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. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed by the University of 19.\" California, Berkeley and its contributors. 20.\" 4. Neither the name of the University nor the names of its contributors 21.\" may be used to endorse or promote products derived from this software 22.\" without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34.\" SUCH DAMAGE. 35.\" 36.\" @(#)fgets.3 8.1 (Berkeley) 6/4/93 37.\" $FreeBSD: src/lib/libc/stdio/fgets.3,v 1.6.2.7 2002/07/02 19:51:21 archie Exp $ 38.\" $DragonFly: src/lib/libc/stdio/fgets.3,v 1.3 2004/06/08 00:29:03 hmp Exp $ 39.\" 40.Dd June 4, 1993 41.Dt FGETS 3 42.Os 43.Sh NAME 44.Nm fgets , 45.Nm gets 46.Nd get a line from a stream 47.Sh LIBRARY 48.Lb libc 49.Sh SYNOPSIS 50.In stdio.h 51.Ft char * 52.Fn fgets "char *str" "int size" "FILE *stream" 53.Ft char * 54.Fn gets "char *str" 55.Sh DESCRIPTION 56The 57.Fn fgets 58function 59reads at most one less than the number of characters specified by 60.Fa size 61from the given 62.Fa stream 63and stores them in the string 64.Fa str . 65Reading stops when a newline character is found, 66at end-of-file or error. 67The newline, if any, is retained. 68If any characters are read and there is no error, a 69.Ql \e0 70character is appended to end the string. 71.Pp 72The 73.Fn gets 74function 75is equivalent to 76.Fn fgets 77with an infinite 78.Fa size 79and a 80.Fa stream 81of 82.Dv stdin , 83except that the newline character (if any) is not stored in the string. 84It is the caller's responsibility to ensure that the input line, 85if any, is sufficiently short to fit in the string. 86.Sh RETURN VALUES 87Upon successful completion, 88.Fn fgets 89and 90.Fn gets 91return 92a pointer to the string. 93If end-of-file occurs before any characters are read, 94they return 95.Dv NULL 96and the buffer contents remain unchanged. 97If an error occurs, 98they return 99.Dv NULL 100and the buffer contents are indeterminate. 101The 102.Fn fgets 103and 104.Fn gets 105functions 106do not distinguish between end-of-file and error, and callers must use 107.Xr feof 3 108and 109.Xr ferror 3 110to determine which occurred. 111.Sh ERRORS 112.Bl -tag -width Er 113.It Bq Er EBADF 114The given 115.Fa stream 116is not a readable stream. 117.El 118.Pp 119The function 120.Fn fgets 121may also fail and set 122.Va errno 123for any of the errors specified for the routines 124.Xr fflush 3 , 125.Xr fstat 2 , 126.Xr read 2 , 127or 128.Xr malloc 3 . 129.Pp 130The function 131.Fn gets 132may also fail and set 133.Va errno 134for any of the errors specified for the routine 135.Xr getchar 3 . 136.Sh SECURITY CONSIDERATIONS 137The 138.Fn gets 139function cannot be used securely. 140Because of its lack of bounds checking, 141and the inability for the calling program 142to reliably determine the length of the next incoming line, 143the use of this function enables malicious users 144to arbitrarily change a running program's functionality through 145a buffer overflow attack. 146.Sh SEE ALSO 147.Xr feof 3 , 148.Xr ferror 3 , 149.Xr fgetln 3 150.Sh STANDARDS 151The functions 152.Fn fgets 153and 154.Fn gets 155conform to 156.St -isoC . 157