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, an error number is returned to indicate the error.
  67 .\" In glibc, the error number is not only returned as the return value
  68 .\" but also stored in errno. But this is not true for musl libc.
  69 .SH ERRORS
  70 .TP
  71 .B EINVAL
  72 .RB ( ptsname_r ()
  73 only)
  74 .I buf
  75 is NULL.
  76 (This error is returned only for
  77 .\" glibc commit 8f0a947cf55f3b0c4ebdf06953c57eff67a22fa9
  78 glibc 2.25 and earlier.)
  79 .TP
  80 .B ENOTTY
  81 .I fd
  82 does not refer to a pseudoterminal master device.
  83 .TP
  84 .B ERANGE
  85 .RB ( ptsname_r ()
  86 only)
  87 .I buf
  88 is too small.
  89 .SH VERSIONS
  90 .BR ptsname ()
  91 is provided in glibc since version 2.1.
  92 .SH ATTRIBUTES
  93 For an explanation of the terms used in this section, see
  94 .BR attributes (7).
  95 .TS
  96 allbox;
  97 lb lb lb
  98 l l l.
  99 Interface       Attribute       Value
 100 T{
 101 .BR ptsname ()
 102 T}      Thread safety   MT-Unsafe race:ptsname
 103 T{
 104 .BR ptsname_r ()
 105 T}      Thread safety   MT-Safe
 106 .TE
 107 .SH CONFORMING TO
 108 .BR ptsname ():
 109  POSIX.1-2001, POSIX.1-2008.
 110 .PP
 111 .BR ptsname ()
 112 is part of the UNIX 98 pseudoterminal support (see
 113 .BR pts (4)).
 114 .PP
 115 .BR ptsname_r ()
 116 is a Linux extension, that is proposed for inclusion
 117 .\" FIXME . for later review when Issue 8 is one day released
 118 .\" http://austingroupbugs.net/tag_view_page.php?tag_id=8
 119 .\" http://austingroupbugs.net/view.php?id=508
 120 in the next major revision of POSIX.1 (Issue 8).
 121 A version of this function is documented on Tru64 and HP-UX, but
 122 on those implementations, \-1 is returned on error, with
 123 .I errno
 124 set to indicate the error.
 125 Avoid using this function in portable programs.
 126 .SH SEE ALSO
 127 .BR grantpt (3),
 128 .BR posix_openpt (3),
 129 .BR ttyname (3),
 130 .BR unlockpt (3),
 131 .BR pts (4),
 132 .BR pty (7)