Hi all,
Today, I am do some works on adding some customized featues to PostgreSQL 9.6 beta1. But, when i do some output to psql using the fuction "do_text_output_multiline" with the string just like mentioned in mail tilte, such as "this is a\ntest for\nnew blank.". the PostgreSQL may lead to corruption in this function, and i debugged it that found this function can not dealt with the boundaries properly. The original function code as :
do_text_output_multiline(TupOutputState *tstate, char *text)
{
Datum values[1];
bool isnull[1] = {false};
while (*text)
{
char *eol;
int len;
eol = strchr(text, '\n');
if (eol)
{
len = eol - text;
eol++;
}
else
{
len = strlen(text);
eol += len;
}
values[0] = PointerGetDatum(cstring_to_text_with_len(text, len));
do_tup_output(tstate, values, isnull);
pfree(DatumGetPointer(values[0]));
text = eol;
}
}
using the string "this is a\ntest for\nnew blank." as the second input parameter, when dealing with the the last part of stirng, "new blank.", the code "eol = strchr(text, '\n');" will return NULL and will go into the "else" part, and the varialbe "eol" will added an integer, which is the length of "new blank.", eol will be 0xa, text is set to 0xa too. this address will is a system used address, then corruption. I think some boundary check will be added as following.
do_text_output_multiline(TupOutputState *tstate, char *text)
{
Datum values[1];
bool isnull[1] = {false};
while (text && *text) //if the text is NULL the return, do nothing.
{
char *eol;
int len;
eol = strchr(text, '\n');
if (eol)
{
len = eol - text;
eol++;
}
else
{
len = strlen(text);
if (eol) //to check whether the eol is NULL or not.
eol += len;
}
values[0] = PointerGetDatum(cstring_to_text_with_len(text, len));
do_tup_output(tstate, values, isnull);
pfree(DatumGetPointer(values[0]));
text = eol;
}
}
Best Regards.
RingsC.