* Infinite loop in dopadding() with doublewidth chars, probably since (mm)
@ 2010-09-28 22:51 Mikael Magnusson
2010-10-02 18:41 ` Peter Stephenson
0 siblings, 1 reply; 2+ messages in thread
From: Mikael Magnusson @ 2010-09-28 22:51 UTC (permalink / raw)
To: zsh workers
Trying to pad a string to a width with a double-width character that
can't be done results in an infinite loop, where old versions just
left it one character too narrow. For example:
echo ${(ml:10::ま:):-hello}
dopadding() seems to consist mostly of special cases, but i ended up
around line 990,
986 if ((m = f % lpremul)) {
here f is 5 "hello", lpremul is 2 "ま", so m is 1
987 /*
988 * Some fraction of the repeated string needed.
989 */
990 /* Need this much... */
991 c = m;
992 /* ...skipping this much first. */
993 m = lpremul - m;
m is still 1 here
994 MB_METACHARINIT();
995 for (t = premul; m > 0; ) {
996 t += MB_METACHARLENCONV(t, &cchar);
this advances t 3 bytes, pointing directly at the null after the ま
997 m -= WCPADWIDTH(cchar, multi_width);
this subtracts 2 from m, leaving -1
998 }
999 /* Now the rest of the repeated string. */
1000 while (c > 0) {
c is still 1 here
1001 cl = MB_METACHARLENCONV(t, &cchar);
this is 0, remember t is ""
1002 while (cl--)
1003 *r++ = *t++;
1004 c -= WCPADWIDTH(cchar, multi_width);
which means c is decremented by 0 here
1005 }
1006 }
I didn't get much further than this. I didn't even dare look in how
many places some similar code exists in the function. :)
--
Mikael Magnusson
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Infinite loop in dopadding() with doublewidth chars, probably since (mm)
2010-09-28 22:51 Infinite loop in dopadding() with doublewidth chars, probably since (mm) Mikael Magnusson
@ 2010-10-02 18:41 ` Peter Stephenson
0 siblings, 0 replies; 2+ messages in thread
From: Peter Stephenson @ 2010-10-02 18:41 UTC (permalink / raw)
To: zsh workers
On Wed, 29 Sep 2010 00:51:58 +0200
Mikael Magnusson <mikachu@gmail.com> wrote:
> Trying to pad a string to a width with a double-width character that
> can't be done results in an infinite loop, where old versions just
> left it one character too narrow. For example:
> echo ${(ml:10::ま:):-hello}
I suppose we just have to stop when there's nothing left.
Index: Src/subst.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/subst.c,v
retrieving revision 1.106
diff -p -u -r1.106 subst.c
--- Src/subst.c 11 Jun 2010 20:08:03 -0000 1.106
+++ Src/subst.c 2 Oct 2010 18:38:42 -0000
@@ -802,12 +802,17 @@ dopadding(char *str, int prenum, int pos
f = -f;
MB_METACHARINIT();
while (f > 0) {
- str += MB_METACHARLENCONV(str, &cchar);
+ cl = MB_METACHARLENCONV(str, &cchar);
+ if (!cl)
+ break;
+ str += cl;
f -= WCPADWIDTH(cchar, multi_width);
}
/* Now finish the first half. */
for (c = prenum; c > 0; ) {
cl = MB_METACHARLENCONV(str, &cchar);
+ if (!cl)
+ break;
while (cl--)
*r++ = *str++;
c -= WCPADWIDTH(cchar, multi_width);
@@ -823,7 +828,10 @@ dopadding(char *str, int prenum, int pos
f = lpreone - f;
/* So skip. */
for (t = preone; f > 0; ) {
- t += MB_METACHARLENCONV(t, &cchar);
+ cl = MB_METACHARLENCONV(t, &cchar);
+ if (!cl)
+ break;
+ t += cl;
f -= WCPADWIDTH(cchar, multi_width);
}
/* Then copy the entire remainder. */
@@ -841,7 +849,10 @@ dopadding(char *str, int prenum, int pos
/* Skip this much. */
m = lpremul - m;
for (t = premul; m > 0; ) {
- t += MB_METACHARLENCONV(t, &cchar);
+ cl = MB_METACHARLENCONV(t, &cchar);
+ if (!cl)
+ break;
+ t += cl;
m -= WCPADWIDTH(cchar, multi_width);
}
/* Output the rest. */
@@ -853,6 +864,8 @@ dopadding(char *str, int prenum, int pos
MB_METACHARINIT();
for (c = lpremul, t = premul; c > 0; ) {
cl = MB_METACHARLENCONV(t, &cchar);
+ if (!cl)
+ break;
while (cl--)
*r++ = *t++;
c -= WCPADWIDTH(cchar, multi_width);
@@ -868,6 +881,8 @@ dopadding(char *str, int prenum, int pos
/* Output the first half width of the original string. */
for (c = ls2; c > 0; ) {
cl = MB_METACHARLENCONV(str, &cchar);
+ if (!cl)
+ break;
c -= WCPADWIDTH(cchar, multi_width);
