diff options
Diffstat (limited to 'newlib/libc/stdio/fseek.c')
| -rw-r--r-- | newlib/libc/stdio/fseek.c | 311 |
1 files changed, 0 insertions, 311 deletions
diff --git a/newlib/libc/stdio/fseek.c b/newlib/libc/stdio/fseek.c deleted file mode 100644 index 1b72989..0000000 --- a/newlib/libc/stdio/fseek.c +++ /dev/null @@ -1,311 +0,0 @@ -/* - * 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 -<<fseek>>---set file position - -INDEX - fseek - -ANSI_SYNOPSIS - #include <stdio.h> - int fseek(FILE *<[fp]>, long <[offset]>, int <[whence]>) - -TRAD_SYNOPSIS - #include <stdio.h> - int fseek(<[fp]>, <[offset]>, <[whence]>) - FILE *<[fp]>; - long <[offset]>; - int <[whence]>; - -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. - -You can use <<fseek>> to set the position for the file identified by -<[fp]>. The value of <[offset]> determines the new position, in one -of three ways selected by the value of <[whence]> (defined as macros -in `<<stdio.h>>'): - -<<SEEK_SET>>---<[offset]> is the absolute file position (an offset -from the beginning of the file) desired. <[offset]> must be positive. - -<<SEEK_CUR>>---<[offset]> is relative to the current file position. -<[offset]> can meaningfully be either positive or negative. - -<<SEEK_END>>---<[offset]> is relative to the current end of file. -<[offset]> can meaningfully be either positive (to increase the size -of the file) or negative. - -See <<ftell>> to determine the current file position. - -RETURNS -<<fseek>> returns <<0>> when successful. If <<fseek>> fails, the -result is <<EOF>>. The reason for failure is indicated in <<errno>>: -either <<ESPIPE>> (the stream identified by <[fp]> doesn't support -repositioning) or <<EINVAL>> (invalid file position). - -PORTABILITY -ANSI C requires <<fseek>>. - -Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>, -<<lseek>>, <<read>>, <<sbrk>>, <<write>>. -*/ - -#include <stdio.h> -#include <time.h> -#include <fcntl.h> -#include <stdlib.h> -#include <errno.h> -#include <sys/stat.h> -#include "local.h" - -#define POS_ERR (-(fpos_t)1) - -/* - * Seek the given file to the given offset. - * `Whence' must be one of the three SEEK_* macros. - */ - -int -fseek (fp, offset, whence) - register FILE *fp; - long offset; - int whence; -{ - struct _reent *ptr; - fpos_t _EXFUN ((*seekfn), (void *, fpos_t, int)); - fpos_t target, curoff; - size_t n; - struct stat st; - int havepos; - - /* Make sure stdio is set up. */ - - CHECK_INIT (fp); - ptr = fp->_data; - - /* If we've been doing some writing, and we're in append mode - then we don't really know where the filepos is. */ - - if (fp->_flags & __SAPP && fp->_flags & __SWR) - { - /* So flush the buffer and seek to the end. */ - fflush (fp); - } - - /* Have to be able to seek. */ - - if ((seekfn = fp->_seek) == NULL) - { - ptr->_errno = ESPIPE; /* ??? */ - return EOF; - } - - /* - * Change any SEEK_CUR to SEEK_SET, and check `whence' argument. - * After this, whence is either SEEK_SET or SEEK_END. - */ - - switch (whence) - { - case SEEK_CUR: - /* - * In order to seek relative to the current stream offset, - * we have to first find the current stream offset a la - * ftell (see ftell for details). - */ - fflush(fp); /* may adjust seek offset on append stream */ - if (fp->_flags & __SOFF) - curoff = fp->_offset; - else - { - curoff = (*seekfn) (fp->_cookie, (fpos_t) 0, SEEK_CUR); - if (curoff == -1L) - return EOF; - } - if (fp->_flags & __SRD) - { - curoff -= fp->_r; - if (HASUB (fp)) - curoff -= fp->_ur; - } - else if (fp->_flags & __SWR && fp->_p != NULL) - curoff += fp->_p - fp->_bf._base; - - offset += curoff; - whence = SEEK_SET; - havepos = 1; - break; - - case SEEK_SET: - case SEEK_END: - havepos = 0; - break; - - default: - ptr->_errno = EINVAL; - return (EOF); - } - - /* - * Can only optimise if: - * reading (and not reading-and-writing); - * not unbuffered; and - * this is a `regular' Unix file (and hence seekfn==__sseek). - * We must check __NBF first, because it is possible to have __NBF - * and __SOPT both set. - */ - - if (fp->_bf._base == NULL) - __smakebuf (fp); - if (fp->_flags & (__SWR | __SRW | __SNBF | __SNPT)) - goto dumb; - if ((fp->_flags & __SOPT) == 0) - { - if (seekfn != __sseek - || fp->_file < 0 - || _fstat_r (ptr, fp->_file, &st) - || (st.st_mode & S_IFMT) != S_IFREG) - { - fp->_flags |= __SNPT; - goto dumb; - } -#ifdef HAVE_BLKSIZE - fp->_blksize = st.st_blksize; -#else - fp->_blksize = 1024; -#endif - fp->_flags |= __SOPT; - } - - /* - * We are reading; we can try to optimise. - * Figure out where we are going and where we are now. - */ - - if (whence == SEEK_SET) - target = offset; - else - { - if (_fstat_r (ptr, fp->_file, &st)) - goto dumb; - target = st.st_size + offset; - } - - if (!havepos) - { - if (fp->_flags & __SOFF) - curoff = fp->_offset; - else - { - curoff = (*seekfn) (fp->_cookie, 0L, SEEK_CUR); - if (curoff == POS_ERR) - goto dumb; - } - curoff -= fp->_r; - if (HASUB (fp)) - curoff -= fp->_ur; - } - - /* - * Compute the number of bytes in the input buffer (pretending - * that any ungetc() input has been discarded). Adjust current - * offset backwards by this count so that it represents the - * file offset for the first byte in the current input buffer. - */ - - if (HASUB (fp)) - { - curoff += fp->_r; /* kill off ungetc */ - n = fp->_up - fp->_bf._base; - curoff -= n; - n += fp->_ur; - } - else - { - n = fp->_p - fp->_bf._base; - curoff -= n; - n += fp->_r; - } - - /* - * If the target offset is within the current buffer, - * simply adjust the pointers, clear EOF, undo ungetc(), - * and return. (If the buffer was modified, we have to - * skip this; see fgetline.c.) - */ - - if ((fp->_flags & __SMOD) == 0 && - target >= curoff && target < curoff + n) - { - register int o = target - curoff; - - fp->_p = fp->_bf._base + o; - fp->_r = n - o; - if (HASUB (fp)) - FREEUB (fp); - fp->_flags &= ~__SEOF; - return 0; - } - - /* - * The place we want to get to is not within the current buffer, - * but we can still be kind to the kernel copyout mechanism. - * By aligning the file offset to a block boundary, we can let - * the kernel use the VM hardware to map pages instead of - * copying bytes laboriously. Using a block boundary also - * ensures that we only read one block, rather than two. - */ - - curoff = target & ~(fp->_blksize - 1); - if ((*seekfn) (fp->_cookie, curoff, SEEK_SET) == POS_ERR) - goto dumb; - fp->_r = 0; - fp->_p = fp->_bf._base; - if (HASUB (fp)) - FREEUB (fp); - fp->_flags &= ~__SEOF; - n = target - curoff; - if (n) - { - if (__srefill (fp) || fp->_r < n) - goto dumb; - fp->_p += n; - fp->_r -= n; - } - return 0; - - /* - * We get here if we cannot optimise the seek ... just - * do it. Allow the seek function to change fp->_bf._base. - */ - -dumb: - if (fflush (fp) || (*seekfn) (fp->_cookie, offset, whence) == POS_ERR) - return EOF; - /* success: clear EOF indicator and discard ungetc() data */ - if (HASUB (fp)) - FREEUB (fp); - fp->_p = fp->_bf._base; - fp->_r = 0; - /* fp->_w = 0; *//* unnecessary (I think...) */ - fp->_flags &= ~__SEOF; - return 0; -} |