dbJLink: Handle NULL returned by jlif::alloc() better

It might not mean out-of-memory, adjust error message.
Add OOM and dbfType error checks to all jlif::alloc() routines.

Change all IFDEBUG() in JLink types to use exported global variables.
This allows debug messages to be output from the jlif::alloc()
routines, since the jlink field isn't set when they're called.

src/ioc/db/dbJLink.c

@@ -2,7 +2,7 @@
 * Copyright (c) 2016 UChicago Argonne LLC, as Operator of Argonne
 *     National Laboratory.
 * EPICS BASE is distributed subject to a Software License Agreement found
-* in file LICENSE that is included with this distribution. 
+* in file LICENSE that is included with this distribution.
 \*************************************************************************/
 /* dbJLink.c */
 
@@ -241,25 +241,29 @@ static int dbjl_map_key(void *ctx, const unsigned char *key, size_t len) {
         return dbjl_return(parser, jlif_stop);
     }
 
-    dbmfFree(link_name);
-
     pjlink = pjlif->alloc_jlink(parser->dbfType);
     if (!pjlink) {
-        errlogPrintf("dbJLinkInit: Out of memory\n");
+        errlogPrintf("dbJLinkInit: Link type '%s' allocation failed. \n",
+            link_name);
+        dbmfFree(link_name);
         return dbjl_return(parser, jlif_stop);
     }
+
     pjlink->pif = pjlif;
-    pjlink->parent = NULL;
     pjlink->parseDepth = 0;
     pjlink->debug = !!parser->lset_debug;
-
     if (parser->pjlink) {
         /* We're starting a child link, save its parent */
         pjlink->parent = parser->pjlink;
     }
+    else
+        pjlink->parent = NULL;
+
     parser->pjlink = pjlink;
     parser->key_is_link = 0;
 
+    dbmfFree(link_name);
+
     IFDEBUG(8)
         printf("dbjl_map_key: New %s@%p\n", pjlink ? pjlink->pif->name : "", pjlink);
 

src/std/link/links.dbd.pod

@@ -33,15 +33,17 @@ database file syntax.
 
 =cut
 
+
 link(const, lnkConstIf)
+variable(lnkConst_debug, int)
 
 =head3 Constant Link C<"const">
 
-Constant links provide one or more values at link initalization time, but do not
-return any data when their C<getValue()> routine is called. Most record types
-support the use of constant links by calling C<recGblInitConstantLink()> at
-record initialization, which results in the constant value being loaded into the
-target field at that time.
+Constant links are input links that provide literal values at link initalization
+time, but do not return any data when their C<getValue()> routine is called.
+Most record types support the use of constant links on their input links by
+calling C<recGblInitConstantLink()> at record initialization, which results in
+the constant value being loaded into the target field at that time.
 
 Note that for most record types (the C<printf> and C<calcout> records are the
 main exceptions) it is pointless to set an input link to a constant link at
@@ -72,14 +74,16 @@ converted to the desired double value at initialization, for example:
 
 =cut
 
+
 link(calc, lnkCalcIf)
+variable(lnkCalc_debug, int)
 
 =head3 Calculation Link C<"calc">
 
-Calculation links can perform simple mathematical expressions on scalar
-(double-precision floating-point) values obtained from other link types and
-return a single double-precision floating-point result. The expressions are
-evaluated by the EPICS Calc engine, and up to 12 inputs can be provided.
+Calculation links are input links that can evaluate mathematical expressions on
+scalar (double- precision floating-point) values obtained from child links, and
+return a double-precision floating-point result. The expressions are evaluated
+by the EPICS Calc engine, and up to 12 inputs can be provided.
 
 =head4 Parameters
 
@@ -132,13 +136,15 @@ atomically with the value of the input argument.
 
 =cut
 
+
 link(state, lnkStateIf)
+variable(lnkState_debug, int)
 
 =head3 dbState Link C<"state">
 
-A dbState link is one that reads or writes a boolean value from/to a named
-global flag as implemented by the dbState facility in C<dbstate.h>. The link
-type can invert the sense of the dbState flag if desired.
+A dbState link is one that gets or puts a boolean value from/to a named global
+flag as implemented by the dbState facility in C<dbstate.h>. The link type can
+invert the sense of the dbState flag during the get or put if desired.
 
 The value of the named flag is read or written at the time of the link I/O
 operation. When reading a flag, the value returned by the link will be zero or
@@ -156,10 +162,10 @@ mechanism.
 
 =head4 Parameters
 
-The link address must be a string providing the name of the dbState object, with
-an optional leading C<!> charater to indicate the flag's value should be
-inverted. The dbState object will be created when the link is initialized if it
-doesn't already exist.
+The link takes a single parameter which must be a string, providing the name of
+the dbState object, with an optional leading C<!> character to indicate that the
+flag's value should be inverted. The dbState object will be created when the
+link is initialized if it doesn't already exist.
 
