plpy_elog.c

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/*
 * reporting Python exceptions as PostgreSQL errors
 *
 * src/pl/plpython/plpy_elog.c
 */
 
#include "postgres.h"
 
#include "lib/stringinfo.h"
#include "plpy_elog.h"
#include "plpy_main.h"
#include "plpy_procedure.h"
#include "plpy_util.h"
 
PyObject   *PLy_exc_error = NULL;
PyObject   *PLy_exc_fatal = NULL;
PyObject   *PLy_exc_spi_error = NULL;
 
 
static void PLy_traceback(PyObject *e, PyObject *v, PyObject *tb,
                          char *volatile *xmsg, char *volatile *tbmsg,
                          int *tb_depth);
static void PLy_get_spi_error_data(PyObject *exc, int *sqlerrcode, char **detail,
                                   char **hint, char **query, int *position,
                                   char **schema_name, char **table_name, char **column_name,
                                   char **datatype_name, char **constraint_name);
static void PLy_get_error_data(PyObject *exc, int *sqlerrcode, char **detail,
                               char **hint, char **schema_name, char **table_name, char **column_name,
                               char **datatype_name, char **constraint_name);
static char *get_source_line(const char *src, int lineno);
 
static void get_string_attr(PyObject *obj, char *attrname, char **str);
static bool set_string_attr(PyObject *obj, char *attrname, char *str);
 
/*
 * Emit a PG error or notice, together with any available info about
 * the current Python error, previously set by PLy_exception_set().
 * This should be used to propagate Python errors into PG.  If fmt is
 * NULL, the Python error becomes the primary error message, otherwise
 * it becomes the detail.  If there is a Python traceback, it is put
 * in the context.
 */
void
PLy_elog_impl(int elevel, const char *fmt,...)
{
    int         save_errno = errno;
    char       *volatile xmsg = NULL;
    char       *volatile tbmsg = NULL;
    int         tb_depth;
    StringInfoData emsg;
    PyObject   *exc,
               *val,
               *tb;
 
    /* If we'll need emsg, must initialize it before entering PG_TRY */
    if (fmt)
        initStringInfo(&emsg);
 
    PyErr_Fetch(&exc, &val, &tb);
 
    /* Use a PG_TRY block to ensure we release the PyObjects just acquired */
    PG_TRY();
    {
        const char *primary = NULL;
        int         sqlerrcode = 0;
        char       *detail = NULL;
        char       *hint = NULL;
        char       *query = NULL;
        int         position = 0;
        char       *schema_name = NULL;
        char       *table_name = NULL;
        char       *column_name = NULL;
        char       *datatype_name = NULL;
        char       *constraint_name = NULL;
 
        if (exc != NULL)
        {
            PyErr_NormalizeException(&exc, &val, &tb);
 
            if (PyErr_GivenExceptionMatches(val, PLy_exc_spi_error))
                PLy_get_spi_error_data(val, &sqlerrcode,
                                       &detail, &hint, &query, &position,
                                       &schema_name, &table_name, &column_name,
                                       &datatype_name, &constraint_name);
            else if (PyErr_GivenExceptionMatches(val, PLy_exc_error))
                PLy_get_error_data(val, &sqlerrcode, &detail, &hint,
                                   &schema_name, &table_name, &column_name,
                                   &datatype_name, &constraint_name);
            else if (PyErr_GivenExceptionMatches(val, PLy_exc_fatal))
                elevel = FATAL;
        }
 
        PLy_traceback(exc, val, tb,
                      &xmsg, &tbmsg, &tb_depth);
 
        if (fmt)
        {
            for (;;)
            {
                va_list     ap;
                int         needed;
 
                errno = save_errno;
                va_start(ap, fmt);
                needed = appendStringInfoVA(&emsg, dgettext(TEXTDOMAIN, fmt), ap);
                va_end(ap);
                if (needed == 0)
                    break;
                enlargeStringInfo(&emsg, needed);
            }
            primary = emsg.data;
 
