Fix translations with DGettext (and other D... func) when the domain name is empty.

According to the doc, NULL allow to use the current domain as fallback:
http://www.gnu.org/software/libc/manual/html_node/Translation-with-gettext.html
If the domainname parameter is the null pointer the dgettext function is exactly equivalent to gettext since the default value for the domain name is used.

1 files changed, 12 insertions, 4 deletions

diff --git a/gettext.go b/gettext.go
index 352c857..624ab34 100644
--- a/gettext.go
+++ b/gettext.go
@@ -120,7 +120,7 @@ func Gettext(msgid string) string {
 
 // Like Gettext(), but looking up the message in the specified domain.
 func DGettext(domain string, msgid string) string {
-	cdomain := C.CString(domain)
+	cdomain := cDomainName(domain)
 	cmsgid := C.CString(msgid)
 
 	res := C.GoString(C.dgettext(cdomain, cmsgid))
@@ -133,7 +133,7 @@ func DGettext(domain string, msgid string) string {
 // Like Gettext(), but looking up the message in the specified domain and
 // category.
 func DCGettext(domain string, msgid string, category uint) string {
-	cdomain := C.CString(domain)
+	cdomain := cDomainName(domain)
 	cmsgid := C.CString(msgid)
 
 	res := C.GoString(C.dcgettext(cdomain, cmsgid, C.int(category)))
@@ -177,7 +177,7 @@ func Sprintf(format string, a ...interface{}) string {
 
 // Like NGettext(), but looking up the message in the specified domain.
 func DNGettext(domainname string, msgid string, msgid_plural string, n uint64) string {
-	cdomainname := C.CString(domainname)
+	cdomainname := cDomainName(domainname)
 	cmsgid := C.CString(msgid)
 	cmsgid_plural := C.CString(msgid_plural)
 
@@ -193,7 +193,7 @@ func DNGettext(domainname string, msgid string, msgid_plural string, n uint64) s
 // Like NGettext(), but looking up the message in the specified domain and
 // category.
 func DCNGettext(domainname string, msgid string, msgid_plural string, n uint64, category uint) string {
-	cdomainname := C.CString(domainname)
+	cdomainname := cDomainName(domainname)
 	cmsgid := C.CString(msgid)
 	cmsgid_plural := C.CString(msgid_plural)
 
@@ -205,3 +205,11 @@ func DCNGettext(domainname string, msgid string, msgid_plural string, n uint64,
 
 	return res
 }
+
+// cDomainName returns the domain name CString that can be nil.
+func cDomainName(domain string) *C.char {
+	if domain == "" {
+		return nil
+	}
+	return C.CString(domain)
+}