Another try at locking

library/DFError.h

@@ -221,6 +221,61 @@ namespace DFHack
                 return "The server process has disappeared";
             }
         };
+        class DFHACK_EXPORT SHMLockingError : public std::exception
+        {
+        public:
+            SHMLockingError(const char* _type) : type(_type) {}
+            virtual ~SHMLockingError() throw(){};
+            
+            std::string type;
+            
+            virtual const char* what() const throw()
+            {
+                std::stringstream s;
+                s << "SHM locking error: " << type;
+                return s.str().c_str();
+            }
+        };
+        class DFHACK_EXPORT SHMAccessDenied : public std::exception
+        {
+        public:
+            SHMAccessDenied() {}
+            virtual ~SHMAccessDenied() throw(){};
+            
+            std::string type;
+            
+            virtual const char* what() const throw()
+            {
+                return "SHM ACCESS DENIED";
+            }
+        };
+        class DFHACK_EXPORT SHMVersionMismatch : public std::exception
+        {
+        public:
+            SHMVersionMismatch() {}
+            virtual ~SHMVersionMismatch() throw(){};
+            
+            std::string type;
+            
+            virtual const char* what() const throw()
+            {
+                return "SHM VERSION MISMATCH";
+            }
+        };
+        class DFHACK_EXPORT SHMAttachFailure : public std::exception
+        {
+        public:
+            SHMAttachFailure() {}
+            virtual ~SHMAttachFailure() throw(){};
+            
+            std::string type;
+            
+            virtual const char* what() const throw()
+            {
+                return "SHM ATTACH FAILURE";
+            }
+        };
+        
     }
 }
 

library/DFHackAPI.cpp

@@ -190,7 +190,7 @@ API::~API()
     delete d;
 }
 
-#define SHMCMD ((shm_cmd *)d->shm_start)->pingpong
+#define SHMCMD(num) ((shm_cmd *)d->shm_start)[num]->pingpong
 #define SHMHDR ((shm_core_hdr *)d->shm_start)
 #define SHMMAPSHDR ((Maps::shm_maps_hdr *)d->shm_start)
 #define SHMDATA(type) ((type *)(d->shm_start + SHM_HEADER))
@@ -243,8 +243,7 @@ bool API::InitMap()
         off->z_count_offset = z_count_offset;
         full_barrier
         const uint32_t cmd = Maps::MAP_INIT + d->maps_module << 16;
-        SHMCMD = cmd;
+        g_pProcess->SetAndWait(cmd);
-        g_pProcess->waitWhile(cmd);
         //cerr << "Map acceleration enabled!" << endl;
     }
     
@@ -324,13 +323,8 @@ bool API::ReadBlock40d(uint32_t x, uint32_t y, uint32_t z, mapblock40d * buffer)
         SHMMAPSHDR->y = y;
         SHMMAPSHDR->z = z;
         volatile uint32_t cmd = Maps::MAP_READ_BLOCK_BY_COORDS + (d->maps_module << 16);
-        full_barrier
+        if(!g_pProcess->SetAndWait(cmd))
-        SHMCMD = cmd;
-        full_barrier
-        if(!g_pProcess->waitWhile(cmd))
-        {
             return false;
-        }
         memcpy(buffer,SHMDATA(mapblock40d),sizeof(mapblock40d));
         return true;
     }

library/DFProcess-linux-SHM.cpp

@@ -43,27 +43,35 @@ class SHMProcess::Private
     public:
     Private()
     {
-        my_descriptor = NULL;
+        memdescriptor = NULL;
-        my_pid = 0;
+        process_ID = 0;
-        my_shm = 0;
+        shm_addr = 0;
-        my_shmid = -1;
+        //shm_addr_with_cl_idx = 0;
-        my_window = NULL;
+        shm_ID = -1;
+        window = NULL;
         attached = false;
         suspended = false;
         identified = false;
         useYield = false;
-        my_SVfileLock = -1;
+        server_lock = -1;
-        my_CLfileLock = -1;
+        client_lock = -1;
+        suspend_lock = -1;
+        attachmentIdx = 0;
+        locked = false;
     };
     ~Private(){};
-    memory_info * my_descriptor;
+    memory_info * memdescriptor;
-    DFWindow * my_window;
+    DFWindow * window;
-    pid_t my_pid;
+    pid_t process_ID;
-    char *my_shm;
+    char *shm_addr;
-    int my_shmid;
+    int shm_ID;
     Process* q;
-    int my_SVfileLock;
+    int server_lock;
-    int my_CLfileLock;
+    int client_lock;
+    int suspend_lock;
+    int attachmentIdx;
+    
+    bool locked;
     
     bool attached;
     bool suspended;
@@ -73,60 +81,36 @@ class SHMProcess::Private
     bool validate(char* exe_file, uint32_t pid, std::vector< memory_info* >& known_versions);
     
     bool Aux_Core_Attach(bool & versionOK, pid_t & PID);
-    bool waitWhile (uint32_t state);
+    //bool waitWhile (uint32_t state);
+    bool SetAndWait (uint32_t state);
     bool GetLocks();
     bool AreLocksOk();
     void FreeLocks();
 };
 
-// some helpful macros to keep the code bloat in check
+#define SHMCMD ( (uint32_t *) shm_addr)[attachmentIdx]
-#define SHMCMD ((shm_cmd *)my_shm)->pingpong
+#define D_SHMCMD ( (uint32_t *) (d->shm_addr))[d->attachmentIdx]
-#define D_SHMCMD ((shm_cmd *)d->my_shm)->pingpong
 
-#define SHMHDR ((shm_core_hdr *)my_shm)
+#define SHMHDR ((shm_core_hdr *)shm_addr)
-#define D_SHMHDR ((shm_core_hdr *)d->my_shm)
+#define D_SHMHDR ((shm_core_hdr *)(d->shm_addr))
 
-#define SHMDATA(type) ((type *)(my_shm + SHM_HEADER))
+#define SHMDATA(type) ((type *)(shm_addr + SHM_HEADER))
-#define D_SHMDATA(type) ((type *)(d->my_shm + SHM_HEADER))
+#define D_SHMDATA(type) ((type *)(d->shm_addr + SHM_HEADER))
 
-/*
+bool SHMProcess::Private::SetAndWait (uint32_t state)
-Yeah. with no way to synchronize things (locks are slow, the OS doesn't give us enough control over scheduling)
-we end up with this silly thing
-*/
-bool SHMProcess::Private::waitWhile (uint32_t state)
 {
     uint32_t cnt = 0;
-    struct shmid_ds descriptor;
+    if(!locked) return false;
+    SHMCMD = state;
     while (SHMCMD == state)
     {
-        if(cnt == 10000)// check if the other process is still there
+        if(cnt == 10000)// check if the other process is still there, don't hammer the kernel too much.
-        {
-            
-            /*
-            shmctl(my_shmid, IPC_STAT, &descriptor);
-            if(descriptor.shm_nattch == 1)// DF crashed or exited - no way to tell?
-            {
-                //detach the shared memory
-                shmdt(my_shm);
-                attached = suspended = false;
-                
-                // we aren't the current process anymore
-                g_pProcess = NULL;
-                
-                throw Error::SHMServerDisappeared();
-                return false;
-            }
-            else
         {
-                cnt = 0;
-            }
-            */
             if(!AreLocksOk())
             {
                 //detach the shared memory
-                shmdt(my_shm);
+                shmdt(shm_addr);
-                attached = suspended = false;
+                attached = suspended = identified = false;
-                
                 // we aren't the current process anymore
                 g_pProcess = NULL;
                 FreeLocks();
@@ -145,12 +129,9 @@ bool SHMProcess::Private::waitWhile (uint32_t state)
         }
         cnt++;
     }
+    // server returned a generic error
     if(SHMCMD == CORE_ERROR)
     {
-        SHMCMD = CORE_RUNNING;
-        attached = suspended = false;
-        cerr << "shm server error!" << endl;
-        assert (false);
         return false;
     }
     return true;
@@ -160,11 +141,19 @@ bool SHMProcess::Private::waitWhile (uint32_t state)
 Yeah. with no way to synchronize things (locks are slow, the OS doesn't give us enough control over scheduling)
 we end up with this silly thing
 */
-bool SHMProcess::waitWhile (uint32_t state)
+bool SHMProcess::SetAndWait (uint32_t state)
 {
-    return d->waitWhile(state);
+    return d->SetAndWait(state);
 }
 
+/*
+// set SHM command.
+void SHMProcess::setCmd (uint32_t newstate)
+{
+    if(d->attached && d->suspended)
+        D_SHMCMD = newstate;
+};
+*/
 uint32_t OS_getAffinity()
 {
     cpu_set_t mask;
@@ -174,15 +163,16 @@ uint32_t OS_getAffinity()
     return affinity;
 }
 