            /* If there's an exception message, it goes in the detail. */
            if (xmsg)
                detail = xmsg;
        }
        else
        {
            if (xmsg)
                primary = xmsg;
        }
 
        ereport(elevel,
                (errcode(sqlerrcode ? sqlerrcode : ERRCODE_EXTERNAL_ROUTINE_EXCEPTION),
                 errmsg_internal("%s", primary ? primary : "no exception data"),
                 (detail) ? errdetail_internal("%s", detail) : 0,
                 (tb_depth > 0 && tbmsg) ? errcontext("%s", tbmsg) : 0,
                 (hint) ? errhint("%s", hint) : 0,
                 (query) ? internalerrquery(query) : 0,
                 (position) ? internalerrposition(position) : 0,
                 (schema_name) ? err_generic_string(PG_DIAG_SCHEMA_NAME,
                                                    schema_name) : 0,
                 (table_name) ? err_generic_string(PG_DIAG_TABLE_NAME,
                                                   table_name) : 0,
                 (column_name) ? err_generic_string(PG_DIAG_COLUMN_NAME,
                                                    column_name) : 0,
                 (datatype_name) ? err_generic_string(PG_DIAG_DATATYPE_NAME,
                                                      datatype_name) : 0,
                 (constraint_name) ? err_generic_string(PG_DIAG_CONSTRAINT_NAME,
                                                        constraint_name) : 0));
    }
    PG_FINALLY();
    {
        Py_XDECREF(exc);
        Py_XDECREF(val);
        Py_XDECREF(tb);
        /* For neatness' sake, also release our string buffers */
        if (fmt)
            pfree(emsg.data);
        if (xmsg)
            pfree(xmsg);
        if (tbmsg)
            pfree(tbmsg);
    }
    PG_END_TRY();
}
 
/*
 * Extract a Python traceback from the given exception data.
 *
 * The exception error message is returned in xmsg, the traceback in
 * tbmsg (both as palloc'd strings) and the traceback depth in
 * tb_depth.
 */
static void
PLy_traceback(PyObject *e, PyObject *v, PyObject *tb,
              char *volatile *xmsg, char *volatile *tbmsg, int *tb_depth)
{
    PyObject   *volatile e_type_o = NULL;
    PyObject   *volatile e_module_o = NULL;
    PyObject   *volatile vob = NULL;
    StringInfoData tbstr;
 
    /*
     * if no exception, return nulls
     */
    if (e == NULL)
    {
        *xmsg = NULL;
        *tbmsg = NULL;
        *tb_depth = 0;
 
        return;
    }
 
    /*
     * Format the exception and its value and put it in xmsg.
     */
    PG_TRY();
    {
        char       *e_type_s = NULL;
        char       *e_module_s = NULL;
        const char *vstr;
        StringInfoData xstr;
 
        e_type_o = PyObject_GetAttrString(e, "__name__");
        e_module_o = PyObject_GetAttrString(e, "__module__");
        if (e_type_o)
            e_type_s = PLyUnicode_AsString(e_type_o);
        if (e_module_o)
            e_module_s = PLyUnicode_AsString(e_module_o);
 
        if (v && ((vob = PyObject_Str(v)) != NULL))
            vstr = PLyUnicode_AsString(vob);
        else
            vstr = "unknown";
 
        initStringInfo(&xstr);
        if (!e_type_s || !e_module_s)
        {
            /* shouldn't happen */
            appendStringInfoString(&xstr, "unrecognized exception");
        }
        /* mimics behavior of traceback.format_exception_only */
        else if (strcmp(e_module_s, "builtins") == 0
                 || strcmp(e_module_s, "__main__") == 0
                 || strcmp(e_module_s, "exceptions") == 0)
            appendStringInfoString(&xstr, e_type_s);
        else
            appendStringInfo(&xstr, "%s.%s", e_module_s, e_type_s);
        appendStringInfo(&xstr, ": %s", vstr);
 
