On 6 September 2017 at 19:03, <[email protected]> wrote: > From: Hiltjo Posthuma [[email protected]] > 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, <[email protected]> wrote: >> > commit 6a5056d4c919bb5ae0222b2fde0ed787d50092cf >> > Author: Joachim Henke <[email protected]> >> > 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. > > Please no const char *const. I'm ok with the other const changes though.
Nice spot! I only glanced at it and didn't notice the pointer qualifiers. This syntax really sucks from a readability point of view. > 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? Are you suggesting to typedef const char *const coChar; or something similar and then using coChar in those places? I would still prefer the old way for readability reasons. There is no real impact either imho. BR, Anselm