-
 bool SHMProcess::Private::Aux_Core_Attach(bool & versionOK, pid_t & PID)
 {
+    if(!locked) return false;
+    
     SHMDATA(coreattach)->cl_affinity = OS_getAffinity();
-    gcc_barrier
+    if(!SetAndWait(CORE_ATTACH)) return false;
-    SHMCMD = CORE_ATTACH;
+    /*
-    if(!waitWhile(CORE_ATTACH))
+    cerr <<"CORE_VERSION" << CORE_VERSION << endl;
-        return false;
+    cerr <<"server CORE_VERSION" << SHMDATA(coreattach)->sv_version << endl;
-    gcc_barrier
+    */
     versionOK =( SHMDATA(coreattach)->sv_version == CORE_VERSION );
     PID = SHMDATA(coreattach)->sv_PID;
     useYield = SHMDATA(coreattach)->sv_useYield;
@@ -192,12 +182,13 @@ bool SHMProcess::Private::Aux_Core_Attach(bool & versionOK, pid_t & PID)
     return true;
 }
 
+// test if we have client and server locks and the server is present
 bool SHMProcess::Private::AreLocksOk()
 {
     // both locks are inited (we hold our lock)
-    if(my_CLfileLock != -1 && my_SVfileLock != -1) 
+    if(client_lock != -1 && server_lock != -1) 
     {
-        if(lockf(my_SVfileLock,F_TEST,0) == -1) // and server holds its lock
+        if(lockf(server_lock,F_TEST,0) == -1) // and server holds its lock
         {
             return true; // OK, locks are good
         }
@@ -208,16 +199,23 @@ bool SHMProcess::Private::AreLocksOk()
 
 void SHMProcess::Private::FreeLocks()
 {
-    if(my_CLfileLock != -1)
+    attachmentIdx = -1;
+    if(client_lock != -1)
+    {
+        lockf(client_lock,F_ULOCK,0);
+        close(client_lock);
+        client_lock = -1;
+    }
+    if(server_lock != -1)
     {
-        lockf(my_CLfileLock,F_ULOCK,0);
+        close(server_lock);
-        close(my_CLfileLock);
+        server_lock = -1;
-        my_CLfileLock = -1;
     }
-    if(my_SVfileLock != -1)
+    if(suspend_lock != -1)
     {
-        close(my_SVfileLock);
+        close(suspend_lock);
-        my_SVfileLock = -1;
+        locked = false;
+        suspend_lock = -1;
     }
 }
 
@@ -226,36 +224,65 @@ bool SHMProcess::Private::GetLocks()
     char name[256];
     // try to acquire locks
     // look at the server lock, if it's locked, the server is present
-    sprintf(name, "/tmp/DFHack/%d/SVlock",my_pid,name);
+    sprintf(name, "/tmp/DFHack/%d/SVlock",process_ID);
-    my_SVfileLock = open(name,O_WRONLY);
+    server_lock = open(name,O_WRONLY);
-    if(my_SVfileLock == -1)
+    if(server_lock == -1)
     {
+        cerr << "can't open sv lock" << endl;
         return false;
     }
     
-    if(lockf( my_SVfileLock, F_TEST, 0 ) != -1)
+    if(lockf( server_lock, F_TEST, 0 ) != -1)
     {
-        close(my_SVfileLock);
+        cerr << "sv lock not locked" << endl;
+        close(server_lock);
+        server_lock = -1;
         return false;
     }
     
-    // open the client lock, try to lock it
+    for(int i = 0; i < SHM_MAX_CLIENTS; i++)
-    sprintf(name, "/tmp/DFHack/%d/CLlock",my_pid,name);
-    my_CLfileLock = open(name,O_WRONLY);
-    if(my_CLfileLock == -1)
     {
-        close(my_SVfileLock);
+        // open the client suspend locked
-        return false;
+        sprintf(name, "/tmp/DFHack/%d/CLSlock%d",process_ID,i);
+        suspend_lock = open(name,O_WRONLY);
+        if(suspend_lock == -1)
+        {
+            cerr << "can't open cl S-lock " << i << endl;
+            // couldn't open lock
+            continue;
+        }
+
+        // open the client lock, try to lock it
+        sprintf(name, "/tmp/DFHack/%d/CLlock%d",process_ID,i);
+        client_lock = open(name,O_WRONLY);
+        if(client_lock == -1)
+        {
+            cerr << "can't open cl lock " << i << endl;
+            close(suspend_lock);
+            locked = false;
+            suspend_lock = -1;
+            // couldn't open lock
+            continue;
         }
-    if(lockf(my_CLfileLock,F_TLOCK, 0) == -1)
+        if(lockf(client_lock,F_TLOCK, 0) == -1)
         {
             // couldn't acquire lock
-        close(my_SVfileLock);
+            cerr << "can't acquire cl lock " << i << endl;
-        close(my_CLfileLock);
+            close(suspend_lock);
-        return false;
+            locked = false;
+            suspend_lock = -1;
+            close(client_lock);
+            client_lock = -1;
+            continue;
         }
-    // ok, we have all the locks!
+        // ok, we have all the locks we need!
+        attachmentIdx = i;
         return true;
+    }
+    close(server_lock);
+    server_lock = -1;
+    cerr << "can't get any client locks" << endl;
+    return false;
 }
 
 SHMProcess::SHMProcess(uint32_t PID, vector< memory_info* >& known_versions)
@@ -268,7 +295,7 @@ SHMProcess::SHMProcess(uint32_t PID, vector< memory_info* >& known_versions)
     /*
      * Locate the segment.
      */
-    if ((d->my_shmid = shmget(SHM_KEY + PID, SHM_SIZE, 0666)) < 0)
+    if ((d->shm_ID = shmget(SHM_KEY + PID, /*SHM_ALL_CLIENTS*/SHM_SIZE, 0666)) < 0)
     {
         return;
     }
@@ -276,68 +303,54 @@ SHMProcess::SHMProcess(uint32_t PID, vector< memory_info* >& known_versions)
     /*
      * Attach the segment
      */
-    if ((d->my_shm = (char *) shmat(d->my_shmid, NULL, 0)) == (char *) -1)
+    /*
+    if ((d->shm_addr = (char *) shmat(d->shm_ID, NULL, 0)) == (char *) -1)
     {
         return;
     }
-    
+    */
-    // set pid and gets lock for it
+    d->process_ID = PID;
-    d->my_pid = PID;
+    if(!attach())
-    if(!d->GetLocks())
     {
-        fprintf(stderr,"Couldn't get locks for PID %d'\n", PID);
+        // couldn't attach to process
-        shmdt(d->my_shm);
         return;
     }
-   
     /*
      * Test bridge version, get PID, sync Yield
      */
     bool bridgeOK;
-    if(!d->Aux_Core_Attach(bridgeOK,d->my_pid))
+    if(!d->Aux_Core_Attach(bridgeOK,d->process_ID))
     {
-        fprintf(stderr,"DF terminated during reading\n");
+        detach();
-        shmdt(d->my_shm);
+        throw Error::SHMAttachFailure();
-        // free locks
-        d->FreeLocks();
         return;
     }
     if(!bridgeOK)
     {
-        fprintf(stderr,"SHM bridge version mismatch\n");
+        detach();
-        shmdt(d->my_shm);
+        throw Error::SHMVersionMismatch();
-        // free locks
-        d->FreeLocks();
         return;
     }
     
     // find the binary
-    sprintf(exe_link_name,"/proc/%d/exe", d->my_pid);
+    sprintf(exe_link_name,"/proc/%d/exe", d->process_ID);
     target_result = readlink(exe_link_name, target_name, sizeof(target_name)-1);
     if (target_result == -1)
     {
         perror("readlink");
-        shmdt(d->my_shm);
+        detach();
-        // free locks
-        d->FreeLocks();
         return;
     }
-    
     // make sure we have a null terminated string...
     // see http://www.opengroup.org/onlinepubs/000095399/functions/readlink.html
     target_name[target_result] = 0;
     
-    // try to identify the DF version
+    // try to identify the DF version (md5 the binary, compare with known versions)
-    d->validate(target_name, d->my_pid, known_versions);
+    d->validate(target_name, d->process_ID, known_versions);
-    d->my_window = new DFWindow(this);
+    d->window = new DFWindow(this);
     
-    gcc_barrier
+    // detach
-    // at this point, DF is stopped and waiting for commands. make it run again
+    detach();
-    D_SHMCMD = CORE_RUNNING;
-    shmdt(d->my_shm); // detach so we don't attach twice when attach() is called
-    
-    // free locks
-    d->FreeLocks();
 }
 
 bool SHMProcess::isSuspended()
@@ -360,7 +373,7 @@ bool SHMProcess::Private::validate(char * exe_file, uint32_t pid, vector <memory
     // get hash of the running DF process
     string hash = md5.getHashFromFile(exe_file);
     vector<memory_info *>::iterator it;
-    cerr << exe_file << " " << hash <<  endl;
+    // cerr << exe_file << " " << hash <<  endl;
     // iterate over the list of memory locations
     for ( it=known_versions.begin() ; it < known_versions.end(); it++ )
     {
@@ -368,10 +381,10 @@ bool SHMProcess::Private::validate(char * exe_file, uint32_t pid, vector <memory
             if(hash == (*it)->getString("md5")) // are the md5 hashes the same?
             {
                 memory_info * m = *it;
-                my_descriptor = m;
+                memdescriptor = m;
-                my_pid = pid;
+                process_ID = pid;
                 identified = true;
-                cerr << "identified " << m->getVersion() << endl;
+                // cerr << "identified " << m->getVersion() << endl;
                 return true;
             }
         }
@@ -390,26 +403,26 @@ SHMProcess::~SHMProcess()
         detach();
     }
     // destroy data model. this is assigned by processmanager
-    if(d->my_window)
+    if(d->window)
     {
-        delete d->my_window;
+        delete d->window;
     }
     delete d;
 }
 
 memory_info * SHMProcess::getDescriptor()
 {
-    return d->my_descriptor;
+    return d->memdescriptor;
 }
 
