Add dom_sid_string_buf

This prints into a fixed buffer with the same overflow semantics as snprintf
has: Return required string length, regardless of whether it fit or not.

diff --git a/libcli/security/dom_sid.c b/libcli/security/dom_sid.c
index 217d7bb8d4fb9525eedc352b7223cdb7f45dd1af..809f20ce263d4b3e6c28ad456858b515ff016e69 100644 (file)
--- a/libcli/security/dom_sid.c
+++ b/libcli/security/dom_sid.c
@@ -347,34 +347,59 @@ bool dom_sid_in_domain(const struct dom_sid *domain_sid,
 }
 
 /*
-  convert a dom_sid to a string
+  Convert a dom_sid to a string, printing into a buffer. Return the
+  string length. If it overflows, return the string length that would
+  result (buflen needs to be +1 for the terminating 0).
 */
-char *dom_sid_string(TALLOC_CTX *mem_ctx, const struct dom_sid *sid)
+int dom_sid_string_buf(const struct dom_sid *sid, char *buf, int buflen)
 {
-       int i, ofs, maxlen;
+       int i, ofs;
        uint32_t ia;
-       char *ret;
 
        if (!sid) {
-               return talloc_strdup(mem_ctx, "(NULL SID)");
+               strlcpy(buf, "(NULL SID)", buflen);
+               return 10;      /* strlen("(NULL SID)") */
        }
 
-       maxlen = sid->num_auths * 11 + 25;
-       ret = talloc_array(mem_ctx, char, maxlen);
-       if (!ret) return talloc_strdup(mem_ctx, "(SID ERR)");
-
        ia = (sid->id_auth[5]) +
                (sid->id_auth[4] << 8 ) +
                (sid->id_auth[3] << 16) +
                (sid->id_auth[2] << 24);
 
-       ofs = snprintf(ret, maxlen, "S-%u-%lu",
+       ofs = snprintf(buf, buflen, "S-%u-%lu",
                       (unsigned int)sid->sid_rev_num, (unsigned long)ia);
 
        for (i = 0; i < sid->num_auths; i++) {
-               ofs += snprintf(ret + ofs, maxlen - ofs, "-%lu",
+               ofs += snprintf(buf + ofs, MAX(buflen - ofs, 0), "-%lu",
                                (unsigned long)sid->sub_auths[i]);
        }
+       return ofs;
+}
 
-       return ret;
+/*
+  convert a dom_sid to a string
+*/
+char *dom_sid_string(TALLOC_CTX *mem_ctx, const struct dom_sid *sid)
+{
+       char buf[DOM_SID_STR_BUFLEN];
+       char *result;
+       int len;
+
+       len = dom_sid_string_buf(sid, buf, sizeof(buf));
+
+       if (len+1 > sizeof(buf)) {
+               return talloc_strdup(mem_ctx, "(SID ERR)");
+       }
+
+       /*
+        * Avoid calling strlen (via talloc_strdup), we already have
+        * the length
+        */
+       result = (char *)talloc_memdup(mem_ctx, buf, len+1);
+
+       /*
+        * beautify the talloc_report output
+        */
+       talloc_set_name_const(result, result);
+       return result;
 }

diff --git a/libcli/security/dom_sid.h b/libcli/security/dom_sid.h
index c65471bf90fa7a5e3ef56c20f39a6d69035a0fae..3493fab83864c426a029e9e6739cd275caa09513 100644 (file)
--- a/libcli/security/dom_sid.h
+++ b/libcli/security/dom_sid.h
@@ -71,6 +71,9 @@ NTSTATUS dom_sid_split_rid(TALLOC_CTX *mem_ctx, const struct dom_sid *sid,
                           struct dom_sid **domain, uint32_t *rid);
 bool dom_sid_in_domain(const struct dom_sid *domain_sid,
                       const struct dom_sid *sid);
+
+#define DOM_SID_STR_BUFLEN (15*11+25)
+int dom_sid_string_buf(const struct dom_sid *sid, char *buf, int buflen);
 char *dom_sid_string(TALLOC_CTX *mem_ctx, const struct dom_sid *sid);