BSD 4_3_Net_2 release

[unix-history] / usr / src / lib / libc / stdio / fopen.3

diff --git a/usr/src/lib/libc/stdio/fopen.3 b/usr/src/lib/libc/stdio/fopen.3
index b35be46..dcb0890 100644 (file)
--- a/usr/src/lib/libc/stdio/fopen.3
+++ b/usr/src/lib/libc/stdio/fopen.3
@@ -1,121 +1,237 @@
-.\" Copyright (c) 1980 Regents of the University of California.
-.\" All rights reserved.  The Berkeley software License Agreement
-.\" specifies the terms and conditions for redistribution.
+.\" Copyright (c) 1990, 1991 The Regents of the University of California.
+.\" All rights reserved.

 .\"
 .\"

-.\"    @(#)fopen.3     6.4 (Berkeley) 4/1/89
+.\" This code is derived from software contributed to Berkeley by
+.\" Chris Torek and the American National Standards Committee X3,
+.\" on Information Processing Systems.

 .\"
 .\"

-.TH FOPEN 3  "April 1, 1989"
-.UC 4
-.SH NAME
-fopen, freopen, fdopen \- open a stream
-.SH SYNOPSIS
-.B #include <stdio.h>
-.PP
-.SM
-.B FILE
-.B *fopen(filename, type)
-.br
-.B char *filename, *type;
-.PP
-.SM
-.B FILE
-.B *freopen(filename, type, stream)
-.br
-.B char *filename, *type;
-.br
-.SM
-.B FILE
-.B *stream;
-.PP
-.SM
-.B FILE
-.B *fdopen(fildes, type)
-.br
-.B char *type;
-.SH DESCRIPTION
-.I Fopen
-opens the file named by
-.I filename
+.\" 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. All advertising materials mentioning features or use of this software
+.\"    must display the following acknowledgement:
+.\"    This product includes software developed by the University of
+.\"    California, Berkeley and its contributors.
+.\" 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.
+.\"
+.\"     @(#)fopen.3    6.8 (Berkeley) 6/29/91
+.\"
+.Dd June 29, 1991
+.Dt FOPEN 3
+.Os
+.Sh NAME
+.Nm fopen ,
+.Nm fdopen ,
+.Nm freopen
+.Nd stream open functions
+.Sh SYNOPSIS
+.Fd #include <stdio.h>
+.Ft FILE *
+.Fn fopen "char *path" "char *mode"
+.Ft FILE *
+.Fn fdopen "int fildes" "char *mode"
+.Ft FILE *
+.Fn freopen "char *path" "char *mode" "FILE *stream"
+.Sh DESCRIPTION
+The
+.Fn fopen
+function
+opens the file whose name is the string pointed to by
+.Fa path

 and associates a stream with it.
 and associates a stream with it.

