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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libc/] [stdio64/] [fseeko64.c] - Rev 283
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/* * 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 <<fseeko64>>---set file position for large file INDEX fseeko64 INDEX _fseeko64_r ANSI_SYNOPSIS #include <stdio.h> int fseeko64(FILE *<[fp]>, _off64_t <[offset]>, int <[whence]>) int _fseeko64_r (struct _reent *<[ptr]>, FILE *<[fp]>, _off64_t <[offset]>, int <[whence]>) TRAD_SYNOPSIS #include <stdio.h> int fseeko64(<[fp]>, <[offset]>, <[whence]>) FILE *<[fp]>; _off64_t <[offset]>; int <[whence]>; int _fseeko64_r (<[ptr]>, <[fp]>, <[offset]>, <[whence]>) struct _reent *<[ptr]>; FILE *<[fp]>; _off64_t <[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 <<fseeko64>> to set the position for the file identified by <[fp]> that was opened via <<fopen64>>. 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 <<ftello64>> to determine the current file position. RETURNS <<fseeko64>> returns <<0>> when successful. On failure, the result is <<EOF>>. The reason for failure is indicated in <<errno>>: either <<ESPIPE>> (the stream identified by <[fp]> doesn't support repositioning or wasn't opened via <<fopen64>>) or <<EINVAL>> (invalid file position). PORTABILITY <<fseeko64>> is a glibc extension. Supporting OS subroutines required: <<close>>, <<fstat64>>, <<isatty>>, <<lseek64>>, <<read>>, <<sbrk>>, <<write>>. */ #include <stdio.h> #include <time.h> #include <fcntl.h> #include <stdlib.h> #include <errno.h> #include <sys/types.h> #include <sys/stat.h> #include "local.h" #define POS_ERR (-(_fpos64_t)1) #ifdef __LARGE64_FILES /* * Seek the given file to the given offset. * `Whence' must be one of the three SEEK_* macros. */ _off64_t _DEFUN (_fseeko64_r, (ptr, fp, offset, whence), struct _reent *ptr _AND register FILE *fp _AND _off64_t offset _AND int whence) { _fpos64_t _EXFNPTR(seekfn, (struct _reent *, void *, _fpos64_t, int)); _fpos64_t target, curoff; size_t n; struct stat64 st; int havepos; /* Only do 64-bit seek on large file. */ if (!(fp->_flags & __SL64)) { if ((_off_t) offset != offset) { ptr->_errno = EOVERFLOW; return EOF; } return (_off64_t) _fseeko_r (ptr, fp, offset, whence); } /* Make sure stdio is set up. */ CHECK_INIT (ptr, fp); _flockfile (fp); curoff = fp->_offset; /* 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_r (ptr, fp); } /* Have to be able to seek. */ if ((seekfn = fp->_seek64) == NULL) { ptr->_errno = ESPIPE; /* ??? */ _funlockfile(fp); 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_r (ptr, fp); /* may adjust seek offset on append stream */ if (fp->_flags & __SOFF) curoff = fp->_offset; else { curoff = seekfn (ptr, fp->_cookie, (_fpos64_t) 0, SEEK_CUR); if (curoff == -1L) { _funlockfile(fp); 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; _funlockfile(fp); 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_r (ptr, fp); if (fp->_flags & (__SWR | __SRW | __SNBF | __SNPT)) goto dumb; if ((fp->_flags & __SOPT) == 0) { if (seekfn != __sseek64 || fp->_file < 0 || _fstat64_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 (_fstat64_r (ptr, fp->_file, &st)) goto dumb; target = st.st_size + offset; } if (!havepos) { if (fp->_flags & __SOFF) curoff = fp->_offset; else { curoff = seekfn (ptr, fp->_cookie, (_fpos64_t)0, 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 (target >= curoff && target < curoff + n) { register int o = target - curoff; fp->_p = fp->_bf._base + o; fp->_r = n - o; if (HASUB (fp)) FREEUB (ptr, fp); fp->_flags &= ~__SEOF; _funlockfile(fp); 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 & ~((_fpos64_t)(fp->_blksize - 1)); if (seekfn (ptr, fp->_cookie, curoff, SEEK_SET) == POS_ERR) goto dumb; fp->_r = 0; fp->_p = fp->_bf._base; if (HASUB (fp)) FREEUB (ptr, fp); fp->_flags &= ~__SEOF; n = target - curoff; if (n) { if (__srefill_r (ptr, fp) || fp->_r < n) goto dumb; fp->_p += n; fp->_r -= n; } _funlockfile(fp); 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_r (ptr, fp) || seekfn (ptr, fp->_cookie, offset, whence) == POS_ERR) { _funlockfile(fp); return EOF; } /* success: clear EOF indicator and discard ungetc() data */ if (HASUB (fp)) FREEUB (ptr, fp); fp->_p = fp->_bf._base; fp->_r = 0; /* fp->_w = 0; *//* unnecessary (I think...) */ fp->_flags &= ~__SEOF; _funlockfile(fp); return 0; } #ifndef _REENT_ONLY _off64_t _DEFUN (fseeko64, (fp, offset, whence), register FILE *fp _AND _off64_t offset _AND int whence) { return _fseeko64_r (_REENT, fp, offset, whence); } #endif /* !_REENT_ONLY */ #endif /* __LARGE64_FILES */
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