exe: add freebsd image_path implementation

exe.cpp

@@ -53,6 +53,33 @@ retry:
         return boost::filesystem::path (resolved.data (), resolved.data () + written);
 }
 
+#elif defined(PLATFORM_FREEBSD)
+
+#include "types.hpp"
+#include "except.hpp"
+
+#include <sys/types.h>
+#include <sys/sysctl.h>
+
+boost::filesystem::path
+util::image_path (void)
+{
+    int name[] = {
+        CTL_KERN,
+        KERN_PROC,
+        KERN_PROC_PATHNAME,
+        -1
+    };
+
+    char data[1024];
+    size_t len = sizeof (data);
+
+    auto err = sysctl (name, elems (name), data, &len, nullptr, 0);
+    errno_error::try_code (err);
+
+    return boost::filesystem::path (std::cbegin (data), std::cbegin (data) + len);
+}
+
 #elif defined(PLATFORM_WIN32)
 
 #include "except.hpp"