Function GetErrorContextStack

src/backend/utils/error/elog.c:2302–2363

* GetErrorContextStack - Return the context stack, for display/diags * * Returns a pstrdup'd string in the caller's context which includes the PG * error call stack. It is the caller's responsibility to ensure this string * is pfree'd (or its context cleaned up) when done. * * This information is collected by traversing the error contexts and calling * each context's callback function, eac

 * errcontext() to return a string which can be presented to the user.
 */
char *
GetErrorContextStack(void)
{
	ErrorData  *edata;
	ErrorContextCallback *econtext;

	/*
	 * Okay, crank up a stack entry to store the info in.
	 */
	recursion_depth++;

	if (++errordata_stack_depth >= ERRORDATA_STACK_SIZE)
	{
		/*
		 * Wups, stack not big enough.  We treat this as a PANIC condition
		 * because it suggests an infinite loop of errors during error
		 * recovery.
		 */
		errordata_stack_depth = -1; /* make room on stack */
		ereport(PANIC, (errmsg_internal("ERRORDATA_STACK_SIZE exceeded")));
	}

	/*
	 * Things look good so far, so initialize our error frame
	 */
	edata = &errordata[errordata_stack_depth];
	MemSet(edata, 0, sizeof(ErrorData));

	/*
	 * Set up assoc_context to be the caller's context, so any allocations
	 * done (which will include edata->context) will use their context.
	 */
	edata->assoc_context = CurrentMemoryContext;

	/*
	 * Call any context callback functions to collect the context information
	 * into edata->context.
	 *
	 * Errors occurring in callback functions should go through the regular
	 * error handling code which should handle any recursive errors, though we
	 * double-check above, just in case.
	 */
	for (econtext = error_context_stack;
		 econtext != NULL;
		 econtext = econtext->previous)
		econtext->callback(econtext->arg);

	/*
	 * Clean ourselves off the stack, any allocations done should have been
	 * using edata->assoc_context, which we set up earlier to be the caller's
	 * context, so we're free to just remove our entry off the stack and
	 * decrement recursion depth and exit.
	 */
	errordata_stack_depth--;
	recursion_depth--;

	/*
	 * Return a pointer to the string the caller asked for, which should have