1.\" Copyright (c) 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Chris Torek and the American National Standards Committee X3, 6.\" on Information Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)fgets.3 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD$ 34.\" 35.Dd May 5, 2012 36.Dt FGETS 3 37.Os 38.Sh NAME 39.Nm fgets , 40.Nm gets 41.Nd get a line from a stream 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In stdio.h 46.Ft char * 47.Fn fgets "char * restrict str" "int size" "FILE * restrict stream" 48.Ft char * 49.Fn gets "char *str" 50.Sh DESCRIPTION 51The 52.Fn fgets 53function 54reads at most one less than the number of characters specified by 55.Fa size 56from the given 57.Fa stream 58and stores them in the string 59.Fa str . 60Reading stops when a newline character is found, 61at end-of-file or error. 62The newline, if any, is retained. 63If any characters are read and there is no error, a 64.Ql \e0 65character is appended to end the string. 66.Pp 67The 68.Fn gets 69function 70is equivalent to 71.Fn fgets 72with an infinite 73.Fa size 74and a 75.Fa stream 76of 77.Dv stdin , 78except that the newline character (if any) is not stored in the string. 79It is the caller's responsibility to ensure that the input line, 80if any, is sufficiently short to fit in the string. 81.Sh RETURN VALUES 82Upon successful completion, 83.Fn fgets 84and 85.Fn gets 86return 87a pointer to the string. 88If end-of-file occurs before any characters are read, 89they return 90.Dv NULL 91and the buffer contents remain unchanged. 92If an error occurs, 93they return 94.Dv NULL 95and the buffer contents are indeterminate. 96The 97.Fn fgets 98and 99.Fn gets 100functions 101do not distinguish between end-of-file and error, and callers must use 102.Xr feof 3 103and 104.Xr ferror 3 105to determine which occurred. 106.Sh ERRORS 107.Bl -tag -width Er 108.It Bq Er EBADF 109The given 110.Fa stream 111is not a readable stream. 112.El 113.Pp 114The function 115.Fn fgets 116may also fail and set 117.Va errno 118for any of the errors specified for the routines 119.Xr fflush 3 , 120.Xr fstat 2 , 121.Xr read 2 , 122or 123.Xr malloc 3 . 124.Pp 125The function 126.Fn gets 127may also fail and set 128.Va errno 129for any of the errors specified for the routine 130.Xr getchar 3 . 131.Sh SEE ALSO 132.Xr feof 3 , 133.Xr ferror 3 , 134.Xr fgetln 3 , 135.Xr fgetws 3 , 136.Xr getline 3 137.Sh STANDARDS 138The functions 139.Fn fgets 140and 141.Fn gets 142conform to 143.St -isoC-99 . 144.Sh SECURITY CONSIDERATIONS 145The 146.Fn gets 147function cannot be used securely. 148Because of its lack of bounds checking, 149and the inability for the calling program 150to reliably determine the length of the next incoming line, 151the use of this function enables malicious users 152to arbitrarily change a running program's functionality through 153a buffer overflow attack. 154It is strongly suggested that the 155.Fn fgets 156function be used in all cases. 157