librpc:ndr: Don’t duplicate strings needlessly

If the source string doesn’t need to be converted, there’s no reason for
it to be talloc‐allocated.

Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>

diff --git a/librpc/ndr/ndr_string.c b/librpc/ndr/ndr_string.c
index 5e8eb895bf7332f051b3a9bb9dd9843df509a997..ae30c4ac2e745fe733eee96a19d6ea9542b34888 100644 (file)
--- a/librpc/ndr/ndr_string.c
+++ b/librpc/ndr/ndr_string.c
@@ -255,7 +255,9 @@ _PUBLIC_ enum ndr_err_code ndr_push_string(struct ndr_push *ndr, ndr_flags_type
        int do_convert = 1, chset = CH_UTF16;
        libndr_flags flags = ndr->flags;
        unsigned byte_mul = 2;
-       uint8_t *dest = NULL;
+       const uint8_t *dest = NULL;
+       uint8_t *dest_to_free = NULL;
+       static const uint8_t null_byte[] = {0};
        enum ndr_err_code ndr_err = NDR_ERR_SUCCESS;
 
        if (!(ndr_flags & NDR_SCALARS)) {
@@ -307,27 +309,21 @@ _PUBLIC_ enum ndr_err_code ndr_push_string(struct ndr_push *ndr, ndr_flags_type
 
        if (s_len == 0) {
                d_len = 0;
-               dest = (uint8_t *)talloc_strdup(ndr, "");
-               if (dest == NULL) {
-                       return ndr_push_error(ndr, NDR_ERR_ALLOC,
-                                             "Failed to talloc_strdup() in ndr_string_push()");
-               }
+               dest = null_byte;
        } else if (!do_convert) {
                d_len = s_len;
-               dest = (uint8_t *)talloc_strndup(ndr, s, s_len);
-               if (dest == NULL) {
-                       return ndr_push_error(ndr, NDR_ERR_ALLOC,
-                                             "Failed to talloc_strndup() in ndr_string_push()");
-               }
+               dest = (const uint8_t *)s;
        } else {
                bool ok;
 
                ok = convert_string_talloc(ndr, CH_UNIX, chset, s, s_len,
-                                          &dest, &d_len);
+                                          &dest_to_free, &d_len);
                if (!ok) {
                        return ndr_push_error(ndr, NDR_ERR_CHARCNV,
                                              "Bad character push conversion with flags 0x%"PRI_LIBNDR_FLAGS, flags);
                }
+
+               dest = dest_to_free;
        }
 
        if (flags & LIBNDR_FLAG_STR_BYTESIZE) {
@@ -423,7 +419,7 @@ _PUBLIC_ enum ndr_err_code ndr_push_string(struct ndr_push *ndr, ndr_flags_type
        }
 
 out:
-       talloc_free(dest);
+       talloc_free(dest_to_free);
        return ndr_err;
 }