Re: [dwm] [patch] simplification to drawtext
On Mon, Jun 02, 2008 at 10:16:34AM +0200, Premysl Hruby wrote: > On (02/06/08 09:56), Enno Gottox Boland wrote: > > To: dynamic window manager > > From: Enno Gottox Boland <[EMAIL PROTECTED]> > > Subject: Re: [dwm] [patch] simplification to drawtext > > Reply-To: dynamic window manager > > List-Id: dynamic window manager > > > > whoops... > > > > memcpy(&buf[MAX(0, len - 3)], "...", MIN(3, len)); > > > > Still, this is not needed, as buf is ALWAYS greater than 3 bytes. So: > > memcpy(&buf[MAX(0, len - 3)], "...", 3); > > is sufficent, this was my thought when I wrote this memcpy variant. Yes, I came to the same conclusion yesterday. Even if len < 3 it doesn't matter, because MAX(0, len - 3) will always evaluate to 0 for len <= 3 and sizeof buf > 3 is a precondition. However memcpy() might be slower than the following replacement: if(len < olen) for(i = len; i >= MAX(0, len - 3); buf[i--] = '.'); memcpy is an additional function call -- the for-solution might not be the fastest because a sane memcpy will attempt to copy 4xlong resp. 1 long in a step for speed reasons, however for the 3 dots this speed hack won't be used anyways. Kind regards, -- Anselm R. Garbe >< http://www.suckless.org/ >< GPG key: 0D73F361
Re: [dwm] [patch] simplification to drawtext
On (02/06/08 09:56), Enno Gottox Boland wrote: > To: dynamic window manager > From: Enno Gottox Boland <[EMAIL PROTECTED]> > Subject: Re: [dwm] [patch] simplification to drawtext > Reply-To: dynamic window manager > List-Id: dynamic window manager > > whoops... > > memcpy(&buf[MAX(0, len - 3)], "...", MIN(3, len)); > Still, this is not needed, as buf is ALWAYS greater than 3 bytes. So: memcpy(&buf[MAX(0, len - 3)], "...", 3); is sufficent, this was my thought when I wrote this memcpy variant. -Ph -- Premysl "Anydot" Hruby, http://www.redrum.cz/
Re: [dwm] [patch] simplification to drawtext
whoops... memcpy(&buf[MAX(0, len - 3)], "...", MIN(3, len)); 2008/6/1, Premysl Hruby <[EMAIL PROTECTED]>: > On (01/06/08 19:30), Enno Gottox Boland wrote: > > To: dynamic window manager > > From: Enno Gottox Boland <[EMAIL PROTECTED]> > > > Subject: Re: [dwm] [patch] simplification to drawtext > > > Reply-To: dynamic window manager > > List-Id: dynamic window manager > > > > > beware that it should be > > > > memcpy(&buf[MAX(0, len - 3)], "...", 4); > > > > not > > > > memcpy(&buf[MAX(0, len - 3)], "...", 3); > > > > otherwise it will overwrite the zero-terminator if len < 3. > > > This is REALLY OK, as that Xlib calls doesn't use zero-terminated > string, but string with length argument! > > > > > > Furthermore it will change the length of the string if len < 3, which > > has no impact on the output, as XDrawString respects len, but it's > > still ugly. > > > > So I still prefer strncpy as the result doing the same with memcopy > > should look like this to work properly: > > memcpy(&buf[MAX(0, len - 3)], "...", MAX(len, 3)); > > > That MAX is baaad, as if len > 4 it will copy some random data after > string "..." which is really bad. > > > > > > I also prefer strncpy over memcpy because we're not copy plain data, > > but strings. > > > No, at that point, we are copying plain data. Not strings[1] > > > > > regards > > Gottox > > > > [1]: meaned as C string == char[] which ends with zero-terminator > > > -- > Premysl "Anydot" Hruby, http://www.redrum.cz/ > > -- http://www.gnuffy.org - Real Community Distro http://www.gnuffy.org/index.php/GnuEm - Gnuffy on Ipaq (Codename Peggy)
Re: [dwm] [patch] simplification to drawtext
On (01/06/08 19:30), Enno Gottox Boland wrote: > To: dynamic window manager > From: Enno Gottox Boland <[EMAIL PROTECTED]> > Subject: Re: [dwm] [patch] simplification to drawtext > Reply-To: dynamic window manager > List-Id: dynamic window manager > > beware that it should be > > memcpy(&buf[MAX(0, len - 3)], "...", 4); > > not > > memcpy(&buf[MAX(0, len - 3)], "...", 3); > > otherwise it will overwrite the zero-terminator if len < 3. This is REALLY OK, as that Xlib calls doesn't use zero-terminated string, but string with length argument! > > Furthermore it will change the length of the string if len < 3, which > has no impact on the output, as XDrawString respects len, but it's > still ugly. > > So I still prefer strncpy as the result doing the same with memcopy > should look like this to work properly: > memcpy(&buf[MAX(0, len - 3)], "...", MAX(len, 3)); That MAX is baaad, as if len > 4 it will copy some random data after string "..." which is really bad. > > I also prefer strncpy over memcpy because we're not copy plain data, > but strings. No, at that point, we are copying plain data. Not strings[1] > > regards > Gottox > [1]: meaned as C string == char[] which ends with zero-terminator -- Premysl "Anydot" Hruby, http://www.redrum.cz/