while (cl--)
*r++ = *str++;
@@ -882,6 +897,8 @@ dopadding(char *str, int prenum, int pos
MB_METACHARINIT();
for (c = postnum; c > 0; ) {
cl = MB_METACHARLENCONV(str, &cchar);
+ if (!cl)
+ break;
c -= WCPADWIDTH(cchar, multi_width);
while (cl--)
*r++ = *str++;
@@ -895,6 +912,8 @@ dopadding(char *str, int prenum, int pos
/* Can't fit unrepeated string, truncate it */
for (c = f; c > 0; ) {
cl = MB_METACHARLENCONV(postone, &cchar);
+ if (!cl)
+ break;
c -= WCPADWIDTH(cchar, multi_width);
while (cl--)
*r++ = *postone++;
@@ -918,6 +937,8 @@ dopadding(char *str, int prenum, int pos
MB_METACHARINIT();
while (m > 0) {
cl = MB_METACHARLENCONV(postmul, &cchar);
+ if (!cl)
+ break;
m -= WCPADWIDTH(cchar, multi_width);
while (cl--)
*r++ = *postmul++;
@@ -941,12 +962,17 @@ dopadding(char *str, int prenum, int pos
f = -f;
MB_METACHARINIT();
while (f > 0) {
- str += MB_METACHARLENCONV(str, &cchar);
+ cl = MB_METACHARLENCONV(str, &cchar);
+ if (!cl)
+ break;
+ str += cl;
f -= WCPADWIDTH(cchar, multi_width);
}
/* Copy the rest of the original string */
for (c = prenum; c > 0; ) {
cl = MB_METACHARLENCONV(str, &cchar);
+ if (!cl)
+ break;
while (cl--)
*r++ = *str++;
c -= WCPADWIDTH(cchar, multi_width);
@@ -969,7 +995,10 @@ dopadding(char *str, int prenum, int pos
f = lpreone - f;
MB_METACHARINIT();
for (t = preone; f > 0; ) {
- t += MB_METACHARLENCONV(t, &cchar);
+ cl = MB_METACHARLENCONV(t, &cchar);
+ if (!cl)
+ break;
+ t += cl;
f -= WCPADWIDTH(cchar, multi_width);
}
/* Copy the rest of preone */
@@ -993,12 +1022,17 @@ dopadding(char *str, int prenum, int pos
m = lpremul - m;
MB_METACHARINIT();
for (t = premul; m > 0; ) {
- t += MB_METACHARLENCONV(t, &cchar);
+ cl = MB_METACHARLENCONV(t, &cchar);
+ if (!cl)
+ break;
+ t += cl;
m -= WCPADWIDTH(cchar, multi_width);
}
/* Now the rest of the repeated string. */
while (c > 0) {
cl = MB_METACHARLENCONV(t, &cchar);
+ if (!cl)
+ break;
while (cl--)
*r++ = *t++;
c -= WCPADWIDTH(cchar, multi_width);
@@ -1011,6 +1045,8 @@ dopadding(char *str, int prenum, int pos
MB_METACHARINIT();
for (c = lpremul, t = premul; c > 0; ) {
cl = MB_METACHARLENCONV(t, &cchar);
+ if (!cl)
+ break;
while (cl--)
*r++ = *t++;
c -= WCPADWIDTH(cchar, multi_width);
@@ -1049,6 +1085,8 @@ dopadding(char *str, int prenum, int pos
*/
for (c = postnum; c > 0; ) {
cl = MB_METACHARLENCONV(str, &cchar);
+ if (!cl)
+ break;
while (cl--)
*r++ = *str++;
c -= WCPADWIDTH(cchar, multi_width);
@@ -1061,6 +1099,8 @@ dopadding(char *str, int prenum, int pos
*/
for (c = ls; *str; ) {
cl = MB_METACHARLENCONV(str, &cchar);
+ if (!cl)
+ break;
while (cl--)
*r++ = *str++;
c -= WCPADWIDTH(cchar, multi_width);
@@ -1074,6 +1114,8 @@ dopadding(char *str, int prenum, int pos
*/
for (c = f; c > 0; ) {
cl = MB_METACHARLENCONV(postone, &cchar);
+ if (!cl)
+ break;
while (cl--)
*r++ = *postone++;
c -= WCPADWIDTH(cchar, multi_width);
@@ -1085,6 +1127,8 @@ dopadding(char *str, int prenum, int pos
/* Copy the entire unrepeated string */
for (c = lpostone; *postone; ) {
cl = MB_METACHARLENCONV(postone, &cchar);
+ if (!cl)
+ break;
while (cl--)
*r++ = *postone++;
c -= WCPADWIDTH(cchar, multi_width);
@@ -1096,6 +1140,8 @@ dopadding(char *str, int prenum, int pos
MB_METACHARINIT();
for (c = lpostmul, t = postmul; *t; ) {
cl = MB_METACHARLENCONV(t, &cchar);
+ if (!cl)
+ break;
while (cl--)
*r++ = *t++;
c -= WCPADWIDTH(cchar, multi_width);
@@ -1109,6 +1155,8 @@ dopadding(char *str, int prenum, int pos
MB_METACHARINIT();
while (m > 0) {
cl = MB_METACHARLENCONV(postmul, &cchar);
+ if (!cl)
+ break;
while (cl--)
*r++ = *postmul++;
m -= WCPADWIDTH(cchar, multi_width);
--
Peter Stephenson <p.w.stephenson@ntlworld.com>
Web page now at http://homepage.ntlworld.com/p.w.stephenson/
^ permalink raw reply [flat|nested] 2+ messages in thread
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2010-09-28 22:51 Infinite loop in dopadding() with doublewidth chars, probably since (mm) Mikael Magnusson
2010-10-02 18:41 ` Peter Stephenson
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