From: Hiltjo Posthuma [hil...@codemadness.org] Sent: Wednesday, September 6, 2017 5:32 PM To: hackers mail list Subject: Re: [hackers] [dwm][PATCH] move config data to read-only sections
On Wed, Sep 06, 2017 at 05:07:06PM +0200, Anselm R Garbe wrote: > Hi Joachim, > > On 6 September 2017 at 17:02, <joachim.he...@t-systems.com> wrote: > > commit 6a5056d4c919bb5ae0222b2fde0ed787d50092cf > > Author: Joachim Henke <joachim.he...@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 > > @@ -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 }, > > @@ -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 } }, > > @@ -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 > > @@ -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; > > @@ -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 > > @@ -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 Please no const char *const. I'm ok with the other const changes though. -- Kind regards, Hiltjo Well, C might not have the most beautiful syntax in this regard, but I see no other way to make a pointer itself read-only (and especially the ...cmd[] pointer arrays really should be). Would using a typedef for that be more comfortable to you? Regards, Jo.