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s/cwd/current working directory/

This commit is contained in:
Michael Kerrisk 2007-12-27 16:01:37 +00:00
parent 0786e30815
commit edd1fa35e3
1 changed files with 13 additions and 12 deletions
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25
man2/pivot_root.2
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@ -11,9 +11,9 @@ pivot_root \- change the root file system
.BI "int pivot_root(const char *" new_root ", const char *" put_old ); .BI "int pivot_root(const char *" new_root ", const char *" put_old );
.SH DESCRIPTION .SH DESCRIPTION
.BR pivot_root () .BR pivot_root ()
moves the root file system of the current process to the moves the root file system of the calling process to the
directory \fIput_old\fP and makes \fInew_root\fP the new root file system directory \fIput_old\fP and makes \fInew_root\fP the new root file system
of the current process. of the calling process.
.\" .\"
.\" The .\" The
.\" .B CAP_SYS_ADMIN .\" .B CAP_SYS_ADMIN
@ -28,14 +28,14 @@ the current root of all relevant processes or threads.
.BR pivot_root () .BR pivot_root ()
may or may not change the current root and the current may or may not change the current root and the current
working directory (cwd) of any processes or threads which use the old working directory of any processes or threads which use the old
root directory. root directory.
The caller of The caller of
.BR pivot_root () .BR pivot_root ()
must ensure that processes with root or cwd at the old root operate must ensure that processes with root or current working directory
correctly in either case. at the old root operate correctly in either case.
An easy way to ensure this is to change their An easy way to ensure this is to change their
root and cwd to \fInew_root\fP before invoking root and current working directory to \fInew_root\fP before invoking
.BR pivot_root (). .BR pivot_root ().
The paragraph above is intentionally vague because the implementation The paragraph above is intentionally vague because the implementation
@ -44,21 +44,22 @@ of
may change in the future. may change in the future.
At the time of writing, At the time of writing,
.BR pivot_root () .BR pivot_root ()
changes root and cwd of each process or changes root and current working directory of each process or
thread to \fInew_root\fP if they point to the old root directory. thread to \fInew_root\fP if they point to the old root directory.
This This
is necessary in order to prevent kernel threads from keeping the old is necessary in order to prevent kernel threads from keeping the old
root directory busy with their root and cwd, even if they never access root directory busy with their root and current working directory,
even if they never access
the file system in any way. the file system in any way.
In the future, there may be a mechanism for In the future, there may be a mechanism for
kernel threads to explicitly relinquish any access to the file system, kernel threads to explicitly relinquish any access to the file system,
such that this fairly intrusive mechanism can be removed from such that this fairly intrusive mechanism can be removed from
.BR pivot_root (). .BR pivot_root ().
Note that this also applies to the current process: Note that this also applies to the calling process:
.BR pivot_root () .BR pivot_root ()
may may
or may not affect its cwd. or may not affect its current working directory.
It is therefore recommended to call It is therefore recommended to call
\fBchdir("/")\fP immediately after \fBchdir("/")\fP immediately after
.BR pivot_root (). .BR pivot_root ().
@ -112,7 +113,7 @@ or a file system is already mounted on \fIput_old\fP.
\fInew_root\fP or \fIput_old\fP is not a directory. \fInew_root\fP or \fIput_old\fP is not a directory.
.TP .TP
.B EPERM .B EPERM
The current process does not have the The calling process does not have the
.B CAP_SYS_ADMIN .B CAP_SYS_ADMIN
capability. capability.
.SH VERSIONS .SH VERSIONS
@ -126,7 +127,7 @@ Glibc does not provide a wrapper for this system call; call it using
.BR syscall (2). .BR syscall (2).
.SH BUGS .SH BUGS
.BR pivot_root () .BR pivot_root ()
should not have to change root and cwd of all other should not have to change root and current working directory of all other
processes in the system. processes in the system.
Some of the more obscure uses of Some of the more obscure uses of