diff options
| author | Jacob McDonnell <jacob@jacobmcdonnell.com> | 2026-04-25 19:55:15 -0400 |
|---|---|---|
| committer | Jacob McDonnell <jacob@jacobmcdonnell.com> | 2026-04-25 19:55:15 -0400 |
| commit | 253e67c8b3a72b3a4757fdbc5845297628db0a4a (patch) | |
| tree | adf53b66087aa30dfbf8bf391a1dadb044c3bf4d /static/netbsd/man3/fgets.3 | |
| parent | a9157ce950dfe2fc30795d43b9d79b9d1bffc48b (diff) | |
docs: Added All NetBSD Manuals
Diffstat (limited to 'static/netbsd/man3/fgets.3')
| -rw-r--r-- | static/netbsd/man3/fgets.3 | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/static/netbsd/man3/fgets.3 b/static/netbsd/man3/fgets.3 new file mode 100644 index 00000000..2c521526 --- /dev/null +++ b/static/netbsd/man3/fgets.3 @@ -0,0 +1,201 @@ +.\" $NetBSD: fgets.3,v 1.22 2010/05/13 18:38:24 jruoho Exp $ +.\" +.\" 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 +.\" +.Dd May 13, 2010 +.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, and 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 +.Em 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 or an error occurs before any characters are read, +they return +.Dv NULL . +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 +.Sh STANDARDS +The functions +.Fn fgets +and +.Fn gets +conform to +.St -ansiC +and +.St -p1003.1-2001 . +The +.St -p1003.1-2008 +revision marked +.Fn gets +as obsolescent. +.Sh CAVEATS +The following bit of code illustrates a case where the programmer assumes a +string is too long if it does not contain a newline: +.Bd -literal + char buf[1024], *p; + + while (fgets(buf, sizeof(buf), fp) != NULL) { + if ((p = strchr(buf, '\en')) == NULL) { + fprintf(stderr, "input line too long.\en"); + exit(1); + } + *p = '\e0'; + printf("%s\en", buf); + } +.Ed +.Pp +While the error would be true if a line longer than 1023 characters +were read, it would be false in two other cases: +.Bl -enum -offset indent +.It +If the last line in a file does not contain a newline, the string returned by +.Fn fgets +will not contain a newline either. +Thus +.Fn strchr +will return +.Dv NULL +and the program will terminate, even if the line was valid. +.It +All C string functions, including +.Fn strchr , +correctly assume the end of the string is represented by a null +.Pq Sq \e0 +character. +If the first character of a line returned by +.Fn fgets +were null, +.Fn strchr +would immediately return without considering the rest of the returned text +which may indeed include a newline. +.El +.Pp +Consider using +.Xr fgetln 3 +instead when dealing with untrusted input. +.Sh SECURITY CONSIDERATIONS +Since it is usually impossible to ensure that the next input line +is less than some arbitrary length, and because overflowing the +input buffer is almost invariably a security violation, programs +should +.Em NEVER +use +.Fn gets . +The +.Fn gets +function +exists purely to conform to +.St -ansiC . |
