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Diffstat (limited to 'lib/libc/stdio/fgets.3')
-rw-r--r-- | lib/libc/stdio/fgets.3 | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/lib/libc/stdio/fgets.3 b/lib/libc/stdio/fgets.3 new file mode 100644 index 0000000..fba7353 --- /dev/null +++ b/lib/libc/stdio/fgets.3 @@ -0,0 +1,158 @@ +.\" 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. +.\" 4. 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 June 4, 1993 +.Dt FGETS 3 +.Os +.Sh NAME +.Nm fgets , +.Nm gets +.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 "char *str" +.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 +function +is equivalent to +.Fn fgets +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 fgets +and +.Fn gets +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 +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 +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 functions +.Fn fgets +and +.Fn gets +conform to +.St -isoC-99 . +.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 +function be used in all cases. +(See +the FSA.) |