ioc: improve long string detection

Partially replicate the '$' handling logic of dbChannelCreate()
in the case where no '$' was provided.

ioc/channel.cpp

@@ -9,9 +9,16 @@
 
 #include <string>
 
+#include <dbAccess.h>
+
 #include "channel.h"
+#include "dbentry.h"
 #include "utilpvt.h"
 
+#ifndef PVLINK_STRINGSZ
+#  define PVLINK_STRINGSZ 1024
+#endif
+
 namespace pvxs {
 namespace ioc {
 /**
@@ -20,17 +27,49 @@ namespace ioc {
  * @param name the db channel name
  */
 Channel::Channel(const char* name)
-        :std::shared_ptr<dbChannel>(std::shared_ptr<dbChannel>(dbChannelCreate(name),
+        :chan(std::shared_ptr<dbChannel>(std::shared_ptr<dbChannel>(dbChannelCreate(name),
         [](dbChannel* ch) {
             if (ch) {
                 dbChannelDelete(ch);
             }
-        }))
+        })))
 {
     if(!*this)
         throw std::runtime_error(SB()<<"Invalid PV: "<<name);
-    if (dbChannelOpen(get()))
-        throw std::invalid_argument(SB() << "Failed dbChannelOpen(\"" << dbChannelName(get()) <<"\")");
+    {
+        DBEntry ent(dbChannelRecord(chan));
+
+        form = ent.info("Q:form", "Default");
+
+        /* ~duplicate '$' handling logic in dbChannelCreate()
+         * when no '$' is present.
+         *
+         * situation circa Base 7.0.7
+         * At this point dbChannelCreate() has initialized chan->addr.
+         * SPC_DBADDR fields have been mangled by record support code.
+         * filter have been parsed, but not opened.
+         */
+
+        auto field_type(dbChannelFieldType(chan));
+        if(field_type==DBF_STRING && dbChannelElements(chan)==1
+                && dbChannelFieldSize(chan)>MAX_STRING_SIZE+1)
+        {
+            // scalar string field with extra capacity
+            chan->addr.no_elements = chan->addr.field_size;
+            chan->addr.field_size = 1;
+            chan->addr.field_type = DBF_CHAR;
+            chan->addr.dbr_field_type = DBR_CHAR;
+            form = "String";
+
+        } else if(field_type >= DBF_INLINK && field_type <= DBF_FWDLINK) {
+            chan->addr.no_elements = PVLINK_STRINGSZ;
+            chan->addr.field_size = 1;
+            chan->addr.dbr_field_type = DBR_CHAR;
+            form = "String";
+        }
+    }
+    if (dbChannelOpen(chan.get()))
+        throw std::invalid_argument(SB() << "Failed dbChannelOpen(\"" << dbChannelName(chan) <<"\")");
 }
 
 } // pvxs

ioc/channel.h

@@ -24,7 +24,21 @@ namespace ioc {
  * from string and dbChannel to make its use simpler.  It can be used wherever a dbChannel is used.
  * As a bonus when constructed with parameters it provides an already open dbChannel.
  */
-class Channel : public std::shared_ptr<dbChannel> {
+class Channel {
+    std::shared_ptr<dbChannel> chan;
+    /* Whenever chan!=nullptr, 'form' points to a string which will out-live
+     * the associated dbChannel*.  eg. either statically allocated, or an
+     * info() tag.  Value should be one of:
+     *      "Default",
+     *      "String",
+     *      "Binary",
+     *      "Decimal",
+     *      "Hex",
+     *      "Exponential",
+     *      "Engineering",
+     * (although it could be anything...)
+     */
+    const char *form = nullptr;
 public:
     Channel() = default;
     Channel(const Channel&) = default;
@@ -40,8 +54,14 @@ class Channel : public std::shared_ptr<dbChannel> {
     Channel& operator=(Channel&&) = default;
 
     operator dbChannel*() const {
-        return get();
+        return chan.get();
     }
+    dbChannel* operator->() const { return chan.get(); }
+
+    dbChannel* get() const { return chan.get(); }
+    const char* format() const { return form; }
+
+    explicit operator bool() const { return chan.operator bool(); }
 };
 