 DFWindow * SHMProcess::getWindow()
 {
-    return d->my_window;
+    return d->window;
 }
 
 int SHMProcess::getPID()
 {
-    return d->my_pid;
+    return d->process_ID;
 }
 
 //FIXME: implement
@@ -424,7 +437,7 @@ void SHMProcess::getMemRanges( vector<t_memrange> & ranges )
     char buffer[1024];
     char permissions[5]; // r/-, w/-, x/-, p/s, 0
     
-    sprintf(buffer, "/proc/%lu/maps", d->my_pid);
+    sprintf(buffer, "/proc/%lu/maps", d->process_ID);
     FILE *mapFile = ::fopen(buffer, "r");
     uint64_t offset, device1, device2, node;
     
@@ -455,13 +468,27 @@ bool SHMProcess::suspend()
     {
         return true;
     }
-    D_SHMCMD = CORE_SUSPEND;
+    
-    if(!waitWhile(CORE_SUSPEND))
+    // did we just resume a moment ago?
+    if(D_SHMCMD == CORE_RUN)
     {
-        return false;
+        //fprintf(stderr,"%d invokes step\n",d->attachmentIdx);
+        D_SHMCMD = CORE_STEP;
+    }
+    else
+    {
+        //fprintf(stderr,"%d invokes suspend\n",d->attachmentIdx);
+        D_SHMCMD = CORE_SUSPEND;
     }
+    //fprintf(stderr,"waiting for lock\n");
+    // we wait for the server to give up our suspend lock (held by default)
+    if(lockf(d->suspend_lock,F_LOCK,0) == 0)
+    {
         d->suspended = true;
+        d->locked = true;
         return true;
+    }
+    return false;
 }
 
 bool SHMProcess::asyncSuspend()
@@ -474,14 +501,37 @@ bool SHMProcess::asyncSuspend()
     {
         return true;
     }
+    
     if(D_SHMCMD == CORE_SUSPENDED)
     {
+        // we have to hold the lock to be really suspended
+        if(lockf(d->suspend_lock,F_LOCK,0) == 0)
+        {
+            d->locked = true;
             d->suspended = true;
             return true;
         }
+        return false;
+    }
+    else
+    {
+        // did we just resume a moment ago?
+        if(D_SHMCMD == CORE_RUN)
+        {
+            D_SHMCMD = CORE_STEP;
+        }
         else
         {
             D_SHMCMD = CORE_SUSPEND;
+        }
+        // try locking
+        if(lockf(d->suspend_lock,F_TLOCK,0) == 0)
+        {
+            d->locked = true;
+            d->suspended = true;
+            return true;
+        }
+        
         return false;
     }
 }
@@ -491,21 +541,29 @@ bool SHMProcess::forceresume()
     return resume();
 }
 
+// FIXME: wait for the server to advance a step!
 bool SHMProcess::resume()
 {
     if(!d->attached)
         return false;
     if(!d->suspended)
         return true;
-    D_SHMCMD = CORE_RUNNING;
+    // set core to run
+    D_SHMCMD = CORE_RUN;
     d->suspended = false;
+    // unlock the suspend lock
+    if(lockf(d->suspend_lock,F_ULOCK,0) == 0)
+    {
+        d->locked = false;
         return true;
+    }
+    throw Error::SHMLockingError("bool SHMProcess::resume()");
+    return false;
 }
 
 
 bool SHMProcess::attach()
 {
-    int status;
     if(g_pProcess != 0)
     {
         // FIXME: throw exception here - programmer error
@@ -521,7 +579,7 @@ bool SHMProcess::attach()
     /*
     * Attach the segment
     */
-    if ((d->my_shm = (char *) shmat(d->my_shmid, NULL, 0)) != (char *) -1)
+    if ((d->shm_addr = (char *) shmat(d->shm_ID, NULL, 0)) != (char *) -1)
     {
         d->attached = true;
         if(suspend())
@@ -532,7 +590,7 @@ bool SHMProcess::attach()
         }
         d->attached = false;
         cerr << "unable to suspend" << endl;
-        shmdt(d->my_shm);
+        shmdt(d->shm_addr);
         d->FreeLocks();
         return false;
     }
@@ -552,11 +610,11 @@ bool SHMProcess::detach()
         resume();
     }
     // detach segment
-    if(shmdt(d->my_shm) != -1)
+    if(shmdt(d->shm_addr) != -1)
     {
         d->attached = false;
         d->suspended = false;
-        d->my_shm = 0;
+        d->shm_addr = 0;
         g_pProcess = 0;
         d->FreeLocks();
         return true;
@@ -569,15 +627,16 @@ bool SHMProcess::detach()
 
 void SHMProcess::read (uint32_t src_address, uint32_t size, uint8_t *target_buffer)
 {
+    if(!d->locked) throw Error::SHMAccessDenied();
+    
     // normal read under 1MB
     if(size <= SHM_BODY)
     {
         D_SHMHDR->address = src_address;
         D_SHMHDR->length = size;
         gcc_barrier
-        D_SHMCMD = CORE_DFPP_READ;
+        d->SetAndWait(CORE_READ);
-        waitWhile(CORE_DFPP_READ);
+        memcpy (target_buffer, D_SHMDATA(void),size);
-        memcpy (target_buffer, d->my_shm + SHM_HEADER,size);
     }
     // a big read, we pull data over the shm in iterations
     else
@@ -590,9 +649,8 @@ void SHMProcess::read (uint32_t src_address, uint32_t size, uint8_t *target_buff
             D_SHMHDR->address = src_address;
             D_SHMHDR->length = to_read;
             gcc_barrier
-            D_SHMCMD = CORE_DFPP_READ;
+            d->SetAndWait(CORE_READ);
-            waitWhile(CORE_DFPP_READ);
+            memcpy (target_buffer, D_SHMDATA(void) ,size);
-            memcpy (target_buffer, d->my_shm + SHM_HEADER,size);
             // decrease size by bytes read
             size -= to_read;
             // move the cursors
@@ -606,54 +664,60 @@ void SHMProcess::read (uint32_t src_address, uint32_t size, uint8_t *target_buff
 
 uint8_t SHMProcess::readByte (const uint32_t offset)
 {
+    if(!d->locked) throw Error::SHMAccessDenied();
+    
     D_SHMHDR->address = offset;
     gcc_barrier
-    D_SHMCMD = CORE_READ_BYTE;
+    d->SetAndWait(CORE_READ_BYTE);
-    waitWhile(CORE_READ_BYTE);
     return D_SHMHDR->value;
 }
 
 void SHMProcess::readByte (const uint32_t offset, uint8_t &val )
 {
+    if(!d->locked) throw Error::SHMAccessDenied();
+    
     D_SHMHDR->address = offset;
     gcc_barrier
-    D_SHMCMD = CORE_READ_BYTE;
+    d->SetAndWait(CORE_READ_BYTE);
-    waitWhile(CORE_READ_BYTE);
     val = D_SHMHDR->value;
 }
 
 uint16_t SHMProcess::readWord (const uint32_t offset)
 {
+    if(!d->locked) throw Error::SHMAccessDenied();
+    
     D_SHMHDR->address = offset;
     gcc_barrier
-    D_SHMCMD = CORE_READ_WORD;
+    d->SetAndWait(CORE_READ_WORD);
-    waitWhile(CORE_READ_WORD);
     return D_SHMHDR->value;
 }
 
 void SHMProcess::readWord (const uint32_t offset, uint16_t &val)
 {
+    if(!d->locked) throw Error::SHMAccessDenied();
+    
     D_SHMHDR->address = offset;
     gcc_barrier
-    D_SHMCMD = CORE_READ_WORD;
+    d->SetAndWait(CORE_READ_WORD);
-    waitWhile(CORE_READ_WORD);
     val = D_SHMHDR->value;
 }
 
 uint32_t SHMProcess::readDWord (const uint32_t offset)
 {
+    if(!d->locked) throw Error::SHMAccessDenied();
+    
     D_SHMHDR->address = offset;
     gcc_barrier
-    D_SHMCMD = CORE_READ_DWORD;
+    d->SetAndWait(CORE_READ_DWORD);
-    waitWhile(CORE_READ_DWORD);
     return D_SHMHDR->value;
 }
 void SHMProcess::readDWord (const uint32_t offset, uint32_t &val)
 {
+    if(!d->locked) throw Error::SHMAccessDenied();
+    
     D_SHMHDR->address = offset;
     gcc_barrier
-    D_SHMCMD = CORE_READ_DWORD;
+    d->SetAndWait(CORE_READ_DWORD);
-    waitWhile(CORE_READ_DWORD);
     val = D_SHMHDR->value;
 }
 
