I use libzip to open zip files in my application and in order to ensure good behavior in case of corrupt zip files I manually corrupted a zip file (by removing a few random lines with a text editor) and try to load that file. However this hangs the entire app because zip_fread() never returns.
Is there a where to determine if a zip file is valid before loading it to avoid such situations?
Update
The behavior seems to depend on the version, so I probably only need to update. This is the code I use on Windows, Mac OS and Linux:
int err;
zip *z= zip_open(zipfile.c_str(), 0, &err);
if (!z)
{
if (err == ZIP_ER_NOZIP)
throw std::runtime_error("The file is not a Workbench document.");
else if (err == ZIP_ER_MEMORY)
throw grt::os_error("Cannot allocate enough memory to open document.");
else if (err == ZIP_ER_NOENT)
throw grt::os_error("File not found.");
int len= zip_error_to_str(NULL, 0, 0, err);
std::string msg;
if (len > 0)
{
char *buf= (char*)g_malloc(len+1);
zip_error_to_str(buf, len+1, 0, err);
msg= buf;
g_free(buf);
}
else
msg= "error opening zip archive";
zip_close(z);
throw std::runtime_error(strfmt(_("Cannot open document file: %s"), msg.c_str()));
}
On OS X this fragment does not return an error (I used the same file for all platforms). Instead the following zip_read() call just hangs. On the other platforms zip_read() immediately returns with a result < 0, so it's easy to catch the error there.
