cargo_from_buck: add the patch section to Cargo workspace and allow workspace appending to existing manifest

Summary:
Two changes here:
1. The `[patch.crates-io]` section of `third-party/rust/Cargo.toml` is being now copied over to workspaces generated by autocargo for OSS and in the runtime generated Cargo.toml file for cargo-fbcode builds. Without that some projects could be buildable in Buck internally, but not externally on GitHub due to missing patches.
2. If a `[workspace]` Cargo.toml file is being generated and there is already a generated Cargo.toml file in the same directory then instead of overriding that file the `[workspace]` (and `[patch]`) sections are appended to that Cargo.toml file.

Reviewed By: farnz

Differential Revision: D22023144

fbshipit-source-id: dec54491c36c2ee0ab29eefb722b3eceaef6ffe1

build/fbcode_builder/getdeps/builder.py

@@ -724,6 +724,9 @@ class OpenSSLBuilder(BuilderBase):
         elif self.build_opts.is_darwin():
             make = "make"
             args = ["darwin64-x86_64-cc"]
+        elif self.build_opts.is_linux():
+            make = "make"
+            args = ["linux-x86_64"]
         else:
             raise Exception("don't know how to build openssl for %r" % self.ctx)
 
@@ -955,6 +958,7 @@ class CargoBuilder(BuilderBase):
         self.add_openssl_to_env(env, install_dirs)
         # Enable using nightly features with stable compiler
         env["RUSTC_BOOTSTRAP"] = "1"
+        env["LIBZ_SYS_STATIC"] = "1"
         cmd = [
             "cargo",
             operation,
@@ -1052,7 +1056,9 @@ git-fetch-with-cli = true
         workspace_dir = self.workspace_dir()
         config = self._resolve_config()
         if config:
-            with open(os.path.join(workspace_dir, "Cargo.toml"), "a") as f:
+            with open(os.path.join(workspace_dir, "Cargo.toml"), "r+") as f:
+                manifest_content = f.read()
+                if "[package]" not in manifest_content:
                     # A fake manifest has to be crated to change the virtual
                     # manifest into a non-virtual. The virtual manifests are limited
                     # in many ways and the inability to define patches on them is
@@ -1069,6 +1075,8 @@ path = "/dev/null"
                             self.manifest.name
                         )
                     )
+                else:
+                    f.write("\n")
                 f.write(config)
 
     def _resolve_config(self):

build/fbcode_builder/manifests/mononoke

@@ -30,6 +30,7 @@ tools/rust/ossconfigs = .
 [shipit.strip]
 # strip all code unrelated to mononoke to prevent triggering unnecessary checks
 ^fbcode/eden/(?!mononoke|scm/lib/xdiff.*)/.*$
+^fbcode/eden/mononoke/Cargo\.toml$
 ^fbcode/eden/mononoke/(?!public_autocargo).+/Cargo\.toml$
 ^fbcode/configerator/structs/scm/mononoke/(?!public_autocargo).+/Cargo\.toml$
 

build/fbcode_builder/manifests/rust-shed

@@ -24,13 +24,9 @@ tools/rust/ossconfigs = .
 
 [dependencies]
 fbthrift
-
 # macOS doesn't expose the openssl api so we need to build our own.
-[dependencies.os=darwin]
-openssl
-
-# Windows doesn't have openssl, so we get to provide it
-[dependencies.os=windows]
+# Windows doesn't have openssl and Linux might contain an old version,
+# so we get to provide it
 openssl
 
 [dependencies.fb=on]