plpy_procedure.c

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/*
 * Python procedure manipulation for plpython
 *
 * src/pl/plpython/plpy_procedure.c
 */

#include "postgres.h"

#include "access/htup_details.h"
#include "access/transam.h"
#include "funcapi.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "plpy_elog.h"
#include "plpy_main.h"
#include "plpy_procedure.h"
#include "plpython.h"
#include "utils/builtins.h"
#include "utils/hsearch.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/syscache.h"

static HTAB *PLy_procedure_cache = NULL;

static PLyProcedure *PLy_procedure_create(HeapTuple procTup, Oid fn_oid, bool is_trigger);
static bool PLy_procedure_valid(PLyProcedure *proc, HeapTuple procTup);
static char *PLy_procedure_munge_source(const char *name, const char *src);


void
init_procedure_caches(void)
{
    HASHCTL     hash_ctl;

    hash_ctl.keysize = sizeof(PLyProcedureKey);
    hash_ctl.entrysize = sizeof(PLyProcedureEntry);
    PLy_procedure_cache = hash_create("PL/Python procedures", 32, &hash_ctl,
                                      HASH_ELEM | HASH_BLOBS);
}

/*
 * PLy_procedure_name: get the name of the specified procedure.
 *
 * NB: this returns the SQL name, not the internal Python procedure name
 */
char *
PLy_procedure_name(PLyProcedure *proc)
{
    if (proc == NULL)
        return "<unknown procedure>";
    return proc->proname;
}

/*
 * PLy_procedure_get: returns a cached PLyProcedure, or creates, stores and
 * returns a new PLyProcedure.
 *
 * fn_oid is the OID of the function requested
 * fn_rel is InvalidOid or the relation this function triggers on
 * is_trigger denotes whether the function is a trigger function
 *
 * The reason that both fn_rel and is_trigger need to be passed is that when
 * trigger functions get validated we don't know which relation(s) they'll
 * be used with, so no sensible fn_rel can be passed.
 */
PLyProcedure *
PLy_procedure_get(Oid fn_oid, Oid fn_rel, bool is_trigger)
{
    bool        use_cache = !(is_trigger && fn_rel == InvalidOid);
    HeapTuple   procTup;
    PLyProcedureKey key;
    PLyProcedureEntry *volatile entry = NULL;
    PLyProcedure *volatile proc = NULL;
    bool        found = false;

    procTup = SearchSysCache1(PROCOID, ObjectIdGetDatum(fn_oid));
    if (!HeapTupleIsValid(procTup))
        elog(ERROR, "cache lookup failed for function %u", fn_oid);

    /*
     * Look for the function in the cache, unless we don't have the necessary
     * information (e.g. during validation). In that case we just don't cache
     * anything.
     */
    if (use_cache)
    {
        key.fn_oid = fn_oid;
        key.fn_rel = fn_rel;
        entry = hash_search(PLy_procedure_cache, &key, HASH_ENTER, &found);
        proc = entry->proc;
    }

    PG_TRY();
    {
        if (!found)
        {
            /* Haven't found it, create a new procedure */
            proc = PLy_procedure_create(procTup, fn_oid, is_trigger);
            if (use_cache)
                entry->proc = proc;
        }
        else if (!PLy_procedure_valid(proc, procTup))
        {
            /* Found it, but it's invalid, free and reuse the cache entry */
            entry->proc = NULL;
            if (proc)
                PLy_procedure_delete(proc);
            proc = PLy_procedure_create(procTup, fn_oid, is_trigger);
            entry->proc = proc;
        }
        /* Found it and it's valid, it's fine to use it */
    }
    PG_CATCH();
    {
        /* Do not leave an uninitialized entry in the cache */
        if (use_cache)
            hash_search(PLy_procedure_cache, &key, HASH_REMOVE, NULL);
        PG_RE_THROW();
    }
    PG_END_TRY();

    ReleaseSysCache(procTup);

    return proc;
}

/*
 * Create a new PLyProcedure structure
 */
static PLyProcedure *
PLy_procedure_create(HeapTuple procTup, Oid fn_oid, bool is_trigger)
{
    char        procName[NAMEDATALEN + 256];
    Form_pg_proc procStruct;
    PLyProcedure *volatile proc;
    MemoryContext cxt;
    MemoryContext oldcxt;
    int         rv;
    char       *ptr;

    procStruct = (Form_pg_proc) GETSTRUCT(procTup);
    rv = snprintf(procName, sizeof(procName),
                  "__plpython_procedure_%s_%u",
                  NameStr(procStruct->proname),
                  fn_oid);
    if (rv >= sizeof(procName) || rv < 0)
        elog(ERROR, "procedure name would overrun buffer");

    /* Replace any not-legal-in-Python-names characters with '_' */
    for (ptr = procName; *ptr; ptr++)
    {
        if (!((*ptr >= 'A' && *ptr <= 'Z') ||
              (*ptr >= 'a' && *ptr <= 'z') ||
              (*ptr >= '0' && *ptr <= '9')))
            *ptr = '_';
    }