        *xmsg = xstr.data;
    }
    PG_FINALLY();
    {
        Py_XDECREF(e_type_o);
        Py_XDECREF(e_module_o);
        Py_XDECREF(vob);
    }
    PG_END_TRY();
 
    /*
     * Now format the traceback and put it in tbmsg.
     */
    *tb_depth = 0;
    initStringInfo(&tbstr);
    /* Mimic Python traceback reporting as close as possible. */
    appendStringInfoString(&tbstr, "Traceback (most recent call last):");
    while (tb != NULL && tb != Py_None)
    {
        PyObject   *volatile frame = NULL;
        PyObject   *volatile code = NULL;
        PyObject   *volatile name = NULL;
        PyObject   *volatile lineno = NULL;
        PyObject   *volatile filename = NULL;
 
        PG_TRY();
        {
            lineno = PyObject_GetAttrString(tb, "tb_lineno");
            if (lineno == NULL)
                elog(ERROR, "could not get line number from Python traceback");
 
            frame = PyObject_GetAttrString(tb, "tb_frame");
            if (frame == NULL)
                elog(ERROR, "could not get frame from Python traceback");
 
            code = PyObject_GetAttrString(frame, "f_code");
            if (code == NULL)
                elog(ERROR, "could not get code object from Python frame");
 
            name = PyObject_GetAttrString(code, "co_name");
            if (name == NULL)
                elog(ERROR, "could not get function name from Python code object");
 
            filename = PyObject_GetAttrString(code, "co_filename");
            if (filename == NULL)
                elog(ERROR, "could not get file name from Python code object");
 
            /* The first frame always points at <module>, skip it. */
            if (*tb_depth > 0)
            {
                PLyExecutionContext *exec_ctx = PLy_current_execution_context();
                char       *proname;
                char       *fname;
                char       *line;
                char       *plain_filename;
                long        plain_lineno;
 
                /*
                 * The second frame points at the internal function, but to
                 * mimic Python error reporting we want to say <module>.
                 */
                if (*tb_depth == 1)
                    fname = "<module>";
                else
                    fname = PLyUnicode_AsString(name);
 
                proname = PLy_procedure_name(exec_ctx->curr_proc);
                plain_filename = PLyUnicode_AsString(filename);
                plain_lineno = PyLong_AsLong(lineno);
 
                if (proname == NULL)
                    appendStringInfo(&tbstr, "\n  PL/Python anonymous code block, line %ld, in %s",
                                     plain_lineno - 1, fname);
                else
                    appendStringInfo(&tbstr, "\n  PL/Python function \"%s\", line %ld, in %s",
                                     proname, plain_lineno - 1, fname);
 
                /*
                 * function code object was compiled with "<string>" as the
                 * filename
                 */
                if (exec_ctx->curr_proc && plain_filename != NULL &&
                    strcmp(plain_filename, "<string>") == 0)
                {
                    /*
                     * If we know the current procedure, append the exact line
                     * from the source, again mimicking Python's traceback.py
                     * module behavior.  We could store the already line-split
                     * source to avoid splitting it every time, but producing
                     * a traceback is not the most important scenario to
                     * optimize for.  But we do not go as far as traceback.py
                     * in reading the source of imported modules.
                     */
                    line = get_source_line(exec_ctx->curr_proc->src, plain_lineno);
                    if (line)
                    {
                        appendStringInfo(&tbstr, "\n    %s", line);
                        pfree(line);
                    }
                }
            }
        }
        PG_FINALLY();
        {
            Py_XDECREF(frame);
            Py_XDECREF(code);
            Py_XDECREF(name);
            Py_XDECREF(lineno);
            Py_XDECREF(filename);
        }
        PG_END_TRY();
 
