From 2ace76ecb302e44164e8bf75e83a5fba1b484982 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Felix=20Geisend=C3=B6rfer?=
 <felix.geisendoerfer@datadoghq.com>
Date: Mon, 22 Mar 2021 15:04:11 +0100
Subject: [PATCH] add stackannotate.star

---
 delve/stackannotate.star | 152 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 152 insertions(+)
 create mode 100644 delve/stackannotate.star

diff --git a/delve/stackannotate.star b/delve/stackannotate.star
new file mode 100644
index 0000000..d5e38ec
--- /dev/null
+++ b/delve/stackannotate.star
@@ -0,0 +1,152 @@
+# TODO
+# Get stack lo from goroutine
+# Use the stacktrace API to unwind the stack and get annotations
+
+word_size = 8 # 64bit
+
+def get_reg(name):
+  for req in registers().Regs:
+    if req.Name == name:
+      return int(req.Value, 16)
+
+def read_word(addr):
+  v = 0
+  m = examine_memory(addr, word_size)
+  s = 1
+  for b in m.Mem:
+    v += b * s
+    s = s * 256
+  return v
+
+def hex(d, n = 0):
+  if d == 0:
+    return lpad("0", n, "0")
+
+  lookup = {10: "a", 11: "b", 12: "c", 13: "d", 14: "e", 15: "e", 16: "f"}
+  s = ""
+  while d > 0:
+    r = d % 16
+    d = d // 16
+    if r >= 10:
+      r = lookup[r]
+    else:
+      r = str(r)
+    s = r + s
+  return lpad(s, n, "0")
+
+def lpad(s, n, c = " "):
+  while len(s) < n:
+    s = c + s
+  return s
+
+def rpad(s, n, c = " "):
+  while len(s) < n:
+    s = s + c
+  return s
+
+def ascii_table(rows, align_right = {}):
+  widths = []
+  for row in rows:
+    for i, col in enumerate(row):
+      if len(widths) < i+1:
+        widths.append(0)
+      widths[i] = max(widths[i], len(col))
+
+  s = ""
+  for row in rows:
+    for i, col in enumerate(row):
+      width = widths[i]
+      if align_right.get(i, False):
+        col = lpad(col, width)
+      else:
+        col = rpad(col, width)
+      s += col + "  "
+    s += "\n"
+  return s
+
+def getg():
+  # TODO(fg) there is probably a better way to implement this.
+  g = raw_command("goroutine").State.SelectedGoroutine
+  for gp in eval(None, "runtime.allgs").Variable.Value:
+    if gp.goid == g.ID:
+      return gp
+
+def stack():
+  g = getg()
+  bp = get_reg("Rbp")
+  ip = get_reg("Rip")
+  sp = get_reg("Rsp")
+  regs = {"sp": sp, "bp": bp, "ip": ip}
+
+  addr_list = []
+  addr_dict = {}
+  offset = 0
+  while True:
+    addr = g.stack.hi+offset-word_size
+    addr_info = {
+      "addr": addr,
+      "val": read_word(addr),
+      "offset": offset,
+      "regs": [],
+      "note": [],
+      "func": None,
+      "arg": None,
+      "local": None,
+      "fp": False,
+    }
+    for (name, val) in regs.items():
+      if addr == val:
+        addr_info["regs"].append(name)
+        
+    addr_list.append(addr_info)
+    addr_dict[addr] = addr_info
+    offset -= word_size
+    if addr <= sp:
+      break
+  
+  for f in stacktrace(g.goid, 128, True).Locations:
+    fp_addr = g.stack.hi+f.FramePointerOffset
+    if fp_addr > 0 and len(addr_dict[fp_addr]["note"]) == 0:
+      addr_dict[fp_addr]["note"].append("frame pointer for "+f.Function.Name_)
+      pc_addr = fp_addr+word_size
+      pc = read_word(pc_addr)
+      ins = disassemble(None, pc, pc+1).Disassemble[0]
+      addr_dict[pc_addr]["note"].append("return addr to "+ins.Loc.Function.Name_)
+
+    for arg in f.Arguments:
+      addr_dict[arg.Addr]["note"].append("arg "+arg.Name+" "+arg.Type)
+    for local in f.Locals:
+      addr = local.Addr // 8 * 8
+      if addr_dict.get(addr):
+        addr_dict[addr]["note"].append("var "+local.Name+" "+local.Type)
+
+  return addr_list
+
+# stackannotate (alias sa) will print an annotated stack dump.
+def command_stackannotate():
+  rows = [["regs", "addr", "offset", "value", "explanation"]]
+  for addr_info in stack():
+    regs = ""
+    if len(addr_info["regs"]) > 0:
+      regs = ",".join(addr_info["regs"])+" -->"
+
+    note = "?"
+    if len(addr_info["note"]) > 0:
+      note = ", ".join(addr_info["note"])
+      
+    rows.append([
+      regs,
+      hex(addr_info["addr"]),
+      lpad(str(addr_info["offset"]), 6),
+      lpad(hex(addr_info["val"]), word_size*2+2),
+      note,
+    ])
+  print(ascii_table(rows))
+
+  #g = getg()
+  #for f in stacktrace(g.goid, 128, True).Locations:
+    #print(f)
+    #break
+
+def main():
+  dlv_command("config alias stackannotate sa")