Automatically generate link_name attributes in boringssl.rs

[joshlf]

Currently, our bindgen.sh script does not automatically generate the link_name attributes that we need in order to perform symbol renaming as described in boringssl/README.md. Instead, we do this manually, which is annoying.

We should do this automatically. One good option would be to implement the bindgen feature described in this issue: https://github.com/rust-lang-nursery/rust-bindgen/issues/1375. It could also be good to have a simpler workaround until that feature is implemented.

[inejge]

Can a workaround be a postprocessing script called from bindgen.sh? I tested the following on a copy of boringssl.rs with #[link name...] lines removed and got the original file back. I can open a PR if the script is good enough.

diff --git a/boringssl/bindgen.sh b/boringssl/bindgen.sh
index 564423c..e52c289 100755
--- a/boringssl/bindgen.sh
+++ b/boringssl/bindgen.sh
@@ -143,3 +143,16 @@ cat boringssl.rs >> "$TMP"

 mv "$TMP" boringssl.rs
 rustfmt boringssl.rs
+
+awk -v "vers=${MAJOR}_${MINOR}_${PATCH}_" '
+/extern "C" {/ {
+    print
+    getline
+    if ($0 ~ "pub fn") {
+        fn = $3
+        sub("[(].*", "", fn)
+        print "    #[link_name = \"__RUST_MUNDANE_" vers fn "\"]"
+    }
+}
+{ print }' boringssl.rs >> "$TMP"
+mv "$TMP" boringssl.rs

[joshlf]

Yeah, that looks awesome! Check out CONTRIBUTING.md to see how to submit it. Would it be possible to also count the number of link_name attributes emitted by the script? We could make sure it matches the number of functions we expect in the script as a sanity check. I'm always a little wary of using simple syntax analysis on code because it can be so error-prone.

[joshlf]

Btw if you want to work on this, it'll probably be easier for you if you work on top of this PR (which is in turn on top of this PR).

[inejge]

Uploaded, let's hope I haven't messed up anything in the procedure.

[joshlf]

Looks like you got all of the Gerrit magic right; well done! Faster than it took me to figure out for sure.