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体验新版 GitCode,发现更多精彩内容 >>
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1b7e190b
编写于
7月 30, 2008
作者:
A
Al Viro
浏览文件
操作
浏览文件
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电子邮件补丁
差异文件
[PATCH] clean dup2() up a bit
Signed-off-by:
N
Al Viro
<
viro@zeniv.linux.org.uk
>
上级
1027abe8
变更
1
隐藏空白更改
内联
并排
Showing
1 changed file
with
27 addition
and
26 deletion
+27
-26
fs/fcntl.c
fs/fcntl.c
+27
-26
未找到文件。
fs/fcntl.c
浏览文件 @
1b7e190b
...
...
@@ -63,31 +63,35 @@ asmlinkage long sys_dup3(unsigned int oldfd, unsigned int newfd, int flags)
return
-
EINVAL
;
spin_lock
(
&
files
->
file_lock
);
if
(
!
(
file
=
fcheck
(
oldfd
)))
goto
out_unlock
;
get_file
(
file
);
/* We are now finished with oldfd */
err
=
expand_files
(
files
,
newfd
);
file
=
fcheck
(
oldfd
);
if
(
unlikely
(
!
file
))
goto
Ebadf
;
if
(
unlikely
(
err
<
0
))
{
if
(
err
==
-
EMFILE
)
err
=
-
EBADF
;
goto
out_
fput
;
goto
Ebadf
;
goto
out_
unlock
;
}
/* To avoid races with open() and dup(), we will mark the fd as
* in-use in the open-file bitmap throughout the entire dup2()
* process. This is quite safe: do_close() uses the fd array
* entry, not the bitmap, to decide what work needs to be
* done. --sct */
/* Doesn't work. open() might be there first. --AV */
/* Yes. It's a race. In user space. Nothing sane to do */
/*
* We need to detect attempts to do dup2() over allocated but still
* not finished descriptor. NB: OpenBSD avoids that at the price of
* extra work in their equivalent of fget() - they insert struct
* file immediately after grabbing descriptor, mark it larval if
* more work (e.g. actual opening) is needed and make sure that
* fget() treats larval files as absent. Potentially interesting,
* but while extra work in fget() is trivial, locking implications
* and amount of surgery on open()-related paths in VFS are not.
* FreeBSD fails with -EBADF in the same situation, NetBSD "solution"
* deadlocks in rather amusing ways, AFAICS. All of that is out of
* scope of POSIX or SUS, since neither considers shared descriptor
* tables and this condition does not arise without those.
*/
err
=
-
EBUSY
;
fdt
=
files_fdtable
(
files
);
tofree
=
fdt
->
fd
[
newfd
];
if
(
!
tofree
&&
FD_ISSET
(
newfd
,
fdt
->
open_fds
))
goto
out_
fput
;
goto
out_
unlock
;
get_file
(
file
);
rcu_assign_pointer
(
fdt
->
fd
[
newfd
],
file
);
FD_SET
(
newfd
,
fdt
->
open_fds
);
if
(
flags
&
O_CLOEXEC
)
...
...
@@ -98,17 +102,14 @@ asmlinkage long sys_dup3(unsigned int oldfd, unsigned int newfd, int flags)
if
(
tofree
)
filp_close
(
tofree
,
files
);
err
=
newfd
;
out:
return
err
;
out_unlock:
spin_unlock
(
&
files
->
file_lock
);
goto
out
;
out_fput:
return
newfd
;
Ebadf:
err
=
-
EBADF
;
out_unlock:
spin_unlock
(
&
files
->
file_lock
);
fput
(
file
);
goto
out
;
return
err
;
}
asmlinkage
long
sys_dup2
(
unsigned
int
oldfd
,
unsigned
int
newfd
)
...
...
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