src: fix some recently introduced coverity issues

[mhdawson]

No description provided.

[mhdawson]

Coverity reports

src/dataqueue/queue.cc
public:
 788  static std::unique_ptr<FdEntry> Create(Environment* env, Local<Value> path) {
 789    // We're only going to create the FdEntry if the file exists.
    	1. var_decl: Declaring variable req without initializer.
 790    uv_fs_t req;
 791    auto cleanup = OnScopeLeave([&] { uv_fs_req_cleanup(&req); });
 792
 793    auto buf = std::make_shared<BufferValue>(env->isolate(), path);
    	2. Condition uv_fs_stat(NULL, &req, buf->out(), NULL) < 0, taking false branch.
 794    if (uv_fs_stat(nullptr, &req, buf->out(), nullptr) < 0) return nullptr;
 795
    	
CID 310020 (#1 of 1): Uninitialized scalar variable (UNINIT)
3. uninit_use_in_call: Using uninitialized value req.statbuf when calling make_unique.
 796    return std::make_unique<FdEntry>(
 797        env, std::move(buf), req.statbuf, 0, req.statbuf.st_size);
 798  }

static bool CheckModified(FdEntry* entry, int fd) {
    	1. var_decl: Declaring variable req without initializer.
 852    uv_fs_t req;
 853    auto cleanup = OnScopeLeave([&] { uv_fs_req_cleanup(&req); });
 854    // TODO(jasnell): Note the use of a sync fs call here is a bit unfortunate.
 855    // Doing this asynchronously creates a bit of a race condition tho, a file
 856    // could be unmodified when we call the operation but then by the time the
 857    // async callback is triggered to give us that answer the file is modified.
 858    // While such silliness is still possible here, the sync call at least makes
 859    // it less likely to hit the race.
    	2. Condition uv_fs_fstat(NULL, &req, fd, NULL) < 0, taking false branch.
 860    if (uv_fs_fstat(nullptr, &req, fd, nullptr) < 0) return true;
    	3. uninit_use_in_call: Using uninitialized value req.statbuf.st_size when calling is_modified. [[show details](https://scan9.scan.coverity.com/eventId=9011842-3&modelId=9011842-0&fileInstanceId=111313726&filePath=%2Fsrc%2Fdataqueue%2Fqueue.cc&fileStart=846&fileEnd=849)]
    	
CID 310018 (#1-2 of 2): Uninitialized scalar variable (UNINIT)
4. uninit_use_in_call: Using uninitialized value req.statbuf.st_mtim.tv_nsec when calling is_modified. [[show details](https://scan9.scan.coverity.com/eventId=9011842-6&modelId=9011842-1&fileInstanceId=111313726&filePath=%2Fsrc%2Fdataqueue%2Fqueue.cc&fileStart=846&fileEnd=849)]
 861    return entry->is_modified(req.statbuf);
 862  }

test/embedding/embedtest.cc

    } else {
   	5. var_decl: Declaring variable req without initializer.
 78      uv_fs_t req;
 79      int statret = uv_fs_stat(nullptr, &req, filename, nullptr);
   	6. Condition statret == 0, taking true branch.
 80      assert(statret == 0);
   	
CID 307777 (#1 of 1): Uninitialized scalar variable (UNINIT)
7. uninit_use: Using uninitialized value req.statbuf.st_size.
 81      size_t filesize = req.statbuf.st_size;
 82      uv_fs_req_cleanup(&req);
 83
 84      std::vector<char> vec(filesize);
 85      size_t read = fread(vec.data(), filesize, 1, fp);
 86      assert(read == 1);
 87      snapshot = node::EmbedderSnapshotData::FromBlob(vec);
 88    }

[mhdawson]

Not sure why it would have failed for coverage and not for my local make test linux run, will have to look at it tomorrow.

[richardlau]

Not sure why it would have failed for coverage and not for my local make test linux run, will have to look at it tomorrow.

My guess would be either compiler level and/or the --error-on-warn configure flag.

[mhdawson]

Updated to initialize in another way, lets see if the compilers are happy with it across platforms. Also compiled ok locally.

[mhdawson]

Requesting ci to check across all platforms

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/50588/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/50600/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/50601/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/50602/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/50604/

[mhdawson]

Landed in fe449a2