        /* Advance to the next frame. */
        tb = PyObject_GetAttrString(tb, "tb_next");
        if (tb == NULL)
            elog(ERROR, "could not traverse Python traceback");
 
        /*
         * Release the refcount that PyObject_GetAttrString acquired on the
         * next frame object.  We don't need it, because our caller has a
         * refcount on the first frame object and the frame objects each have
         * a refcount on the next one.  If we tried to hold this refcount
         * longer, it would greatly complicate cleanup in the event of a
         * failure in the above PG_TRY block.
         */
        Py_DECREF(tb);
 
        (*tb_depth)++;
    }
 
    /* Return the traceback. */
    *tbmsg = tbstr.data;
}
 
/*
 * Extract error code from SPIError's sqlstate attribute.
 */
static void
PLy_get_sqlerrcode(PyObject *exc, int *sqlerrcode)
{
    PyObject   *sqlstate;
    char       *buffer;
 
    sqlstate = PyObject_GetAttrString(exc, "sqlstate");
    if (sqlstate == NULL)
        return;
 
    buffer = PLyUnicode_AsString(sqlstate);
    if (strlen(buffer) == 5 &&
        strspn(buffer, "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ") == 5)
    {
        *sqlerrcode = MAKE_SQLSTATE(buffer[0], buffer[1], buffer[2],
                                    buffer[3], buffer[4]);
    }
 
    Py_DECREF(sqlstate);
}
 
/*
 * Extract the error data from a SPIError
 *
 * Note: the returned string values are pointers into the given PyObject.
 * They must not be free()'d, and are not guaranteed to be valid once
 * we stop holding a reference on the PyObject.
 */
static void
PLy_get_spi_error_data(PyObject *exc, int *sqlerrcode, char **detail,
                       char **hint, char **query, int *position,
                       char **schema_name, char **table_name,
                       char **column_name,
                       char **datatype_name, char **constraint_name)
{
    PyObject   *spidata;
 
    spidata = PyObject_GetAttrString(exc, "spidata");
 
    if (spidata != NULL)
    {
        PyArg_ParseTuple(spidata, "izzzizzzzz",
                         sqlerrcode, detail, hint, query, position,
                         schema_name, table_name, column_name,
                         datatype_name, constraint_name);
    }
    else
    {
        /*
         * If there's no spidata, at least set the sqlerrcode. This can happen
         * if someone explicitly raises a SPI exception from Python code.
         */
        PLy_get_sqlerrcode(exc, sqlerrcode);
    }
 
    Py_XDECREF(spidata);
}
 
/*
 * Extract the error data from an Error.
 *
 * Note: position and query attributes are never set for Error so, unlike
 * PLy_get_spi_error_data, this function doesn't return them.
 *
 * Note: the returned string values are palloc'd in the current context.
 * While our caller could pfree them later, there's no real need to do so,
 * and it would be complicated to handle both this convention and that of
 * PLy_get_spi_error_data.
 */
static void
PLy_get_error_data(PyObject *exc, int *sqlerrcode, char **detail, char **hint,
                   char **schema_name, char **table_name, char **column_name,
                   char **datatype_name, char **constraint_name)
{
    PLy_get_sqlerrcode(exc, sqlerrcode);
    get_string_attr(exc, "detail", detail);
    get_string_attr(exc, "hint", hint);
    get_string_attr(exc, "schema_name", schema_name);
    get_string_attr(exc, "table_name", table_name);
    get_string_attr(exc, "column_name", column_name);
    get_string_attr(exc, "datatype_name", datatype_name);
    get_string_attr(exc, "constraint_name", constraint_name);
}
 
/*
 * Get the given source line as a palloc'd string
 */
static char *
get_source_line(const char *src, int lineno)
{
    const char *s = NULL;
    const char *next = src;
    int         current = 0;
 
