#41 printing open bracket { (ASCII123) freezes gui

[Anonymous]

On WinXP and Miller's pd039_test7 typing '{' (ascii
123) after print in an object box hangs the gui,
apparently because the tcl is waiting for a closing '}'
before proceeding.

In the source code, dopost() in s_print.c, it looks
like four characters are escaped: '\', '{', '}', and ';'.
But if they are escaped they should not freeze the gui...

static void dopost(const char *s)
{
...
if (c == '\\' || c == '{' || c == '}' || c
== ';') <- if it's a dangerous character for tcl
upbuf[ptout++] = '\\'; <- add a
backslash before the dangerous character
upbuf[ptout] = s[ptin]; <- then put the
character
...
sys_vgui("pdtk_post {%s}\n", upbuf); <- then
send it to tcl interpreter

If I try entering them in a print box I get different
results. '\' and '}' are rejected:
\}: dropped
\\: dropped
';' is accepted
'{' freezes the gui.

In g_editor.c:

void canvas_key(t_canvas *x, t_symbol *s, int ac,
t_atom *av)
{

...
if (keynum == '\\' || keynum == '{' || keynum ==
'}') <-a dangerous character
{
post("%c: dropped", (int)keynum); <-should be
dropped, but for '{' this doesn't get printed
return;
}
...dopost() is called from post() so '{' is causing
trouble even when it is escaped with a backslash.

Submitted by Martin Peach
martinrp@vax2.condordia.ca

[Anonymous]

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fixed in DesireData today.

[Thomas Grill]

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first, Matju 's fixes for the dopost function in s_print.c

static void dopost(const char *s)
{
if (sys_printhook)
(*sys_printhook)(s);
else if (sys_printtostderr)
fprintf(stderr, "%s", s);
else
{
char upbuf[MAXPDSTRING];
int i,j=0;
for(i=0; s[i] && j<MAXPDSTRING-16; i++)
{
if (strchr("\\\"[]$\n",s[i])) upbuf[j++]='\\';
if (s[i]=='\n') upbuf[j++]='n';
else upbuf[j++] = s[i];
}
upbuf[j] = 0;
sys_vgui("pdtk_post \"%s\"\n",upbuf);
}
}

[Thomas Grill]

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second:

it's pretty clear that the bug must be in the socket
receiver code for pd.tk inside t_tkcmd.c. In pd_readsocket
starting with line 168 it says:
/* search for locations that terminate a complete TK
command. These are carriage returns which are not inside
any braces. Braces can be escaped with backslashes (but
backslashes themselves can't.) */

When a "{: dropped" post comes in, the code in pd_readsocket
must get confused because a brace is opened but none closed.
There's no command-delimiting newline character found in
that case.

[Claude Heiland-Allen]

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In pd-0.39-2, typing { in a new object box hangs pd-gui
until you type a corresponding }, at which point the
following is printed in the console:

\{: dropped
\{: dropped
\}: dropped
\}: dropped

The text typed (exclusively) between { and } is entered into
the object box when the } is typed, too.

[Claude Heiland-Allen]

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Originator: NO

This bug is still present in pd-0.40-3.

I noticed it when pdlua tried to print a "syntax error" message containing Lua source code on a line containing '{'.

[Jonathan Wilkes]

Is this bug still present in 0.43? If so it needs to be addressed.