Implement POSIX grantpt(3) functionality, and add a pt_chown utility (akin
to Solaris, it is in /usr/libexec) to perform the handing over of tty nodes to the user being granted the pty. Submitted by: Ryan Younce <ryany@pobox.com> Reviewed by: security-officer@, standards@, mike@
This commit is contained in:
Juli Mallett
parent
a3929677dd
commit
d3951ad162
@ -184,7 +184,7 @@ double erand48(unsigned short[3]);
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int getsubopt(char **, char *const *, char **);
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#define _GETSUBOPT_DECLARED
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#endif
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/* int grantpt(int); */
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int grantpt(int);
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char *initstate(unsigned long /* XSI requires u_int */, char *, long);
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long jrand48(unsigned short[3]);
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/* char *l64a(long); */
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@ -200,8 +200,8 @@ char *mktemp(char *);
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#endif
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long mrand48(void);
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long nrand48(unsigned short[3]);
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/* int posix_openpt(int); */
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/* char *ptsname(int); */
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int posix_openpt(int);
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char *ptsname(int);
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int putenv(const char *);
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long random(void);
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char *realpath(const char *, char resolved_path[]);
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@ -214,7 +214,7 @@ int setkey(const char *);
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char *setstate(/* const */ char *);
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void srand48(long);
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void srandom(unsigned long);
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/* int unlockpt(int); */
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int unlockpt(int);
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#endif /* __XSI_VISIBLE */
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#if __BSD_VISIBLE
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@ -6,11 +6,11 @@
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MISRCS+=_Exit.c abort.c abs.c atexit.c atof.c atoi.c atol.c atoll.c \
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bsearch.c calloc.c div.c exit.c getenv.c getopt.c getopt_long.c \
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getsubopt.c hcreate.c heapsort.c imaxabs.c imaxdiv.c insque.c \
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labs.c ldiv.c llabs.c lldiv.c lsearch.c malloc.c merge.c putenv.c \
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qsort.c qsort_r.c radixsort.c rand.c random.c reallocf.c realpath.c \
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remque.c setenv.c strfmon.c strhash.c strtod.c strtoimax.c strtol.c \
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strtoll.c strtoq.c strtoul.c strtoull.c strtoumax.c strtouq.c \
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getsubopt.c grantpt.c hcreate.c heapsort.c imaxabs.c imaxdiv.c \
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insque.c labs.c ldiv.c llabs.c lldiv.c lsearch.c malloc.c merge.c \
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putenv.c qsort.c qsort_r.c radixsort.c rand.c random.c reallocf.c \
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realpath.c remque.c setenv.c strfmon.c strhash.c strtod.c strtoimax.c \
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strtol.c strtoll.c strtoq.c strtoul.c strtoull.c strtoumax.c strtouq.c \
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system.c tdelete.c tfind.c tsearch.c twalk.c
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# machine-dependent stdlib sources
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@ -19,14 +19,15 @@ MISRCS+=_Exit.c abort.c abs.c atexit.c atof.c atoi.c atol.c atoll.c \
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.endif
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MAN+= abort.3 abs.3 alloca.3 atexit.3 atof.3 atoi.3 atol.3 bsearch.3 \
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div.3 exit.3 getenv.3 getopt.3 getopt_long.3 getsubopt.3 hcreate.3 \
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imaxabs.3 imaxdiv.3 insque.3 labs.3 ldiv.3 llabs.3 lldiv.3 \
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div.3 exit.3 getenv.3 getopt.3 getopt_long.3 getsubopt.3 grantpt.3 \
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hcreate.3 imaxabs.3 imaxdiv.3 insque.3 labs.3 ldiv.3 llabs.3 lldiv.3 \
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lsearch.3 malloc.3 memory.3 qsort.3 radixsort.3 rand.3 random.3 \
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realpath.3 strfmon.3 strtod.3 strtol.3 strtoul.3 system.3 tsearch.3
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MLINKS+=atol.3 atoll.3
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MLINKS+=exit.3 _Exit.3
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MLINKS+=getenv.3 putenv.3 getenv.3 setenv.3 getenv.3 unsetenv.3
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MLINKS+=grantpt.3 posix_openpt.3 grantpt.3 ptsname.3 grantpt.3 unlockpt.3
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MLINKS+=hcreate.3 hdestroy.3 hcreate.3 hsearch.3
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MLINKS+=insque.3 remque.3
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MLINKS+=lsearch.3 lfind.3
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224
lib/libc/stdlib/grantpt.3
Normal file
224
lib/libc/stdlib/grantpt.3
Normal file
@ -0,0 +1,224 @@
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.\"
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.\" Copyright (c) 2002 The FreeBSD Project, Inc.