    /* sanity check */
    if (lineno <= 0)
        return NULL;
 
    while (current < lineno)
    {
        s = next;
        next = strchr(s + 1, '\n');
        current++;
        if (next == NULL)
            break;
    }
 
    if (current != lineno)
        return NULL;
 
    while (*s && isspace((unsigned char) *s))
        s++;
 
    if (next == NULL)
        return pstrdup(s);
 
    /*
     * Sanity check, next < s if the line was all-whitespace, which should
     * never happen if Python reported a frame created on that line, but check
     * anyway.
     */
    if (next < s)
        return NULL;
 
    return pnstrdup(s, next - s);
}
 
 
/* call PyErr_SetString with a vprint interface and translation support */
void
PLy_exception_set(PyObject *exc, const char *fmt,...)
{
    char        buf[1024];
    va_list     ap;
 
    va_start(ap, fmt);
    vsnprintf(buf, sizeof(buf), dgettext(TEXTDOMAIN, fmt), ap);
    va_end(ap);
 
    PyErr_SetString(exc, buf);
}
 
/* same, with pluralized message */
void
PLy_exception_set_plural(PyObject *exc,
                         const char *fmt_singular, const char *fmt_plural,
                         unsigned long n,...)
{
    char        buf[1024];
    va_list     ap;
 
    va_start(ap, n);
    vsnprintf(buf, sizeof(buf),
              dngettext(TEXTDOMAIN, fmt_singular, fmt_plural, n),
              ap);
    va_end(ap);
 
    PyErr_SetString(exc, buf);
}
 
/* set attributes of the given exception to details from ErrorData */
void
PLy_exception_set_with_details(PyObject *excclass, ErrorData *edata)
{
    PyObject   *args = NULL;
    PyObject   *error = NULL;
 
    args = Py_BuildValue("(s)", edata->message);
    if (!args)
        goto failure;
 
    /* create a new exception with the error message as the parameter */
    error = PyObject_CallObject(excclass, args);
    if (!error)
        goto failure;
 
    if (!set_string_attr(error, "sqlstate",
                         unpack_sql_state(edata->sqlerrcode)))
        goto failure;
 
    if (!set_string_attr(error, "detail", edata->detail))
        goto failure;
 
    if (!set_string_attr(error, "hint", edata->hint))
        goto failure;
 
    if (!set_string_attr(error, "query", edata->internalquery))
        goto failure;
 
    if (!set_string_attr(error, "schema_name", edata->schema_name))
        goto failure;
 
    if (!set_string_attr(error, "table_name", edata->table_name))
        goto failure;
 
    if (!set_string_attr(error, "column_name", edata->column_name))
        goto failure;
 
    if (!set_string_attr(error, "datatype_name", edata->datatype_name))
        goto failure;
 
    if (!set_string_attr(error, "constraint_name", edata->constraint_name))
        goto failure;
 
    PyErr_SetObject(excclass, error);
 
    Py_DECREF(args);
    Py_DECREF(error);
 
    return;
 
failure:
    Py_XDECREF(args);
    Py_XDECREF(error);
 
    elog(ERROR, "could not convert error to Python exception");
}
 
/* get string value of an object attribute */
static void
get_string_attr(PyObject *obj, char *attrname, char **str)
{
    PyObject   *val;
 
    val = PyObject_GetAttrString(obj, attrname);
    if (val != NULL && val != Py_None)
    {
        *str = PLyUnicode_AsString(val);
    }
    Py_XDECREF(val);
}
 
/* set an object attribute to a string value, returns true when the set was
 * successful
 */
static bool
set_string_attr(PyObject *obj, char *attrname, char *str)
{
    int         result;
    PyObject   *val;
 
    if (str != NULL)
    {
        val = PLyUnicode_FromString(str);
        if (!val)
            return false;
    }
    else
    {
        val = Py_None;
        Py_INCREF(Py_None);
    }
 
    result = PyObject_SetAttrString(obj, attrname, val);
    Py_DECREF(val);
 
    return result != -1;
}