1 files changed, 48 insertions, 4 deletions

diff --git a/libgo/go/plugin/plugin_dlopen.go b/libgo/go/plugin/plugin_dlopen.go
index c5b0a4721c5..3237598f06b 100644
--- a/libgo/go/plugin/plugin_dlopen.go
+++ b/libgo/go/plugin/plugin_dlopen.go
@@ -39,6 +39,47 @@ import (
 	"unsafe"
 )
 
+// avoid a dependency on strings
+func lastIndexByte(s string, c byte) int {
+	for i := len(s) - 1; i >= 0; i-- {
+		if s[i] == c {
+			return i
+		}
+	}
+	return -1
+}
+
+// pathToPrefix converts raw string to the prefix that will be used in the symbol
+// table. If modifying, modify the version in internal/obj/sym.go as well.
+func pathToPrefix(s string) string {
+	slash := lastIndexByte(s, '/')
+	// check for chars that need escaping
+	n := 0
+	for r := 0; r < len(s); r++ {
+		if c := s[r]; c <= ' ' || (c == '.' && r > slash) || c == '%' || c == '"' || c >= 0x7F {
+			n++
+		}
+	}
+
+	// quick exit
+	if n == 0 {
+		return s
+	}
+
+	// escape
+	const hex = "0123456789abcdef"
+	p := make([]byte, 0, len(s)+2*n)
+	for r := 0; r < len(s); r++ {
+		if c := s[r]; c <= ' ' || (c == '.' && r > slash) || c == '%' || c == '"' || c >= 0x7F {
+			p = append(p, '%', hex[c>>4], hex[c&0xF])
+		} else {
+			p = append(p, c)
+		}
+	}
+
+	return string(p)
+}
+
 func open(name string) (*Plugin, error) {
 	cPath := (*C.char)(C.malloc(C.PATH_MAX + 1))
 	defer C.free(unsafe.Pointer(cPath))
@@ -82,7 +123,6 @@ func open(name string) (*Plugin, error) {
 	p := &Plugin{
 		pluginpath: pluginpath,
 		loaded:     make(chan struct{}),
-		syms:       syms,
 	}
 	plugins[filepath] = p
 	pluginsMu.Unlock()
@@ -97,14 +137,14 @@ func open(name string) (*Plugin, error) {
 	}
 
 	// Fill out the value of each plugin symbol.
+	updatedSyms := map[string]interface{}{}
 	for symName, sym := range syms {
 		isFunc := symName[0] == '.'
 		if isFunc {
 			delete(syms, symName)
 			symName = symName[1:]
 		}
-
-		cname := C.CString(pluginpath + "." + symName)
+		cname := C.CString(pathToPrefix(pluginpath) + "." + symName)
 		p := C.pluginLookup(h, cname, &cErr)
 		C.free(unsafe.Pointer(cname))
 		if p == nil {
@@ -116,8 +156,12 @@ func open(name string) (*Plugin, error) {
 		} else {
 			(*valp)[1] = p
 		}
-		syms[symName] = sym
+		// we can't add to syms during iteration as we'll end up processing
+		// some symbols twice with the inability to tell if the symbol is a function
+		updatedSyms[symName] = sym
 	}
+	p.syms = updatedSyms
+
 	close(p.loaded)
 	return p, nil
 }