Re: [hackers] [dwm][PATCH] move config data to read-only sections

From: Anselm R Garbe <garbeam_AT_gmail.com>
Date: Wed, 6 Sep 2017 17:07:06 +0200

Hi Joachim,

On 6 September 2017 at 17:02, <Joachim.Henke_AT_t-systems.com> wrote:
> commit 6a5056d4c919bb5ae0222b2fde0ed787d50092cf
> Author: Joachim Henke <joachim.henke_AT_t-systems.com>
> AuthorDate: Wed, 6 Sep 2017 16:26:42 +0200
>
> The configuration data is just used read-only. So making it immutable
> might improve security. Testing on x86_64 showed that the .data section
> shrunk considerably: by ~2500 bytes.
>
> diff --git a/config.def.h b/config.def.h
> index a9ac303..a43a03c 100644
> --- a/config.def.h
> +++ b/config.def.h
> _AT_@ -5,14 +5,14 @@ static const unsigned int borderpx = 1; /* border pixel of windows */
> static const unsigned int snap = 32; /* snap pixel */
> static const int showbar = 1; /* 0 means no bar */
> static const int topbar = 1; /* 0 means bottom bar */
> -static const char *fonts[] = { "monospace:size=10" };
> +static const char *const fonts[] = { "monospace:size=10" };
> static const char dmenufont[] = "monospace:size=10";
> static const char col_gray1[] = "#222222";
> static const char col_gray2[] = "#444444";
> static const char col_gray3[] = "#bbbbbb";
> static const char col_gray4[] = "#eeeeee";
> static const char col_cyan[] = "#005577";
> -static const char *colors[][3] = {
> +static const char *const colors[][3] = {
> /* fg bg border */
> [SchemeNorm] = { col_gray3, col_gray1, col_gray2 },
> [SchemeSel] = { col_gray4, col_cyan, col_cyan },
> _AT_@ -56,10 +56,10 @@ static const Layout layouts[] = {
>
> /* commands */
> static char dmenumon[2] = "0"; /* component of dmenucmd, manipulated in spawn() */
> -static const char *dmenucmd[] = { "dmenu_run", "-m", dmenumon, "-fn", dmenufont, "-nb", col_gray1, "-nf", col_gray3, "-sb", col_cyan, "-sf", col_gray4, NULL };
> -static const char *termcmd[] = { "st", NULL };
> +static const char *const dmenucmd[] = { "dmenu_run", "-m", dmenumon, "-fn", dmenufont, "-nb", col_gray1, "-nf", col_gray3, "-sb", col_cyan, "-sf", col_gray4, NULL };
> +static const char *const termcmd[] = { "st", NULL };
>
> -static Key keys[] = {
> +static const Key keys[] = {
> /* modifier key function argument */
> { MODKEY, XK_p, spawn, {.v = dmenucmd } },
> { MODKEY|ShiftMask, XK_Return, spawn, {.v = termcmd } },
> _AT_@ -98,7 +98,7 @@ static Key keys[] = {
>
> /* button definitions */
> /* click can be ClkLtSymbol, ClkStatusText, ClkWinTitle, ClkClientWin, or ClkRootWin */
> -static Button buttons[] = {
> +static const Button buttons[] = {
> /* click event mask button function argument */
> { ClkLtSymbol, 0, Button1, setlayout, {0} },
> { ClkLtSymbol, 0, Button3, setlayout, {.v = &layouts[2]} },
> diff --git a/drw.c b/drw.c
> index 319eb6b..902976f 100644
> --- a/drw.c
> +++ b/drw.c
> _AT_@ -153,7 +153,7 @@ xfont_free(Fnt *font)
> }
>
> Fnt*
> -drw_fontset_create(Drw* drw, const char *fonts[], size_t fontcount)
> +drw_fontset_create(Drw* drw, const char *const fonts[], size_t fontcount)
> {
> Fnt *cur, *ret = NULL;
> size_t i;
> _AT_@ -194,7 +194,7 @@ drw_clr_create(Drw *drw, XftColor *dest, const char *clrname)
> /* Wrapper to create color schemes. The caller has to call free(3) on the
> * returned color scheme when done using it. */
> Scm
> -drw_scm_create(Drw *drw, const char *clrnames[], size_t clrcount)
> +drw_scm_create(Drw *drw, const char *const clrnames[], size_t clrcount)
> {
> size_t i;
> Scm ret;
> diff --git a/drw.h b/drw.h
> index ff4355b..2de6a6f 100644
> --- a/drw.h
> +++ b/drw.h
> _AT_@ -32,14 +32,14 @@ void drw_resize(Drw *drw, unsigned int w, unsigned int h);
> void drw_free(Drw *drw);
>
> /* Fnt abstraction */
> -Fnt *drw_fontset_create(Drw* drw, const char *fonts[], size_t fontcount);
> +Fnt *drw_fontset_create(Drw* drw, const char *const fonts[], size_t fontcount);
> void drw_fontset_free(Fnt* set);
> unsigned int drw_fontset_getwidth(Drw *drw, const char *text);
> void drw_font_getexts(Fnt *font, const char *text, unsigned int len, unsigned int *w, unsigned int *h);
>
> /* Colorscheme abstraction */
> void drw_clr_create(Drw *drw, XftColor *dest, const char *clrname);
> -Scm drw_scm_create(Drw *drw, const char *clrnames[], size_t clrcount);
> +Scm drw_scm_create(Drw *drw, const char *const clrnames[], size_t clrcount);
>
> /* Cursor abstraction */
> Cur *drw_cur_create(Drw *drw, int shape);

I like your patch, at first glance it makes config.h more consistent
with the other const declarations, however I need to browse through
the patches if there were any places, where the non-const declaration
was on purpose for some reason prior to accepting this upstream.

BR,
Anselm
Received on Wed Sep 06 2017 - 17:07:06 CEST