Rename libps to libpsnative

And impl to native

native/getusername.cpp

@@ -0,0 +1,77 @@
+//! @file getusername.cpp
+//! @author Andrew Schwartzmeyer <andschwa@microsoft.com>
+//! @brief Implements GetUserName for Linux
+
+#include <errno.h>
+#include <langinfo.h>
+#include <locale.h>
+#include <unistd.h>
+#include <string>
+#include <unicode/unistr.h>
+#include <pwd.h>
+#include "getusername.h"
+
+//! @brief GetUserName retrieves the name of the user associated with
+//! the current thread.
+//!
+//! @exception errno Passes these errors via errno to GetLastError:
+//! - ERROR_INVALID_PARAMETER: parameter is not valid
+//! - ERROR_BAD_ENVIRONMENT: locale is not UTF-8
+//! - ERROR_NO_SUCH_USER: there was no corresponding user
+//! - ERROR_GEN_FAILURE: sysconf() or getpwuid() failed for unknown reasons
+//!
+//! @retval username as UTF-8 string, or null if unsuccessful
+char* GetUserName()
+{
+    errno = 0;
+
+    // Select locale from environment
+    setlocale(LC_ALL, "");
+    // Check that locale is UTF-8
+    if (nl_langinfo(CODESET) != std::string("UTF-8"))
+    {
+        errno = ERROR_BAD_ENVIRONMENT;
+        return NULL;
+    }
+
+    struct passwd pwd;
+    struct passwd* result;
+    // gets the initial suggested size for buf
+    int buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+    if (buflen == -1)
+    {
+        errno = ERROR_GEN_FAILURE;
+        return FALSE;
+    }
+    std::string buf(buflen, 0);
+
+    // geteuid() gets the effective user ID of the calling process, and is always successful
+    int ret = getpwuid_r(geteuid(), &pwd, &buf[0], buflen, &result);
+
+    // Map errno to Win32 Error Codes
+    if (ret)
+    {
+        switch (errno)
+        {
+        case ENOENT:
+        case ESRCH:
+        case EBADF:
+        case EPERM:
+            errno = ERROR_NO_SUCH_USER;
+            break;
+        default:
+            errno = ERROR_GEN_FAILURE;
+        }
+        return NULL;
+    }
+
+    // Check if no user matched
+    if (result == NULL)
+    {
+        errno = ERROR_NO_SUCH_USER;
+        return NULL;
+    }
+
+    // allocate copy on heap so CLR can free it
+    return strdup(result->pw_name);
+}