-.I Fopen
-returns a pointer to be used to identify the stream in subsequent operations.
-.PP
-.I Type
-is a character string having one of the following values:
-.TP 5
-"r"
-open for reading
-.ns
-.TP 5
-"w"
-create for writing
-.ns
-.TP 5
-"a"
-append: open for writing at end of file, or create for writing
-.PP
-In addition, each
-.I type
-may be followed by a "+" to have the file opened for reading and writing.
-"r+" positions the stream at the beginning of the file, "w+" creates
-or truncates it, and "a+" positions it at the end.  Both reads and writes
-may be used on read/write streams, with the limitation that an
-.I fseek, rewind,
-or reading an end-of-file must be used between a read and a write or vice-versa.
-.PP
-.I Freopen
-substitutes the named file in place of the open
-.IR stream .
-It returns the original value of
-.IR stream .
-The original stream is closed.
-.PP
-.I Freopen
-is typically used to attach the preopened constant names,
-.B stdin, stdout, stderr,
-to specified files.
-.PP
-.I Fdopen
-associates a stream with a file descriptor obtained from
-.I open, dup, creat,
+.Pp
+The argument
+.Fa mode
+points to a string beginning with one of the following
+sequences (Additional characters may follow these sequences.):
+.Bl -tag -width indent
+.It Dq Li r
+Open text file for reading.
+The stream is positioned at the beginning of the file.
+.It Dq Li r+
+Open for reading and writing.
+The stream is positioned at the beginning of the file.
+.It Dq Li w
+Truncate file to zero length or create text file for writing.
+The stream is positioned at the beginning of the file.
+.No It Dq Li w+
+Open for reading and writing.
+The file is created if it does not exist, otherwise it is truncated.
+The stream is positioned at the beginning of the file.
+.It Dq Li a
+Open for writing.
+The file is created if it does not exist.
+The stream is positioned at the end of the file.
+.It Dq Li a+
+Open for reading and writing.
+The file is created if it does not exist.
+The stream is positioned at the end of the file.
+.El
+.Pp
+The
+.Fa mode
+string can also include the letter ``b'' either as a third character or
+as a character between the characters in any of the two-character strings
+described above.
+This is strictly for compatibility with
+.St -ansiC
+and has no effect; the ``b'' is ignored.
+.Pp
+Any created files will have mode
+.Pf \\*q Dv S_IRUSR
+\&|
+.Dv S_IWUSR
+\&|
+.Dv S_IRGRP
+\&|
+.Dv S_IWGRP
+\&|
+.Dv S_IROTH
+\&|
+.Dv S_IWOTH Ns \\*q
+.Pq Li 0666 ,
+as modified by the process'
+umask value (see
+.Xr umask 2 ) .
+.Pp
+Reads and writes may be intermixed on read/write streams in any order,
+and do not require an intermediate seek as in previous versions of
+.Em stdio .
+This is not portable to other systems, however;
+.Tn ANSI C
+requires that
+a file positioning function intervene between output and input, unless
+an input operation encounters end-of-file.
+.Pp
+The
+.Fn fdopen
+function associates a stream with the existing file descriptor,
+.Fa fildes .
+The
+.Fa mode
+of the stream must be compatible with the mode of the file descriptor.
+.Pp
+The
+.Fn freopen
+function
+opens the file whose name is the string pointed to by
+.Fa path
+and associates the stream pointed to by
+.Fa stream
+with it.
+The original stream (if it exists) is closed.
+The
+.Fa mode
+argument is used just as in the
+.Xr fopen
+function.
+The primary use of the
+.Fn freopen
+function
+is to change the file associated with a
+standard text stream
+.Pf ( Em stderr ,
+.Em stdin ,
+or
+.Em stdout ) .
+.Sh RETURN VALUES
+Upon successful completion
+.Fn fopen ,
+.Fn fdopen
+and
+.Fn freopen
+return a
+.Tn FILE
+pointer.
+Otherwise,
+.Dv NULL
+is returned and the global variable
+.Va errno
+is set to indicate the error.
+.Sh ERRORS
+.Bl -tag -width [EINVAL]
+.It Bq Er EINVAL
+The
+.Fa mode
+provided to
+.Fn fopen ,
+.Fn fdopen ,

 or
 or

-.IR pipe (2).
+.Fn freopen
+was invalid.
+.El
+.Pp
+The
+.Fn fopen ,
+.Fn fdopen
+and
+.Fn freopen
+functions
+may also fail and set
+.Va errno
+for any of the errors specified for the routine
+.Xr malloc 3 .
+.Pp
+The
+.Fn fopen
+function
+may also fail and set
+.Va errno
+for any of the errors specified for the routine
+.Xr open 2 .
+.Pp
+The
+.Fn fdopen
+function
+may also fail and set
+.Va errno
+for any of the errors specified for the routine
+.Xr fcntl 2 .
+.Pp
+The
+.Fn freopen
+function
+may also fail and set
+.Va errno
+for any of the errors specified for the routines
+.Xr open 2 ,
+.Xr fclose 3
+and
+.Xr fflush 3 .
+.Sh SEE ALSO
+.Xr open 2 ,
+.Xr fclose 3 ,
+.Xr fseek 3 ,
+.Xr funopen 3
+.Sh STANDARDS
+The
+.Fn fopen
+and
+.Fn freopen
+functions
+conform to
+.St -ansiC .

 The
 The

-.I type
-of the stream must agree with the mode of the open file.
-.SH "SEE ALSO"
-open(2),
-fclose(3)
-.SH DIAGNOSTICS
-.I Fopen
-and 
-.I freopen
-return the pointer
-.SM
-.B NULL
-if
-.I filename
-cannot be accessed,
-if too many files are already open,
-or if other resources needed cannot be allocated.
-.SH BUGS
-.I Fdopen
-is not portable to systems other than UNIX.
-.PP
-The read/write 
-.I types
-do not exist on all systems.  Those systems without
-read/write modes will probably treat the 
-.I type
-as if the "+" was not present.  These are unreliable in any event.
-.PP
-In order to support the same number of open files as does the system,
-.I fopen
-must allocate additional memory for data structures using
-.I calloc
-after 20 files have been opened.
-This confuses some programs which use their own memory allocators.
-An undocumented routine,
-.IR f_prealloc ,
-may be called to force immediate allocation of all internal memory
-except for buffers.
+.Fn fdopen
+function
+conforms to
+.St -p1003.1-88 .