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.\" All rights reserved.
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.\"
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.\" This software includes code contributed to the FreeBSD Project
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.\" by Ryan Younce of North Carolina State University.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the FreeBSD Project nor the names of its
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.\" contributors may be used to endorse or promote products derived from
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.\" this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE FREEBSD PROJECT AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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.\" PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FREEBSD PROJECT
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.\" OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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.\" TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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.\" PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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.\" LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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.\" NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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.\" SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd December 23, 2002
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.Os
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.Dt GRANTPT 3
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.Sh NAME
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.Nm grantpt ,
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.Nm ptsname ,
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.Nm unlockpt ,
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.Nm posix_openpt
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.Nd pseudo-terminal access functions
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In stdlib.h
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.Ft int
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.Fn grantpt "int fildes"
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.Ft char *
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.Fn ptsname "int fildes"
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.Ft int
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.Fn unlockpt "int fildes"
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.In fcntl.h
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.Ft int
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.Fn posix_openpt "int mode"
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.Sh DESCRIPTION
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The
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.Fn grantpt ,
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.Fn ptsname ,
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.Fn unlockpt ,
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and
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.Fn posix_openpt
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functions allow access to pseudo-terminal devices.
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The first three functions accept a file descriptor
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that references the master half of a pseudo-terminal pair.
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This file descriptor is created with
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.Fn posix_openpt .
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.Pp
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The
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.Fn grantpt
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function is used to establish ownership and permissions
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of the slave device counterpart to the master device
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specified with
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.Va fildes .
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The slave device's ownership is set to the real user ID
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of the calling process, and the permissions are set to
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user readable-writable and group writable.
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The group owner of the slave device is also set to the
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group "tty" if it exists on the system; otherwise, it
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is left untouched.
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.Pp
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The
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.Fn ptsname
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function returns the full pathname of the slave device
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counterpart to the master device specified with
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.Va fildes .
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This value can be used
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to subsequently open the appropriate slave after
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.Fn posix_openpt
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and
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.Fn grantpt
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have been called.
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.Pp
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The
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.Fn unlockpt
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function clears the lock held on the pseudo-terminal pair
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for the master device specified with
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.Va fildes .
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.Pp
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The
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.Fn posix_openpt
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function opens the first available master pseudo-terminal
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device and returns a descriptor to it.
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.Va mode
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specifies the flags used for opening the device:
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.Bl -tag -width O_NOCTTY
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.It Dv O_RDWR
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Open for reading and writing.
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.It Dv O_NOCTTY
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If set, do not allow the terminal to become
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the controlling terminal for the calling process.
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.El
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.Sh RETURN VALUES
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The
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.Fn grantpt
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and
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.Fn unlockpt
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functions return 0 on success; otherwise -1 is returned and
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.Va errno
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is set to indicate the error.
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.Pp
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The
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.Fn ptsname
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function returns a pointer to the name
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of the slave device on success;
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otherwise a NULL pointer is returned and
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.Va errno
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is set to indicate the error.
