From: Nathaniel Talbott <nathaniel@...>
Date: 2003-11-11T03:55:00+09:00
Subject: Re: Segfault in Ruby/ODBC

Nathaniel Talbott [mailto:nathaniel@NOSPAMtalbott.ws] wrote:

> I'll dig in to do_fetch and 
> see if I can find the memory problem.

OK, I'm pretty sure I've fixed the problem... for anyone who's interested,
I've included a patch with all of my changes to odbc.c.

Turns out the problem lay in one of the underlying library functions
(SQLColAttributes) claiming to return a zero-length string when the
requested value (SQL_COLUMN_TABLE_NAME) didn't exist, but instead not
returning anything, leaving the buffer the value was supposed to be put in
to in a hosed state. I've fixed it for the time being by making sure the
buffer always starts with a NULL value, so that it will always be
interpreted as an empty string if the function doesn't do anything to it. I
don't know if this will work if the extension is built with unicode support,
but since I don't have to deal with that environment, I don't really care at
this point. If there's a better solution, I'm all ears.

Thanks for all your help,


Nathaniel

<:((><


--- ../odbc.c.old	Thu Aug 21 14:44:37 2003
+++ odbc.c	Mon Nov 10 12:51:05 2003
@@ -1021,7 +1021,7 @@
  */
 
 static VALUE
-env_new(self)
+env_new(VALUE self)
 {
     ENV *e;
     SQLHENV henv = SQL_NULL_HENV;
@@ -1904,6 +1904,7 @@
     char name[SQL_MAX_MESSAGE_LENGTH];
 #endif
 
+    name[0] = 0;
     if (!succeeded(SQL_NULL_HENV, SQL_NULL_HDBC, hstmt,
 		   SQLColAttributes(hstmt, ic, SQL_COLUMN_LABEL, name,
 				    (SQLSMALLINT) sizeof (name),
@@ -1940,6 +1941,7 @@
     rb_iv_set(obj, "@name", rb_tainted_str_new2(upcase_if(name, upc)));
 #endif
     v = Qnil;
+    name[0] = 0;
     if (succeeded(SQL_NULL_HENV, SQL_NULL_HDBC, hstmt,
 		  SQLColAttributes(hstmt, ic, SQL_COLUMN_TABLE_NAME, name,
 				   (SQLSMALLINT) sizeof (name),
@@ -3713,6 +3715,7 @@
 #endif
 
 	    for (i = 0; i < q->ncols; i++) {
+                name[0] = 0;
 		if (!succeeded(SQL_NULL_HENV, SQL_NULL_HDBC, q->hstmt,
 			       SQLColAttributes(q->hstmt,
 						(SQLUSMALLINT) (i + 1),
@@ -3730,6 +3733,7 @@
 #else
 		need += 2 * (strlen(name) + 1);
 #endif
+                name[0] = 0;
 		if (!succeeded(SQL_NULL_HENV, SQL_NULL_HDBC, q->hstmt,
 			       SQLColAttributes(q->hstmt,
 						(SQLUSMALLINT) (i + 1),
@@ -3757,6 +3761,7 @@
 	    for (i = 0; i < q->ncols; i++) {
 		char *p0;
 
+                name[0] = 0;
 		tracesql(SQL_NULL_HENV, SQL_NULL_HDBC, q->hstmt,
 			 SQLColAttributes(q->hstmt, (SQLUSMALLINT) (i + 1),
 					  SQL_COLUMN_TABLE_NAME, name,
@@ -3771,6 +3776,7 @@
 		strcat(p, ".");
 		p += strlen(p);
 		p0 = p;
+                name[0] = 0;
 		tracesql(SQL_NULL_HENV, SQL_NULL_HDBC, q->hstmt,
 			 SQLColAttributes(q->hstmt, (SQLUSMALLINT) (i + 1),
 					  SQL_COLUMN_LABEL, name,
@@ -5426,8 +5432,11 @@
     rb_define_method(Cproc, "initialize", stmt_proc_init, -1);
     rb_define_method(Cproc, "call", stmt_proc_call, -1);
     rb_define_method(Cproc, "[]", stmt_proc_call, -1);
+
+#ifndef HAVE_RB_DEFINE_ALLOC_FUNC
     rb_enable_super(Cproc, "call");
     rb_enable_super(Cproc, "[]");
+#endif
 
     /* constants */
     for (i = 0; o_const[i].name != NULL; i++) {