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* libio/fileops.c (_IO_file_seekoff_mmap): Leave read pointers at EOF
if seek would go past it. (mmap_remap_check): If file position is at or past EOF after check, leave read pointers at EOF and don't seek. * libio/tst-mmap-offend.c: New file. * libio/Makefile (tests): Add it.
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@ -665,22 +665,30 @@ mmap_remap_check (_IO_FILE *fp)
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# undef ROUNDED
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fp->_offset -= fp->_IO_read_end - fp->_IO_read_ptr;
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_IO_setg (fp, fp->_IO_buf_base, fp->_IO_buf_base + fp->_offset,
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_IO_setg (fp, fp->_IO_buf_base,
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fp->_offset < fp->_IO_buf_end - fp->_IO_buf_base
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? fp->_IO_buf_base + fp->_offset : fp->_IO_buf_end,
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fp->_IO_buf_end);
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if (
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# ifdef _G_LSEEK64
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_G_LSEEK64
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# else
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__lseek
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# endif
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(fp->_fileno, fp->_IO_buf_end - fp->_IO_buf_base, SEEK_SET)
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!= fp->_IO_buf_end - fp->_IO_buf_base)
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/* If we are already positioned at or past the end of the file, don't
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change the current offset. If not, seek past what we have mapped,
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mimicking the position left by a normal underflow reading into its
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buffer until EOF. */
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if (fp->_offset < fp->_IO_buf_end - fp->_IO_buf_base)
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{
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fp->_flags |= _IO_ERR_SEEN;
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return EOF;
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if (
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# ifdef _G_LSEEK64
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_G_LSEEK64
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# else
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__lseek
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# endif
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(fp->_fileno, fp->_IO_buf_end - fp->_IO_buf_base, SEEK_SET)
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!= fp->_IO_buf_end - fp->_IO_buf_base)
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fp->_flags |= _IO_ERR_SEEN;
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else
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fp->_offset = fp->_IO_buf_end - fp->_IO_buf_base;
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}
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fp->_offset = fp->_IO_buf_end - fp->_IO_buf_base;
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return 0;
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}
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@ -1152,8 +1160,17 @@ _IO_file_seekoff_mmap (fp, offset, dir, mode)
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if (result < 0)
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return EOF;
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_IO_setg (fp, fp->_IO_buf_base, fp->_IO_buf_base + offset,
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fp->_IO_buf_base + offset);
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if (offset > fp->_IO_buf_end - fp->_IO_buf_base)
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/* One can fseek arbitrarily past the end of the file
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and it is meaningless until one attempts to read.
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Leave the buffer pointers in EOF state until underflow. */
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_IO_setg (fp, fp->_IO_buf_base, fp->_IO_buf_end, fp->_IO_buf_end);
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else
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/* Adjust the read pointers to match the file position,
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but so the next read attempt will call underflow. */
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_IO_setg (fp, fp->_IO_buf_base, fp->_IO_buf_base + offset,
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fp->_IO_buf_base + offset);
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fp->_offset = result;
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_IO_mask_flags (fp, 0, _IO_EOF_SEEN);
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