Re: libpq bug?

Hi,
So, does anybody have an idea?

I do have following code at the beginning of the cpp file:

#ifdef WIN32
#include <windows.h>
#pragma execution_character_set("utf-8")
#endif

but even running it on OSX, I am getting this same error.

Thank you.

On Fri, Dec 28, 2018 at 11:30 PM Igor Korot <ikorot01(at)gmail(dot)com> wrote:
>
> Hi,
>
> On Sat, Dec 29, 2018 at 1:37 AM patrick keshishian <pkeshish(at)gmail(dot)com> wrote:
> &gt;
> &gt; On Fri, Dec 28, 2018 at 5:40 PM Igor Korot <ikorot01(at)gmail(dot)com> wrote:
> &gt;&gt;
> &gt;&gt; Hi, Patrick,
> &gt;&gt;
> &gt;&gt; Here is my new code:
> &gt;&gt;
> &gt;&gt; int PostgresDatabase::GetTableOwner (const std::wstring
> &amp;schemaName,
> &gt;&gt; const std::wstring &amp;tableName, std::wstring &amp;owner,
> &gt;&gt; std::vector<std::wstring> &amp;errorMsg)
> &gt;&gt; {
> &gt;&gt; int result = 0;
> &gt;&gt; std::wstring query = L"SELECT u.usename FROM pg_class c, pg_user
> &gt;&gt; u, pg_namespace n WHERE n.oid = c.relnamespace AND u.usesysid =
> &gt;&gt; c.relowner AND n.nspname = $1 AND relname = $2";
> &gt;&gt; char *values[2];
> &gt;&gt; values[0] = NULL, values[1] = NULL;
> &gt;&gt; int charlength1 = schemaName.length() * sizeof( wchar_t ),
> &gt;&gt; charlength2 = tableName.length() * sizeof( wchar_t );
> &gt;&gt; values[0] = new char[schemaName.length() * sizeof( wchar_t ) + 1];
> &gt;&gt; values[1] = new char[tableName.length() * sizeof( wchar_t ) + 1];
> &gt;&gt; memset( values[0], '\0', schemaName.length() * sizeof(
> wchar_t ) + 1 );
> &gt;&gt; memset( values[1], '\0', tableName.length() * sizeof(
> wchar_t ) + 1 );
> &gt;&gt; strcpy( values[0], m_pimpl-&gt;m_myconv.to_bytes(
> schemaName.c_str()
> &gt;&gt; ).c_str() );
> &gt;&gt; strcpy( values[1], m_pimpl-&gt;m_myconv.to_bytes( tableName.c_str()
> &gt;&gt; ).c_str() );
> &gt;&gt; int len1 = (int) schemaName.length() * sizeof( wchar_t );
> &gt;&gt; int len2 = (int) tableName.length() * sizeof( wchar_t );
> &gt;&gt; int length[2] = { len1, len2 };
> &gt;&gt; int formats[2] = { 1, 1 };
> &gt;&gt; PGresult *res = PQexecParams( m_db, m_pimpl-&gt;m_myconv.to_bytes(
> &gt;&gt; query.c_str() ).c_str(), 2, NULL, values, length, formats, 1 );
> &gt;&gt; ExecStatusType status = PQresultStatus( res );
> &gt;&gt; if( status != PGRES_COMMAND_OK &amp;&amp; status !=
> PGRES_TUPLES_OK )
> &gt;&gt; {
> &gt;&gt; result = 1;
> &gt;&gt; std::wstring err = m_pimpl-&gt;m_myconv.from_bytes(
> &gt;&gt; PQerrorMessage( m_db ) );
> &gt;&gt; errorMsg.push_back( L"Error executing query: " + err );
> &gt;&gt; PQclear( res );
> &gt;&gt; }
> &gt;&gt; else
> &gt;&gt; {
> &gt;&gt; owner = m_pimpl-&gt;m_myconv.from_bytes( PQgetvalue(
> res, 0, 0 ) );
> &gt;&gt; }
> &gt;&gt; return result;
> &gt;&gt; }
> &gt;&gt;
> &gt;&gt; The charlength2 variable contains the value of 8 and I'm still getting
> &gt;&gt; the same error.
> &gt;
> &gt;
> &gt; I was hoping someone more versed in C++ would jump in to answer
> your question. I haven't used C++ in at least a decade.
> &gt; You need to convert the wchar_t data that wstring stores into
> UTF-8. Personally, I would use iconv (common enough).
>
> But that is very weird.
> When I check what is stored in the values[1] array, I see the same
