bcc: Allow the runner to parse some arguments

src/lua/bcc/libbcc.lua

@@ -98,4 +98,4 @@ int perf_reader_fd(struct perf_reader *reader);
 void perf_reader_set_fd(struct perf_reader *reader, int fd);
 ]]
 
-return ffi.load(rawget(_G, "LIBBCC_SO_PATH") or "bcc")
+return ffi.load(os.getenv("LIBBCC_SO_PATH") or rawget(_G, "LIBBCC_SO_PATH") or "bcc")

src/lua/bcc/run.lua

@@ -14,11 +14,51 @@ See the License for the specific language governing permissions and
 limitations under the License.
 ]]
 
+local function print_usage()
+  io.stderr:write(
+  "usage: bcc-probe [[--so-path=PATH|--version|--quiet] --] path_to_script.lua [...]\n")
+  os.exit(1)
+end
+
+local function has_prefix(s,p)
+  return string.sub(s,1,string.len(p))==p
+end
+
+local function strip_prefix(s,p)
+  return string.sub(s, string.len(p) + 1)
+end
+
 return function()
+  local logging = true
+
+  while arg[1] and has_prefix(arg[1], "-") do
+    local k = table.remove(arg, 1) 
+
+    if k == "--" then
+      break
+    elseif has_prefix(k, "--so-path=") then
+      rawset(_G, "LIBBCC_SO_PATH", strip_prefix(k, "--so-path="))
+    elseif k == "-q" or k == "--quiet" then
+      logging = false
+    elseif k == "-v" or k == "--version" then
+      local jit = require("jit")
+      print(string.format("bcc-probe %s -- Running on %s (%s/%s)",
+        rawget(_G, "BCC_VERSION") or "HEAD",
+        jit.version, jit.os, jit.arch))
+      return true
+    else
+      print_usage()
+    end
+  end
+
+  local tracefile = table.remove(arg, 1)
+  if not tracefile then print_usage() end
+
   local BCC = require("bcc.init")
   local BPF = BCC.BPF
 
-  BPF.script_root(arg[1])
+  BPF.script_root(tracefile)
+  log.enabled = logging
 
   local utils = {
     argparse = require("bcc.vendor.argparse"),
@@ -26,7 +66,6 @@ return function()
     sym = BCC.sym
   }
 
-  local tracefile = table.remove(arg, 1)
   local command = dofile(tracefile)
   local res, err = pcall(command, BPF, utils)