mirror of https://github.com/mkerrisk/man-pages
fcntl.2: srcfix: start new sentences on new lines; rewrap source lines
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
parent
a25d701d19
commit
12cfd6227c
76
man2/fcntl.2
76
man2/fcntl.2
|
@ -1300,19 +1300,25 @@ of buffer space currently used to store data produces the error
|
|||
.BR F_GETPIPE_SZ " (\fIvoid\fP; since Linux 2.6.35)"
|
||||
Return (as the function result) the capacity of the pipe referred to by
|
||||
.IR fd .
|
||||
.\"
|
||||
.SS File Sealing
|
||||
File seals limit the set of allowed operations on a given file. For each
|
||||
seal that is set on a file, a specific set of operations will fail with
|
||||
File seals limit the set of allowed operations on a given file.
|
||||
For each seal that is set on a file,
|
||||
a specific set of operations will fail with
|
||||
.B EPERM
|
||||
on this file from now on. The file is said to be sealed. The default set of
|
||||
seals depends on the type of the underlying file and filesystem. Currently, only
|
||||
shmem supports sealing. On other filesystems, all
|
||||
on this file from now on.
|
||||
The file is said to be sealed.
|
||||
The default set of seals depends on the type of the underlying
|
||||
file and filesystem.
|
||||
Currently, only shmem supports sealing.
|
||||
On other filesystems, all
|
||||
.BR fcntl (2)
|
||||
operations that operate on seals will return
|
||||
.BR EINVAL .
|
||||
Seals are a property of an inode. Thus, all open files on an inode share the
|
||||
same set of seals. Furthermore, seals can never be removed, only added. If a
|
||||
seal is set, it is guaranteed to be enforced immediately.
|
||||
Seals are a property of an inode.
|
||||
Thus, all open files on an inode share the same set of seals.
|
||||
Furthermore, seals can never be removed, only added.
|
||||
If a seal is set, it is guaranteed to be enforced immediately.
|
||||
The following set of seals is available so far:
|
||||
.RS
|
||||
.TP
|
||||
|
@ -1323,14 +1329,14 @@ with
|
|||
.B F_ADD_SEALS
|
||||
will fail with
|
||||
.BR EPERM .
|
||||
Therefore, this seal prevents any modifications to the set of seals itself. If
|
||||
the initial set of seals of a file includes
|
||||
Therefore, this seal prevents any modifications to the set of seals itself.
|
||||
If the initial set of seals of a file includes
|
||||
.BR F_SEAL_SEAL ,
|
||||
then this effectively causes the set of seals to be constant and locked.
|
||||
.TP
|
||||
.BR F_SEAL_SHRINK
|
||||
If this seal is set, the file in question cannot be reduced in size. This
|
||||
affects
|
||||
If this seal is set, the file in question cannot be reduced in size.
|
||||
This affects
|
||||
.BR open (2)
|
||||
with the
|
||||
.B O_TRUNC
|
||||
|
@ -1338,12 +1344,12 @@ flag and
|
|||
.BR ftruncate (2).
|
||||
They will fail with
|
||||
.B EPERM
|
||||
if you try to shrink the file in question. Increasing the file size is still
|
||||
possible.
|
||||
if you try to shrink the file in question.
|
||||
Increasing the file size is still possible.
|
||||
.TP
|
||||
.BR F_SEAL_GROW
|
||||
If this seal is set, the size of the file in question cannot be increased. This
|
||||
affects
|
||||
If this seal is set, the size of the file in question cannot be increased.
|
||||
This affects
|
||||
.BR write (2)
|
||||
if you write across size boundaries,
|
||||
.BR ftruncate (2)
|
||||
|
@ -1351,23 +1357,25 @@ and
|
|||
.BR fallocate (2).
|
||||
These calls will fail with
|
||||
.B EPERM
|
||||
if you use them to increase the file size or write beyond size boundaries. If
|
||||
you keep the size or shrink it, those calls still work as expected.
|
||||
if you use them to increase the file size or write beyond size boundaries.
|
||||
If you keep the size or shrink it, those calls still work as expected.
|
||||
.TP
|
||||
.BR F_SEAL_WRITE
|
||||
If this seal is set, you cannot modify data contents of the file. Note that
|
||||
shrinking or growing the size of the file is still possible and allowed. Thus,
|
||||
this seal is normally used in combination with one of the other seals. This seal
|
||||
affects
|
||||
If this seal is set, you cannot modify data contents of the file.
|
||||
Note that shrinking or growing the size of the file is
|
||||
still possible and allowed.
|
||||
Thus, this seal is normally used in combination with one of the other seals.
|
||||
This seal affects
|
||||
.BR write (2)
|
||||
and
|
||||
.BR fallocate (2)
|
||||
(only in combination with the
|
||||
.B FALLOC_FL_PUNCH_HOLE
|
||||
flag). Those calls will fail with
|
||||
flag).
|
||||
Those calls will fail with
|
||||
.B EPERM
|
||||
if this seal is set. Furthermore, trying to create new shared, writable
|
||||
memory-mappings via
|
||||
if this seal is set.
|
||||
Furthermore, trying to create new shared, writable memory-mappings via
|
||||
.BR mmap (2)
|
||||
will also fail with
|
||||
.BR EPERM .
|
||||
|
@ -1379,8 +1387,9 @@ with
|
|||
.B F_ADD_SEALS
|
||||
will fail with
|
||||
.B EBUSY
|
||||
if any writable, shared mapping exists. You have to unmap
|
||||
those before you can add this seal. Furthermore, if there are any asynchronous
|
||||
if any writable, shared mapping exists.
|
||||
You have to unmap those before you can add this seal.
|
||||
Furthermore, if there are any asynchronous
|
||||
I/O operations pending on the file, all outstanding writes will be discarded.
|
||||
.RE
|
||||
.TP
|
||||
|
@ -1389,8 +1398,9 @@ Add the seals given in
|
|||
.I arg
|
||||
to the set of seals of the inode pointed to by the file-descriptor
|
||||
.IR fd .
|
||||
Seals cannot be removed again. Once this call succeeds, the seals are enforced
|
||||
by the kernel immediately. If the current set of seals includes
|
||||
Seals cannot be removed again.
|
||||
Once this call succeeds, the seals are enforced by the kernel immediately.
|
||||
If the current set of seals includes
|
||||
.B F_SEAL_SEAL
|
||||
then this call will be rejected with
|
||||
.BR EPERM .
|
||||
|
@ -1399,11 +1409,11 @@ Adding a seal that is already set is a no-op, in case
|
|||
is not set already.
|
||||
.TP
|
||||
.BR F_GET_SEALS " (\fIvoid\fP; since Linux TBD)"
|
||||
Return (as the function result) the current set of seals of the inode referred
|
||||
to by
|
||||
Return (as the function result) the current set of seals
|
||||
of the inode referred to by
|
||||
.IR fd .
|
||||
If no seals are set, 0 is returned. If the file does not support sealing, -1 is
|
||||
returned and
|
||||
If no seals are set, 0 is returned.
|
||||
If the file does not support sealing, -1 is returned and
|
||||
.I errno
|
||||
is set to
|
||||
.BR EINVAL .
|
||||
|
|
Loading…
Reference in New Issue