Possible memory leak of `logLevelStr` in `logging` (never freed on any path)

[OvOhao]

Possible memory leak of logLevelStr in logging (never freed on any path)

I found a possible per-operation heap leak in the logging N-API method. When called with a
string argument (to set the libav log level), the function mallocs a buffer to hold a UTF-8
copy of the argument, but that buffer is never freed on any path — neither the error path
(unrecognised level throws and returns) nor the normal success path. Every call to
beamcoder.logging('<level>') leaks the allocation.

File: src/log.cc

Function: logging

    status = napi_get_value_string_utf8(env, args[0], nullptr, 0, &strLen);
    CHECK_STATUS;
    logLevelStr = (char*) malloc(sizeof(char) * (strLen + 1));
    CHECK_STATUS;
    status = napi_get_value_string_utf8(env, args[0], logLevelStr, strLen + 1, &strLen);
    CHECK_STATUS;

    logLevel = beam_lookup_enum(beam_logging_level->inverse, logLevelStr);
    if (logLevel == BEAM_ENUM_UNKNOWN) {
      NAPI_THROW_ERROR("Logging level string unrecognised");   // returns, logLevelStr leaked
    }
    av_log_set_level(logLevel);

    status = napi_get_undefined(env, &result);
    CHECK_STATUS;
  }

  return result;   // success path also returns without free(logLevelStr)

1. logLevelStr = (char*) malloc(strLen + 1) allocates a heap buffer holding the argument string.
2. If the string is not a known level, NAPI_THROW_ERROR(...) expands to napi_throw_error(...); return nullptr; — it does not free logLevelStr, so the buffer leaks on the error path.
3. On the normal path, after av_log_set_level(logLevel), the function falls through to
   return result;. There is no free(logLevelStr) anywhere in the function (confirmed: the only
   references to logLevelStr in log.cc are the declaration, the malloc, the fill, and the
   lookup). So the buffer leaks on the success path too.

This is a per-operation leak: it happens on every invocation with a string, not just a one-time
init, and the amount leaked scales with the argument length.

JS trigger (if applicable):

const beamcoder = require('beamcoder');
for (let i = 0; i < 1e6; i++) beamcoder.logging('debug'); // leaks a buffer each call
beamcoder.logging('not-a-level'); // also leaks (and throws)

Suggested fix: free(logLevelStr) before both the NAPI_THROW_ERROR return and the final
return result; (or use a small RAII/std::string holder for the copied string).