fexecve

       #include <unistd.h>

       int fexecve(int fd, char *const argv[], char *const envp[]);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       fexecve():
           Since glibc 2.10:
               _XOPEN_SOURCE >= 700 || _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:
               _GNU_SOURCE

DESCRIPTION
       fexecve() performs the same task as execve(2), with the difference that
       the file to be executed is specified via a file descriptor, fd,  rather
       than  via a pathname.  The file descriptor fd must be opened read-only,
       and the caller must have permission to execute the file that it  refers
       to.

RETURN VALUE
       A  successful  call to fexecve() never returns.  On error, the function
       does return, with a result value of -1, and errno is set appropriately.

ERRORS
       Errors are as for execve(2), with the following additions:

       EINVAL fd is not a valid file descriptor, or argv is NULL, or  envp  is
              NULL.

       ENOSYS The /proc filesystem could not be accessed.

VERSIONS
       fexecve() is implemented since glibc 2.3.2.

ATTRIBUTES
       For   an   explanation   of   the  terms  used  in  this  section,  see
       attributes(7).

       +----------+---------------+---------+
       |Interface | Attribute     | Value   |
       +----------+---------------+---------+
       |fexecve() | Thread safety | MT-Safe |
       +----------+---------------+---------+

CONFORMING TO
       POSIX.1-2008.  This function is not specified in POSIX.1-2001,  and  is
       not   widely   available   on   other  systems.   It  is  specified  in
       POSIX.1-2008.

NOTES
       On Linux, fexecve() is implemented using  the  proc(5)  filesystem,  so
       /proc needs to be mounted and available at the time of the call.

       The  idea  behind fexecve() is to allow the caller to verify (checksum)
       that is executed.  This approach is natural for two reasons.  First, it
       prevents  file descriptors being consumed unnecessarily.  (The executed
       program normally has no need of a file descriptor that  refers  to  the
       program  itself.)   Second, if fexecve() is used recursively, employing
       the close-on-exec flag prevents the  file  descriptor  exhaustion  that
       would  result from the fact that each step in the recursion would cause
       one more file descriptor to be passed to the  new  program.   (But  see
       BUGS.)

BUGS
       If  fd  refers  to  a  script (i.e., it is an executable text file that
       names a script interpreter with a first line that begins with the char-
       acters  #!)   and the close-on-exec flag has been set for fd, then fex-
       ecve() fails with the error ENOENT.  This error occurs because, by  the
       time  the  script  interpreter  is executed, fd has already been closed
       because of the close-on-exec flag.  Thus, the close-on-exec flag  can't
       be  set  on  fd  if  it  refers  to  a  script, leading to the problems
       described in NOTES.

SEE ALSO
       execve(2), execveat(2)

COLOPHON
       This page is part of release 4.04 of the Linux  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/.

Linux                             2015-07-23                        FEXECVE(3)
Man Pages Copyright Respective Owners. Site Copyright (C) 1994 - 2019 Hurricane Electric. All Rights Reserved.