* src/process.c (Fnetwork_interface_list): Correctly determine buffer

size.

1 files changed, 41 insertions, 22 deletions

diff --git a/src/process.c b/src/process.c
index 71a6f91a7bb..2125478907f 100644
--- a/src/process.c
+++ b/src/process.c
@@ -3580,38 +3580,57 @@ format; see the description of ADDRESS in `make-network-process'.  */)
   if (s < 0)
     return Qnil;
 
- again:
-  buf_size *= 2;
-  buf = xrealloc(buf, buf_size);
-  if (!buf)
+  ifconf.ifc_buf = 0;
+  ifconf.ifc_len = 0;
+  if (ioctl (s, SIOCGIFCONF, &ifconf) == 0 && ifconf.ifc_len > 0)
     {
-      close (s);
-      return Qnil;
+      ifconf.ifc_buf = xmalloc (ifconf.ifc_len);
+      if (ifconf.ifc_buf == NULL)
+        {
+          close (s);
+          return Qnil;
+        }
+      if (ioctl (s, SIOCGIFCONF, &ifconf))
+        {
+          close (s);
+          xfree (ifconf.ifc_buf);
+          return Qnil;
+        }
     }
+  else
+    do
+      {
+        buf_size *= 2;
+        buf = xrealloc (buf, buf_size);
+        if (!buf)
+          {
+            close (s);
+            return Qnil;
+          }
 
-  ifconf.ifc_buf = buf;
-  if (ioctl (s, SIOCGIFCONF, &ifconf))
-    {
-      close (s);
-      xfree (buf);
-      return Qnil;
-    }
+        ifconf.ifc_buf = buf;
+        ifconf.ifc_len = buf_size;
+        if (ioctl (s, SIOCGIFCONF, &ifconf))
+          {
+            close (s);
+            xfree (buf);
+            return Qnil;
+          }
 
-  if (ifconf.ifc_len == buf_size)
-    goto again;
+      }
+    while (ifconf.ifc_len == buf_size);
 
   close (s);
 
   res = Qnil;
-  for (ifreq = ifconf.ifc_req;
-       (char *) ifreq < (char *) (ifconf.ifc_req) + ifconf.ifc_len;
-       )
+  ifreq = ifconf.ifc_req;
+  while ((char *) ifreq < (char *) ifconf.ifc_req + ifconf.ifc_len)
     {
       struct ifreq *ifq = ifreq;
 #ifdef HAVE_STRUCT_IFREQ_IFR_ADDR_SA_LEN
-#define SIZEOF_IFREQ(sif)                                               \
-      ((sif)->ifr_addr.sa_len < sizeof(struct sockaddr) ?               \
-       sizeof((*sif)) : sizeof ((sif)->ifr_name) + sif->ifr_addr.sa_len)
+#define SIZEOF_IFREQ(sif)                                               \
+      ((sif)->ifr_addr.sa_len < sizeof (struct sockaddr)                \
+       ? sizeof (*(sif)) : sizeof ((sif)->ifr_name) + (sif)->ifr_addr.sa_len)
 
       int len = SIZEOF_IFREQ (ifq);
 #else
@@ -3619,7 +3638,7 @@ format; see the description of ADDRESS in `make-network-process'.  */)
 #endif
       char namebuf[sizeof (ifq->ifr_name) + 1];
       i += len;
-      ifreq = (struct ifreq*) ((char*) ifreq + len);
+      ifreq = (struct ifreq *) ((char *) ifreq + len);
 
       if (ifq->ifr_addr.sa_family != AF_INET)
         continue;