@@ -663,43 +727,47 @@ void SHMProcess::readDWord (const uint32_t offset, uint32_t &val)
 
 void SHMProcess::writeDWord (uint32_t offset, uint32_t data)
 {
+    if(!d->locked) throw Error::SHMAccessDenied();
+    
     D_SHMHDR->address = offset;
     D_SHMHDR->value = data;
     gcc_barrier
-    D_SHMCMD = CORE_WRITE_DWORD;
+    d->SetAndWait(CORE_WRITE_DWORD);
-    waitWhile(CORE_WRITE_DWORD);
 }
 
 // using these is expensive.
 void SHMProcess::writeWord (uint32_t offset, uint16_t data)
 {
+    if(!d->locked) throw Error::SHMAccessDenied();
+    
     D_SHMHDR->address = offset;
     D_SHMHDR->value = data;
     gcc_barrier
-    D_SHMCMD = CORE_WRITE_WORD;
+    d->SetAndWait(CORE_WRITE_WORD);
-    waitWhile(CORE_WRITE_WORD);
 }
 
 void SHMProcess::writeByte (uint32_t offset, uint8_t data)
 {
+    if(!d->locked) throw Error::SHMAccessDenied();
+    
     D_SHMHDR->address = offset;
     D_SHMHDR->value = data;
     gcc_barrier
-    D_SHMCMD = CORE_WRITE_BYTE;
+    d->SetAndWait(CORE_WRITE_BYTE);
-    waitWhile(CORE_WRITE_BYTE);
 }
 
 void SHMProcess::write (uint32_t dst_address, uint32_t size, uint8_t *source_buffer)
 {
+    if(!d->locked) throw Error::SHMAccessDenied();
+    
     // normal write under 1MB
     if(size <= SHM_BODY)
     {
         D_SHMHDR->address = dst_address;
         D_SHMHDR->length = size;
-        memcpy(d->my_shm+SHM_HEADER,source_buffer, size);
+        memcpy(D_SHMDATA(void),source_buffer, size);
         gcc_barrier
-        D_SHMCMD = CORE_WRITE;
+        d->SetAndWait(CORE_WRITE);
-        waitWhile(CORE_WRITE);
     }
     // a big write, we push this over the shm in iterations
     else
@@ -711,10 +779,9 @@ void SHMProcess::write (uint32_t dst_address, uint32_t size, uint8_t *source_buf
             // write to_write bytes to dst_cursor
             D_SHMHDR->address = dst_address;
             D_SHMHDR->length = to_write;
-            memcpy(d->my_shm+SHM_HEADER,source_buffer, to_write);
+            memcpy(D_SHMDATA(void),source_buffer, to_write);
             gcc_barrier
-            D_SHMCMD = CORE_WRITE;
+            d->SetAndWait(CORE_WRITE);
-            waitWhile(CORE_WRITE);
             // decrease size by bytes written
             size -= to_write;
             // move the cursors
@@ -729,6 +796,8 @@ void SHMProcess::write (uint32_t dst_address, uint32_t size, uint8_t *source_buf
 // FIXME: butt-fugly
 const std::string SHMProcess::readCString (uint32_t offset)
 {
+    if(!d->locked) throw Error::SHMAccessDenied();
+        
     std::string temp;
     char temp_c[256];
     int counter = 0;
@@ -746,6 +815,8 @@ const std::string SHMProcess::readCString (uint32_t offset)
 
 DfVector SHMProcess::readVector (uint32_t offset, uint32_t item_size)
 {
+    if(!d->locked) throw Error::SHMAccessDenied();
+    
     /*
         GNU libstdc++ vector is three pointers long
         ptr start
@@ -762,38 +833,43 @@ DfVector SHMProcess::readVector (uint32_t offset, uint32_t item_size)
 
 const std::string SHMProcess::readSTLString(uint32_t offset)
 {
+    if(!d->locked) throw Error::SHMAccessDenied();
+        
     D_SHMHDR->address = offset;
     full_barrier
-    D_SHMCMD = CORE_READ_STL_STRING;
+    d->SetAndWait(CORE_READ_STL_STRING);
-    waitWhile(CORE_READ_STL_STRING);
     //int length = ((shm_retval *)d->my_shm)->value;
-    return(string( (char *)d->my_shm+SHM_HEADER));
+    return(string( D_SHMDATA(char) ));
 }
 
 size_t SHMProcess::readSTLString (uint32_t offset, char * buffer, size_t bufcapacity)
 {
+    if(!d->locked) throw Error::SHMAccessDenied();
+        
     D_SHMHDR->address = offset;
     full_barrier
-    D_SHMCMD = CORE_READ_STL_STRING;
+    d->SetAndWait(CORE_READ_STL_STRING);
-    waitWhile(CORE_READ_STL_STRING);
     size_t length = D_SHMHDR->value;
     size_t fit = min(bufcapacity - 1, length);
-    strncpy(buffer,(char *)d->my_shm+SHM_HEADER,fit);
+    strncpy(buffer,D_SHMDATA(char),fit);
     buffer[fit] = 0;
     return fit;
 }
 
 void SHMProcess::writeSTLString(const uint32_t address, const std::string writeString)
 {
+    if(!d->locked) throw Error::SHMAccessDenied();
+        
     D_SHMHDR->address = address;
-    strncpy(d->my_shm+SHM_HEADER,writeString.c_str(),writeString.length()+1); // length + 1 for the null terminator
+    strncpy(D_SHMDATA(char),writeString.c_str(),writeString.length()+1); // length + 1 for the null terminator
     full_barrier
-    D_SHMCMD = CORE_WRITE_STL_STRING;
+    d->SetAndWait(CORE_WRITE_STL_STRING);
-    waitWhile(CORE_WRITE_STL_STRING);
 }
 
 string SHMProcess::readClassName (uint32_t vptr)
 {
+    if(!d->locked) throw Error::SHMAccessDenied();
+        
     int typeinfo = readDWord(vptr - 0x4);
     int typestring = readDWord(typeinfo + 0x4);
     string raw = readCString(typestring);
@@ -802,22 +878,18 @@ string SHMProcess::readClassName (uint32_t vptr)
     return raw.substr(start,end-start - 2); // trim the 'st' from the end
 }
 
-// FIXME: having this around could lead to bad things in the hands of unsuspecting fools
+// get module index by name and version. bool 0 = error
-// *!!DON'T BE AN UNSUSPECTING FOOL!!*
-// the whole SHM thing works only because copying DWORDS is an atomic operation on i386 and x86_64 archs
-// get module index by name and version. bool 1 = error
 bool SHMProcess::getModuleIndex (const char * name, const uint32_t version, uint32_t & OUTPUT)
 {
-    modulelookup * payload = (modulelookup *) (d->my_shm + SHM_HEADER);
+    if(!d->locked) throw Error::SHMAccessDenied();
+        
+    modulelookup * payload = D_SHMDATA(modulelookup);
     payload->version = version;
     
     strncpy(payload->name,name,255);
     payload->name[255] = 0;
     
-    full_barrier
+    if(!SetAndWait(CORE_ACQUIRE_MODULE))
-    
-    D_SHMCMD = CORE_ACQUIRE_MODULE;
-    if(!waitWhile(CORE_ACQUIRE_MODULE))
     {
         return false; // FIXME: throw a fatal exception instead
     }
@@ -832,5 +904,7 @@ bool SHMProcess::getModuleIndex (const char * name, const uint32_t version, uint
 
 char * SHMProcess::getSHMStart (void)
 {
-    return d->my_shm;
+    if(!d->locked) return 0; //THROW HERE!
+        
+    return /*d->shm_addr_with_cl_idx*/ d->shm_addr;
 }

library/DFProcess-windows-SHM.cpp

@@ -32,10 +32,10 @@ class SHMProcess::Private
     public:
     Private()
     {
-        my_descriptor = NULL;
+        memdescriptor = NULL;
-        my_pid = 0;
+        process_ID = 0;
-        my_shm = 0;
+        shm_addr = 0;
-        my_window = NULL;
+        window = NULL;
         attached = false;
         suspended = false;
         identified = false;
@@ -44,10 +44,10 @@ class SHMProcess::Private
         DFCLMutex = 0;
     };
     ~Private(){};
-    memory_info * my_descriptor;
+    memory_info * memdescriptor;
-    DFWindow * my_window;
+    DFWindow * window;
-    uint32_t my_pid;
+    uint32_t process_ID;
-    char *my_shm;
+    char *shm_addr;
     HANDLE DFSVMutex;
     HANDLE DFCLMutex;
     
