intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 67 insertions, 0 deletions

diff --git a/util/system/env.cpp b/util/system/env.cpp
new file mode 100644
index 00000000000..ead9b566a5f
--- /dev/null
+++ b/util/system/env.cpp
@@ -0,0 +1,67 @@
+#include "env.h"
+
+#include <util/generic/string.h>
+#include <util/generic/yexception.h>
+
+#ifdef _win_
+    #include <util/generic/vector.h>
+    #include "winint.h"
+#else
+    #include <cerrno>
+    #include <cstdlib>
+#endif
+
+/**
+ * On Windows there may be many copies of enviroment variables, there at least two known, one is
+ * manipulated by Win32 API, another by C runtime, so we must be consistent in the choice of
+ * functions used to manipulate them.
+ *
+ * Relevant links:
+ *  - http://bugs.python.org/issue16633
+ *  - https://a.yandex-team.ru/review/108892/details
+ */
+
+TString GetEnv(const TString& key, const TString& def) {
+#ifdef _win_
+    size_t len = GetEnvironmentVariableA(key.data(), nullptr, 0);
+
+    if (len == 0) {
+        if (GetLastError() == ERROR_ENVVAR_NOT_FOUND) {
+            return def;
+        }
+        return TString{};
+    }
+
+    TVector<char> buffer(len);
+    size_t bufferSize;
+    do {
+        bufferSize = buffer.size();
+        len = GetEnvironmentVariableA(key.data(), buffer.data(), static_cast<DWORD>(bufferSize));
+        if (len > bufferSize) {
+            buffer.resize(len);
+        }
+    } while (len > bufferSize);
+
+    return TString(buffer.data(), len);
+#else
+    const char* env = getenv(key.data());
+    return env ? TString(env) : def;
+#endif
+}
+
+void SetEnv(const TString& key, const TString& value) {
+    bool isOk = false;
+    int errorCode = 0;
+#ifdef _win_
+    isOk = SetEnvironmentVariable(key.data(), value.data());
+    if (!isOk) {
+        errorCode = GetLastError();
+    }
+#else
+    isOk = (0 == setenv(key.data(), value.data(), true /*replace*/));
+    if (!isOk) {
+        errorCode = errno;
+    }
+#endif
+    Y_ENSURE_EX(isOk, TSystemError() << "failed to SetEnv with error-code " << errorCode);
+}