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.Pp
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The
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.Fn posix_openpt
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function returns a file descriptor to the first
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available master pseudo-terminal device on success;
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otherwise -1 is returned and
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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The
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.Fn grantpt ,
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.Fn ptsname ,
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and
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.Fn unlockpt
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functions may fail and set
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.Va errno
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to:
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.Bl -tag -width Er
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.It EINVAL
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.Va fildes
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is not a master pseudo-terminal device.
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.El
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.Pp
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In addition, the
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.Fn grantpt
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function may set
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.Va errno
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to:
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.Bl -tag -width Er
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.It EACCES
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The slave pseudo-terminal device could not be accessed.
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.El
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.Pp
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The
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.Fn posix_openpt
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function may fail and set
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.Va errno
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to:
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.Bl -tag -width Er
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.It EINVAL
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.Va mode
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consists an an invalid mode bit.
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.It EAGAIN
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The system has no available pseudo-terminal devices.
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.El
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.Pp
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The
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.Fn grantpt ,
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.Fn ptsname ,
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and
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.Fn unlockpt
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functions may also fail and set
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.Va errno
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for any of the errors specified for the routine
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.Xr fstat 2 .
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.Pp
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The
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.Fn posix_openpt
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function may also fail and set
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.Va errno
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for any of the errors specified for the routine
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.Xr open 2 .
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.Sh SEE ALSO
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.Xr open 2 ,
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.Xr pty 4 ,
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.Xr tty 4
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.Sh STANDARDS
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The
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.Fn grantpt ,
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.Fn ptsname ,
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.Fn unlockpt ,
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and
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.Fn posix_openpt
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functions conform to
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.St -p1003.1-2001 .
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.Sh HISTORY
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The
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.Fn grantpt ,
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.Fn ptsname ,
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.Fn unlockpt ,
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and
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.Fn posix_openpt
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functions appeared in
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.Fx 5.0 .
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.Sh NOTES
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The purpose of the
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.Fn unlockpt
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function has no meaning in
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.Fx .
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.Pp
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The flag
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.Dv O_NOCTTY
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is included for compatibility; in
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.Fx ,
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opening a terminal does not cause it to become
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a process's controlling terminal.
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259
lib/libc/stdlib/grantpt.c
Normal file
259
lib/libc/stdlib/grantpt.c
Normal file
@ -0,0 +1,259 @@
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/*
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* Copyright (c) 2002 The FreeBSD Project, Inc.
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* All rights reserved.
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*
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* This software includes code contributed to the FreeBSD Project
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* by Ryan Younce of North Carolina State University.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
|
||||
* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the FreeBSD Project nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE FREEBSD PROJECT AND CONTRIBUTORS ``AS IS''
|
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
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* ARE DISCLAIMED. IN NO EVENT SHALL THE FREEBSD PROJECT OR ITS CONTRIBUTORS
|
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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__FBSDID("$FreeBSD$");
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#endif /* not lint */
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#include "namespace.h"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include <sys/time.h>
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#include <sys/resource.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <grp.h>
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#include <paths.h>
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#include <signal.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sysexits.h>
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#include <unistd.h>
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#include "un-namespace.h"
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#define PTM_MAJOR 6 /* pseudo tty master major */
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#define PTS_MAJOR 5 /* pseudo tty slave major */
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#define PTM_PREFIX "pty" /* pseudo tty master naming convention */
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#define PTS_PREFIX "tty" /* pseudo tty slave naming convention */
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/*
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* The following are range values for pseudo TTY devices. Pseudo TTYs have a
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* name of /dev/[pt]ty[p-sP-S][0-9a-v], yielding 256 combinations per major.
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*/
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#define PT_MAX 256
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#define PT_DEV1 "pqrsPQRS"
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#define PT_DEV2 "0123456789abcdefghijklmnopqrstuv"
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/*
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* grantpt(3) support utility.
