Re: yacc: malloc+copy -> strndup()
On Fri, Nov 03, 2017 at 09:29:16AM +0100, Otto Moerbeek wrote:
> On Fri, Nov 03, 2017 at 04:22:43PM +0800, Michael W. Bombardieri wrote:
>
> > On Fri, Nov 03, 2017 at 04:03:44PM +0800, Michael W. Bombardieri wrote:
> > > Hello,
> > >
> > > In yacc the dup_line() function malloc()'ed a buffer and copied
> > > a line into it. The copied line includes \n.
> > > Allocate-and-copy can be done by strndup() in one hit.
> > > I ran this on i386 with awk/awkgram.y and rcs/date.y and didn't
> > > see any difference in y.tab.c compared to the system's yacc.
> > >
> > > - Michael
> >
> > Forgot to mention. The assert() is triggered if '\0' is encountered before
> > '\n'.
> > Even if that is ok, a better error message could be printed instead of
> > assert().
>
> Yes, we are very reluctant to use assert()... what if somebody compiles
> with NDEBUG?
When I put '\0' in an input file it seems to trigger syntax_error()
earlier on, so I decided to follow this. syntax_error() at least prints
the input line number.
Index: reader.c
===
RCS file: /cvs/src/usr.bin/yacc/reader.c,v
retrieving revision 1.34
diff -u -p -u -r1.34 reader.c
--- reader.c25 May 2017 20:11:03 - 1.34
+++ reader.c3 Nov 2017 09:07:47 -
@@ -171,21 +171,17 @@ get_line(void)
char *
dup_line(void)
{
- char *p, *s, *t;
+ char *p, *end;
+ size_t len;
if (line == NULL)
- return (0);
- s = line;
- while (*s != '\n')
- ++s;
- p = malloc(s - line + 1);
+ return (NULL);
+ if ((end = strchr(line, '\n')) == NULL)
+ syntax_error(lineno, line, line + strlen(line));
+ len = end - line + 1;
+ p = strndup(line, len);
if (p == NULL)
no_space();
-
- s = line;
- t = p;
- while ((*t++ = *s++) != '\n')
- continue;
return (p);
}
Re: yacc: malloc+copy -> strndup()
On Fri, Nov 03, 2017 at 04:22:43PM +0800, Michael W. Bombardieri wrote:
> On Fri, Nov 03, 2017 at 04:03:44PM +0800, Michael W. Bombardieri wrote:
> > Hello,
> >
> > In yacc the dup_line() function malloc()'ed a buffer and copied
> > a line into it. The copied line includes \n.
> > Allocate-and-copy can be done by strndup() in one hit.
> > I ran this on i386 with awk/awkgram.y and rcs/date.y and didn't
> > see any difference in y.tab.c compared to the system's yacc.
> >
> > - Michael
>
> Forgot to mention. The assert() is triggered if '\0' is encountered before
> '\n'.
> Even if that is ok, a better error message could be printed instead of
> assert().
Yes, we are very reluctant to use assert()... what if somebody compiles
with NDEBUG?
-Otto
>
> >
> >
> > Index: reader.c
> > ===
> > RCS file: /cvs/src/usr.bin/yacc/reader.c,v
> > retrieving revision 1.34
> > diff -u -p -u -r1.34 reader.c
> > --- reader.c25 May 2017 20:11:03 - 1.34
> > +++ reader.c3 Nov 2017 07:48:08 -
> > @@ -171,21 +171,17 @@ get_line(void)
> > char *
> > dup_line(void)
> > {
> > - char *p, *s, *t;
> > + char *p, *end;
> > + size_t len;
> >
> > if (line == NULL)
> > - return (0);
> > - s = line;
> > - while (*s != '\n')
> > - ++s;
> > - p = malloc(s - line + 1);
> > + return (NULL);
> > + end = strchr(line, '\n');
> > + assert(end != NULL);
> > + len = end - line + 1;
> > + p = strndup(line, len);
> > if (p == NULL)
> > no_space();
> > -
> > - s = line;
> > - t = p;
> > - while ((*t++ = *s++) != '\n')
> > - continue;
> > return (p);
> > }
> >
Re: yacc: malloc+copy -> strndup()
On Fri, Nov 03, 2017 at 04:03:44PM +0800, Michael W. Bombardieri wrote:
> Hello,
>
> In yacc the dup_line() function malloc()'ed a buffer and copied
> a line into it. The copied line includes \n.
> Allocate-and-copy can be done by strndup() in one hit.
> I ran this on i386 with awk/awkgram.y and rcs/date.y and didn't
> see any difference in y.tab.c compared to the system's yacc.
>
> - Michael
Forgot to mention. The assert() is triggered if '\0' is encountered before '\n'.
Even if that is ok, a better error message could be printed instead of assert().
>
>
> Index: reader.c
> ===
> RCS file: /cvs/src/usr.bin/yacc/reader.c,v
> retrieving revision 1.34
> diff -u -p -u -r1.34 reader.c
> --- reader.c 25 May 2017 20:11:03 - 1.34
> +++ reader.c 3 Nov 2017 07:48:08 -
> @@ -171,21 +171,17 @@ get_line(void)
> char *
> dup_line(void)
> {
> - char *p, *s, *t;
> + char *p, *end;
> + size_t len;
>
> if (line == NULL)
> - return (0);
> - s = line;
> - while (*s != '\n')
> - ++s;
> - p = malloc(s - line + 1);
> + return (NULL);
> + end = strchr(line, '\n');
> + assert(end != NULL);
> + len = end - line + 1;
> + p = strndup(line, len);
> if (p == NULL)
> no_space();
> -
> - s = line;
> - t = p;
> - while ((*t++ = *s++) != '\n')
> - continue;
> return (p);
> }
>
yacc: malloc+copy -> strndup()
Hello,
In yacc the dup_line() function malloc()'ed a buffer and copied
a line into it. The copied line includes \n.
Allocate-and-copy can be done by strndup() in one hit.
I ran this on i386 with awk/awkgram.y and rcs/date.y and didn't
see any difference in y.tab.c compared to the system's yacc.
- Michael
Index: reader.c
===
RCS file: /cvs/src/usr.bin/yacc/reader.c,v
retrieving revision 1.34
diff -u -p -u -r1.34 reader.c
--- reader.c25 May 2017 20:11:03 - 1.34
+++ reader.c3 Nov 2017 07:48:08 -
@@ -171,21 +171,17 @@ get_line(void)
char *
dup_line(void)
{
- char *p, *s, *t;
+ char *p, *end;
+ size_t len;
if (line == NULL)
- return (0);
- s = line;
- while (*s != '\n')
- ++s;
- p = malloc(s - line + 1);
+ return (NULL);
+ end = strchr(line, '\n');
+ assert(end != NULL);
+ len = end - line + 1;
+ p = strndup(line, len);
if (p == NULL)
no_space();
-
- s = line;
- t = p;
- while ((*t++ = *s++) != '\n')
- continue;
return (p);
}