 } // pvxs

ioc/groupconfigprocessor.cpp

@@ -577,7 +577,7 @@ void GroupConfigProcessor::addTemplatesForDefinedFields(std::vector<Member>& gro
                                                         const GroupDefinition& groupDefinition) {
     for (auto& fieldDefinition: groupDefinition.fields) {
         auto& field = group[fieldDefinition.name];
-        dbChannel* pDbChannel = field.value;
+        auto& pDbChannel(field.value);
         switch(fieldDefinition.info.type) {
         case MappingInfo::Scalar:
             addMembersForScalarType(groupMembers, field, pDbChannel);
@@ -868,7 +868,7 @@ const char* GroupConfigProcessor::infoField(DBEntry& dbEntry, const char* key, c
  * @param pDbChannel the db channel to get information on what scalar type to create
  */
 void GroupConfigProcessor::addMembersForScalarType(std::vector<Member>& groupMembers, const Field& groupField,
-                                                   const dbChannel* pDbChannel) {
+                                                   const Channel& pDbChannel) {
     using namespace pvxs::members;
     assert(!groupField.fieldName.empty()); // Must not call with empty field name
 
@@ -887,7 +887,7 @@ void GroupConfigProcessor::addMembersForScalarType(std::vector<Member>& groupMem
  * @param pDbChannel the channel used to get the type of the leaf member
  */
 void GroupConfigProcessor::addMembersForPlainType(std::vector<Member>& groupMembers, const Field& groupField,
-                                                  const dbChannel* pDbChannel) {
+                                                  const Channel &pDbChannel) {
     assert(!groupField.fieldName.empty()); // Must not call with empty field name
 
     // Get the type for the leaf
@@ -960,7 +960,7 @@ void GroupConfigProcessor::addMembersForMetaData(std::vector<Member>& groupMembe
  * @param pDbChannel the channel to define the type definition for
  * @return the TypeDef for the channel
  */
-TypeDef GroupConfigProcessor::getTypeDefForChannel(const dbChannel* pDbChannel) {
+TypeDef GroupConfigProcessor::getTypeDefForChannel(const Channel& pDbChannel) {
     // Get the type for the leaf
     auto leafCode(IOCSource::getChannelValueType(pDbChannel, true));
     TypeDef leaf;

ioc/groupconfigprocessor.h

@@ -65,9 +65,9 @@ class GroupConfigProcessor {
     static void addMembersForAnyType(std::vector<Member>& groupMembers, const Field& groupField);
     static void addMembersForMetaData(std::vector<Member>& groupMembers, const Field& groupField);
     static void addMembersForPlainType(std::vector<Member>& groupMembers, const Field& groupField,
-                                       const dbChannel* pDbChannel);
+                                       const Channel& pDbChannel);
     static void addMembersForScalarType(std::vector<Member>& groupMembers, const Field& groupField,
-                                        const dbChannel* pDbChannel);
+                                        const Channel &pDbChannel);
     static void addMembersForStructureType(std::vector<Member>& groupMembers, const Field& groupField);
     static void defineGroupTriggers(FieldDefinition& fieldDefinition, const GroupDefinition& groupDefinition,
                                     const TriggerNames& triggerNames, const std::string& groupName);
@@ -84,7 +84,7 @@ class GroupConfigProcessor {
     static bool yajlParseHelper(std::istream& jsonGroupDefinitionStream, yajl_handle handle);
     static void initialiseDbLocker(Group& group);
     static void initialiseTriggers(Group& group, const GroupDefinition& groupDefinition);
-    static TypeDef getTypeDefForChannel(const dbChannel* pDbChannel);
+    static TypeDef getTypeDefForChannel(const Channel &pDbChannel);
 };
 
 } // ioc

ioc/iocsource.cpp

@@ -72,7 +72,7 @@ bool IOCSource::enabled()
     return e==1;
 }
 
-void IOCSource::initialize(Value& value, const MappingInfo &info, dbChannel *chan)
+void IOCSource::initialize(Value& value, const MappingInfo &info, const Channel& chan)
 {
     if(info.type==MappingInfo::Scalar) {
         if(auto fld = value["display.form.choices"]) {
@@ -88,14 +88,11 @@ void IOCSource::initialize(Value& value, const MappingInfo &info, dbChannel *cha
             fld = choices;
 
             if(dbIsValueField(dbChannelFldDes(chan))) { // only apply Q:form to VAL
-                DBEntry ent(dbChannelRecord(chan));
-
-                if(auto tag = ent.info("Q:form")) {
-                    for(auto i : range(choices.size())) {
-                        if(choices[i] == tag) {
-                            value["display.form.index"] = i;
-                            break;
-                        }
+                auto tag(chan.format());
+                for(auto i : range(choices.size())) {
+                    if(choices[i] == tag) {
+                        value["display.form.index"] = i;
+                        break;
                     }
                 }
             }
@@ -652,7 +649,7 @@ void IOCSource::put(dbChannel* pDbChannel, const Value& node, const MappingInfo
  * @param errOnLinks determines whether to throw an error on finding links, default no
  * @return the TypeCode that the channel is configured for
  */
-TypeCode IOCSource::getChannelValueType(const dbChannel* chan, const bool errOnLinks) {
+TypeCode IOCSource::getChannelValueType(const Channel& chan, const bool errOnLinks) {
     /* for links, could check dbChannelFieldType().
      * for long strings, dbChannelCreate() '$' handling overwrites dbAddr::field_type
      *   (for some reason...)
@@ -666,10 +663,9 @@ TypeCode IOCSource::getChannelValueType(const dbChannel* chan, const bool errOnL
         throw std::runtime_error("Link fields not allowed in this context");
 