    /* Create long-lived context that all procedure info will live in */
    cxt = AllocSetContextCreate(TopMemoryContext,
                                "PL/Python function",
                                ALLOCSET_DEFAULT_SIZES);

    oldcxt = MemoryContextSwitchTo(cxt);

    proc = (PLyProcedure *) palloc0(sizeof(PLyProcedure));
    proc->mcxt = cxt;

    PG_TRY();
    {
        Datum       protrftypes_datum;
        Datum       prosrcdatum;
        bool        isnull;
        char       *procSource;
        int         i;

        proc->proname = pstrdup(NameStr(procStruct->proname));
        MemoryContextSetIdentifier(cxt, proc->proname);
        proc->pyname = pstrdup(procName);
        proc->fn_xmin = HeapTupleHeaderGetRawXmin(procTup->t_data);
        proc->fn_tid = procTup->t_self;
        proc->fn_readonly = (procStruct->provolatile != PROVOLATILE_VOLATILE);
        proc->is_setof = procStruct->proretset;
        proc->is_procedure = (procStruct->prokind == PROKIND_PROCEDURE);
        proc->src = NULL;
        proc->argnames = NULL;
        proc->args = NULL;
        proc->nargs = 0;
        proc->langid = procStruct->prolang;
        protrftypes_datum = SysCacheGetAttr(PROCOID, procTup,
                                            Anum_pg_proc_protrftypes,
                                            &isnull);
        proc->trftypes = isnull ? NIL : oid_array_to_list(protrftypes_datum);
        proc->code = NULL;
        proc->statics = NULL;
        proc->globals = NULL;
        proc->calldepth = 0;
        proc->argstack = NULL;

        /*
         * get information required for output conversion of the return value,
         * but only if this isn't a trigger.
         */
        if (!is_trigger)
        {
            Oid         rettype = procStruct->prorettype;
            HeapTuple   rvTypeTup;
            Form_pg_type rvTypeStruct;

            rvTypeTup = SearchSysCache1(TYPEOID, ObjectIdGetDatum(rettype));
            if (!HeapTupleIsValid(rvTypeTup))
                elog(ERROR, "cache lookup failed for type %u", rettype);
            rvTypeStruct = (Form_pg_type) GETSTRUCT(rvTypeTup);

            /* Disallow pseudotype result, except for void or record */
            if (rvTypeStruct->typtype == TYPTYPE_PSEUDO)
            {
                if (rettype == VOIDOID ||
                    rettype == RECORDOID)
                     /* okay */ ;
                else if (rettype == TRIGGEROID || rettype == EVENT_TRIGGEROID)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("trigger functions can only be called as triggers")));
                else
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("PL/Python functions cannot return type %s",
                                    format_type_be(rettype))));
            }

            /* set up output function for procedure result */
            PLy_output_setup_func(&proc->result, proc->mcxt,
                                  rettype, -1, proc);

            ReleaseSysCache(rvTypeTup);
        }
        else
        {
            /*
             * In a trigger function, we use proc->result and proc->result_in
             * for converting tuples, but we don't yet have enough info to set
             * them up.  PLy_exec_trigger will deal with it.
             */
            proc->result.typoid = InvalidOid;
            proc->result_in.typoid = InvalidOid;
        }

        /*
         * Now get information required for input conversion of the
         * procedure's arguments.  Note that we ignore output arguments here.
         * If the function returns record, those I/O functions will be set up
         * when the function is first called.
         */
        if (procStruct->pronargs)
        {
            Oid        *types;
            char      **names,
                       *modes;
            int         pos,
                        total;

            /* extract argument type info from the pg_proc tuple */
            total = get_func_arg_info(procTup, &types, &names, &modes);

            /* count number of in+inout args into proc->nargs */
            if (modes == NULL)
                proc->nargs = total;
            else
            {
                /* proc->nargs was initialized to 0 above */
                for (i = 0; i < total; i++)
                {
                    if (modes[i] != PROARGMODE_OUT &&
                        modes[i] != PROARGMODE_TABLE)
                        (proc->nargs)++;
                }
            }

            /* Allocate arrays for per-input-argument data */
            proc->argnames = (char **) palloc0(sizeof(char *) * proc->nargs);
            proc->args = (PLyDatumToOb *) palloc0(sizeof(PLyDatumToOb) * proc->nargs);

            for (i = pos = 0; i < total; i++)
            {
                HeapTuple   argTypeTup;
                Form_pg_type argTypeStruct;

                if (modes &&
                    (modes[i] == PROARGMODE_OUT ||
                     modes[i] == PROARGMODE_TABLE))
                    continue;   /* skip OUT arguments */

