xref: /dflybsd-src/lib/libc/stdio/gets.3 (revision 086b156cdf18f6fbb398ffa6f62a25f4f158853e)

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.\"     @(#)fgets.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD: src/lib/libc/stdio/fgets.3,v 1.22 2009/02/28 06:00:58 das Exp $
.\"
.Dd September 9, 2019
.Dt GETS 3
.Os
.Sh NAME
.Nm gets
.Nd get a line from a stream
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdio.h
.Ft char *
.Fn gets "char *str"
.Sh DESCRIPTION
.Bf -symbolic
This interface is made obsolete by
.Xr fgets 3
and
.Xr gets_s 3 .
See
.Sx SECURITY CONSIDERATIONS
below.
.Ef
.Pp
The
.Fn gets
function
is equivalent to
.Xr fgets 3
with an infinite
.Fa size
and a
.Fa stream
of
.Dv stdin ,
except that the newline character (if any) is not stored in the string.
It is the caller's responsibility to ensure that the input line,
if any, is sufficiently short to fit in the string.
.Sh RETURN VALUES
Upon successful completion,
.Fn gets
returns
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 gets
function
does 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
.Fn gets
function may also fail and set
.Va errno
for any of the errors specified for the routine
.Xr getchar 3 .
.Sh SECURITY CONSIDERATIONS
The
.Fn gets
function cannot be used securely.
Because of its lack of bounds checking,
and the inability for the calling program
to reliably determine the length of the next incoming line,
the use of this function enables malicious users
to arbitrarily change a running program's functionality through
a buffer overflow attack.
It is strongly suggested that the
.Fn fgets
and
.Fn gets_s
functions be used in all cases.
.Sh SEE ALSO
.Xr fgets 3 ,
.Xr gets_s 3
.Sh STANDARDS
The
.Fn gets
function conforms to
.St -isoC-99 .