man3/ptsname.3

   1 .\" %%%LICENSE_START(PUBLIC_DOMAIN)
   2 .\" This page is in the public domain. - aeb
   3 .\" %%%LICENSE_END
   4 .\"
   5 .\" 2004-12-17, mtk, added description of ptsname_r() + ERRORS
   6 .\"
   7 .TH PTSNAME 3 2017-09-15 "" "Linux Programmer's Manual"
   8 .SH NAME
   9 ptsname, ptsname_r \- get the name of the slave pseudoterminal
  10 .SH SYNOPSIS
  11 .B #include <stdlib.h>
  12 .PP
  13 .BI "char *ptsname(int " fd ");"
  14 .br
  15 .BI "int ptsname_r(int " fd ", char *" buf ", size_t " buflen ");"
  16 .PP
  17 .in -4n
  18 Feature Test Macro Requirements for glibc (see
  19 .BR feature_test_macros (7)):
  20 .in
  21 .PP
  22 .ad l
  23 .BR ptsname ():
  24 .br
  25 .RS 4
  26 Since glibc 2.24:
  27     _XOPEN_SOURCE\ >=\ 500 ||
  28         (_XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED)
  29 .br
  30 Glibc 2.23 and earlier:
  31     _XOPEN_SOURCE
  32 .RE
  33 .PP
  34 .BR ptsname_r ():
  35     _GNU_SOURCE
  36 .ad
  37 .SH DESCRIPTION
  38 The
  39 .BR ptsname ()
  40 function returns the name of the slave pseudoterminal device
  41 corresponding to the master referred to by
  42 .IR fd .
  43 .PP
  44 The
  45 .BR ptsname_r ()
  46 function is the reentrant equivalent of
  47 .BR ptsname ().
  48 It returns the name of the slave pseudoterminal device as a
  49 null-terminated string in the buffer pointed to by
  50 .IR buf .
  51 The
  52 .I buflen
  53 argument specifies the number of bytes available in
  54 .IR buf .
  55 .SH RETURN VALUE
  56 On success,
  57 .BR ptsname ()
  58 returns a pointer to a string in static storage which will be
  59 overwritten by subsequent calls.
  60 This pointer must not be freed.
  61 On failure, NULL is returned.
  62 .PP
  63 On success,
  64 .BR ptsname_r ()
  65 returns 0.
  66 On failure, a nonzero value is returned
  67 and
  68 .I errno
  69 is set to indicate the error.
  70 .\" In fact the errno value is also returned as the function
  71 .\" result -- MTK, Dec 04
  72 .SH ERRORS
  73 .TP
  74 .B EINVAL
  75 .RB ( ptsname_r ()
  76 only)
  77 .I buf
  78 is NULL.
  79 (This error is returned only for
  80 .\" glibc commit 8f0a947cf55f3b0c4ebdf06953c57eff67a22fa9
  81 glibc 2.25 and earlier.)
  82 .TP
  83 .B ENOTTY
  84 .I fd
  85 does not refer to a pseudoterminal master device.
  86 .TP
  87 .B ERANGE
  88 .RB ( ptsname_r ()
  89 only)
  90 .I buf
  91 is too small.
  92 .SH VERSIONS
  93 .BR ptsname ()
  94 is provided in glibc since version 2.1.
  95 .SH ATTRIBUTES
  96 For an explanation of the terms used in this section, see
  97 .BR attributes (7).
  98 .TS
  99 allbox;
 100 lb lb lb
 101 l l l.
 102 Interface       Attribute       Value
 103 T{
 104 .BR ptsname ()
 105 T}      Thread safety   MT-Unsafe race:ptsname
 106 T{
 107 .BR ptsname_r ()
 108 T}      Thread safety   MT-Safe
 109 .TE
 110 .SH CONFORMING TO
 111 .BR ptsname ():
 112  POSIX.1-2001, POSIX.1-2008.
 113 .PP
 114 .BR ptsname ()
 115 is part of the UNIX 98 pseudoterminal support (see
 116 .BR pts (4)).
 117 .PP
 118 .BR ptsname_r ()
 119 is a Linux extension, that is proposed for inclusion
 120 .\" FIXME . for later review when Issue 8 is one day released
 121 .\" http://austingroupbugs.net/tag_view_page.php?tag_id=8
 122 .\" http://austingroupbugs.net/view.php?id=508
 123 in the next major revision of POSIX.1 (Issue 8).
 124 A version of this function is documented on Tru64 and HP-UX, but
 125 on those implementations, \-1 is returned on error, with
 126 .I errno
 127 set to indicate the error.
 128 Avoid using this function in portable programs.
 129 .SH SEE ALSO
 130 .BR grantpt (3),
 131 .BR posix_openpt (3),
 132 .BR ttyname (3),
 133 .BR unlockpt (3),
 134 .BR pts (4),
 135 .BR pty (7)