@@ -120,7 +120,7 @@ bool SHMProcess::Private::waitWhile (uint32_t state)
             {
                 attached = suspended = false;
                 ReleaseMutex(DFCLMutex);
-                UnmapViewOfFile(my_shm);
+                UnmapViewOfFile(shm_addr);
                 throw Error::SHMServerDisappeared();
                 return false;
             }
@@ -185,7 +185,7 @@ SHMProcess::SHMProcess(uint32_t PID, vector <memory_info *> & known_versions)
     {
         return;
     }
-    d->my_pid = PID;
+    d->process_ID = PID;
     
     // attach the SHM
     if(!attach())
@@ -196,7 +196,7 @@ SHMProcess::SHMProcess(uint32_t PID, vector <memory_info *> & known_versions)
     // Test bridge version, get PID, sync Yield
     bool bridgeOK;
     bool error = 0;
-    if(!d->Aux_Core_Attach(bridgeOK,d->my_pid))
+    if(!d->Aux_Core_Attach(bridgeOK,d->process_ID))
     {
         fprintf(stderr,"DF terminated during reading\n");
         error = 1;
@@ -209,7 +209,7 @@ SHMProcess::SHMProcess(uint32_t PID, vector <memory_info *> & known_versions)
     if(error)
     {
         D_SHMCMD = CORE_RUNNING;
-        UnmapViewOfFile(d->my_shm);
+        UnmapViewOfFile(d->shm_addr);
         ReleaseMutex(d->DFCLMutex);
         CloseHandle(d->DFSVMutex);
         d->DFSVMutex = 0;
@@ -229,7 +229,7 @@ SHMProcess::SHMProcess(uint32_t PID, vector <memory_info *> & known_versions)
         bool found = false;
         d->identified = false;
         // open process, we only need the process open 
-        hProcess = OpenProcess( PROCESS_ALL_ACCESS, FALSE, d->my_pid );
+        hProcess = OpenProcess( PROCESS_ALL_ACCESS, FALSE, d->process_ID );
         if (NULL == hProcess)
             break;
         
@@ -265,7 +265,7 @@ SHMProcess::SHMProcess(uint32_t PID, vector <memory_info *> & known_versions)
             {
                 memory_info *m = new memory_info(**it);
                 m->RebaseAll(base);
-                d->my_descriptor = m;
+                d->memdescriptor = m;
                 d->identified = true;
                 cerr << "identified " << m->getVersion() << endl;
                 break;
@@ -276,13 +276,13 @@ SHMProcess::SHMProcess(uint32_t PID, vector <memory_info *> & known_versions)
     
     if(d->identified)
     {
-        d->my_window = new DFWindow(this);
+        d->window = new DFWindow(this);
     }
     else
     {
         D_SHMCMD = CORE_RUNNING;
-        UnmapViewOfFile(d->my_shm);
+        UnmapViewOfFile(d->shm_addr);
-        d->my_shm = 0;
+        d->shm_addr = 0;
         ReleaseMutex(d->DFCLMutex);
         CloseHandle(d->DFSVMutex);
         d->DFSVMutex = 0;
@@ -316,13 +316,13 @@ SHMProcess::~SHMProcess()
         detach();
     }
     // destroy data model. this is assigned by processmanager
-    if(d->my_descriptor)
+    if(d->memdescriptor)
     {
-        delete d->my_descriptor;
+        delete d->memdescriptor;
     }
-    if(d->my_window)
+    if(d->window)
     {
-        delete d->my_window;
+        delete d->window;
     }
     // release mutex handles we have
     if(d->DFCLMutex)
@@ -338,17 +338,17 @@ SHMProcess::~SHMProcess()
 
 memory_info * SHMProcess::getDescriptor()
 {
-    return d->my_descriptor;
+    return d->memdescriptor;
 }
 
 DFWindow * SHMProcess::getWindow()
 {
-    return d->my_window;
+    return d->window;
 }
 
 int SHMProcess::getPID()
 {
-    return d->my_pid;
+    return d->process_ID;
 }
 
 //FIXME: implement
@@ -363,7 +363,7 @@ void SHMProcess::getMemRanges( vector<t_memrange> & ranges )
     char buffer[1024];
     char permissions[5]; // r/-, w/-, x/-, p/s, 0
     
-    sprintf(buffer, "/proc/%lu/maps", d->my_pid);
+    sprintf(buffer, "/proc/%lu/maps", d->process_ID);
     FILE *mapFile = ::fopen(buffer, "r");
     uint64_t offset, device1, device2, node;
     
@@ -476,7 +476,7 @@ bool SHMProcess::attach()
     }
 
     char shmname [256];
-    sprintf(shmname,"DFShm-%d",d->my_pid);
+    sprintf(shmname,"DFShm-%d",d->process_ID);
 
     // now try getting and attaching the shared memory
     HANDLE shmHandle = OpenFileMapping(FILE_MAP_ALL_ACCESS,false,shmname);
@@ -487,8 +487,8 @@ bool SHMProcess::attach()
     }
 
     // attempt to attach the opened mapping
-    d->my_shm = (char *) MapViewOfFile(shmHandle,FILE_MAP_ALL_ACCESS, 0,0, SHM_SIZE);
+    d->shm_addr = (char *) MapViewOfFile(shmHandle,FILE_MAP_ALL_ACCESS, 0,0, SHM_ALL_CLIENTS);
-    if(!d->my_shm)
+    if(!d->shm_addr)
     {
         CloseHandle(shmHandle);
         ReleaseMutex(d->DFCLMutex);
@@ -509,7 +509,7 @@ bool SHMProcess::detach()
         return false;
     }
     // detach segment
-    UnmapViewOfFile(d->my_shm);
+    UnmapViewOfFile(d->shm_addr);
     // release it for some other client
     ReleaseMutex(d->DFCLMutex); // we keep the mutex handles
     d->attached = false;
@@ -528,7 +528,7 @@ void SHMProcess::read (uint32_t src_address, uint32_t size, uint8_t *target_buff
         full_barrier
         D_SHMCMD = CORE_DFPP_READ;
         d->waitWhile(CORE_DFPP_READ);
-        memcpy (target_buffer, d->my_shm + SHM_HEADER,size);
+        memcpy (target_buffer, d->shm_addr + SHM_HEADER,size);
     }
     // a big read, we pull data over the shm in iterations
     else
@@ -543,7 +543,7 @@ void SHMProcess::read (uint32_t src_address, uint32_t size, uint8_t *target_buff
             full_barrier
             D_SHMCMD = CORE_DFPP_READ;
             d->waitWhile(CORE_DFPP_READ);
-            memcpy (target_buffer, d->my_shm + SHM_HEADER,size);
+            memcpy (target_buffer, d->shm_addr + SHM_HEADER,size);
             // decrease size by bytes read
             size -= to_read;
             // move the cursors
@@ -647,7 +647,7 @@ void SHMProcess::write (uint32_t dst_address, uint32_t size, uint8_t *source_buf
     {
         D_SHMHDR->address = dst_address;
         D_SHMHDR->length = size;
-        memcpy(d->my_shm+SHM_HEADER,source_buffer, size);
+        memcpy(d->shm_addr+SHM_HEADER,source_buffer, size);
         full_barrier
         D_SHMCMD = CORE_WRITE;
         d->waitWhile(CORE_WRITE);
@@ -662,7 +662,7 @@ void SHMProcess::write (uint32_t dst_address, uint32_t size, uint8_t *source_buf
             // write to_write bytes to dst_cursor
             D_SHMHDR->address = dst_address;
             D_SHMHDR->length = to_write;
-            memcpy(d->my_shm+SHM_HEADER,source_buffer, to_write);
+            memcpy(d->shm_addr+SHM_HEADER,source_buffer, to_write);
             full_barrier
             D_SHMCMD = CORE_WRITE;
             d->waitWhile(CORE_WRITE);
@@ -723,7 +723,7 @@ const std::string SHMProcess::readSTLString(uint32_t offset)
     int length = D_SHMHDR->value;
 //    char temp_c[256];
 //    strncpy(temp_c, d->my_shm+SHM_HEADER,length+1); // length + 1 for the null terminator
-    return(string(d->my_shm+SHM_HEADER));
+    return(string(d->shm_addr+SHM_HEADER));
 }
 
