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DREAMWEB: Check for exFrame data corruption on load

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This provides earlier detection for corrupted savegames caused by
bug #3591088
This commit is contained in:
Willem Jan Palenstijn 2012-12-01 12:29:17 +01:00
parent 8881f71ac5
commit 02fe2ded35
1 changed files with 44 additions and 0 deletions
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44
engines/dreamweb/saveload.cpp
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@ -574,6 +574,14 @@ void DreamWebEngine::savePosition(unsigned int slot, const char *descbuf) {
delete outSaveFile;
}
// Utility struct for a savegame sanity check in loadPosition
struct FrameExtent {
uint16 start;
uint16 length;
bool operator<(const struct FrameExtent& other) const { return start<other.start; }
};
void DreamWebEngine::loadPosition(unsigned int slot) {
_timeCount = 0;
clearChanges();
@ -653,6 +661,42 @@ void DreamWebEngine::loadPosition(unsigned int slot) {
}
delete inSaveFile;
// Do a sanity check on exFrames data to detect exFrames corruption
// caused by a (now fixed) bug in emergencyPurge. See bug #3591088.
// Gather the location of frame data of all used ex object frames.
Common::List<FrameExtent> flist;
for (unsigned int i = 0; i < kNumexobjects; ++i) {
if (_exData[i].mapad[0] != 0xff) {
FrameExtent fe;
Frame *frame = &_exFrames._frames[3*i+0];
fe.start = frame->ptr();
fe.length = frame->width * frame->height;
flist.push_back(fe);
frame = &_exFrames._frames[3*i+1];
fe.start = frame->ptr();
fe.length = frame->width * frame->height;
flist.push_back(fe);
}
}
// ...and check if the frames overlap.
Common::sort(flist.begin(), flist.end(), Common::Less<FrameExtent>());
Common::List<FrameExtent>::const_iterator iter;
uint16 curEnd = 0;
for (iter = flist.begin(); iter != flist.end(); ++iter) {
if (iter->start < curEnd)
error("exFrames data corruption in savegame");
curEnd = iter->start + iter->length;
}
if (curEnd > _vars._exFramePos) {
if (curEnd > kExframeslen)
error("exFrames data corruption in savegame");
warning("Fixing up exFramePos");
_vars._exFramePos = curEnd;
}
// (end of sanity check)
}
// Count number of save files, and load their descriptions into _saveNames