Compute variable link header if we are computing the link payload.

[libpcap] / gencode.c

diff --git a/gencode.c b/gencode.c
index 6f03326c73aee59c0632986f780299dc36c312c7..ac03afeb139f067d16cfb9ff6165ff9459cfe344 100644 (file)
--- a/gencode.c
+++ b/gencode.c
@@ -2574,6 +2574,15 @@ insert_compute_vloffsets(b)
 {
        struct slist *s;
 
+       /* There is an implicit dependency between the link
+        * payload and link header since the payload computation
+        * includes the variable part of the header. Therefore,
+        * if nobody else has allocated a register for the link
+        * header and we need it, do it now. */
+       if (off_linkpl.reg != -1 && off_linkhdr.is_variable &&
+           off_linkhdr.reg == -1)
+               off_linkhdr.reg = alloc_reg();
+
        /*
         * For link-layer types that have a variable-length header
         * preceding the link-layer header, generate code to load