 size_t SHMProcess::readSTLString (uint32_t offset, char * buffer, size_t bufcapacity)
@@ -735,7 +735,7 @@ size_t SHMProcess::readSTLString (uint32_t offset, char * buffer, size_t bufcapa
     d->waitWhile(CORE_READ_STL_STRING);
     size_t length = D_SHMHDR->value;
     size_t real = min(length, bufcapacity - 1);
-    strncpy(buffer, d->my_shm+SHM_HEADER,real); // length + 1 for the null terminator
+    strncpy(buffer, d->shm_addr+SHM_HEADER,real); // length + 1 for the null terminator
     buffer[real] = 0;
     return real;
 }
@@ -743,7 +743,7 @@ size_t SHMProcess::readSTLString (uint32_t offset, char * buffer, size_t bufcapa
 void SHMProcess::writeSTLString(const uint32_t address, const std::string writeString)
 {
     D_SHMHDR->address = address/*-4*/;
-    strncpy(d->my_shm+SHM_HEADER,writeString.c_str(),writeString.length()+1); // length + 1 for the null terminator
+    strncpy(d->shm_addr+SHM_HEADER,writeString.c_str(),writeString.length()+1); // length + 1 for the null terminator
     full_barrier
     D_SHMCMD = CORE_WRITE_STL_STRING;
     d->waitWhile(CORE_WRITE_STL_STRING);
@@ -761,7 +761,7 @@ string SHMProcess::readClassName (uint32_t vptr)
 // get module index by name and version. bool 1 = error
 bool SHMProcess::getModuleIndex (const char * name, const uint32_t version, uint32_t & OUTPUT)
 {
-    modulelookup * payload = (modulelookup *) (d->my_shm + SHM_HEADER);
+    modulelookup * payload = (modulelookup *) (d->shm_addr + SHM_HEADER);
     payload->version = version;
     strcpy(payload->name,name);
     full_barrier
@@ -774,5 +774,5 @@ bool SHMProcess::getModuleIndex (const char * name, const uint32_t version, uint
 
 char * SHMProcess::getSHMStart (void)
 {
-    return d->my_shm;
+    return d->shm_addr;
 }

library/DFProcess.h

@@ -123,8 +123,14 @@ namespace DFHack
             virtual bool getModuleIndex (const char * name, const uint32_t version, uint32_t & OUTPUT) = 0;
             // get the SHM start if available
             virtual char * getSHMStart (void) = 0;
-            // wait for a SHM state. returns 0 without the SHM
+            // set a SHM command and wait for a response, return 0 on error or throw exception
+            virtual bool SetAndWait (uint32_t state) = 0;
+            /*
+            // wait while SHM command == state. returns 0 without the SHM
             virtual bool waitWhile (uint32_t state) = 0;
+            // set SHM command.
+            virtual void setCmd (uint32_t newstate) = 0;
+            */
     };
 
     class DFHACK_EXPORT NormalProcess : virtual public Process
@@ -181,8 +187,14 @@ namespace DFHack
             bool getModuleIndex (const char * name, const uint32_t version, uint32_t & OUTPUT) {return false;};
             // get the SHM start if available
             char * getSHMStart (void){return 0;};
+            // set a SHM command and wait for a response
+            bool SetAndWait (uint32_t state){return false;};
+            /*
             // wait for a SHM state. returns 0 without the SHM
             bool waitWhile (uint32_t state){return false;};
+            // set SHM command.
+            void setCmd (uint32_t newstate){};
+            */
     };
     
     class DFHACK_EXPORT SHMProcess : virtual public Process
@@ -240,8 +252,13 @@ namespace DFHack
             bool getModuleIndex (const char * name, const uint32_t version, uint32_t & OUTPUT);
             // get the SHM start if available
             char * getSHMStart (void);
+            bool SetAndWait (uint32_t state);
+            /*
             // wait for a SHM state. returns 0 without the SHM
             bool waitWhile (uint32_t state);
+            // set SHM command.
+            void setCmd (uint32_t newstate);
+            */
     };
 
 #ifdef LINUX_BUILD
@@ -299,8 +316,13 @@ namespace DFHack
             bool getModuleIndex (const char * name, const uint32_t version, uint32_t & OUTPUT) {return false;};
             // get the SHM start if available
             char * getSHMStart (void){return 0;};
+            bool SetAndWait (uint32_t state){return false;};
+            /*
             // wait for a SHM state. returns 0 without the SHM
             bool waitWhile (uint32_t state){return false;};
+            // set SHM command.
+            void setCmd (uint32_t newstate){};
+            */
     };
 #endif
 }

shmserver/mod-core.cpp

@@ -41,19 +41,22 @@ distribution.
 
 std::vector <DFPP_module> module_registry;
 
-// various crud
+// shared by shms_OS
 extern int errorstate;
 extern char *shm;
 extern int shmid;
+
+// file-globals
 bool useYield = 0;
+int currentClient = -1;
 
 #define SHMHDR ((shm_core_hdr *)shm)
-#define SHMCMD ((shm_cmd *)shm)->pingpong
+#define SHMCMDPP ((shm_core_hdr *) shm)->cmd[currentClient].pingpong
 #define SHMDATA(type) ((type *)(shm + SHM_HEADER))
 
 void ReadRaw (void * data)
 {
-    memcpy(shm + SHM_HEADER, (void *) SHMHDR->address,SHMHDR->length);
+    memcpy(SHMDATA(void), (void *) SHMHDR->address,SHMHDR->length);
 }
 
 void ReadDWord (void * data)
@@ -73,7 +76,7 @@ void ReadByte (void * data)
 
 void WriteRaw (void * data)
 {
-    memcpy((void *)SHMHDR->address, shm + SHM_HEADER,SHMHDR->length);
+    memcpy((void *)SHMHDR->address, SHMDATA(void),SHMHDR->length);
 }
 
 void WriteDWord (void * data)
@@ -97,14 +100,14 @@ void ReadSTLString (void * data)
     unsigned int l = myStringPtr->length();
     SHMHDR->value = l;
     // FIXME: there doesn't have to be a null terminator!
-    strncpy(shm+SHM_HEADER,myStringPtr->c_str(),l+1);
+    strncpy( SHMDATA(char),myStringPtr->c_str(),l+1);
 }
 
 void WriteSTLString (void * data)
 {
     std::string * myStringPtr = (std::string *) SHMHDR->address;
     // here we DO expect a 0 terminator
-    myStringPtr->assign((const char *) (shm + SHM_HEADER));
+    myStringPtr->assign( SHMDATA(const char) );
 }
 
 // MIT HAKMEM bitcount
@@ -133,7 +136,7 @@ void CoreAttach (void * data)
 void FindModule (void * data)
 {
     bool found = false;
-    modulelookup * payload = (modulelookup *) (shm + SHM_HEADER);
+    modulelookup * payload =  SHMDATA(modulelookup);
     std::string test = payload->name;
     uint32_t version = payload->version;
     for(unsigned int i = 0; i < module_registry.size();i++)
@@ -175,6 +178,11 @@ void FindCommand (void * data)
     SHMHDR->error = true;
 }
 
+void ReleaseSuspendLock( void * data )
+{
+    OS_releaseSuspendLock(currentClient);
+}
+
 DFPP_module InitCore(void)
 {
     DFPP_module core;
@@ -185,7 +193,9 @@ DFPP_module InitCore(void)
     core.reserve(NUM_CORE_CMDS);
     // basic states
     core.set_command(CORE_RUNNING, CANCELLATION, "Running");
-    core.set_command(CORE_SUSPEND, CLIENT_WAIT, "Suspend", 0 , CORE_SUSPENDED);
+    core.set_command(CORE_RUN, FUNCTION, "Run!",0,CORE_RUNNING);
+    core.set_command(CORE_STEP, CANCELLATION, "Suspend on next step",0,CORE_SUSPEND);// set command to CORE_SUSPEND, check next client
+    core.set_command(CORE_SUSPEND, FUNCTION, "Suspend", ReleaseSuspendLock , CORE_SUSPENDED);
     core.set_command(CORE_SUSPENDED, CLIENT_WAIT, "Suspended");
     core.set_command(CORE_ERROR, CANCELLATION, "Error");
     
@@ -195,7 +205,7 @@ DFPP_module InitCore(void)
     core.set_command(CORE_ACQUIRE_COMMAND, FUNCTION, "Command lookup", FindCommand, CORE_SUSPENDED);
     
     // raw reads
-    core.set_command(CORE_DFPP_READ, FUNCTION,"Raw read",ReadRaw, CORE_SUSPENDED);
+    core.set_command(CORE_READ, FUNCTION,"Raw read",ReadRaw, CORE_SUSPENDED);
     core.set_command(CORE_READ_DWORD, FUNCTION,"Read DWORD",ReadDWord, CORE_SUSPENDED);
     core.set_command(CORE_READ_WORD, FUNCTION,"Read WORD",ReadWord, CORE_SUSPENDED);
     core.set_command(CORE_READ_BYTE, FUNCTION,"Read BYTE",ReadByte, CORE_SUSPENDED);
@@ -233,52 +243,71 @@ void KillModules (void)
 
 void SHM_Act (void)
 {
+    volatile uint32_t atomic = 0;
     if(errorstate)
     {
         return;
     }
+    //static uint oldcl = 88;
+    for(currentClient = 0; currentClient < SHM_MAX_CLIENTS;currentClient++)
+    {
+        // set the offset for the shared memory used for the client
         uint32_t numwaits = 0;
         check_again: // goto target!!!
         if(numwaits == 10000)
         {
             // this tests if there's a process on the other side
-        if(isValidSHM())
+            if(isValidSHM(currentClient))
             {
                 numwaits = 0;
             }
             else
             {
                 full_barrier
-            SHMCMD = CORE_RUNNING;
+                SHMCMDPP = CORE_RUNNING;
                 fprintf(stderr,"dfhack: Broke out of loop, other process disappeared.\n");
             }
         }
+        full_barrier // I don't want the compiler to reorder my code.
+
+
+        //fprintf(stderr,"%d: %x %x\n",currentClient, (uint) SHMHDR, (uint) &(SHMHDR->cmd[currentClient]));
         