Re: [dwm] [patch] simplification to drawtext
beware that it should be memcpy(&buf[MAX(0, len - 3)], "...", 4); not memcpy(&buf[MAX(0, len - 3)], "...", 3); otherwise it will overwrite the zero-terminator if len < 3. Furthermore it will change the length of the string if len < 3, which has no impact on the output, as XDrawString respects len, but it's still ugly. So I still prefer strncpy as the result doing the same with memcopy should look like this to work properly: memcpy(&buf[MAX(0, len - 3)], "...", MAX(len, 3)); I also prefer strncpy over memcpy because we're not copy plain data, but strings. regards Gottox 2008/6/1, Anselm R. Garbe <[EMAIL PROTECTED]>: > On Sun, Jun 01, 2008 at 01:21:03PM +0200, Premysl Hruby wrote: > > Not much readable (because it firstly looks like it's error (buf maybe > > not ended with \0)). I am against using strncpy in case that dest string > > is not C string, but char[] + length. > > > > Maybe: > > > > memcpy(&buf[MAX(0, len - 3)], "...", 3); > > > > would be somewhat better ;) > > > > > > > XSetForeground(dpy, dc.gc, col[invert ? ColBG : ColFG]); > > > if(dc.font.set) > > > XmbDrawString(dpy, dc.drawable, dc.font.set, dc.gc, x, y, > buf, len); > > > I though a while about this, and I think the memcpy() idea is > best. > > Kind regards, > > -- > Anselm R. Garbe >< http://www.suckless.org/ >< GPG key: 0D73F361 > > -- http://www.gnuffy.org - Real Community Distro http://www.gnuffy.org/index.php/GnuEm - Gnuffy on Ipaq (Codename Peggy)
Re: [dwm] [patch] simplification to drawtext
On Sun, Jun 01, 2008 at 01:21:03PM +0200, Premysl Hruby wrote: > Not much readable (because it firstly looks like it's error (buf maybe > not ended with \0)). I am against using strncpy in case that dest string > is not C string, but char[] + length. > > Maybe: > > memcpy(&buf[MAX(0, len - 3)], "...", 3); > > would be somewhat better ;) > > > > XSetForeground(dpy, dc.gc, col[invert ? ColBG : ColFG]); > > if(dc.font.set) > > XmbDrawString(dpy, dc.drawable, dc.font.set, dc.gc, x, y, buf, > > len); I though a while about this, and I think the memcpy() idea is best. Kind regards, -- Anselm R. Garbe >< http://www.suckless.org/ >< GPG key: 0D73F361
Re: [dwm] [patch] simplification to drawtext
On (01/06/08 12:38), Enno Gottox Boland wrote:
> To: dynamic window manager
> From: Enno Gottox Boland <[EMAIL PROTECTED]>
> Subject: [dwm] [patch] simplification to drawtext
> Reply-To: dynamic window manager
> List-Id: dynamic window manager
>
> Hi!
>
> Here's a small simplification to drawtext.
>
> regards
> Gottox
>
> diff -r 2488c46e002c dwm.c
> --- a/dwm.c Thu May 29 18:42:53 2008 +0100
> +++ b/dwm.c Sun Jun 01 12:36:37 2008 +0200
> @@ -571,14 +571,8 @@
> for(; len && (w = textnw(buf, len)) > dc.w - h; len--);
> if(!len)
> return;
> - if(len < olen) {
> - if(len > 1)
> - buf[len - 1] = '.';
> - if(len > 2)
> - buf[len - 2] = '.';
> - if(len > 3)
> - buf[len - 3] = '.';
> - }
> + if(len < olen)
> + strncpy(&buf[MAX(0, len - 3)], "...", len);
Not much readable (because it firstly looks like it's error (buf maybe
not ended with \0)). I am against using strncpy in case that dest string
is not C string, but char[] + length.
Maybe:
memcpy(&buf[MAX(0, len - 3)], "...", 3);
would be somewhat better ;)
> XSetForeground(dpy, dc.gc, col[invert ? ColBG : ColFG]);
> if(dc.font.set)
> XmbDrawString(dpy, dc.drawable, dc.font.set, dc.gc, x, y, buf,
> len);
--
Premysl "Anydot" Hruby, http://www.redrum.cz/
[dwm] [patch] simplification to drawtext
Hi!
Here's a small simplification to drawtext.
regards
Gottox
--
http://www.gnuffy.org - Real Community Distro
http://www.gnuffy.org/index.php/GnuEm - Gnuffy on Ipaq (Codename Peggy)
diff -r 2488c46e002c dwm.c
--- a/dwm.c Thu May 29 18:42:53 2008 +0100
+++ b/dwm.c Sun Jun 01 12:36:37 2008 +0200
@@ -571,14 +571,8 @@
for(; len && (w = textnw(buf, len)) > dc.w - h; len--);
if(!len)
return;
- if(len < olen) {
- if(len > 1)
- buf[len - 1] = '.';
- if(len > 2)
- buf[len - 2] = '.';
- if(len > 3)
- buf[len - 3] = '.';
- }
+ if(len < olen)
+ strncpy(&buf[MAX(0, len - 3)], "...", len);
XSetForeground(dpy, dc.gc, col[invert ? ColBG : ColFG]);
if(dc.font.set)
XmbDrawString(dpy, dc.drawable, dc.font.set, dc.gc, x, y, buf,
len);