> byte sequence as what I got from the database
> information_schema.tables..
> Maybe I should just upgrade the libpq and try the latest release?
>
> &gt;
> &gt; I assume the PostgresDatabase class is your own (?) I would add a
> helper function to do the conversion. Here is a very rough template
> for you to adapt if you think it helps you.
>
> Yes, PostgresDatabase is my class.
> I will look at that later today, but it would definitely be
> interesting to get someone with the current C++
> experience (especially with C++11), because I believe that I am doing
> a conversion into UTF8.
>
> The m_convert variable is declared as:
>
> std::wstring_convert<std::codecvt_utf8<wchar_t> > m_myconv;
>
> and so I think it is converting to the UTF8.
>
> Thank you.
>
> >
> >
> > #include <err.h>
> >
> > #include <stdlib.h>
> >
> > #include <string.h>
> >
> > #include <iostream>
> >
> > #include <string>
> >
> >
> > #include <iconv.h>
> >
> >
> > class PGDB {
> >
> > public:
> >
> > // your stuff ...
> >
> > iconv_t ic;
> >
> >
> > PGDB(void) {
> >
> > setlocale(LC_CTYPE, "");
> >
> > ic = iconv_open("UTF-8", "wchar_t");
> >
> > if ((iconv_t)-1 == ic)
> >
> > errx(1, "iconv_open");
> >
> > }
> >
> > ~PGDB() {
> >
> > iconv_close(ic);
> >
> > }
> >
> > // caller should free()
> >
> > char *wchar2utf8(std::wstring const &ws) {
> >
> > char *in, *buf, *out;
> >
> > size_t bufsz, inbytes, outbytes;
> >
> >
> > in = (char *)ws.data();
> >
> > inbytes = ws.length() * sizeof(wchar_t);
> >
> > outbytes = inbytes;
> >
> > bufsz = inbytes + 1; // XXX check for overflow
> >
> >
> > buf = (char *)calloc(bufsz, 1);
> >
> > if (NULL == buf)
> >
> > err(1, NULL); // or throw something
> >
> >
> > out = buf;
> >
> > if ((size_t)-1 == iconv(ic, &in, &inbytes, &out, &outbytes))
> >
> > errx(1, "iconv"); // or throw ...
> >
> >
> > // TODO ensure inbytes is 0 (meaning all input consumed)
> >
> > return buf;
> >
> > }
> >
> > };
> >
> >
> > // demo using above PGDB class/code
> >
> > int main(int argc, char *argv[])
> >
> > {
> >
> > char *str;
> >
> > size_t i, n;
> >
> > std::wstring tab;
> >
> > PGDB pg;
> >
> >
> > tab = L"ºabcß";
> >
> > str = pg.wchar2utf8(tab);
> >
> >
> > n = strlen(str);
> >
> > for (i = 0; i < n; ++i) {
> >
> > printf("%02hhx ", str[i]);
> >
> > }
> >
> > printf("\n");
> >
> > printf("->%s<-\n", str);
> >
> >
> > free(str);
> >
> > return 0;
> >
> > }
> >
> >
> >
> > So in GetTableOwner() you'd call wchar2utf8() for the input wstring data and you don't do the new/memset/strcpy. Just remember to free() the returned utf8 string pointers after call to PQexecParams().
> >
> > cheers,
> > --patrick
> >
> >
> >
> >>
> >> Any idea?
> >>
> >> Thank you.
> >>
> >> On Fri, Dec 28, 2018 at 5:40 PM patrick keshishian <pkeshish(at)gmail(dot)com> wrote:
> >> >
> >> > On Fri, Dec 28, 2018 at 3:07 PM Igor Korot <ikorot01(at)gmail(dot)com> wrote:
> >> >>
> >> >> Hi,
> >> >>
> >> >> On Fri, Dec 28, 2018 at 4:51 PM patrick keshishian <pkeshish(at)gmail(dot)com> wrote:
> >> >> >
> >> >> >
> >> >> > On Fri, Dec 28, 2018 at 2:00 PM Igor Korot <ikorot01(at)gmail(dot)com> wrote:
> >> >> >>
> >> >> >> Hi, ALL,
> >> >> >> Following code:
> >> >> >>
> >> >> >> int PostgresDatabase::GetTableOwner (const std::wstring &schemaName,
