msghdr.c: enhance representation of unprintable part of msg_control array

* msghdr.c (decode_msg_control): When msg_control array has an
unprintable part, print its address.

diff --git a/msghdr.c b/msghdr.c
index ed56849b43dd9e330be3a6fd4b8369fc6db4436e..bd15da00101a7c49374755b52183a4a33905b32a 100644 (file)
--- a/msghdr.c
+++ b/msghdr.c
@@ -265,20 +265,21 @@ print_cmsg_type_data(struct tcb *tcp, const int cmsg_level, const int cmsg_type,
 }
 
 static void
-decode_msg_control(struct tcb *tcp, unsigned long addr, size_t len)
+decode_msg_control(struct tcb *tcp, unsigned long addr, const size_t control_len)
 {
+       if (!control_len)
+               return;
+       tprints(", msg_control=");
+
        const size_t cmsg_size =
 #if SUPPORTED_PERSONALITIES > 1 && SIZEOF_LONG > 4
                (current_wordsize < sizeof(long)) ? sizeof(struct cmsghdr32) :
 #endif
                        sizeof(struct cmsghdr);
 
-       if (!len)
-               return;
-       tprints(", msg_control=");
-
-       char *buf = len < cmsg_size ? NULL : malloc(len);
-       if (!buf || umoven(tcp, addr, len, buf) < 0) {
+       size_t buf_len = control_len;
+       char *buf = buf_len < cmsg_size ? NULL : malloc(buf_len);
+       if (!buf || umoven(tcp, addr, buf_len, buf) < 0) {
                printaddr(addr);
                free(buf);
                return;
@@ -287,18 +288,18 @@ decode_msg_control(struct tcb *tcp, unsigned long addr, size_t len)
        union_cmsghdr u = { .ptr = buf };
 
        tprints("[");
-       while (len >= cmsg_size) {
-               size_t cmsg_len =
+       while (buf_len >= cmsg_size) {
+               const size_t cmsg_len =
 #if SUPPORTED_PERSONALITIES > 1 && SIZEOF_LONG > 4
                        (current_wordsize < sizeof(long)) ? u.cmsg32->cmsg_len :
 #endif
                                u.cmsg->cmsg_len;
-               int cmsg_level =
+               const int cmsg_level =
 #if SUPPORTED_PERSONALITIES > 1 && SIZEOF_LONG > 4
                        (current_wordsize < sizeof(long)) ? u.cmsg32->cmsg_level :
 #endif
                                u.cmsg->cmsg_level;
-               int cmsg_type =
+               const int cmsg_type =
 #if SUPPORTED_PERSONALITIES > 1 && SIZEOF_LONG > 4
                        (current_wordsize < sizeof(long)) ? u.cmsg32->cmsg_type :
 #endif
@@ -310,29 +311,30 @@ decode_msg_control(struct tcb *tcp, unsigned long addr, size_t len)
                printxval(socketlayers, cmsg_level, "SOL_???");
                tprints(", cmsg_type=");
 
-               if (cmsg_len > len)
-                       cmsg_len = len;
+               size_t len = cmsg_len > buf_len ? buf_len : cmsg_len;
 
                print_cmsg_type_data(tcp, cmsg_level, cmsg_type,
                                     (const void *) (u.ptr + cmsg_size),
-                                    cmsg_len > cmsg_size ? cmsg_len - cmsg_size: 0);
+                                    len > cmsg_size ? len - cmsg_size: 0);
                tprints("}");
 
-               if (cmsg_len < cmsg_size) {
-                       len -= cmsg_size;
+               if (len < cmsg_size) {
+                       buf_len -= cmsg_size;
                        break;
                }
-               cmsg_len = (cmsg_len + current_wordsize - 1) &
+               len = (cmsg_len + current_wordsize - 1) &
                        (size_t) ~(current_wordsize - 1);
-               if (cmsg_len >= len) {
-                       len = 0;
+               if (len >= buf_len) {
+                       buf_len = 0;
                        break;
                }
-               u.ptr += cmsg_len;
-               len -= cmsg_len;
+               u.ptr += len;
+               buf_len -= len;
+       }
+       if (buf_len) {
+               tprints(", ");
+               printaddr(addr + (control_len - buf_len));
        }
-       if (len)
-               tprints(", ...");
        tprints("]");
        free(buf);
 }