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*/
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#define _PATH_PTCHOWN "/usr/libexec/pt_chown"
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/*
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* ISPTM(x) returns 0 for struct stat x if x is not a pty master.
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* The bounds checking may be unnecessary but it does eliminate doubt.
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*/
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#define ISPTM(x) (S_ISCHR((x).st_mode) && \
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major((x).st_rdev) == PTM_MAJOR && \
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minor((x).st_rdev) >= 0 && \
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minor((x).st_rdev) < PT_MAX)
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/*
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* grantpt(): grant ownership of a slave pseudo-terminal device to the
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* current user.
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*/
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int
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grantpt(int fildes)
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{
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int retval, serrno, status;
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pid_t pid, spid;
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gid_t gid;
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char *slave;
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sigset_t oblock, nblock;
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struct stat sbuf;
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struct group *grp;
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retval = -1;
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serrno = errno;
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if ((slave = ptsname(fildes)) != NULL) {
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/*
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* Block SIGCHLD.
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*/
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(void)sigemptyset(&nblock);
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(void)sigaddset(&nblock, SIGCHLD);
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(void)_sigprocmask(SIG_BLOCK, &nblock, &oblock);
|
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switch (pid = fork()) {
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case -1:
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break;
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case 0: /* child */
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/*
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* pt_chown expects the master pseudo TTY to be its
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* standard input.
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*/
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(void)_dup2(fildes, STDIN_FILENO);
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(void)_sigprocmask(SIG_SETMASK, &oblock, NULL);
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execl(_PATH_PTCHOWN, _PATH_PTCHOWN, (char *)NULL);
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_exit(EX_UNAVAILABLE);
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/* NOTREACHED */
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default: /* parent */
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/*
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* Just wait for the process. Error checking is
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* done below.
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*/
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while ((spid = _waitpid(pid, &status, 0)) == -1 &&
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(errno == EINTR))
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;
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if (spid != -1 && WIFEXITED(status) &&
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WEXITSTATUS(status) == EX_OK)
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retval = 0;
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else
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errno = EACCES;
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break;
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}
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/*
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* Restore process's signal mask.
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*/
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(void)_sigprocmask(SIG_SETMASK, &oblock, NULL);
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if (retval) {
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/*
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* pt_chown failed. Try to manually change the
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* permissions for the slave.
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*/
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gid = (grp = getgrnam("tty")) ? grp->gr_gid : -1;
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if (chown(slave, getuid(), gid) == -1 ||
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chmod(slave, S_IRUSR | S_IWUSR | S_IWGRP) == -1)
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errno = EACCES;
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else
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retval = 0;
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}
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}
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if (!retval)
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errno = serrno;
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return (retval);
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}
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/*
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* posix_openpt(): open the first available master pseudo-terminal device
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* and return descriptor.
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*/
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int
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posix_openpt(int oflag)
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{
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char *mc1, *mc2, master[] = _PATH_DEV PTM_PREFIX "XY";
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const char *pc1, *pc2;
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int fildes, bflag, serrno;
|
||||
|
||||
fildes = -1;
|
||||
bflag = 0;
|
||||
serrno = errno;
|
||||
|
||||
/*
|
||||
* Check flag validity. POSIX doesn't require it,
|
||||
* but we still do so.
|
||||
*/
|
||||
if (oflag & ~(O_RDWR | O_NOCTTY))
|
||||
errno = EINVAL;
|
||||
else {
|
||||
mc1 = master + strlen(_PATH_DEV PTM_PREFIX);
|
||||
mc2 = mc1 + 1;
|
||||
|
||||
/* Cycle through all possible master PTY devices. */
|
||||
for (pc1 = PT_DEV1; !bflag && (*mc1 = *pc1); ++pc1)
|
||||
for (pc2 = PT_DEV2; *mc2 = *pc2; ++pc2) {
|
||||
/*
|
||||
* Break out if we successfully open a PTY,
|
||||
* or if open() fails due to limits.
