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Diffstat (limited to 'newlib/libc/stdio/fopen.c')
| -rw-r--r-- | newlib/libc/stdio/fopen.c | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/newlib/libc/stdio/fopen.c b/newlib/libc/stdio/fopen.c new file mode 100644 index 0000000..30aa54e --- /dev/null +++ b/newlib/libc/stdio/fopen.c @@ -0,0 +1,165 @@ +/* + * Copyright (c) 1990 The Regents of the University of California. + * All rights reserved. + * + * Redistribution and use in source and binary forms are permitted + * provided that the above copyright notice and this paragraph are + * duplicated in all such forms and that any documentation, + * advertising materials, and other materials related to such + * distribution and use acknowledge that the software was developed + * by the University of California, Berkeley. The name of the + * University may not be used to endorse or promote products derived + * from this software without specific prior written permission. + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. + */ + +/* +FUNCTION +<<fopen>>---open a file + +INDEX + fopen +INDEX + _fopen_r + +ANSI_SYNOPSIS + #include <stdio.h> + FILE *fopen(const char *<[file]>, const char *<[mode]>); + + FILE *_fopen_r(void *<[reent]>, + const char *<[file]>, const char *<[mode]>); + +TRAD_SYNOPSIS + #include <stdio.h> + FILE *fopen(<[file]>, <[mode]>) + char *<[file]>; + char *<[mode]>; + + FILE *_fopen_r(<[reent]>, <[file]>, <[mode]>) + char *<[reent]>; + char *<[file]>; + char *<[mode]>; + +DESCRIPTION +<<fopen>> initializes the data structures needed to read or write a +file. Specify the file's name as the string at <[file]>, and the kind +of access you need to the file with the string at <[mode]>. + +The alternate function <<_fopen_r>> is a reentrant version. +The extra argument <[reent]> is a pointer to a reentrancy structure. + +Three fundamental kinds of access are available: read, write, and append. +<<*<[mode]>>> must begin with one of the three characters `<<r>>', +`<<w>>', or `<<a>>', to select one of these: + +o+ +o r +Open the file for reading; the operation will fail if the file does +not exist, or if the host system does not permit you to read it. + +o w +Open the file for writing @emph{from the beginning} of the file: +effectively, this always creates a new file. If the file whose name you +specified already existed, its old contents are discarded. + +o a +Open the file for appending data, that is writing from the end of +file. When you open a file this way, all data always goes to the +current end of file; you cannot change this using <<fseek>>. +o- + +Some host systems distinguish between ``binary'' and ``text'' files. +Such systems may perform data transformations on data written to, or +read from, files opened as ``text''. +If your system is one of these, then you can append a `<<b>>' to any +of the three modes above, to specify that you are opening the file as +a binary file (the default is to open the file as a text file). + +`<<rb>>', then, means ``read binary''; `<<wb>>', ``write binary''; and +`<<ab>>', ``append binary''. + +To make C programs more portable, the `<<b>>' is accepted on all +systems, whether or not it makes a difference. + +Finally, you might need to both read and write from the same file. +You can also append a `<<+>>' to any of the three modes, to permit +this. (If you want to append both `<<b>>' and `<<+>>', you can do it +in either order: for example, <<"rb+">> means the same thing as +<<"r+b">> when used as a mode string.) + +Use <<"r+">> (or <<"rb+">>) to permit reading and writing anywhere in +an existing file, without discarding any data; <<"w+">> (or <<"wb+">>) +to create a new file (or begin by discarding all data from an old one) +that permits reading and writing anywhere in it; and <<"a+">> (or +<<"ab+">>) to permit reading anywhere in an existing file, but writing +only at the end. + +RETURNS +<<fopen>> returns a file pointer which you can use for other file +operations, unless the file you requested could not be opened; in that +situation, the result is <<NULL>>. If the reason for failure was an +invalid string at <[mode]>, <<errno>> is set to <<EINVAL>>. + +PORTABILITY +<<fopen>> is required by ANSI C. + +Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>, +<<lseek>>, <<open>>, <<read>>, <<sbrk>>, <<write>>. +*/ + +#if defined(LIBC_SCCS) && !defined(lint) +static char sccsid[] = "%W% (Berkeley) %G%"; +#endif /* LIBC_SCCS and not lint */ + +#include <stdio.h> +#include <errno.h> +#include "local.h" + +FILE * +_DEFUN (_fopen_r, (ptr, file, mode), + struct _reent *ptr _AND + _CONST char *file _AND + _CONST char *mode) +{ + register FILE *fp; + register int f; + int flags, oflags; + + if ((flags = __sflags (ptr, mode, &oflags)) == 0) + return NULL; + if ((fp = __sfp (ptr)) == NULL) + return NULL; + + if ((f = _open_r (fp->_data, file, oflags, 0666)) < 0) + { + fp->_flags = 0; /* release */ + return NULL; + } + + fp->_file = f; + fp->_flags = flags; + fp->_cookie = (_PTR) fp; + fp->_read = __sread; + fp->_write = __swrite; + fp->_seek = __sseek; + fp->_close = __sclose; + + if (fp->_flags & __SAPP) + fseek (fp, 0, SEEK_END); + + return fp; +} + +#ifndef _REENT_ONLY + +FILE * +_DEFUN (fopen, (file, mode), + _CONST char *file _AND + _CONST char *mode) +{ + return _fopen_r (_REENT, file, mode); +} + +#endif |