To: vim_dev@googlegroups.com
Subject: Patch 9.0.0810
Fcc: outbox
From: Bram Moolenaar <Bram@moolenaar.net>
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------------

Patch 9.0.0810
Problem:    readblob() returns empty when trying to read too much.
Solution:   Return what is available.
Files:      runtime/doc/builtin.txt, src/blob.c, src/testdir/test_blob.vim


*** ../vim-9.0.0809/runtime/doc/builtin.txt	2022-10-20 13:28:43.773615380 +0100
--- runtime/doc/builtin.txt	2022-10-21 11:21:08.784981677 +0100
***************
*** 6865,6872 ****
  			readblob('/dev/ttyS0', 0, 10)
  <		When the file can't be opened an error message is given and
  		the result is an empty |Blob|.
! 		When trying to read bytes beyond the end of the file the
! 		result is an empty blob.
  		Also see |readfile()| and |writefile()|.
  
  
--- 6864,6873 ----
  			readblob('/dev/ttyS0', 0, 10)
  <		When the file can't be opened an error message is given and
  		the result is an empty |Blob|.
! 		When the offset is beyond the end of the file the result is an
! 		empty blob.
! 		When trying to read more bytes than are available the result
! 		is truncated.
  		Also see |readfile()| and |writefile()|.
  
  
*** ../vim-9.0.0809/src/blob.c	2022-10-20 13:28:43.777615365 +0100
--- src/blob.c	2022-10-21 11:11:30.697952099 +0100
***************
*** 199,222 ****
  
      if (offset >= 0)
      {
! 	if (size == -1)
  	    // size may become negative, checked below
  	    size = st.st_size - offset;
  	whence = SEEK_SET;
      }
      else
      {
! 	if (size == -1)
  	    size = -offset;
  	whence = SEEK_END;
      }
!     // Trying to read bytes that aren't there results in an empty blob, not an
!     // error.
!     if (size <= 0 || (
! #ifdef S_ISCHR
! 		!S_ISCHR(st.st_mode) &&
! #endif
! 		size > st.st_size))
  	return OK;
      if (offset != 0 && vim_fseek(fd, offset, whence) != 0)
  	return OK;
--- 199,230 ----
  
      if (offset >= 0)
      {
! 	// The size defaults to the whole file.  If a size is given it is
! 	// limited to not go past the end of the file.
! 	if (size == -1 || (size > st.st_size - offset
! #ifdef S_ISCHR
! 		    && !S_ISCHR(st.st_mode)
! #endif
! 		    ))
  	    // size may become negative, checked below
  	    size = st.st_size - offset;
  	whence = SEEK_SET;
      }
      else
      {
! 	// limit the offset to not go before the start of the file
! 	if (-offset > st.st_size
! #ifdef S_ISCHR
! 		    && !S_ISCHR(st.st_mode)
! #endif
! 		    )
! 	    offset = -st.st_size;
! 	// Size defaults to reading until the end of the file.
! 	if (size == -1 || size > -offset)
  	    size = -offset;
  	whence = SEEK_END;
      }
!     if (size <= 0)
  	return OK;
      if (offset != 0 && vim_fseek(fd, offset, whence) != 0)
  	return OK;
*** ../vim-9.0.0809/src/testdir/test_blob.vim	2022-10-20 13:28:43.777615365 +0100
--- src/testdir/test_blob.vim	2022-10-21 11:19:25.372629712 +0100
***************
*** 499,508 ****
        VAR br6 = readblob('Xblob', -3, 2)
        call assert_equal(b[-3 : -2], br6)
        
        VAR br1e = readblob('Xblob', 10000)
        call assert_equal(0z, br1e)
!       VAR br2e = readblob('Xblob', -10000)
!       call assert_equal(0z, br2e)
  
        call delete('Xblob')
    END
--- 499,515 ----
        VAR br6 = readblob('Xblob', -3, 2)
        call assert_equal(b[-3 : -2], br6)
        
+       #" reading past end of file, empty result
        VAR br1e = readblob('Xblob', 10000)
        call assert_equal(0z, br1e)
! 
!       #" reading too much, result is truncated
!       VAR blong = readblob('Xblob', -1000)
!       call assert_equal(b, blong)
!       LET blong = readblob('Xblob', -10, 8)
!       call assert_equal(b, blong)
!       LET blong = readblob('Xblob', 0, 10)
!       call assert_equal(b, blong)
  
        call delete('Xblob')
    END
*** ../vim-9.0.0809/src/version.c	2022-10-20 21:14:14.664098677 +0100
--- src/version.c	2022-10-21 11:21:28.445042427 +0100
***************
*** 697,698 ****
--- 697,700 ----
  {   /* Add new patch number below this line */
+ /**/
+     810,
  /**/

-- 
SUPERIMPOSE "England AD 787".  After a few more seconds we hear hoofbeats in
the distance.  They come slowly closer.  Then out of the mist comes KING
ARTHUR followed by a SERVANT who is banging two half coconuts together.
                 "Monty Python and the Holy Grail" PYTHON (MONTY) PICTURES LTD

 /// Bram Moolenaar -- Bram@Moolenaar.net -- http://www.Moolenaar.net   \\\
///                                                                      \\\
\\\        sponsor Vim, vote for features -- http://www.Vim.org/sponsor/ ///
 \\\            help me help AIDS victims -- http://ICCF-Holland.org    ///