|
||||
*/
|
||||
if ((fildes = _open(master, oflag)) != -1 ||
|
||||
(errno == EMFILE || errno == ENFILE)) {
|
||||
++bflag;
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
if (fildes != -1)
|
||||
errno = serrno;
|
||||
else if (!bflag)
|
||||
errno = EAGAIN;
|
||||
}
|
||||
|
||||
return (fildes);
|
||||
}
|
||||
|
||||
/*
|
||||
* ptsname(): return the pathname of the slave pseudo-terminal device
|
||||
* associated with the specified master.
|
||||
*/
|
||||
char *
|
||||
ptsname(int fildes)
|
||||
{
|
||||
static char slave[] = _PATH_DEV PTS_PREFIX "XY";
|
||||
char *retval;
|
||||
struct stat sbuf;
|
||||
|
||||
retval = NULL;
|
||||
|
||||
if (_fstat(fildes, &sbuf) == 0) {
|
||||
if (!ISPTM(sbuf))
|
||||
errno = EINVAL;
|
||||
else {
|
||||
(void)sprintf(slave, _PATH_DEV PTS_PREFIX "%c%c",
|
||||
PT_DEV1[minor(sbuf.st_rdev) / 32],
|
||||
PT_DEV2[minor(sbuf.st_rdev) % 32]);
|
||||
retval = slave;
|
||||
}
|
||||
}
|
||||
|
||||
return (retval);
|
||||
}
|
||||
|
||||
/*
|
||||
* unlockpt(): unlock a pseudo-terminal device pair.
|
||||
*/
|
||||
int
|
||||
unlockpt(int fildes)
|
||||
{
|
||||
int retval;
|
||||
struct stat sbuf;
|
||||
|
||||
/*
|
||||
* Unlocking a master/slave pseudo-terminal pair has no meaning in a
|
||||
* non-streams PTY environment. However, we do ensure fildes is a
|
||||
* valid master pseudo-terminal device.
|
||||
*/
|
||||
if ((retval = _fstat(fildes, &sbuf)) == 0 && !ISPTM(sbuf)) {
|
||||
errno = EINVAL;
|
||||
retval = -1;
|
||||
}
|
||||
|
||||
return (retval);
|
||||
}
|
||||
@ -12,6 +12,7 @@ SUBDIR= atrun \
|
||||
makekey \
|
||||
mknetid \
|
||||
pppoed \
|
||||
pt_chown \
|
||||
rbootd \
|
||||
revnetgroup \
|
||||
rexecd \
|
||||
|
||||
9
libexec/pt_chown/Makefile
Normal file
9
libexec/pt_chown/Makefile
Normal file
@ -0,0 +1,9 @@
|
||||
# $FreeBSD$
|
||||
|
||||
PROG= pt_chown
|
||||
SRCS= pt_chown.c
|
||||
BINOWN= root
|
||||
BINMODE=4555
|
||||
NOMAN= yes
|
||||
|
||||
.include <bsd.prog.mk>
|
||||
103
libexec/pt_chown/pt_chown.c
Normal file
103
libexec/pt_chown/pt_chown.c
Normal file
@ -0,0 +1,103 @@
|
||||
/*
|
||||
* Copyright (c) 2002 The FreeBSD Project, Inc.
|
||||
* All rights reserved.
|
||||
*
|
||||
* This software includes code contributed to the FreeBSD Project
|
||||
* by Ryan Younce of North Carolina State University.
|
||||
*
|
||||
* Redistribution and use in source and binary forms, with or without
|
||||
* modification, are permitted provided that the following conditions
|
||||
* are met:
|
||||
* 1. Redistributions of source code must retain the above copyright
|
||||
* notice, this list of conditions and the following disclaimer.
|
||||
* 2. Redistributions in binary form must reproduce the above copyright
|
||||
* notice, this list of conditions and the following disclaimer in the
|
||||
* documentation and/or other materials provided with the distribution.
