--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/genericopenlibs/cstdlib/LSTDIO/FSEEK.C Fri Jun 04 16:20:51 2010 +0100
@@ -0,0 +1,318 @@
+/* FSEEK.C
+ *
+ * Portions Copyright (c) 1990-2004 Nokia Corporation and/or its subsidiary(-ies).
+ * All rights reserved.
+ */
+
+/*
+ * 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_r.h>
+#include <time.h>
+#include <fcntl.h>
+#include <stdlib_r.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.
+ */
+
+/**
+ Reposition stream's position indicator.
+@return If successful the function returns 0. Otherwise it returns nonzero.
+@param fp Pointer to an open file.
+@param offset Number of bytes from origin.
+@param whence Initial position from where offset is applied.
+*/
+EXPORT_C int
+fseek (register FILE *fp,long offset,int whence)
+{
+ struct _reent *ptr;
+ fpos_t (*seekfn)(void *, fpos_t, int);
+ fpos_t target, curoff = -1;
+ 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).
+ */
+ 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))
+ {
+ 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 < (fpos_t)(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;
+ if (HASUB (fp))
+ FREEUB (fp);
+ fp->_flags &= ~__SEOF;
+ n = target - curoff;
+ if (n)
+ {
+ if (__srefill (fp) || fp->_r < (fpos_t)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;
+}