 =head4 Examples
 

src/std/link/lnkCalc.c

@@ -40,7 +40,10 @@
 
 typedef long (*FASTCONVERT)();
 
-#define IFDEBUG(n) if(clink->jlink.debug)
+int lnkCalc_debug;
+epicsExportAddress(int, lnkCalc_debug);
+
+#define IFDEBUG(n) if (lnkCalc_debug >= (n))
 
 typedef struct calc_link {
     jlink jlink;        /* embedded object */
@@ -77,10 +80,21 @@ static lset lnkCalc_lset;
 
 static jlink* lnkCalc_alloc(short dbfType)
 {
-    calc_link *clink = calloc(1, sizeof(struct calc_link));
+    calc_link *clink;
 
     IFDEBUG(10)
-        printf("lnkCalc_alloc()\n");
+        printf("lnkCalc_alloc(%d)\n", dbfType);
+
+    if (dbfType != DBF_INLINK) {
+        errlogPrintf("lnkCalc: Only works with input links\n");
+        return NULL;
+    }
+
+    clink = calloc(1, sizeof(struct calc_link));
+    if (!clink) {
+        errlogPrintf("lnkCalc: calloc() failed.\n");
+        return NULL;
+    }
 
     clink->nArgs = 0;
     clink->pstate = ps_init;
@@ -355,8 +369,6 @@ static void lnkCalc_end_child(jlink *parent, jlink *child)
 
 static struct lset* lnkCalc_get_lset(const jlink *pjlink)
 {
-    calc_link *clink = CONTAINER(pjlink, struct calc_link, jlink);
-
     IFDEBUG(10)
         printf("lnkCalc_get_lset(calc@%p)\n", pjlink);
 

src/std/link/lnkConst.c

@@ -2,7 +2,7 @@
 * Copyright (c) 2016 UChicago Argonne LLC, as Operator of Argonne
 *     National Laboratory.
 * EPICS BASE is distributed subject to a Software License Agreement found
-* in file LICENSE that is included with this distribution. 
+* in file LICENSE that is included with this distribution.
 \*************************************************************************/
 /* lnkConst.c */
 
@@ -22,7 +22,10 @@
 #include "epicsExport.h"
 
 
-#define IFDEBUG(n) if (clink->jlink.debug)
+int lnkConst_debug;
+epicsExportAddress(int, lnkConst_debug);
+
+#define IFDEBUG(n) if (lnkConst_debug >= (n))
 
 typedef long (*FASTCONVERT)();
 
@@ -48,10 +51,21 @@ static lset lnkConst_lset;
 
 static jlink* lnkConst_alloc(short dbfType)
 {
-    const_link *clink = calloc(1, sizeof(*clink));
+    const_link *clink;
 
     IFDEBUG(10)
-        printf("lnkConst_alloc()\n");
+        printf("lnkConst_alloc(%d)\n", dbfType);
+
+    if (dbfType != DBF_INLINK) {
+        errlogPrintf("lnkConst: Only works with input links\n");
+        return NULL;
+    }
+
+    clink = calloc(1, sizeof(*clink));
+    if (!clink) {
+        errlogPrintf("lnkConst: calloc() failed.\n");
+        return NULL;
+    }
 
     clink->type = s0;
     clink->nElems = 0;
@@ -146,7 +160,6 @@ static jlif_result lnkConst_integer(jlink *pjlink, long long num)
 
 static jlif_result lnkConst_boolean(jlink *pjlink, int val)
 {
-    const_link *clink = CONTAINER(pjlink, const_link, jlink);
     IFDEBUG(10)
         printf("lnkConst_boolean(const@%p, %d)\n", pjlink, val);
 
@@ -276,8 +289,6 @@ static jlif_result lnkConst_start_array(jlink *pjlink)
 
 static jlif_result lnkConst_end_array(jlink *pjlink)
 {
-    const_link *clink = CONTAINER(pjlink, const_link, jlink);
-
     IFDEBUG(10)
         printf("lnkConst_end_array(const@%p)\n", pjlink);
 
@@ -286,8 +297,6 @@ static jlif_result lnkConst_end_array(jlink *pjlink)
 
 static struct lset* lnkConst_get_lset(const jlink *pjlink)
 {
-    const_link *clink = CONTAINER(pjlink, const_link, jlink);
-
     IFDEBUG(10)
         printf("lnkConst_get_lset(const@%p)\n", pjlink);
 
@@ -629,4 +638,3 @@ static jlif lnkConstIf = {
     lnkConst_report, NULL
 };
 epicsExportAddress(jlif, lnkConstIf);
-

src/std/link/lnkState.c

@@ -35,7 +35,10 @@
 
 typedef long (*FASTCONVERT)();
 
-#define IFDEBUG(n) if(slink->jlink.debug)
+int lnkState_debug;
+epicsExportAddress(int, lnkState_debug);
+
+#define IFDEBUG(n) if (lnkState_debug >= (n))
 
 typedef struct state_link {
     jlink jlink;        /* embedded object */
@@ -52,10 +55,21 @@ static lset lnkState_lset;
 
 static jlink* lnkState_alloc(short dbfType)
 {
-    state_link *slink = calloc(1, sizeof(struct state_link));
+    state_link *slink;
 
     IFDEBUG(10)
-        printf("lnkState_alloc()\n");
+        printf("lnkState_alloc(%d)\n", dbfType);
+
+    if (dbfType == DBF_FWDLINK) {
+        errlogPrintf("lnkState: DBF_FWDLINK not supported\n");
+        return NULL;
+    }
+
+    slink = calloc(1, sizeof(struct state_link));
+    if (!slink) {
+        errlogPrintf("lnkState: calloc() failed.\n");
+        return NULL;
+    }
 
     slink->name = NULL;
     slink->state = NULL;
@@ -97,8 +111,6 @@ static jlif_result lnkState_string(jlink *pjlink, const char *val, size_t len)
 
 static struct lset* lnkState_get_lset(const jlink *pjlink)
 {
-    state_link *slink = CONTAINER(pjlink, struct state_link, jlink);
-
     IFDEBUG(10)
         printf("lnkState_get_lset(state@%p)\n", pjlink);