         // this is very important! copying two words separately from the command variable leads to inconsistency.
         // Always copy the thing in one go.
         // Also, this whole SHM thing probably only works on intel processors
-    
+        atomic  = *(uint32_t *) (shm + 4*currentClient); //SHMHDR->cmd[currentClient];
-    volatile shm_cmd atomic = SHMHDR->cmd;
-    full_barrier
-    DFPP_module & mod = module_registry[atomic.parts.module];
-    DFPP_command & cmd = mod.commands[atomic.parts.command];
         full_barrier
+        
+        DFPP_module & mod = module_registry[ ((shm_cmd)atomic).parts.module ];
+        DFPP_command & cmd = mod.commands[ ((shm_cmd)atomic).parts.command ];
         /*
-    fprintf(stderr, "Called %x\0", cmd._function);
+        if(atomic == CORE_RUNNING)
-    fprintf(stderr, "Client invoked %d:%d = ",atomic.parts.module,atomic.parts.command);
+        {
-    fprintf(stderr, "%s\n",cmd.name.c_str());
+            // we are running again for this process
-    */
+            // reaquire the suspend lock
+            OS_lockSuspendLock(currentClient);
+            continue;
+        }
         full_barrier
+        */
         if(cmd._function)
         {
             cmd._function(mod.modulestate);
         }
         full_barrier
+        
         if(cmd.nextState != -1)
         {
-        SHMCMD = cmd.nextState;
+            fprintf(stderr, "Client %d invoked %d:%d = %x = ",
+                    currentClient,((shm_cmd)atomic).parts.module,((shm_cmd)atomic).parts.command, cmd._function);
+            fprintf(stderr, "%s\n",cmd.name.c_str());
+            // FIXME: WHAT HAPPENS WHEN A 'NEXTSTATE' IS FROM A DIFFERENT MODULE THAN 'CORE'? Yeah. It doesn't work.
+            SHMCMDPP = cmd.nextState;
+            fprintf(stderr, "Server set %d\n",cmd.nextState);
         }
         full_barrier
+        
         if(cmd.type != CANCELLATION)
         {
             if(useYield)
@@ -288,5 +317,10 @@ void SHM_Act (void)
             numwaits ++; // watchdog timeout
             goto check_again;
         }
-}
+        full_barrier
         
+        // we are running again for this process
+        // reaquire the suspend lock
+        OS_lockSuspendLock(currentClient);
+    }
+}

shmserver/mod-core.h

@@ -26,11 +26,11 @@ distribution.
 #define SHMS_CORE_H
 
 // increment on every core change
-#define CORE_VERSION 7
+#define CORE_VERSION 8
 
 typedef struct
 {
-    shm_cmd cmd;
+    shm_cmd cmd[SHM_MAX_CLIENTS]; // MANDATORY!
     uint32_t address;
     uint32_t value;
     uint32_t length;
@@ -62,6 +62,8 @@ enum CORE_COMMAND
 {
     // basic states
     CORE_RUNNING = 0, // no command, normal server execution
+    CORE_RUN, // sent by the client to restart the server execution
+    CORE_STEP, // client suspend sets step
     CORE_SUSPEND, // client notifies server to wait for commands (server is stalled in busy wait)
     CORE_SUSPENDED, // response to WAIT, server is stalled in busy wait
     CORE_ERROR, // there was a server error
@@ -72,7 +74,7 @@ enum CORE_COMMAND
     CORE_ACQUIRE_COMMAND, // get module::command callsign by module name, command name and module version
 
     // raw reads
-    CORE_DFPP_READ, // cl -> sv, read some data
+    CORE_READ, // cl -> sv, read some data
     CORE_READ_DWORD, // cl -> sv, read a dword
     CORE_READ_WORD, // cl -> sv, read a word
     CORE_READ_BYTE, // cl -> sv, read a byte

shmserver/mod-maps.cpp

@@ -19,7 +19,7 @@ extern char *shm;
 
 #define SHMHDR ((shm_maps_hdr *)shm)
 #define SHMCMD ((shm_cmd *)shm)->pingpong
-#define SHMDATA ((char *)(shm + SHM_HEADER))
+#define SHMDATA(type) ((type *)(shm + SHM_HEADER))
 
 void NullCommand (void* data)
 {
@@ -28,7 +28,7 @@ void NullCommand (void* data)
 void InitOffsets (void* data)
 {
     maps_modulestate * state = (maps_modulestate *) data;
-    memcpy((void *) &(state->offsets), SHMDATA, sizeof(maps_offsets));
+    memcpy((void *) &(state->offsets), SHMDATA(void), sizeof(maps_offsets));
     ((maps_modulestate *) data)->inited = true;
 }
 
@@ -53,8 +53,6 @@ struct mblock
     uint32_t * ptr_to_dirty;
 };
 
-#define SHMBLOCK ((mapblock40d *)(shm + SHM_HEADER))
-
 inline void ReadBlockByAddress (void * data)
 {
     maps_modulestate * state = (maps_modulestate *) data;
@@ -62,13 +60,13 @@ inline void ReadBlockByAddress (void * data)
     mblock * block = (mblock *) SHMHDR->address;
     if(block)
     {
-        memcpy(&(SHMBLOCK->tiletypes), ((char *) block) + offsets.tile_type_offset, sizeof(SHMBLOCK->tiletypes));
+        memcpy(&(SHMDATA(mapblock40d)->tiletypes), ((char *) block) + offsets.tile_type_offset, sizeof(SHMDATA(mapblock40d)->tiletypes));
-        memcpy(&(SHMBLOCK->designaton), ((char *) block) + offsets.designation_offset, sizeof(SHMBLOCK->designaton));
+        memcpy(&(SHMDATA(mapblock40d)->designaton), ((char *) block) + offsets.designation_offset, sizeof(SHMDATA(mapblock40d)->designaton));
-        memcpy(&(SHMBLOCK->occupancy), ((char *) block) + offsets.occupancy_offset, sizeof(SHMBLOCK->occupancy));
+        memcpy(&(SHMDATA(mapblock40d)->occupancy), ((char *) block) + offsets.occupancy_offset, sizeof(SHMDATA(mapblock40d)->occupancy));
-        memcpy(&(SHMBLOCK->biome_indices), ((char *) block) + offsets.biome_stuffs, sizeof(SHMBLOCK->biome_indices));
+        memcpy(&(SHMDATA(mapblock40d)->biome_indices), ((char *) block) + offsets.biome_stuffs, sizeof(SHMDATA(mapblock40d)->biome_indices));
-        SHMBLOCK->dirty_dword = *block->ptr_to_dirty;
+        SHMDATA(mapblock40d)->dirty_dword = *block->ptr_to_dirty;
         
-        SHMBLOCK->origin = (uint32_t)block;
+        SHMDATA(mapblock40d)->origin = (uint32_t)block;
         SHMHDR->error = false;
     }
     else

shmserver/mod-maps.h

@@ -71,7 +71,7 @@ typedef struct
 
 typedef struct
 {
-    shm_cmd cmd;
+    shm_cmd cmd[SHM_MAX_CLIENTS]; // MANDATORY!
     uint32_t x;
     uint32_t y;
     uint32_t z;

shmserver/shms-linux.cpp

@@ -51,38 +51,27 @@ char *shm = 0;
 int shmid = 0;
 bool inited = 0;
 
-int fd_svlock = 0;
+int fd_svlock = -1;
-int fd_cllock = 0;
+int fd_cllock[SHM_MAX_CLIENTS];
-
+int fd_clSlock[SHM_MAX_CLIENTS];
+int held_clSlock[SHM_MAX_CLIENTS];
+int numheld = SHM_MAX_CLIENTS;
 
 /*******************************************************************************
 *                           SHM part starts here                               *
 *******************************************************************************/
-/*
-// FIXME: add error checking?
-bool isValidSHM()
-{
-    shmid_ds descriptor;
-    shmctl(shmid, IPC_STAT, &descriptor);
-    //fprintf(stderr,"ID %d, attached: %d\n",shmid, descriptor.shm_nattch);
-    return (descriptor.shm_nattch == 2);
-}
-*/
-
 // is the other side still there?
-bool isValidSHM()
+bool isValidSHM(int which)
 {
-    // try if CL lock file is free
+    // if we get the client lock here, the client process failed and we need to reclaim our suspend lock
-    int result = lockf(fd_cllock,F_TEST,0);
+    if(lockf(fd_cllock[which],F_TLOCK,0) == 0)
-    /*
+    {
-    F_TEST: Test the lock:
+        // we get back our suspend lock from the cold, dead hands of the former client :P
-    return 0 if the specified section is unlocked or locked by this process;
+        OS_lockSuspendLock(which);
-    return -1, set errno to EAGAIN (EACCES on some other systems), if another process holds a lock.
+        // free the client lock again
-    */
+        lockf(fd_cllock[which],F_ULOCK,0);
-    
+        return false;
-    // if nobody holds the lock, the SHM isn't valid. file locks are unlocked when the owner closes or crashes.
+    }
-    if(result == 0) return false;
-    
     return true;
 }
 
