+++ /dev/null
-.\" Copyright (c) 2014 Google, Inc., written by David Drysdale
-.\" and Copyright (c) 2015, Michael Kerrisk <mtk.manpages@gmail.com>
-.\"
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-.\" preserved on all copies.
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-.\" manual under the conditions for verbatim copying, provided that the
-.\" entire resulting derived work is distributed under the terms of a
-.\" permission notice identical to this one.
-.\"
-.\" Since the Linux kernel and libraries are constantly changing, this
-.\" manual page may be incorrect or out-of-date. The author(s) assume no
-.\" responsibility for errors or omissions, or for damages resulting from
-.\" the use of the information contained herein. The author(s) may not
-.\" have taken the same level of care in the production of this manual,
-.\" which is licensed free of charge, as they might when working
-.\" professionally.
-.\"
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-.\" the source, must acknowledge the copyright and authors of this work.
-.\" %%%LICENSE_END
-.\"
-.TH EXECVEAT 2 2015-01-22 "Linux" "Linux Programmer's Manual"
-.SH NAME
-execveat \- execute program relative to a directory file descriptor
-.SH SYNOPSIS
-.B #include <unistd.h>
-.sp
-.BI "int execveat(int " dirfd ", const char *" pathname ","
-.br
-.BI " char *const " argv "[], char *const " envp "[],"
-.br
-.BI " int " flags );
-.SH DESCRIPTION
-.\" commit 51f39a1f0cea1cacf8c787f652f26dfee9611874
-The
-.BR execveat ()
-system call executes the program referred to by the combination of
-.I dirfd
-and
-.IR pathname .
-It operates in exactly the same way as
-.BR execve (2),
-except for the differences described in this manual page.
-
-If the pathname given in
-.I pathname
-is relative, then it is interpreted relative to the directory
-referred to by the file descriptor
-.I dirfd
-(rather than relative to the current working directory of
-the calling process, as is done by
-.BR execve (2)
-for a relative pathname).
-
-If
-.I pathname
-is relative and
-.I dirfd
-is the special value
-.BR AT_FDCWD ,
-then
-.I pathname
-is interpreted relative to the current working
-directory of the calling process (like
-.BR execve (2)).
-
-If
-.I pathname
-is absolute, then
-.I dirfd
-is ignored.
-
-If
-.I pathname
-is an empty string and the
-.BR AT_EMPTY_PATH
-flag is specified, then the file descriptor
-.I dirfd
-specifies the file to be executed (i.e.,
-.IR dirfd
-refers to an executable file, rather than a directory).
-
-The
-.I flags
-argument is a bit mask that can include zero or more of the following flags:
-.TP
-.BR AT_EMPTY_PATH
-If
-.I pathname
-is an empty string, operate on the file referred to by
-.IR dirfd
-(which may have been obtained using the
-.BR open (2)
-.B O_PATH
-flag).
-.TP
-.B AT_SYMLINK_NOFOLLOW
-If the file identified by
-.I dirfd
-and a non-NULL
-.I pathname
-is a symbolic link, then the call fails with the error
-.BR ELOOP .
-.SH "RETURN VALUE"
-On success,
-.BR execveat ()
-does not return.
-On error, \-1 is returned, and
-.I errno
-is set appropriately.
-.SH ERRORS
-The same errors that occur for
-.BR execve (2)
-can also occur for
-.BR execveat ().
-The following additional errors can occur for
-.BR execveat ():
-.TP
-.B EBADF
-.I dirfd
-is not a valid file descriptor.
-.TP
-.B EINVAL
-Invalid flag specified in
-.IR flags .
-.TP
-.B ELOOP
-.I flags
-includes
-.BR AT_SYMLINK_NOFOLLOW
-and the file identified by
-.I dirfd
-and a non-NULL
-.I pathname
-is a symbolic link.
-.TP
-.B ENOENT
-The program identified by
-.I dirfd
-and
-.I pathname
-requires the use of an interpreter program
-(such as a script starting with "#!"), but the file descriptor
-.I dirfd
-was opened with the
-.B O_CLOEXEC
-flag, with the result that
-the program file is inaccessible to the launched interpreter.
-See BUGS.
-.TP
-.B ENOTDIR
-.I pathname
-is relative and
-.I dirfd
-is a file descriptor referring to a file other than a directory.
-.SH VERSIONS
-.BR execveat ()
-was added to Linux in kernel 3.19.
-GNU C library support is pending.
-.\" FIXME . check for glibc support in a future release
-.SH CONFORMING TO
-The
-.BR execveat ()
-system call is Linux-specific.
-.SH NOTES
-In addition to the reasons explained in
-.BR openat (2),
-the
-.BR execveat ()
-system call is also needed to allow
-.BR fexecve (3)
-to be implemented on systems that do not have the
-.I /proc
-filesystem mounted.
-
-When asked to execute a script file, the
-.IR argv[0]
-that is passed to the script interpreter is a string of the form
-.IR /dev/fd/N
-or
-.IR /dev/fd/N/P ,
-where
-.I N
-is the number of the file descriptor passed via the
-.IR dirfd
-argument.
-A string of the first form occurs when
-.BR AT_EMPTY_PATH
-is employed.
-A string of the second form occurs when the script is specified via both
-.IR dirfd
-and
-.IR pathname ;
-in this case,
-.IR P
-is the value given in
-.IR pathname .
-
-For the same reasons described in
-.BR fexecve (3),
-the natural idiom when using
-.BR execveat (2)
-is to set the close-on-exec flag on
-.IR dirfd .
-(But see BUGS.)
-.SH BUGS
-The
-.B ENOENT
-error described above means that it is not possible to set the
-close-on-exec flag on the file descriptor given to a call of the form:
-
- execveat(fd, "", argv, envp, AT_EMPTY_PATH);
-
-However, the inability to set the close-on-exec flag means that a file
-descriptor referring to the script leaks through to the script itself.
-As well as wasting a file descriptor,
-this leakage can lead to file-descriptor exhaustion in scenarios
-where scripts recursively employ
-.BR execveat ().
-.\" For an example, see Michael Kerrisk's 2015-01-10 reply in this LKML
-.\" thread (http://thread.gmane.org/gmane.linux.kernel/1836105/focus=20229):
-.\"
-.\" Subject: [PATCHv10 man-pages 5/5] execveat.2: initial man page.\" for execveat(2
-.\" Date: Mon, 24 Nov 2014 11:53:59 +0000
-.SH SEE ALSO
-.BR execve (2),
-.BR openat (2),
-.BR fexecve (3)
-.SH COLOPHON
-This page is part of release 3.79 of the Linux
-.I man-pages
-project.
-A description of the project,
-information about reporting bugs,
-and the latest version of this page,
-can be found at
-\%http://www.kernel.org/doc/man\-pages/.
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