Eliminate memory leaks in plperl's spi_prepare() function.

Careless use of TopMemoryContext for I/O function data meant that repeated
use of spi_prepare and spi_freeplan would leak memory at the session level,
as per report from Christian Schröder.  In addition, spi_prepare
leaked a lot of transient data within the current plperl function's SPI
Proc context, which would be a problem for repeated use of spi_prepare
within a single plperl function call; and it wasn't terribly careful
about releasing permanent allocations in event of an error, either.

In passing, clean up some copy-and-pasteos in query-lookup error messages.

Alex Hunsaker and Tom Lane

diff --git a/src/pl/plperl/plperl.c b/src/pl/plperl/plperl.c
index c1e81b4d0297ae74de91ab48fe5d14a33b2889df..1463618e420bac84dc62446040fea960b33ff5dc 100644 (file)
--- a/src/pl/plperl/plperl.c
+++ b/src/pl/plperl/plperl.c
@@ -184,6 +184,7 @@ typedef struct plperl_call_data
 typedef struct plperl_query_desc
 {
    char        qname[24];
+   MemoryContext plan_cxt;     /* context holding this struct */
    SPIPlanPtr  plan;
    int         nargs;
    Oid        *argtypes;
@@ -3209,33 +3210,57 @@ plperl_spi_cursor_close(char *cursor)
 SV *
 plperl_spi_prepare(char *query, int argc, SV **argv)
 {
-   plperl_query_desc *qdesc;
-   plperl_query_entry *hash_entry;
-   bool        found;
-   SPIPlanPtr  plan;
-   int         i;
-
+   volatile SPIPlanPtr plan = NULL;
+   volatile MemoryContext plan_cxt = NULL;
+   plperl_query_desc *volatile qdesc = NULL;
+   plperl_query_entry *volatile hash_entry = NULL;
    MemoryContext oldcontext = CurrentMemoryContext;
    ResourceOwner oldowner = CurrentResourceOwner;
+   MemoryContext work_cxt;
+   bool        found;
+   int         i;
 
    check_spi_usage_allowed();
 
    BeginInternalSubTransaction(NULL);
    MemoryContextSwitchTo(oldcontext);
 
-   /************************************************************
-    * Allocate the new querydesc structure
-    ************************************************************/
-   qdesc = (plperl_query_desc *) malloc(sizeof(plperl_query_desc));
-   MemSet(qdesc, 0, sizeof(plperl_query_desc));
-   snprintf(qdesc->qname, sizeof(qdesc->qname), "%p", qdesc);
-   qdesc->nargs = argc;
-   qdesc->argtypes = (Oid *) malloc(argc * sizeof(Oid));
-   qdesc->arginfuncs = (FmgrInfo *) malloc(argc * sizeof(FmgrInfo));
-   qdesc->argtypioparams = (Oid *) malloc(argc * sizeof(Oid));
-
    PG_TRY();
    {
+       CHECK_FOR_INTERRUPTS();
+
+       /************************************************************
+        * Allocate the new querydesc structure
+        *
+        * The qdesc struct, as well as all its subsidiary data, lives in its
+        * plan_cxt.  But note that the SPIPlan does not.
+        ************************************************************/
+       plan_cxt = AllocSetContextCreate(TopMemoryContext,
+                                        "PL/Perl spi_prepare query",
+                                        ALLOCSET_SMALL_MINSIZE,
+                                        ALLOCSET_SMALL_INITSIZE,
+                                        ALLOCSET_SMALL_MAXSIZE);
+       MemoryContextSwitchTo(plan_cxt);
+       qdesc = (plperl_query_desc *) palloc0(sizeof(plperl_query_desc));
+       snprintf(qdesc->qname, sizeof(qdesc->qname), "%p", qdesc);
+       qdesc->plan_cxt = plan_cxt;
+       qdesc->nargs = argc;
+       qdesc->argtypes = (Oid *) palloc(argc * sizeof(Oid));
+       qdesc->arginfuncs = (FmgrInfo *) palloc(argc * sizeof(FmgrInfo));
+       qdesc->argtypioparams = (Oid *) palloc(argc * sizeof(Oid));
+       MemoryContextSwitchTo(oldcontext);
+
+       /************************************************************
+        * Do the following work in a short-lived context so that we don't
+        * leak a lot of memory in the PL/Perl function's SPI Proc context.
+        ************************************************************/
+       work_cxt = AllocSetContextCreate(CurrentMemoryContext,
+                                        "PL/Perl spi_prepare workspace",
+                                        ALLOCSET_DEFAULT_MINSIZE,
+                                        ALLOCSET_DEFAULT_INITSIZE,
+                                        ALLOCSET_DEFAULT_MAXSIZE);
+       MemoryContextSwitchTo(work_cxt);
+
        /************************************************************
         * Resolve argument type names and then look them up by oid
         * in the system cache, and remember the required information
@@ -3256,7 +3281,7 @@ plperl_spi_prepare(char *query, int argc, SV **argv)
            getTypeInputInfo(typId, &typInput, &typIOParam);
 
            qdesc->argtypes[i] = typId;
-           perm_fmgr_info(typInput, &(qdesc->arginfuncs[i]));
+           fmgr_info_cxt(typInput, &(qdesc->arginfuncs[i]), plan_cxt);
            qdesc->argtypioparams[i] = typIOParam;
        }
 