|
||||
* 3. Neither the name of the FreeBSD Project nor the names of its
|
||||
* contributors may be used to endorse or promote products derived from
|
||||
* this software without specific prior written permission.
|
||||
*
|
||||
* THIS SOFTWARE IS PROVIDED BY THE FREEBSD PROJECT AND CONTRIBUTORS ``AS IS''
|
||||
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||||
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
||||
* ARE DISCLAIMED. IN NO EVENT SHALL THE FREEBSD PROJECT OR ITS CONTRIBUTORS
|
||||
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
||||
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
||||
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
||||
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
||||
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
||||
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
||||
* POSSIBILITY OF SUCH DAMAGE.
|
||||
*/
|
||||
|
||||
#include <sys/cdefs.h>
|
||||
#ifndef lint
|
||||
__FBSDID("$FreeBSD$");
|
||||
#endif /* not lint */
|
||||
|
||||
#include <sys/stat.h>
|
||||
|
||||
#include <grp.h>
|
||||
#include <stdlib.h>
|
||||
#include <sysexits.h>
|
||||
#include <unistd.h>
|
||||
|
||||
/*
|
||||
* pt_chown
|
||||
* Utility support routine for grantpt(3).
|
||||
*
|
||||
* According to IEEE Std 1003.1-2001, grantpt(3) changes ownership and
|
||||
* permission bits of a slave pseudo-terminal device associated with a
|
||||
* master.
|
||||
*
|
||||
* Since doing this if we are not the owner of the slave (which would
|
||||
* rarely happen) cannot be done by conventional methods, grantpt(3)
|
||||
* has to rely on this support program, which is setuid root, to change
|
||||
* the slave's owner, group, and permission mode attributes. It's
|
||||
* a rather undesirable approach, but Digital Unix and Solaris also seem
|
||||
* to rely on this approach to pull this off.
|
||||
*
|
||||
* This program hangs around long enough to do just these things upon
|
||||
* its standard input (which is set up by grantpt(3) to be the master's
|
||||
* descriptor, the one passed to it). The rationale behind this
|
||||
* approach not allowing somebody to modify ownership of another active
|
||||
* pseudo terminal is:
|
||||
*
|
||||
* 1) This program only operates on its standard input. If STDIN_FILENO
|
||||
* is not open or is not a pseudo-terminal master, no action is
|
||||
* taken and the program exits (ptsname() is called for a non-NULL
|
||||
* return).
|
||||
* 2) Only one active file description for a pseudo-terminal master
|
||||
* can exist at a time (attempting to open an active PTY returns with
|
||||
* EIO - I/O Error). Thus, if the pseudo-terminal is already in
|
||||
* use by somebody else, it could not have been opened to begin
|
||||
* with, and thus this program would be useless in such situations.
|
||||
*/
|
||||
int
|
||||
main(int argc, char *argv[])
|
||||
{
|
||||
int retcode;
|
||||
char *slave;
|
||||
gid_t gid;
|
||||
struct group *grp;
|
||||
|
||||
retcode = EX_OK;
|
||||
|
||||
if ((slave = ptsname(STDIN_FILENO)) == NULL)
|
||||
retcode = EX_USAGE;
|
||||
else {
|
||||
gid = (grp = getgrnam("tty")) ? grp->gr_gid : -1;
|
||||
if (chown(slave, getuid(), gid) == 0 &&
|
||||
chmod(slave, S_IRUSR | S_IWUSR | S_IWGRP) == 0)
|
||||
retcode = 0;
|
||||
else
|
||||
retcode = EX_NOPERM;
|
||||
}
|
||||
|
||||
/*
|
||||
* grantpt(3) checks the retcode for being either zero or
|
||||
* nonzero. Any nonzero return results in errno being set
|
||||
* to EACCES.
|
||||
*/
|
||||
exit(retcode);
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user