2 @@ -71,6 +71,11 @@ is specified in then the mount properties of the mount identified by .I dirfd are changed. +(See +.BR openat (2) +for an explanation of why the +.I dirfd +argument is useful.) .PP The .BR mount_setattr () diff --git a/man2/statx.2 b/man2/statx.2 index 85b23dd59c..9e3aeaa36f 100644 --- a/man2/statx.2 +++ b/man2/statx.2 @@ -142,6 +142,9 @@ is a file descriptor that refers to a directory, then is a relative pathname that is interpreted relative to the directory referred to by .IR dirfd . +(See +.BR openat (2) +for an explanation of why this is useful.) .TP By file descriptor If diff --git a/man2/symlink.2 b/man2/symlink.2 index 83d29d3e94..f0c4293a7f 100644 --- a/man2/symlink.2 +++ b/man2/symlink.2 @@ -131,6 +131,11 @@ If is absolute, then .I newdirfd is ignored. +.PP +See +.BR openat (2) +for an explanation of the need for +.BR symlinkat (). .SH RETURN VALUE On success, zero is returned. On error, \-1 is returned, and diff --git a/man3/mkfifo.3 b/man3/mkfifo.3 index 9a4a360df5..3aba5498cc 100644 --- a/man3/mkfifo.3 +++ b/man3/mkfifo.3 @@ -111,6 +111,11 @@ If is absolute, then .I dirfd is ignored. +.PP +See +.BR openat (2) +for an explanation of the need for +.BR mkfifoat (). .SH RETURN VALUE On success .BR mkfifo () |