stdio/FreeBSD/fgetln.3

   1 .\" Copyright (c) 1990, 1991, 1993
   2 .\"     The Regents of the University of California.  All rights reserved.
   3 .\"
   4 .\" Redistribution and use in source and binary forms, with or without
   5 .\" modification, are permitted provided that the following conditions
   6 .\" are met:
   7 .\" 1. Redistributions of source code must retain the above copyright
   8 .\"    notice, this list of conditions and the following disclaimer.
   9 .\" 2. Redistributions in binary form must reproduce the above copyright
  10 .\"    notice, this list of conditions and the following disclaimer in the
  11 .\"    documentation and/or other materials provided with the distribution.
  12 .\" 4. Neither the name of the University nor the names of its contributors
  13 .\"    may be used to endorse or promote products derived from this software
  14 .\"    without specific prior written permission.
  15 .\"
  16 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  17 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19 .\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  20 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26 .\" SUCH DAMAGE.
  27 .\"
  28 .\"     @(#)fgetln.3    8.3 (Berkeley) 4/19/94
  29 .\" $FreeBSD: src/lib/libc/stdio/fgetln.3,v 1.10 2009/02/28 06:00:58 das Exp $
  30 .\"
  31 .Dd April 19, 1994
  32 .Dt FGETLN 3
  33 .Os
  34 .Sh NAME
  35 .Nm fgetln
  36 .Nd get a line from a stream
  37 .Sh LIBRARY
  38 .Lb libc
  39 .Sh SYNOPSIS
  40 .In stdio.h
  41 .Ft char *
  42 .Fn fgetln "FILE *stream" "size_t *len"
  43 .Sh DESCRIPTION
  44 The
  45 .Fn fgetln
  46 function
  47 returns a pointer to the next line from the stream referenced by
  48 .Fa stream .
  49 This line is
  50 .Em not
  51 a C string as it does not end with a terminating
  52 .Dv NUL
  53 character.
  54 The length of the line, including the final newline,
  55 is stored in the memory location to which
  56 .Fa len
  57 points.
  58 (Note, however, that if the line is the last
  59 in a file that does not end in a newline,
  60 the returned text will not contain a newline.)
  61 .Sh RETURN VALUES
  62 Upon successful completion a pointer is returned;
  63 this pointer becomes invalid after the next
  64 .Tn I/O
  65 operation on
  66 .Fa stream
  67 (whether successful or not)
  68 or as soon as the stream is closed.
  69 Otherwise,
  70 .Dv NULL
  71 is returned.
  72 The
  73 .Fn fgetln
  74 function
  75 does not distinguish between end-of-file and error; the routines
  76 .Xr feof 3
  77 and
  78 .Xr ferror 3
  79 must be used
  80 to determine which occurred.
  81 If an error occurs, the global variable
  82 .Va errno
  83 is set to indicate the error.
  84 The end-of-file condition is remembered, even on a terminal, and all
  85 subsequent attempts to read will return
  86 .Dv NULL
  87 until the condition is
  88 cleared with
  89 .Xr clearerr 3 .
  90 .Pp
  91 The text to which the returned pointer points may be modified,
  92 provided that no changes are made beyond the returned size.
  93 These changes are lost as soon as the pointer becomes invalid.
  94 .Sh ERRORS
  95 .Bl -tag -width Er
  96 .It Bq Er EBADF
  97 The argument
  98 .Fa stream
  99 is not a stream open for reading.
 100 .It Bq Er ENOMEM
 101 The internal line buffer could not be expanded due to lack of available memory,
 102 or because it would need to expand beyond INT_MAX in size.
 103 .El
 104 .Pp
 105 The
 106 .Fn fgetln
 107 function
 108 may also fail and set
 109 .Va errno
 110 for any of the errors specified for the routines
 111 .Xr fflush 3 ,
 112 .Xr malloc 3 ,
 113 .Xr read 2 ,
 114 .Xr stat 2 ,
 115 or
 116 .Xr realloc 3 .
 117 .Sh SEE ALSO
 118 .Xr ferror 3 ,
 119 .Xr fgets 3 ,
 120 .Xr fgetwln 3 ,
 121 .Xr fopen 3 ,
 122 .Xr getline 3 ,
 123 .Xr putc 3
 124 .Sh HISTORY
 125 The
 126 .Fn fgetln
 127 function first appeared in
 128 .Bx 4.4 .