namspace: format NW_HPATH debug output safely

Stop logging NW_HPATH path component buffers with %s in MAPDEBUG output.

The namespace path buffer is not a NUL-terminated C string. It contains a list
of length-prefixed components, so printing it directly can over-read into
following packet or process memory and pollute unrelated client/test output.

Add small debug formatters for complete NW_HPATH component lists and individual
components, and use them in build_base/add_hpath_to_nwpath debug messages.

No protocol behavior change.

src/namspace.c

@@ -508,6 +508,77 @@ static void rmdir_from_structures(char *unname, DIR_BASE_ENTRY *dbe)
 }
 
 
+
+static char *debug_hpath_components(NW_HPATH *nwp, uint8 *pp_pathes)
+/*
+ * Format NW_HPATH path components for debug output.
+ *
+ * The on-wire path buffer is not a NUL-terminated C string; it is a list of
+ * length-prefixed components.  Logging it with %s can over-read into following
+ * packet memory and pollute unrelated client/test output files.
+ */
+{
+  char buf[768];
+  int pos = 0;
+  int k;
+
+  if (!nwp || !pp_pathes || !nwp->components)
+    return(gettmpstr("", 0, 0));
+
+  for (k = 0; k < nwp->components && pos < (int)sizeof(buf) - 1; k++) {
+    int len = (int)*(pp_pathes++);
+    int i;
+
+    if (k && pos < (int)sizeof(buf) - 1)
+      buf[pos++] = '/';
+
+    if (!len) {
+      if (pos < (int)sizeof(buf) - 1) buf[pos++] = '.';
+      if (pos < (int)sizeof(buf) - 1) buf[pos++] = '.';
+      continue;
+    }
+
+    for (i = 0; i < len && pos < (int)sizeof(buf) - 1; i++) {
+      unsigned char c = pp_pathes[i];
+      if (c < 32 || c == 127 || c == '`')
+        c = '?';
+      buf[pos++] = (char)c;
+    }
+    pp_pathes += len;
+  }
+
+  if (k < nwp->components && pos < (int)sizeof(buf) - 1) {
+    buf[pos++] = '/';
+    if (pos < (int)sizeof(buf) - 1) buf[pos++] = '.';
+    if (pos < (int)sizeof(buf) - 1) buf[pos++] = '.';
+    if (pos < (int)sizeof(buf) - 1) buf[pos++] = '.';
+  }
+
+  buf[pos] = '\0';
+  return(gettmpstr(buf, pos, 0));
+}
+
+static char *debug_hpath_component(uint8 *path, int len)
+/* Format one length-prefixed NW_HPATH component for debug output. */
+{
+  char buf[260];
+  int i;
+  int pos = 0;
+
+  if (!path || len <= 0)
+    return(gettmpstr("", 0, 0));
+
+  for (i = 0; i < len && pos < (int)sizeof(buf) - 1; i++) {
+    unsigned char c = path[i];
+    if (c < 32 || c == 127 || c == '`')
+      c = '?';
+    buf[pos++] = (char)c;
+  }
+
+  buf[pos] = '\0';
+  return(gettmpstr(buf, pos, 0));
+}
+
 static int get_comp_pathes_size(NW_HPATH *nwp, uint8 *pp_pathes)
 /* returns size of path components in bytes */
 {
@@ -545,7 +616,7 @@ static int add_hpath_to_nwpath(N_NW_PATH *nwpath,
     pp_pathes+=len;
     
     XDPRINTF((5, 0, "component %2d, len=%3d, path='%s'",
-                    k, len, gettmpstr(p, len, 0) ));
+                    k, len, debug_hpath_component(p, len) ));
     
     if (!len) {  /* this means '..' ! */
       if (pp > nwpath->path) {