8248905: [macos] symbolic links not properly resolved

Reviewed-by: herrick, asemenyuk

src/jdk.incubator.jpackage/macosx/native/common/MacSysInfo.cpp

@@ -23,12 +23,39 @@
  * questions.
  */
 
+#include <sys/stat.h>
+#include <unistd.h>
 #include <mach-o/dyld.h>
 #include "FileUtils.h"
 #include "ErrorHandling.h"
 
 namespace SysInfo {
 
+tstring getRealPath(const std::vector<char>& in) {
+    std::vector<char> out(PATH_MAX);
+
+    struct stat sb;
+    if (lstat(in.data(), &sb) == -1) {
+        JP_THROW(tstrings::any() << "lstat(" << in.data()
+                << ") failed. Error: " << lastCRTError());
+    }
+
+    // readlink() will fail if called on real path, so if we have real path, then just
+    // use it
+    if (!S_ISLNK(sb.st_mode)) {
+        return tstring(in.data(), in.size() - 1 /* don't count trailing '0' */);
+    }
+
+    // Get real path, since _NSGetExecutablePath can return symbolic link
+    ssize_t len = readlink(in.data(), out.data(), PATH_MAX);
+    if (len < 0) {
+        JP_THROW(tstrings::any() << "readlink(" << in.data()
+                << ") failed. Error: " << lastCRTError());
+    }
+
+    return tstring(out.data(), len);
+}
+
 tstring getProcessModulePath() {
     std::vector<char> buffer;
     uint32_t bufferSize = 0;
@@ -44,8 +71,9 @@ tstring getProcessModulePath() {
 
         buffer.resize(bufferSize);
     } while (true);
-    tstring reply = tstring(buffer.data(),
-            buffer.size() - 1 /* don't count trailing '0' */);
+
+    tstring reply = getRealPath(buffer);
+
     return FileUtils::toAbsolutePath(reply);
 }