Crash issue having multiple active_displays in a config


simon smith <si.c....@...>
 

I'm testing out some code and I've noticed a crash issue when a config (such as ACES, from the ICIO website) contain multiple active displays or views.

Basically, the code in ICIOYaml.cpp that takes an array of displays tries to join them together into one string using the JoinStringEnvStyle function (in ParseUtils.cpp) is flawed.

JoinStringEnvStyle will return a new std::string instance if more than one string is found in the array (it will pass the original "array" string back if there is only one entry in it).

The caller of JoinStringEnvStylein OCIOYaml.cpp takes a const pointer to this returned std::string to pass to the next function (setActiveDisplays) but it falls out of scope as soon as the const char* has been taken (it goes out of scope as it enters the next line of code). Thus on the next line the pointer is pointing to freed memory. You probably get away with this in release, but in debug (under windows) it will write freed memory markers as guards for this type of thing.

The code currently is:

std::vector<std::string> display;
load(second, display);
const char* displays = JoinStringEnvStyle(display).c_str();
c->setActiveDisplays(displays);

You can easily see the scope issue here.
I suspect a fix would be along the lines of:

std::vector<std::string> display;
load(second, display);
std::string strDisplays = JoinStringEnvStyle(display).c_str();
const char* displays = strDisplays.c_str();
c->setActiveDisplays(displays);

I thought I'd pass this on as I've not seen any notes on it anywhere, but it must be an issue for everyone.


 - Simon.

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