[PATCH 3/3 v2] Implement _fseek_r() with _fseeko_r()

[Sebastian Huber <sebastian dot huber at embedded-brains dot de>]

2012-11-22  Sebastian Huber <sebastian.huber@embedded-brains.de>

	* libc/stdio/fseek.c: Use _fseeko_r().
	* libc/stdio/fseeko.c: Copy implementation from previous
	_fseek_r().

This patch assumes sizeof(long) <= sizeof(off_t).
---
 newlib/libc/stdio/fseek.c  |  271 +---------------------------------
 newlib/libc/stdio/fseeko.c |  355 +++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 352 insertions(+), 274 deletions(-)

diff --git a/newlib/libc/stdio/fseek.c b/newlib/libc/stdio/fseek.c
index 099a958..34147fa 100644
--- a/newlib/libc/stdio/fseek.c
+++ b/newlib/libc/stdio/fseek.c
@@ -101,21 +101,9 @@ Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
 #include <_ansi.h>
 #include <reent.h>
 #include <stdio.h>
-#include <string.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
 _DEFUN(_fseek_r, (ptr, fp, offset, whence),
        struct _reent *ptr _AND
@@ -123,264 +111,7 @@ _DEFUN(_fseek_r, (ptr, fp, offset, whence),
        long offset        _AND
        int whence)
 {
-  _fpos_t _EXFNPTR(seekfn, (struct _reent *, _PTR, _fpos_t, int));
-  _fpos_t target;
-  _fpos_t curoff = 0;
-  size_t n;
-#ifdef __USE_INTERNAL_STAT64
-  struct stat64 st;
-#else
-  struct stat st;
-#endif
-  int havepos;
-
-  /* Make sure stdio is set up.  */
-
-  CHECK_INIT (ptr, fp);
-
-  _newlib_flockfile_start (fp);
-
-  /* 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->_seek) == NULL)
-    {
-      ptr->_errno = ESPIPE;	/* ??? */
-      _newlib_flockfile_exit (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, (_fpos_t) 0, SEEK_CUR);
-	  if (curoff == -1L)
-	    {
-	      _newlib_flockfile_exit (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;
-      _newlib_flockfile_exit (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 != __sseek
-	  || fp->_file < 0
-#ifdef __USE_INTERNAL_STAT64
-	  || _fstat64_r (ptr, fp->_file, &st)
-#else
-	  || _fstat_r (ptr, fp->_file, &st)
-#endif
-	  || (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
-    {
-#ifdef __USE_INTERNAL_STAT64
-      if (_fstat64_r (ptr, fp->_file, &st))
-#else
-      if (_fstat_r (ptr, fp->_file, &st))
-#endif
-	goto dumb;
-      target = st.st_size + offset;
-    }
-  if ((long)target != target)
-    {
-      ptr->_errno = EOVERFLOW;
-      _newlib_flockfile_exit (fp);
-      return EOF;
-    }
-
-  if (!havepos)
-    {
-      if (fp->_flags & __SOFF)
-	curoff = fp->_offset;
-      else
-	{
-	  curoff = seekfn (ptr, 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 (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;
-      memset (&fp->_mbstate, 0, sizeof (_mbstate_t));
-      _newlib_flockfile_exit (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 & ~(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;
-    }
-  memset (&fp->_mbstate, 0, sizeof (_mbstate_t));
-  _newlib_flockfile_exit (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)
-    {
-      _newlib_flockfile_exit (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;
-  /* Reset no-optimization flag after successful seek.  The
-     no-optimization flag may be set in the case of a read
-     stream that is flushed which by POSIX/SUSv3 standards,
-     means that a corresponding seek must not optimize.  The
-     optimization is then allowed if no subsequent flush
-     is performed.  */
-  fp->_flags &= ~__SNPT;
-  memset (&fp->_mbstate, 0, sizeof (_mbstate_t));
-  _newlib_flockfile_end (fp);
-  return 0;
+  return _fseeko_r (ptr, fp, offset, whence);
 }
 
 #ifndef _REENT_ONLY
diff --git a/newlib/libc/stdio/fseeko.c b/newlib/libc/stdio/fseeko.c
index 0d655d0..97eafd9 100644
--- a/newlib/libc/stdio/fseeko.c
+++ b/newlib/libc/stdio/fseeko.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, Red Hat Inc.
+ * Copyright (c) 1990 The Regents of the University of California.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms are permitted
@@ -15,9 +15,106 @@
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  */
 
