Print Cause when WbAbstractCamera Fails to Create Memory Mapped File

src/webots/core/WbPosixMemoryMappedFile.cpp

@@ -14,7 +14,9 @@
 
 #include "WbPosixMemoryMappedFile.hpp"
 
+#include <errno.h>
 #include <fcntl.h>
+#include <string.h>
 #include <sys/mman.h>
 #include <unistd.h>
 
@@ -30,14 +32,20 @@ WbPosixMemoryMappedFile::~WbPosixMemoryMappedFile() {
 bool WbPosixMemoryMappedFile::create(int size) {
   unlink(mName.toUtf8());                                 // delete a possibly existing memory mapped file with the same name
   int fd = open(mName.toUtf8(), O_CREAT | O_RDWR, 0666);  // returns -1 in case of failure
-  if (fd < 0)
+  if (fd < 0) {
+    mErrorString = QString("Cannot open file: %1 (%2)").arg(mName).arg(strerror(errno));
     return false;
-  if (ftruncate(fd, size) == -1)
+  }
+  if (ftruncate(fd, size) == -1) {
+    mErrorString = QString("Cannot truncate file: %1 (%2)").arg(mName).arg(strerror(errno));
     return false;
+  }
   mData = mmap(0, size, PROT_WRITE | PROT_READ, MAP_SHARED, fd, 0);
   close(fd);
-  if (mData == MAP_FAILED)
+  if (mData == MAP_FAILED) {
+    mErrorString = QString("Cannot map file: %1 (%2)").arg(mName).arg(strerror(errno));
     return false;
+  }
   mSize = size;
   return true;
 }

src/webots/core/WbPosixMemoryMappedFile.hpp

@@ -27,11 +27,13 @@ class WbPosixMemoryMappedFile {
   int size() const { return mSize; }
   void *data() const { return mData; }
   const QString &nativeKey() const { return mName; }
+  const QString &errorString() const { return mErrorString; }
 
 private:
   QString mName;
   int mSize;
   void *mData;
+  QString mErrorString;
 };
 
 #endif

src/webots/nodes/WbAbstractCamera.cpp

@@ -198,13 +198,15 @@ WbMemoryMappedFile *WbAbstractCamera::initializeMemoryMappedFile(const QString &
   const QString folder = WbStandardPaths::webotsTmpPath() + "ipc/" + QUrl::toPercentEncoding(robot()->name());
   const QString memoryMappedFileName = folder + "/snap.webots." + QUrl::toPercentEncoding(name()) + id;
   QDir().mkdir(folder);
+  info(tr("Allocating memory mapped file '%1'").arg(memoryMappedFileName));
   WbMemoryMappedFile *imageMemoryMappedFile = new WbMemoryMappedFile(memoryMappedFileName);
   // A controller of the previous simulation may have not released cleanly the memory mapped file (e.g. when the controller
   // crashes). This can be detected by trying to attach, and the memory mapped file may be cleaned by detaching.
   if (imageMemoryMappedFile->attach())
     imageMemoryMappedFile->detach();
   if (!imageMemoryMappedFile->create(size())) {
-    const QString message = tr("Cannot allocate memory mapped file for camera image.");
+    const QString message =
+      tr("Cannot allocate memory mapped file for camera image.\nCaused by: %1.").arg(imageMemoryMappedFile->errorString());
     warn(message);
     delete imageMemoryMappedFile;
     return NULL;