> >> >> >> const std::wstring &tableName, std::wstring &owner,
> >> >> >> std::vector<std::wstring> &errorMsg)
> >> >> >> {
> >> >> >> int result = 0;
> >> >> >> std::wstring query = L"SELECT u.usename FROM pg_class c, pg_user
> >> >> >> u, pg_namespace n WHERE n.oid = c.relnamespace AND u.usesysid =
> >> >> >> c.relowner AND n.nspname = $1 AND relname = $2";
> >> >> >> char *values[2];
> >> >> >> values[0] = NULL, values[1] = NULL;
> >> >> >> values[0] = new char[schemaName.length() + 1];
> >> >> >> values[1] = new char[tableName.length() + 1];
> >> >> >> memset( values[0], '\0', schemaName.length() + 1 );
> >> >> >> memset( values[1], '\0', tableName.length() + 1 );
> >> >> >> strcpy( values[0], m_pimpl->m_myconv.to_bytes( schemaName.c_str()
> >> >> >> ).c_str() );
> >> >> >> strcpy( values[1], m_pimpl->m_myconv.to_bytes( tableName.c_str()
> >> >> >> ).c_str() );
> >> >> >> int len1 = (int) schemaName.length();
> >> >> >> int len2 = (int) tableName.length();
> >> >> >> int length[2] = { len1, len2 };
> >> >> >> int formats[2] = { 1, 1 };
> >> >> >> PGresult *res = PQexecParams( m_db, m_pimpl->m_myconv.to_bytes(
> >> >> >> query.c_str() ).c_str(), 2, NULL, values, length, formats, 1 );
> >> >> >> ExecStatusType status = PQresultStatus( res );
> >> >> >> if( status != PGRES_COMMAND_OK && status != PGRES_TUPLES_OK )
> >> >> >> {
> >> >> >> result = 1;
> >> >> >> std::wstring err = m_pimpl->m_myconv.from_bytes(
> >> >> >> PQerrorMessage( m_db ) );
> >> >> >> errorMsg.push_back( L"Error executing query: " + err );
> >> >> >> PQclear( res );
> >> >> >> }
> >> >> >> else
> >> >> >> {
> >> >> >> owner = m_pimpl->m_myconv.from_bytes( PQgetvalue( res, 0, 0 ) );
> >> >> >> }
> >> >> >> return result;
> >> >> >> }
> >> >> >>
> >> >> >> when ran with the call of
> >> >> >>
> >> >> >> GetTableOwner( "public", "abcß", owner, errorMsg );
> >> >> >>
> >> >> >> returns:
> >> >> >>
> >> >> >> ERROR: Invalid byte sequence for encoding UTF8.
> >> >> >>
> >> >> >> Does this mean I found the bug in the library?
> >> >> >
> >> >> >
> >> >> > The bug is in your C++ code. "abcß" as tableName.lenght() (wstring) returns 4 (as in four characters) not number of bytes required to represent the intended string: 61 62 63 c3 9f
> >> >> > Since the last character is a 2 bytes in length. Therefore, your call to PQexecParams() specifies a shorter length and hence an invalid UTF-8 sequence.
> >> >> >
> >> >> > Furthermore, your value[] array allocation is in error since wstring::length returns number of characters, not number of bytes. so you will end up with buffer-overflows.
> >> >>
> >> >> So I should use
> >> >> https://stackoverflow.com/questions/9278723/how-can-i-get-the-byte-size-of-stdwstring
> >> >> in both places?
> >> >
> >> >
> >> > size() also returns 4. If you multiply it with sizeof(wchar_t) you will end up with maximum buffers size necessary to hold the string (minus terminating \0), but not the correct length you are after. I am unsure of the "correct" C++ solution.
> >> >
> >> > Sorry,
> >> > --patrick
> >> >
> >> >
> >> >>
> >> >> Thank you.
> >> >>
> >> >> >
> >> >> > HTH,
> >> >> > --patrick
> >> >> >
> >> >> >
> >> >> >>
> >> >> >> Any idea what I can do?
> >> >> >>
> >> >> >> Thank you.
> >> >> >>