Fix audio-related static analysis issues

include/support.h

@@ -34,6 +34,11 @@
 #define strncasecmp(a, b, n) _strnicmp(a, b, n)
 #endif
 
+// Include a message in assert, similar to static_assert:
+#define assertm(exp, msg) assert(((void)msg, exp))
+// Use (void) to silent unused warnings.
+// https://en.cppreference.com/w/cpp/error/assert
+
 /// Copy a string into C array
 ///
 /// This function copies string pointed by src to fixed-size buffer dst.

src/dos/cdrom_image.cpp

@@ -667,7 +667,7 @@ track_iter CDROM_Interface_Image::GetTrack(const int sector)
 		if (lower_bound <= sector && sector < upper_bound) {
 			break;
 		}
-		track++;
+		++track;
 		lower_bound = upper_bound;
 	} // If we made it here without breaking, then the track
 	  // wasn't found and the iterator is now the end() item.
@@ -978,7 +978,7 @@ bool CDROM_Interface_Image::LoadCueSheet(char *cuefile)
 		// ignored commands
 		else if (command == "CDTEXTFILE" || command == "FLAGS"   || command == "ISRC" ||
 		         command == "PERFORMER"  || command == "POSTGAP" || command == "REM" ||
-		         command == "SONGWRITER" || command == "TITLE"   || command == "") {
+		         command == "SONGWRITER" || command == "TITLE"   || command.empty()) {
 			success = true;
 		}
 		// failure

src/dos/dos_mscdex.cpp

@@ -18,6 +18,7 @@
 
 #include "dos_mscdex.h"
 
+#include <cassert>
 #include <cctype>
 #include <cstring>
 #include <sys/stat.h>
@@ -174,11 +175,10 @@ public:
 CMscdex::CMscdex()
 	: numDrives(0),
 	  defaultBufSeg(0),
+	  cdrom{nullptr},
 	  rootDriverHeaderSeg(0)
 {
 	memset(dinfo, 0, sizeof(dinfo));
-	for (auto &drive : cdrom)
-		drive = nullptr;
 }
 
 CMscdex::~CMscdex()
@@ -282,10 +282,11 @@ int CMscdex::AddDrive(Bit16u _drive, char* physicalPath, Bit8u& subUnit)
 
 	if (rootDriverHeaderSeg==0) {
 		
-		Bit16u driverSize = sizeof(DOS_DeviceHeader::sDeviceHeader) + 10; // 10 = Bytes for 3 callbacks
+		constexpr uint16_t driverSize = sizeof(DOS_DeviceHeader::sDeviceHeader) + 10; // 10 = Bytes for 3 callbacks
 		
 		// Create Device Header
-		Bit16u seg = DOS_GetMemory(driverSize/16+((driverSize%16)>0));
+		static_assert((driverSize % 16) == 0, "should always be zero");
+		Bit16u seg = DOS_GetMemory(driverSize / 16);
 		DOS_DeviceHeader devHeader(PhysMake(seg,0));
 		devHeader.SetNextDeviceHeader	(0xFFFFFFFF);
 		devHeader.SetAttribute(0xc800);
@@ -710,8 +711,7 @@ bool CMscdex::GetDirectoryEntry(Bit16u drive, bool copyFlag, PhysPt pathname, Ph
 					LOG(LOG_MISC,LOG_WARN)("MSCDEX: GetDirEntry: Copyflag structure not entirely accurate maybe");
 					Bit8u readBuf[256];
 					Bit8u writeBuf[256];
-					if (entryLength > 256)
-						return false;
+					assertm(entryLength <= 256, "entryLength should never exceed 256");
 					MEM_BlockRead( defBuffer+index, readBuf, entryLength );
 					writeBuf[0] = readBuf[1];						// 00h	BYTE	length of XAR in Logical Block Numbers
 					memcpy( &writeBuf[1], &readBuf[0x2], 4);		// 01h	DWORD	Logical Block Number of file start

src/libs/decoders/SDL_sound.c

@@ -345,28 +345,24 @@ static Sound_Sample *alloc_sample(SDL_RWops *rw, Sound_AudioInfo *desired)
      * !!! FIXME: We're going to need to pool samples, since the mixer
      * !!! FIXME:  might be allocating tons of these on a regular basis.
      */
-    Sound_Sample *retval = malloc(sizeof (Sound_Sample));
+    Sound_Sample *retval = NULL;
+    Sound_Sample *sample = malloc(sizeof (Sound_Sample));
     Sound_SampleInternal *internal = malloc(sizeof (Sound_SampleInternal));
-    if ((retval == NULL) || (internal == NULL))
-    {
+    if (sample && internal) {
+        memset(sample, '\0', sizeof (Sound_Sample));
+        memset(internal, '\0', sizeof (Sound_SampleInternal));
+        if (desired != NULL) {
+            memcpy(&sample->desired, desired, sizeof (Sound_AudioInfo));
+        }
+        internal->rw = rw;
+        sample->opaque = internal;
+        retval = sample;
+    } else {
         __Sound_SetError(ERR_OUT_OF_MEMORY);
-        if (retval)
-            free(retval);
-        if (internal)
-            free(internal);
-
-        return(NULL);
-    } /* if */
-
-    memset(retval, '\0', sizeof (Sound_Sample));
-    memset(internal, '\0', sizeof (Sound_SampleInternal));
-
-    if (desired != NULL)
-        memcpy(&retval->desired, desired, sizeof (Sound_AudioInfo));
-
-    internal->rw = rw;
-    retval->opaque = internal;
-    return(retval);
+        free(sample);
+        free(internal);
+    }
+    return retval;
 } /* alloc_sample */