Grcov report - dash-infinite-loop.c

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/*

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 * Copyright © 2009 M Joonas Pihlaja

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 * Permission is hereby granted, free of charge, to any person

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 * obtaining a copy of this software and associated documentation

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 * files (the "Software"), to deal in the Software without

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 * restriction, including without limitation the rights to use, copy,

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 * modify, merge, publish, distribute, sublicense, and/or sell copies

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 * of the Software, and to permit persons to whom the Software is

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 * furnished to do so, subject to the following conditions:

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 * The above copyright notice and this permission notice shall be

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 * included in all copies or substantial portions of the Software.

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 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

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 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

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 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

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 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS

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 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN

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 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN

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 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

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 * SOFTWARE.

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 * Author: M Joonas Pihlaja <jpihlaja@cc.helsinki.fi>

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*/

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#include "cairo-test.h"

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/* When faced with very small dash lengths the stroker is liable to

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 * get stuck in an infinite loop when advancing the dash offset.  This

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 * test attempts to hit each of the locations in the stroker code

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 * where the dash offset is advanced in a loop.

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 * Reported to the cairo mailing list by Hans Breuer.

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 * https://lists.cairographics.org/archives/cairo/2009-June/017506.html

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*/

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#define EPS 1e-30

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/* This should be comfortably smaller than the unit epsilon of the

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 * floating point type used to advance the dashing, yet not small

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 * enough that it underflows to zero.  1e-30 works to foil up to 80

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 * bit extended precision arithmetic.  We want to avoid zero dash

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 * lengths because those trigger special processing in the stroker. */

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static void

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do_dash (cairo_t *cr, double dx, double dy, double offset)

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    /* Set the dash pattern to be predominantly ON so that we can

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     * create a reference image by just ignoring the dashing. */

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    static double dash[] = { EPS, EPS/512 };

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    cairo_set_dash (cr, dash, 2, offset);

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    cairo_move_to (cr, 10, 10);

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    cairo_rel_line_to (cr, dx, dy);

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    cairo_stroke (cr);

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    cairo_translate (cr, dx, dy);

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static cairo_test_status_t

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draw (cairo_t *cr, int width, int height)

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    (void)width; (void)height;

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    cairo_set_source_rgb (cr, 1,1,1);

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    cairo_paint (cr);

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    cairo_set_source_rgb (cr, 0,0,0);

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    cairo_set_line_width (cr, 10);

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    /* The following calls will wedge in various places that try

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     * to advance the dashing in a loop inside the stroker. */

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    do_dash (cr, 30, 30, 0); /* _cairo_stroker_line_to_dashed */

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    do_dash (cr, 30,  0, 0); /* _cairo_rectilinear_stroker_line_to_dashed */

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    do_dash (cr, 30, 30, 1); /* _cairo_stroker_dash_start */

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    return CAIRO_TEST_SUCCESS;

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CAIRO_TEST (dash_infinite_loop,

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            "Test dashing with extremely small dash lengths.",

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            "dash",

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            NULL,

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            100, 100,

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            NULL, draw);