@@ -100,6 +89,45 @@ uint32_t OS_getAffinity()
     return affinity;
 }
 
+void OS_lockSuspendLock(int which)
+{
+    if(numheld == SHM_MAX_CLIENTS)
+        return;
+    // lock not held by server and can be picked up. OK.
+    if(held_clSlock[which] == 0 && lockf(fd_clSlock[which],F_LOCK,0) == 0)
+    {
+        held_clSlock[which] = 1;
+        numheld++;
+    }
+    // lock couldn't be picked up!
+    else if (held_clSlock[which] == 0)
+    {
+        fprintf(stderr,"lock %d failed to lock\n", which);
+    }
+}
+
+void OS_releaseSuspendLock(int which)
+{
+    /*
+    if(which >=0 && which < SHM_MAX_CLIENTS)
+        return;
+    */
+    if(numheld != SHM_MAX_CLIENTS)
+    {
+        fprintf(stderr,"TOTAL FAILURE OF LOCKING SYSTEM\n");
+        return;
+    }
+    // lock hel by server and can be released -> OK
+    if(held_clSlock[which] == 1 && lockf(fd_clSlock[which],F_ULOCK,0) == 0)
+    {
+        numheld--;
+        held_clSlock[which] = 0;
+    }
+    // locked and not can't be released? FAIL!
+    else if (held_clSlock[which] == 1)
+        fprintf(stderr,"lock %d failed to unlock\n", which);
+}
+
 void SHM_Init ( void )
 {
     // check that we do this only once per process
@@ -111,7 +139,6 @@ void SHM_Init ( void )
     inited = true;
     char name[256];
     char name2[256];
-    
     // make folder structure for our lock files
     sprintf(name, "/tmp/DFHack/%d",OS_getPID());
     mode_t createmode = S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH;
@@ -123,9 +150,17 @@ void SHM_Init ( void )
     fd_svlock = open(name2,O_WRONLY | O_CREAT, createmode);
     lockf( fd_svlock, F_LOCK, 0 );
     
+    for(int i = 0; i < SHM_MAX_CLIENTS; i++)
+    {
         // create the client lock file
-    sprintf(name2, "%s/CLlock",name);
+        sprintf(name2, "%s/CLlock%d",name,i);
-    fd_cllock = open(name2,O_WRONLY | O_CREAT, createmode);
+        fd_cllock[i] = open(name2,O_WRONLY | O_CREAT, createmode);
+        // get and lock the suspend locks
+        sprintf(name2, "%s/CLSlock%d",name,i);
+        fd_clSlock[i] = open(name2,O_WRONLY | O_CREAT, createmode);
+        lockf(fd_clSlock[i],F_LOCK,0);
+        held_clSlock[i] = 1;
+    }
     
     // name for the segment, an accident waiting to happen
     key_t key = SHM_KEY + OS_getPID();
@@ -159,7 +194,10 @@ void SHM_Init ( void )
     }
     full_barrier
     // make sure we don't stall or do crazy stuff
-    ((shm_cmd *)shm)->pingpong = CORE_RUNNING;
+    for(int i = 0; i < SHM_MAX_CLIENTS;i++)
+    {
+        ((shm_cmd *)shm)[i].pingpong = CORE_RUNNING;
+    }
     InitModules();
 }
 
@@ -177,21 +215,29 @@ void SHM_Destroy ( void )
         }
         shmctl(shmid,IPC_RMID,NULL);
         
-        // unlock and close server lock, close client lock
-        lockf(fd_svlock,F_ULOCK,0);
-        close(fd_svlock);
-        close(fd_cllock);
-        fd_svlock = 0;
-        fd_cllock = 0;
-
-        // destroy lock files
         char name[256];
         char name2[256];
         sprintf(name, "/tmp/DFHack/%d",OS_getPID());
-        sprintf(name2, "%s/SVlock",name);
+        
+        // unlock and close server lock, close client lock, destroy files
+        lockf(fd_svlock,F_ULOCK,0);
+        for(int i = 0; i < SHM_MAX_CLIENTS; i++)
+        {
+            close(fd_cllock[i]);
+            fd_cllock[i] = 0;
+            close(fd_clSlock[i]);
+            fd_clSlock[i] = 0;
+            held_clSlock[i] = 0;
+            sprintf(name2, "%s/CLlock%d",name,i);
             unlink(name2);
-        sprintf(name2, "%s/CLlock",name);
+            sprintf(name2, "%s/CLSlock%d",name,i);
             unlink(name2);
+        }
+        close(fd_svlock);
+        fd_svlock = 0;
+        sprintf(name2, "%s/SVlock",name);
+        unlink(name2);
+        // remove the PID folder
         rmdir(name);
         fprintf(stderr,"dfhack: destroyed shared segment.\n");
         inited = false;
@@ -213,7 +259,7 @@ DFhackCExport void SDL_GL_SwapBuffers(void)
 {
     if(_SDL_GL_SwapBuffers)
     {
-        if(!errorstate && ((shm_cmd *)shm)->pingpong != CORE_RUNNING)
+        if(!errorstate)
         {
             SHM_Act();
         }
@@ -227,7 +273,7 @@ DFhackCExport int SDL_Flip(void * some_ptr)
 {
     if(_SDL_Flip)
     {
-        if(!errorstate && ((shm_cmd *)shm)->pingpong != CORE_RUNNING)
+        if(!errorstate)
         {
             SHM_Act();
         }
@@ -285,7 +331,7 @@ DFhackCExport int refresh (void)
 {
     if(_refresh)
     {
-        if(!errorstate && ((shm_cmd *)shm)->pingpong != CORE_RUNNING)
+        if(!errorstate)
         {
             SHM_Act();
         }

shmserver/shms-windows.cpp

@@ -117,7 +117,7 @@ void SHM_Init ( void )
     }
     
     // create virtual memory mapping
-    shmHandle = CreateFileMapping(INVALID_HANDLE_VALUE,NULL,PAGE_READWRITE,0,SHM_SIZE,shmname);
+    shmHandle = CreateFileMapping(INVALID_HANDLE_VALUE,NULL,PAGE_READWRITE,0,SHM_ALL_CLIENTS,shmname);
     // if can't create or already exists -> nothing happens
     if(GetLastError() == ERROR_ALREADY_EXISTS)
     {
@@ -138,7 +138,7 @@ void SHM_Init ( void )
         return;
     }
     // attempt to attach the created mapping
-    shm = (char *) MapViewOfFile(shmHandle,FILE_MAP_ALL_ACCESS, 0,0, SHM_SIZE);
+    shm = (char *) MapViewOfFile(shmHandle,FILE_MAP_ALL_ACCESS, 0,0, SHM_ALL_CLIENTS);
     if(shm)
     {
         ((shm_cmd *)shm)->pingpong = CORE_RUNNING;

shmserver/shms.h

@@ -2,10 +2,12 @@
 #define DFCONNECT_H
 
 #define SHM_KEY 123466
+#define SHM_MAX_CLIENTS 4
 #define SHM_HEADER 1024 // 1kB reserved for a header
-#define SHM_BODY 1024*1024 // 1MB reserved for bulk data transfer
+#define SHM_BODY 1024*1024 // 4MB reserved for bulk data transfer
 #define SHM_SIZE SHM_HEADER+SHM_BODY
-
+//#define SHM_ALL_CLIENTS SHM_MAX_CLIENTS*(SHM_SIZE)
+//#define SHM_CL(client_idx) client_idx*(SHM_SIZE)
 
 // FIXME: add YIELD for linux, add single-core and multi-core compile targets for optimal speed
 #ifdef LINUX_BUILD
@@ -79,7 +81,7 @@ struct DFPP_module
     void * modulestate;
 };
 
-typedef union
+union shm_cmd
 {
     struct
         {
@@ -87,18 +89,20 @@ typedef union
             volatile uint16_t module;
         } parts;
     volatile uint32_t pingpong;
-    inline void set(uint16_t module, uint16_t command)
+    shm_cmd(volatile uint32_t z)
     {
-        pingpong = module + command << 16;
+        pingpong = z;
     }
-} shm_cmd;
+};
 
 void SHM_Act (void);
 void InitModules (void);
 void KillModules (void);
-bool isValidSHM();
+bool isValidSHM(int current);
 uint32_t OS_getPID();
 DFPP_module InitMaps(void);
 uint32_t OS_getAffinity(); // limited to 32 processors. Silly, eh?
+void OS_releaseSuspendLock(int currentClient);
+void OS_lockSuspendLock(int currentClient);
 
 #endif