| 0,0 → 1,177 |
|---|
| /* |
| * 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 |
| <<ftell>>, <<ftello>>---return position in a stream or file |
| |
| INDEX |
| ftell |
| INDEX |
| ftello |
| INDEX |
| _ftell_r |
| INDEX |
| _ftello_r |
| |
| ANSI_SYNOPSIS |
| #include <stdio.h> |
| long ftell(FILE *<[fp]>); |
| off_t ftello(FILE *<[fp]>); |
| long _ftell_r(struct _reent *<[ptr]>, FILE *<[fp]>); |
| off_t _ftello_r(struct _reent *<[ptr]>, FILE *<[fp]>); |
| |
| TRAD_SYNOPSIS |
| #include <stdio.h> |
| long ftell(<[fp]>) |
| FILE *<[fp]>; |
| |
| off_t ftello(<[fp]>) |
| FILE *<[fp]>; |
| |
| long _ftell_r(<[ptr]>, <[fp]>) |
| struct _reent *<[ptr]>; |
| FILE *<[fp]>; |
| |
| off_t _ftello_r(<[ptr]>, <[fp]>) |
| struct _reent *<[ptr]>; |
| FILE *<[fp]>; |
| |
| DESCRIPTION |
| Objects of type <<FILE>> can have a ``position'' that records how much |
| of the file your program has already read. Many of the <<stdio>> functions |
| depend on this position, and many change it as a side effect. |
| |
| The result of <<ftell>>/<<ftello>> is the current position for a file |
| identified by <[fp]>. If you record this result, you can later |
| use it with <<fseek>>/<<fseeko>> to return the file to this |
| position. The difference between <<ftell>> and <<ftello>> is that |
| <<ftell>> returns <<long>> and <<ftello>> returns <<off_t>>. |
| |
| In the current implementation, <<ftell>>/<<ftello>> simply uses a character |
| count to represent the file position; this is the same number that |
| would be recorded by <<fgetpos>>. |
| |
| RETURNS |
| <<ftell>>/<<ftello>> return the file position, if possible. If they cannot do |
| this, they return <<-1L>>. Failure occurs on streams that do not support |
| positioning; the global <<errno>> indicates this condition with the |
| value <<ESPIPE>>. |
| |
| PORTABILITY |
| <<ftell>> is required by the ANSI C standard, but the meaning of its |
| result (when successful) is not specified beyond requiring that it be |
| acceptable as an argument to <<fseek>>. In particular, other |
| conforming C implementations may return a different result from |
| <<ftell>> than what <<fgetpos>> records. |
| |
| <<ftello>> is defined by the Single Unix specification. |
| |
| No supporting OS subroutines are required. |
| */ |
| |
| #if defined(LIBC_SCCS) && !defined(lint) |
| static char sccsid[] = "%W% (Berkeley) %G%"; |
| #endif /* LIBC_SCCS and not lint */ |
| |
| /* |
| * ftell: return current offset. |
| */ |
| |
| #include <_ansi.h> |
| #include <reent.h> |
| #include <stdio.h> |
| #include <errno.h> |
| #include "local.h" |
| |
| long |
| _DEFUN(_ftell_r, (ptr, fp), |
| struct _reent *ptr _AND |
| register FILE * fp) |
| { |
| _fpos_t pos; |
| |
| /* Ensure stdio is set up. */ |
| |
| CHECK_INIT (ptr, fp); |
| |
| _flockfile (fp); |
| |
| if (fp->_seek == NULL) |
| { |
| ptr->_errno = ESPIPE; |
| _funlockfile (fp); |
| return -1L; |
| } |
| |
| /* Find offset of underlying I/O object, then adjust for buffered |
| bytes. Flush a write stream, since the offset may be altered if |
| the stream is appending. Do not flush a read stream, since we |
| must not lose the ungetc buffer. */ |
| if (fp->_flags & __SWR) |
| _fflush_r (ptr, fp); |
| if (fp->_flags & __SOFF) |
| pos = fp->_offset; |
| else |
| { |
| pos = fp->_seek (ptr, fp->_cookie, (_fpos_t) 0, SEEK_CUR); |
| if (pos == -1L) |
| { |
| _funlockfile (fp); |
| return pos; |
| } |
| } |
| if (fp->_flags & __SRD) |
| { |
| /* |
| * Reading. Any unread characters (including |
| * those from ungetc) cause the position to be |
| * smaller than that in the underlying object. |
| */ |
| pos -= fp->_r; |
| if (HASUB (fp)) |
| pos -= fp->_ur; |
| } |
| else if ((fp->_flags & __SWR) && fp->_p != NULL) |
| { |
| /* |
| * Writing. Any buffered characters cause the |
| * position to be greater than that in the |
| * underlying object. |
| */ |
| pos += fp->_p - fp->_bf._base; |
| } |
| |
| _funlockfile (fp); |
| if ((long)pos != pos) |
| { |
| pos = -1; |
| ptr->_errno = EOVERFLOW; |
| } |
| return pos; |
| } |
| |
| #ifndef _REENT_ONLY |
| |
| long |
| _DEFUN(ftell, (fp), |
| register FILE * fp) |
| { |
| return _ftell_r (_REENT, fp); |
| } |
| |
| #endif /* !_REENT_ONLY */ |