Get the os info from repo ctx (#58)

buf/internal/toolchain.bzl

@@ -80,54 +80,19 @@ def _register_toolchains(repo, cmd):
         ),
     )
 
-# Copied from rules_go: https://github.com/bazelbuild/rules_go/blob/bd44f4242b46e73fb2a81fc87ea4b52173bde84e/go/private/sdk.bzl#L240
-#
-# NOTE: This doesn't check for windows/arm64
-# We can upgrade to repository_ctx.os.name and repository_ctx.os.arch once bazel 5.1 releases bazelbuild/bazel#14685
+# Copied from rules_go: https://github.com/bazelbuild/rules_go/blob/19ad920c6869a179d186a365d117ab82f38d0f3a/go/private/sdk.bzl#L517
 def _detect_host_platform(ctx):
-    if ctx.os.name == "linux":
-        goos, goarch = "linux", "amd64"
-        res = ctx.execute(["uname", "-p"])
-        if res.return_code == 0:
-            uname = res.stdout.strip()
-            if uname == "s390x":
-                goarch = "s390x"
-            elif uname == "i686":
-                goarch = "386"
-
-        # uname -p is not working on Aarch64 boards
-        # or for ppc64le on some distros
-        res = ctx.execute(["uname", "-m"])
-        if res.return_code == 0:
-            uname = res.stdout.strip()
-            if uname == "aarch64":
-                goarch = "arm64"
-            elif uname == "armv6l":
-                goarch = "arm"
-            elif uname == "armv7l":
-                goarch = "arm"
-            elif uname == "ppc64le":
-                goarch = "ppc64le"
-
-        # Default to amd64 when uname doesn't return a known value.
-
-    elif ctx.os.name == "mac os x":
-        goos, goarch = "darwin", "amd64"
-
-        res = ctx.execute(["uname", "-m"])
-        if res.return_code == 0:
-            uname = res.stdout.strip()
-            if uname == "arm64":
-                goarch = "arm64"
-
-        # Default to amd64 when uname doesn't return a known value.
-
-    elif ctx.os.name.startswith("windows"):
-        goos, goarch = "windows", "amd64"
-    elif ctx.os.name == "freebsd":
-        goos, goarch = "freebsd", "amd64"
-    else:
-        fail("Unsupported operating system: " + ctx.os.name)
+    goos = ctx.os.name
+    if goos == "mac os x":
+        goos = "darwin"
+    elif goos.startswith("windows"):
+        goos = "windows"
+
+    goarch = ctx.os.arch
+    if goarch == "aarch64":
+        goarch = "arm64"
+    elif goarch == "x86_64":
+        goarch = "amd64"
 
     return goos, goarch