xref: /freebsd/lib/libc/stdio/fgets.3 (revision 7381dcc9eeb7da1b1ba103212e15561e14b48a8d)

.\" Copyright (c) 1990, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Chris Torek and the American National Standards Committee X3,
.\" on Information Processing Systems.
.\"
.\" 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 University 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 REGENTS 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 REGENTS OR 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.
.\"
.\"     @(#)fgets.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
.Dd September 1, 2019
.Dt FGETS 3
.Os
.Sh NAME
.Nm fgets ,
.Nm gets_s
.Nd get a line from a stream
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdio.h
.Ft char *
.Fn fgets "char * restrict str" "int size" "FILE * restrict stream"
.Ft char *
.Fn gets_s "char *str" "rsize_t size"
.Sh DESCRIPTION
The
.Fn fgets
function
reads at most one less than the number of characters specified by
.Fa size
from the given
.Fa stream
and stores them in the string
.Fa str .
Reading stops when a newline character is found,
at end-of-file or error.
The newline, if any, is retained.
If any characters are read and there is no error, a
.Ql \e0
character is appended to end the string.
.Pp
The
.Fn gets_s
function
is equivalent to
.Fn fgets
with a
.Fa stream
of
.Dv stdin ,
except that the newline character (if any) is not stored in the string.
.Pp
The
.Fn gets
function
was unsafe and is no longer available.
.Sh RETURN VALUES
Upon successful completion,
.Fn fgets
and
.Fn gets_s
return
a pointer to the string.
If end-of-file occurs before any characters are read,
they return
.Dv NULL
and the buffer contents remain unchanged.
If an error occurs,
they return
.Dv NULL
and the buffer contents are indeterminate.
The
.Fn fgets
and
.Fn gets_s
functions
do not distinguish between end-of-file and error, and callers must use
.Xr feof 3
and
.Xr ferror 3
to determine which occurred.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EBADF
The given
.Fa stream
is not a readable stream.
.El
.Pp
The function
.Fn fgets
may also fail and set
.Va errno
for any of the errors specified for the routines
.Xr fflush 3 ,
.Xr fstat 2 ,
.Xr read 2 ,
or
.Xr malloc 3 .
.Pp
The function
.Fn gets_s
may also fail and set
.Va errno
for any of the errors specified for the routine
.Xr getchar 3 .
.Sh SEE ALSO
.Xr feof 3 ,
.Xr ferror 3 ,
.Xr fgetln 3 ,
.Xr fgetws 3 ,
.Xr getline 3
.Sh STANDARDS
The
.Fn fgets
function conforms to
.St -isoC-99 .
.Fn gets_s
conforms to
.St -isoC-2011
K.3.7.4.1.
.Fn gets
has been removed from
.St -isoC-2011 .