     bool isArray = dbChannelFinalElements(chan)!=1;
-    bool stringlike = (field_type >= DBF_INLINK && field_type <= DBF_OUTLINK) || field_type == DBF_STRING;
 
     // string-like field being treated as single char[].  aka. long string
-    if(stringlike && final_field_type==DBR_CHAR && isArray)
+    if(final_field_type==DBR_CHAR && isArray && strcmp(chan.format(), "String")==0)
         return TypeCode::String;
 
     TypeCode valueType(fromDbrType(final_field_type));

ioc/iocsource.h

@@ -45,7 +45,7 @@ class IOCSource {
 public:
     static bool enabled();
 
-    static void initialize(Value& value, const MappingInfo &info, dbChannel *chan);
+    static void initialize(Value& value, const MappingInfo &info, const Channel &chan);
 
     static void get(Value& valuePrototype,
                     const MappingInfo& info, const Value &anyType,
@@ -62,7 +62,7 @@ class IOCSource {
     // Common Utils
     //////////////////////////////
     // Utility function to get the TypeCode that the given database channel is configured for
-    static TypeCode getChannelValueType(const dbChannel* pDbChannel, bool errOnLinks = false);
+    static TypeCode getChannelValueType(const Channel &pDbChannel, bool errOnLinks = false);
     static void
     setForceProcessingFlag(const Value& pvRequest, const std::shared_ptr<SecurityControlObject>& securityControlObject);
 };

ioc/singlesource.cpp

@@ -146,7 +146,7 @@ void onSubscribe(const std::shared_ptr<SingleSourceSubscriptionCtx>& subscriptio
  * @return a value prototype for the given channel
  */
 Value getValuePrototype(const std::shared_ptr<SingleInfo>& sinfo) {
-    dbChannel* chan(sinfo->chan);
+    auto& chan(sinfo->chan);
     short dbrType(dbChannelFinalFieldType(chan));
     auto valueType(IOCSource::getChannelValueType(chan));
 
@@ -237,7 +237,7 @@ void doneCallback(struct processNotify* notify) {
 void singleGet(const SingleInfo& info,
                std::unique_ptr<server::ExecOp>& getOperation,
                const Value& valuePrototype) {
-    dbChannel* pDbChannel(info.chan);
+    auto& pDbChannel(info.chan);
     try {
         auto returnValue = valuePrototype.cloneEmpty();
         // TODO: MappingInfo::nsecMask

test/Makefile

@@ -134,6 +134,7 @@ testqsingle_SRCS += testioc_registerRecordDeviceDriver.cpp
 testqsingle_LIBS = pvxsIoc pvxs $(EPICS_BASE_IOC_LIBS)
 TESTFILES += ../testqsingle.db
 TESTFILES += ../testqsingle64.db
+TESTFILES += ../testqsinglelsi.db
 TESTFILES += ../testioc.acf
 TESTS += testqsingle
 

test/testqsingle.cpp

@@ -20,6 +20,10 @@
 #include "testioc.h"
 #include "utilpvt.h"
 
+#if EPICS_VERSION_INT >= VERSION_INT(3, 15, 0, 2)
+#  define HAVE_lsi
+#endif
+
 extern "C" {
 extern int testioc_registerRecordDeviceDriver(struct dbBase*);
 }
@@ -251,14 +255,14 @@ void testGetScalar()
               "    } display\n"
               "}\n");
 
