Fix #4: Segfault on nonexisting disk image

.gitignore

@@ -1,4 +1,4 @@
 cmake-build-debug/
 cmake-build-release/
-build/
+build**/
 .idea/

src/DiskFile.cpp

@@ -100,64 +100,57 @@
  **/
 #include "DiskFile.h"
 #include "StdAfx.h"
+#include <fstream>
+#include <iostream>
 
 CDiskFile::CDiskFile(CConfigurator *cfg, CSystem *sys, CDiskController *c,
                      int idebus, int idedev)
     : CDisk(cfg, sys, c, idebus, idedev) {
+
+  /* If the filename exists in the config, use that,
+   * otherwise, use a default filename */
   filename = myCfg->get_text_value("file");
   if (!filename) {
-    FAILURE_1(Configuration, "%s: Disk has no file attached!\n", devid_string);
+    defaultFilename = std::string(devid_string) + ".default.img";
+    std::cerr << devid_string
+              << ": Disk has no filename attached! Assuming default: "
+              << defaultFilename << std::endl;
+    filename = const_cast<char *>(defaultFilename.c_str());
   }
 
-#ifdef HAVE_FOPEN64
-    handle = fopen64(filename, read_only ? "rb" : "rb+");
-#else
-    handle = fopen(filename, read_only ? "rb" : "rb+");
-#endif
-
-  if (!handle) {
-    printf("%s: Could not open file %s!\n", devid_string, filename);
-
-    int sz = myCfg->get_num_value("autocreate_size", false, 0) / 1024 / 1024;
-    if (!sz)
-      FAILURE_1(Runtime, "%s: File does not exist and no autocreate_size set",
+  /* if the file does not exist, create it. ifs actually checks for
+   * accessibility, not for existence, but for compatibility with
+   * platforms without c++17/boost and std::filesystem::exists, this
+   * is good enough. ifstream.good() returns false if the file does
+   * not exist.*/
+  std::ifstream ifs(filename, std::ios::binary);
+  if (!ifs.good()) {
+    std::cerr << devid_string << ": file does not exist: " << filename
+              << std::endl;
+
+    /* If the disk file size was not set and the disk file does not exist, do
+     * not create it, but exit */
+    int diskFileSize = myCfg->get_num_value("autocreate_size", false, 0);
+    if (!diskFileSize) {
+      FAILURE_1(Runtime, "%s: file does not exist and no autocreate_size set.",
                 devid_string);
-
-    void *crt_buf;
-    handle = fopen_large(filename, "wb");
-    if (!handle)
-      FAILURE_1(Runtime, "%s: File does not exist and could not be created",
-                devid_string);
-    crt_buf = calloc(1024, 1024);
-    printf("%s: writing %d 1kB blocks:   0%%\b\b\b\b", devid_string, sz);
-
-    int lastpc = 0;
-    for (int a = 0; a < sz; a++) {
-      fwrite(crt_buf, 1024, 1024, handle);
-
-      int pc = a * 100 / sz;
-      if (pc != lastpc) {
-        printf("%3d\b\b\b", pc);
-        lastpc = pc;
-      }
-
-      fflush(stdout);
     }
 
-    printf("100%%\n");
-    fclose(handle);
-    free(crt_buf);
-    if (read_only)
-      handle = fopen_large(filename, "rb");
-    else
-      handle = fopen_large(filename, "rb+");
-    if (!handle) {
-      FAILURE_1(Runtime, "%s: File created could not be opened", devid_string);
+    /* Don't create disk file if it's supposed to be a cdrom */
+    if (is_cdrom) {
+      FAILURE_1(Runtime, "%s: file does not exist and is configured as cdrom.",
+                devid_string);
     }
 
-    printf("%s: %d MB file %s created.\n", devid_string, sz, filename);
+    createDiskFile(filename, diskFileSize);
   }
 
+#ifdef HAVE_FOPEN64
+  handle = fopen64(filename, read_only ? "rb" : "rb+");
+#else
+  handle = fopen(filename, read_only ? "rb" : "rb+");
+#endif
+
   // determine size...
   fseek_large(handle, 0, SEEK_END);
   byte_size = ftell_large(handle);
@@ -192,6 +185,20 @@ CDiskFile::CDiskFile(CConfigurator *cfg, CSystem *sys, CDiskController *c,
          cylinders, heads, sectors);
 }
 
+void CDiskFile::createDiskFile(const std::string &fileName, int diskFileSize) {
+
+  std::ofstream ofs(fileName, std::ios::binary);
+  if (ofs.is_open() && ofs.good()) {
+    ofs.seekp((diskFileSize)-1);
+    ofs.write("", 1);
+  } else {
+    FAILURE_1(Runtime, "%s: File does not exist and could not be created", devid_string);
+  }
+
+  std::cout << devid_string << " " << (diskFileSize / 1024 / 1024) << "MB file "
+            << filename << " created" << std::endl;
+}
+
 CDiskFile::~CDiskFile(void) {
   printf("%s: Closing file.\n", devid_string);
   fclose(handle);

src/DiskFile.h

@@ -74,5 +74,8 @@ class CDiskFile : public CDisk {
 protected:
   FILE *handle;
   char *filename;
+
+  void createDiskFile(const std::string &filename, int diskFileSize);
+  std::string defaultFilename;
 };
 #endif //! defined(__DISKFILE_H__)

src/System.cpp

@@ -421,10 +421,15 @@ void CSystem::ResetMem(unsigned int membits) {
 /**
  * Register a device.
  **/
-int CSystem::RegisterComponent(CSystemComponent *component) {
+void CSystem::RegisterComponent(CSystemComponent *component) {
   acComponents[iNumComponents] = component;
   iNumComponents++;
-  return 0;
+}
+
+void CSystem::UnregisterComponent(CSystemComponent *component) {
+  if (acComponents[iNumComponents] == component)
+    acComponents[iNumComponents] = nullptr;
+  iNumComponents--;
 }
 
 /**

src/System.h

@@ -210,7 +210,7 @@ struct SConfig {
  * The ES40 emulator has the following chipset configuration:
  *   - 1 x 21274-C1 Cchip (controller chip) - The Cchip controls the other chips
  *in the chipset, as well as the DRAM memory array in a system. The Cchip
- *interfaces with the CPU�s command and address buses.
+ *interfaces with the CPU's command and address buses.
  *   - 8 x 21274-D1 Dchip (data slice chip) - The Dchips interface with the
  *system data bus and provide the data path between the CPU, DRAM memory, and
  *the Pchip(s).
@@ -241,7 +241,8 @@ class CSystem {
 
   int RegisterMemory(CSystemComponent *component, int index, u64 base,
                      u64 length);
-  int RegisterComponent(CSystemComponent *component);
+  void RegisterComponent(CSystemComponent *component);
+  void UnregisterComponent(CSystemComponent *component);
   int RegisterCPU(class CAlphaCPU *cpu);
 
   CSystem(CConfigurator *cfg);

src/SystemComponent.cpp

@@ -92,6 +92,7 @@ CSystemComponent::CSystemComponent(CConfigurator *cfg, CSystem *system) {
  * destructor.
  **/
 CSystemComponent::~CSystemComponent() {
+  cSystem->UnregisterComponent(this);
   free(devid_string);
   devid_string = nullptr;
 }