                Assert(types[i] == procStruct->proargtypes.values[pos]);

                argTypeTup = SearchSysCache1(TYPEOID,
                                             ObjectIdGetDatum(types[i]));
                if (!HeapTupleIsValid(argTypeTup))
                    elog(ERROR, "cache lookup failed for type %u", types[i]);
                argTypeStruct = (Form_pg_type) GETSTRUCT(argTypeTup);

                /* disallow pseudotype arguments */
                if (argTypeStruct->typtype == TYPTYPE_PSEUDO)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("PL/Python functions cannot accept type %s",
                                    format_type_be(types[i]))));

                /* set up I/O function info */
                PLy_input_setup_func(&proc->args[pos], proc->mcxt,
                                     types[i], -1,  /* typmod not known */
                                     proc);

                /* get argument name */
                proc->argnames[pos] = names ? pstrdup(names[i]) : NULL;

                ReleaseSysCache(argTypeTup);

                pos++;
            }
        }

        /*
         * get the text of the function.
         */
        prosrcdatum = SysCacheGetAttr(PROCOID, procTup,
                                      Anum_pg_proc_prosrc, &isnull);
        if (isnull)
            elog(ERROR, "null prosrc");
        procSource = TextDatumGetCString(prosrcdatum);

        PLy_procedure_compile(proc, procSource);

        pfree(procSource);
    }
    PG_CATCH();
    {
        MemoryContextSwitchTo(oldcxt);
        PLy_procedure_delete(proc);
        PG_RE_THROW();
    }
    PG_END_TRY();

    MemoryContextSwitchTo(oldcxt);
    return proc;
}

/*
 * Insert the procedure into the Python interpreter
 */
void
PLy_procedure_compile(PLyProcedure *proc, const char *src)
{
    PyObject   *crv = NULL;
    char       *msrc;

    proc->globals = PyDict_Copy(PLy_interp_globals);

    /*
     * SD is private preserved data between calls. GD is global data shared by
     * all functions
     */
    proc->statics = PyDict_New();
    if (!proc->statics)
        PLy_elog(ERROR, NULL);
    PyDict_SetItemString(proc->globals, "SD", proc->statics);

    /*
     * insert the function code into the interpreter
     */
    msrc = PLy_procedure_munge_source(proc->pyname, src);
    /* Save the mangled source for later inclusion in tracebacks */
    proc->src = MemoryContextStrdup(proc->mcxt, msrc);
    crv = PyRun_String(msrc, Py_file_input, proc->globals, NULL);
    pfree(msrc);

    if (crv != NULL)
    {
        int         clen;
        char        call[NAMEDATALEN + 256];

        Py_DECREF(crv);

        /*
         * compile a call to the function
         */
        clen = snprintf(call, sizeof(call), "%s()", proc->pyname);
        if (clen < 0 || clen >= sizeof(call))
            elog(ERROR, "string would overflow buffer");
        proc->code = Py_CompileString(call, "<string>", Py_eval_input);
        if (proc->code != NULL)
            return;
    }

    if (proc->proname)
        PLy_elog(ERROR, "could not compile PL/Python function \"%s\"",
                 proc->proname);
    else
        PLy_elog(ERROR, "could not compile anonymous PL/Python code block");
}

void
PLy_procedure_delete(PLyProcedure *proc)
{
    Py_XDECREF(proc->code);
    Py_XDECREF(proc->statics);
    Py_XDECREF(proc->globals);
    MemoryContextDelete(proc->mcxt);
}

/*
 * Decide whether a cached PLyProcedure struct is still valid
 */
static bool
PLy_procedure_valid(PLyProcedure *proc, HeapTuple procTup)
{
    if (proc == NULL)
        return false;

    /* If the pg_proc tuple has changed, it's not valid */
    if (!(proc->fn_xmin == HeapTupleHeaderGetRawXmin(procTup->t_data) &&
          ItemPointerEquals(&proc->fn_tid, &procTup->t_self)))
        return false;

    return true;
}

static char *
PLy_procedure_munge_source(const char *name, const char *src)
{
    char       *mrc,
               *mp;
    const char *sp;
    size_t      mlen;
    int         plen;

    /*
     * room for function source and the def statement
     */
    mlen = (strlen(src) * 2) + strlen(name) + 16;

    mrc = palloc(mlen);
    plen = snprintf(mrc, mlen, "def %s():\n\t", name);
    Assert(plen >= 0 && plen < mlen);

    sp = src;
    mp = mrc + plen;

    while (*sp != '\0')
    {
        if (*sp == '\r' && *(sp + 1) == '\n')
            sp++;

        if (*sp == '\n' || *sp == '\r')
        {
            *mp++ = '\n';
            *mp++ = '\t';
            sp++;
        }
        else
            *mp++ = *sp++;
    }
    *mp++ = '\n';
    *mp++ = '\n';
    *mp = '\0';

    if (mp > (mrc + mlen))
        elog(FATAL, "buffer overrun in PLy_procedure_munge_source");

    return mrc;
}