-    testFldEq<std::string>(ctxt.get("test:this:is:a:really:really:long:record:name.NAME").exec()->wait(5.0),
-                           "value", "test:this:is:a:really:really:long:recor");
+    testFldEq<std::string>(ctxt.get("test:this:is:a:really:really:long:record:name.NAME").exec()->wait(5000.0),
+                           "value", "test:this:is:a:really:really:long:record:name");
 
     testFldEq<std::string>(ctxt.get("test:this:is:a:really:really:long:record:name.NAME$").exec()->wait(5.0),
                            "value", "test:this:is:a:really:really:long:record:name");
 
     testFldEq<std::string>(ctxt.get("test:src.INP").exec()->wait(5.0),
-                           "value", "test:this:is:a:really:really:long:recor");
+                           "value", "test:this:is:a:really:really:long:record:name NPP NMS");
 
     testFldEq<std::string>(ctxt.get("test:src.INP$").exec()->wait(5.0),
                            "value", "test:this:is:a:really:really:long:record:name NPP NMS");
@@ -284,6 +288,7 @@ void testGetScalar()
               "display.limitHigh int32_t = 0\n"
               "display.description string = \"\"\n"
               "display.units string = \"\"\n"
+              "display.form.index int32_t = 0\n"
               "display.form.choices string[] = {7}[\"Default\", \"String\", \"Binary\", \"Decimal\", \"Hex\", \"Exponential\", \"Engineering\"]\n"
               "control.limitLow int32_t = 0\n"
               "control.limitHigh int32_t = 0\n"
@@ -293,6 +298,30 @@ void testGetScalar()
               "valueAlarm.highAlarmLimit int32_t = 0\n");
 }
 
+void testLongString()
+{
+    testDiag("%s", __func__);
+    TestClient ctxt;
+
+    ctxt.put("test:long:str:wf")
+            .set("value", "test:this:is:a:really:really:long:string:value")
+            .exec()->wait(5.0);
+
+    auto val(ctxt.get("test:long:str:wf").exec()->wait(5.0));
+    testEq(val["value"].as<std::string>(), "test:this:is:a:really:really:long:string:value");
+
+#ifdef HAVE_lsi
+    ctxt.put("test:long:str:lsi.VAL")
+            .set("value", "test:this:is:a:really:really:long:string:value")
+            .exec()->wait(5.0);
+
+    val = ctxt.get("test:long:str:lsi.VAL").exec()->wait(5.0);
+    testEq(val["value"].as<std::string>(), "test:this:is:a:really:really:long:string:value");
+
+#else
+    testSkip(1, "No lsiRecord");
+#endif
+}
 
 void testGetArray()
 {
@@ -373,6 +402,7 @@ void testGetArray()
               "display.limitHigh int32_t = 0\n"
               "display.description string = \"\"\n"
               "display.units string = \"\"\n"
+              "display.form.index int32_t = 0\n"
               "display.form.choices string[] = {7}[\"Default\", \"String\", \"Binary\", \"Decimal\", \"Hex\", \"Exponential\", \"Engineering\"]\n"
               "control.limitLow int32_t = 0\n"
               "control.limitHigh int32_t = 0\n");
@@ -503,6 +533,7 @@ void testGetPut64()
               "display.limitHigh uint64_t = 0\n"
               "display.description string = \"\"\n"
               "display.units string = \"\"\n"
+              "display.form.index int32_t = 0\n"
               "display.form.choices string[] = {7}[\"Default\", \"String\", \"Binary\", \"Decimal\", \"Hex\", \"Exponential\", \"Engineering\"]\n"
               "control.limitLow uint64_t = 0\n"
               "control.limitHigh uint64_t = 0\n");
@@ -835,7 +866,7 @@ void testMonitorAIFilt(TestClient& ctxt)
 
 MAIN(testqsingle)
 {
-    testPlan(82);
+    testPlan(84);
     testSetup();
     pvxs::logger_config_env();
     {
@@ -845,11 +876,15 @@ MAIN(testqsingle)
         testdbReadDatabase("testioc.dbd", nullptr, nullptr);
         testOk1(!testioc_registerRecordDeviceDriver(pdbbase));
         testdbReadDatabase("testqsingle.db", nullptr, nullptr);
+#ifdef HAVE_lsi
+        testdbReadDatabase("testqsinglelsi.db", nullptr, nullptr);
+#endif
 #ifdef DBR_UINT64
         testdbReadDatabase("testqsingle64.db", nullptr, nullptr);
 #endif
         ioc.init();
         testGetScalar();
+        testLongString();
         testGetArray();
         testPut();
         testGetPut64();

test/testqsingle.db

@@ -22,6 +22,11 @@ record(ai, "test:this:is:a:really:really:long:record:name") {}
 record(ai, "test:src") {
     field(INP , "test:this:is:a:really:really:long:record:name NPP")
 }
+record(waveform, "test:long:str:wf") {
+    field(FTVL, "CHAR")
+    field(NELM, "128")
+    info(Q:form, "String")
+}
 record(bo, "test:bo") {
     field(ZNAM, "Zero")
     field(ONAM, "One")

test/testqsinglelsi.db

@@ -0,0 +1,4 @@
+record(lsi, "test:long:str:lsi")
+{
+    field(SIZV, 128)
+}