@@ -3280,6 +3305,17 @@ plperl_spi_prepare(char *query, int argc, SV **argv)
            elog(ERROR, "SPI_keepplan() failed");
        qdesc->plan = plan;
 
+       /************************************************************
+        * Insert a hashtable entry for the plan.
+        ************************************************************/
+       hash_entry = hash_search(plperl_active_interp->query_hash,
+                                qdesc->qname,
+                                HASH_ENTER, &found);
+       hash_entry->query_data = qdesc;
+
+       /* Get rid of workspace */
+       MemoryContextDelete(work_cxt);
+
        /* Commit the inner transaction, return to outer xact context */
        ReleaseCurrentSubTransaction();
        MemoryContextSwitchTo(oldcontext);
@@ -3295,16 +3331,21 @@ plperl_spi_prepare(char *query, int argc, SV **argv)
    {
        ErrorData  *edata;
 
-       free(qdesc->argtypes);
-       free(qdesc->arginfuncs);
-       free(qdesc->argtypioparams);
-       free(qdesc);
-
        /* Save error info */
        MemoryContextSwitchTo(oldcontext);
        edata = CopyErrorData();
        FlushErrorState();
 
+       /* Drop anything we managed to allocate */
+       if (hash_entry)
+           hash_search(plperl_active_interp->query_hash,
+                       qdesc->qname,
+                       HASH_REMOVE, NULL);
+       if (plan_cxt)
+           MemoryContextDelete(plan_cxt);
+       if (plan)
+           SPI_freeplan(plan);
+
        /* Abort the inner transaction */
        RollbackAndReleaseCurrentSubTransaction();
        MemoryContextSwitchTo(oldcontext);
@@ -3326,14 +3367,8 @@ plperl_spi_prepare(char *query, int argc, SV **argv)
    PG_END_TRY();
 
    /************************************************************
-    * Insert a hashtable entry for the plan and return
-    * the key to the caller.
+    * Return the query's hash key to the caller.
     ************************************************************/
-
-   hash_entry = hash_search(plperl_active_interp->query_hash, qdesc->qname,
-                            HASH_ENTER, &found);
-   hash_entry->query_data = qdesc;
-
    return cstr2sv(qdesc->qname);
 }
 
@@ -3368,16 +3403,14 @@ plperl_spi_exec_prepared(char *query, HV *attr, int argc, SV **argv)
        /************************************************************
         * Fetch the saved plan descriptor, see if it's o.k.
         ************************************************************/
-
        hash_entry = hash_search(plperl_active_interp->query_hash, query,
                                 HASH_FIND, NULL);
        if (hash_entry == NULL)
            elog(ERROR, "spi_exec_prepared: Invalid prepared query passed");
 
        qdesc = hash_entry->query_data;
-
        if (qdesc == NULL)
-           elog(ERROR, "spi_exec_prepared: panic - plperl query_hash value vanished");
+           elog(ERROR, "spi_exec_prepared: plperl query_hash value vanished");
 
        if (qdesc->nargs != argc)
            elog(ERROR, "spi_exec_prepared: expected %d argument(s), %d passed",
@@ -3509,12 +3542,11 @@ plperl_spi_query_prepared(char *query, int argc, SV **argv)
        hash_entry = hash_search(plperl_active_interp->query_hash, query,
                                 HASH_FIND, NULL);
        if (hash_entry == NULL)
-           elog(ERROR, "spi_exec_prepared: Invalid prepared query passed");
+           elog(ERROR, "spi_query_prepared: Invalid prepared query passed");
 
        qdesc = hash_entry->query_data;
-
        if (qdesc == NULL)
-           elog(ERROR, "spi_query_prepared: panic - plperl query_hash value vanished");
+           elog(ERROR, "spi_query_prepared: plperl query_hash value vanished");
 
        if (qdesc->nargs != argc)
            elog(ERROR, "spi_query_prepared: expected %d argument(s), %d passed",
@@ -3619,12 +3651,12 @@ plperl_spi_freeplan(char *query)
    hash_entry = hash_search(plperl_active_interp->query_hash, query,
                             HASH_FIND, NULL);
    if (hash_entry == NULL)
-       elog(ERROR, "spi_exec_prepared: Invalid prepared query passed");
+       elog(ERROR, "spi_freeplan: Invalid prepared query passed");
 
    qdesc = hash_entry->query_data;
-
    if (qdesc == NULL)
-       elog(ERROR, "spi_exec_freeplan: panic - plperl query_hash value vanished");
+       elog(ERROR, "spi_freeplan: plperl query_hash value vanished");
+   plan = qdesc->plan;
 
    /*
     * free all memory before SPI_freeplan, so if it dies, nothing will be
@@ -3633,11 +3665,7 @@ plperl_spi_freeplan(char *query)
    hash_search(plperl_active_interp->query_hash, query,
                HASH_REMOVE, NULL);
 
-   plan = qdesc->plan;
-   free(qdesc->argtypes);
-   free(qdesc->arginfuncs);
-   free(qdesc->argtypioparams);
-   free(qdesc);
+   MemoryContextDelete(qdesc->plan_cxt);
 
    SPI_freeplan(plan);
 }