+/*
+FUNCTION
+<<fseek>>, <<fseeko>>---set file position
+
+INDEX
+	fseek
+INDEX
+	fseeko
+INDEX
+	_fseek_r
+INDEX
+	_fseeko_r
+
+ANSI_SYNOPSIS
+	#include <stdio.h>
+	int fseek(FILE *<[fp]>, long <[offset]>, int <[whence]>)
+	int fseeko(FILE *<[fp]>, off_t <[offset]>, int <[whence]>)
+	int _fseek_r(struct _reent *<[ptr]>, FILE *<[fp]>,
+	             long <[offset]>, int <[whence]>)
+	int _fseeko_r(struct _reent *<[ptr]>, FILE *<[fp]>,
+	             off_t <[offset]>, int <[whence]>)
+
+TRAD_SYNOPSIS
+	#include <stdio.h>
+	int fseek(<[fp]>, <[offset]>, <[whence]>)
+	FILE *<[fp]>;
+	long <[offset]>;
+	int <[whence]>;
+
+	int fseeko(<[fp]>, <[offset]>, <[whence]>)
+	FILE *<[fp]>;
+	off_t <[offset]>;
+	int <[whence]>;
+
+	int _fseek_r(<[ptr]>, <[fp]>, <[offset]>, <[whence]>)
+	struct _reent *<[ptr]>;
+	FILE *<[fp]>;
+	long <[offset]>;
+	int <[whence]>;
+
+	int _fseeko_r(<[ptr]>, <[fp]>, <[offset]>, <[whence]>)
+	struct _reent *<[ptr]>;
+	FILE *<[fp]>;
+	off_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 <<fseek>>/<<fseeko>> 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>>/<<ftello>> to determine the current file position.
+
+RETURNS
+<<fseek>>/<<fseeko>> return <<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 <<EINVAL>> (invalid file position).
+
+PORTABILITY
+ANSI C requires <<fseek>>.
+
+<<fseeko>> is defined by the Single Unix specification.
+
+Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
+<<lseek>>, <<read>>, <<sbrk>>, <<write>>.
+*/
+
 #include <_ansi.h>
 #include <reent.h>
 #include <stdio.h>
+#include <string.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
 _DEFUN(_fseeko_r, (ptr, fp, offset, whence),
@@ -26,7 +123,258 @@ _DEFUN(_fseeko_r, (ptr, fp, offset, whence),
        _off_t offset      _AND
        int whence)
 {
-  return _fseek_r (ptr, fp, (long)offset, whence);
+  _fpos_t _EXFNPTR(seekfn, (struct _reent *, _PTR, _fpos_t, int));
+  _fpos_t target;
+  _fpos_t curoff = 0;
+  size_t n;
+#ifdef __USE_INTERNAL_STAT64
+  struct stat64 st;
+#else
+  struct stat st;
+#endif
+  int havepos;
+
+  /* Make sure stdio is set up.  */
+
+  CHECK_INIT (ptr, fp);
+
+  _newlib_flockfile_start (fp);
+
+  /* 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->_seek) == NULL)
+    {
+      ptr->_errno = ESPIPE;	/* ??? */
+      _newlib_flockfile_exit (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, (_fpos_t) 0, SEEK_CUR);
+	  if (curoff == -1L)
+	    {
+	      _newlib_flockfile_exit (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;
+      _newlib_flockfile_exit (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 != __sseek
+	  || fp->_file < 0
+#ifdef __USE_INTERNAL_STAT64
+	  || _fstat64_r (ptr, fp->_file, &st)
+#else
+	  || _fstat_r (ptr, fp->_file, &st)
+#endif
+	  || (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
+    {
+#ifdef __USE_INTERNAL_STAT64
+      if (_fstat64_r (ptr, fp->_file, &st))
+#else
+      if (_fstat_r (ptr, fp->_file, &st))
+#endif
+	goto dumb;
+      target = st.st_size + offset;
+    }
+
+  if (!havepos)
+    {
+      if (fp->_flags & __SOFF)
+	curoff = fp->_offset;
+      else
+	{
+	  curoff = seekfn (ptr, 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 (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;
+      memset (&fp->_mbstate, 0, sizeof (_mbstate_t));
+      _newlib_flockfile_exit (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 & ~(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;
+    }
+  memset (&fp->_mbstate, 0, sizeof (_mbstate_t));
+  _newlib_flockfile_exit (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)
+    {
+      _newlib_flockfile_exit (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;
+  /* Reset no-optimization flag after successful seek.  The
+     no-optimization flag may be set in the case of a read
+     stream that is flushed which by POSIX/SUSv3 standards,
+     means that a corresponding seek must not optimize.  The
+     optimization is then allowed if no subsequent flush
+     is performed.  */
+  fp->_flags &= ~__SNPT;
+  memset (&fp->_mbstate, 0, sizeof (_mbstate_t));
+  _newlib_flockfile_end (fp);
+  return 0;
 }
 
 #ifndef _REENT_ONLY
@@ -37,8 +385,7 @@ _DEFUN(fseeko, (fp, offset, whence),
        _off_t offset     _AND
        int whence)
 {
-  /* for now we simply cast since off_t should be long */
-  return _fseek_r (_REENT, fp, (long)offset, whence);
+  return _fseeko_r (_REENT, fp, offset, whence);
 }
 
 #endif /* !_REENT_ONLY */
-- 
1.7.7