Fix bug in $LINENO implementation.

The location was set AFTER evaluating the argv array!  So the argv array
itself had an old value of $LINENO.

This is issue #113 reported by BatmanAoD.

Also: dump more parts of the stack.  Preparing to expose all this
information in a more principled way.

core/cmd_exec.py

@@ -630,30 +630,9 @@ def _Dispatch(self, node, fork_external):
 
     if node.tag == command_e.SimpleCommand:
       check_errexit = True
-      # PROBLEM: We want to log argv in 'xtrace' mode, but we may have already
-      # redirected here, which screws up logging.  For example, 'echo hi
-      # >/dev/null 2>&1'.  We want to evaluate argv and log it BEFORE applying
-      # redirects.
-
-      # Another problem:
-      # - tracing can be called concurrently from multiple processes, leading
-      # to overlap.  Maybe have a mode that creates a file per process.
-      # xtrace-proc
-      # - line numbers for every command would be very nice.  But then you have
-      # to print the filename too.
-
-      words = braces.BraceExpandWords(node.words)
-      argv = self.word_ev.EvalWordSequence(words)
-
-      # This is a very basic implementation for PS4='+$SOURCE_NAME:$LINENO:'
-
-      # TODO:
-      # - It should be a stack eventually.  So if there is an exception we can
-      # print the full stack trace.  Python has a list of frame objects, and
-      # each one has a location?
-      # - The API to get DebugInfo is overly long.
-      # - Maybe just do a simple thing like osh-o line-trace without any PS4?
 
+      # Find span_id for a basic implementation of $LINENO, e.g.
+      # PS4='+$SOURCE_NAME:$LINENO:'
       # NOTE: osh2oil uses node.more_env, but we don't need that.
       found = False
       if node.words:
@@ -664,13 +643,29 @@ def _Dispatch(self, node, fork_external):
         else:
           found = True
 
+      # TODO: Move this before word evaluation!
       if found:
         # NOTE: This is what we want to expose as variables for PS4.
         #ui.PrintFilenameAndLine(span_id, self.arena)
         self._SetSourceLocation(span_id)
       else:
         self.mem.SetSourceLocation('<unknown>', -1)
 
+      # PROBLEM: We want to log argv in 'xtrace' mode, but we may have already
+      # redirected here, which screws up logging.  For example, 'echo hi
+      # >/dev/null 2>&1'.  We want to evaluate argv and log it BEFORE applying
+      # redirects.
+
+      # Another problem:
+      # - tracing can be called concurrently from multiple processes, leading
+      # to overlap.  Maybe have a mode that creates a file per process.
+      # xtrace-proc
+      # - line numbers for every command would be very nice.  But then you have
+      # to print the filename too.
+
+      words = braces.BraceExpandWords(node.words)
+      argv = self.word_ev.EvalWordSequence(words)
+
       # This comes before evaluating env, in case there are problems evaluating
       # it.  We could trace the env separately?  Also trace unevaluated code
       # with set-o verbose?

core/dev.py

@@ -60,10 +60,11 @@ def MaybeCollect(self, ex):
     if not self.do_collect:  # Either we already did it, or there is no file
       return
 
-    # this is a string
-    ex.mem
-    self.func_name_stack = list(ex.mem.func_name_stack)
-    self.var_stack = state._FormatStack(ex.mem.var_stack)
+    # Copy stack
+    self.var_stack, self.argv_stack, self.func_name_stack = ex.mem.Dump()
+
+    # TODO: Also do functions, aliases, etc.
+
     self.do_collect = False
     self.collected = True
 
@@ -92,10 +93,13 @@ def MaybeDump(self, status):
       return
 
     d = {
-        #'var_stack': self.var_stack,
+        'var_stack': self.var_stack,
+        'argv_stack': self.argv_stack,
         'func_name_stack': self.func_name_stack,
     }
     path = os.path.join(self.crash_dump_dir, 'osh-crash-dump.json')
     with open(path, 'w') as f:
-      print(repr(d), file=f)
+      import json
+      json.dump(d, f, indent=2)
+      #print(repr(d), file=f)
     util.log('Wrote crash dump to %s', path)

core/state.py

@@ -291,6 +291,12 @@ def __init__(self, argv):
   def __repr__(self):
     return '<_ArgFrame %s %d at %x>' % (self.argv, self.num_shifted, id(self))
 
+  def Dump(self):
+    return {
+        'argv': self.argv,
+        'num_shifted': self.num_shifted,
+    }
+
   def GetArgNum(self, arg_num):
     index = self.num_shifted + arg_num - 1
     if index >= len(self.argv):
@@ -314,6 +320,16 @@ def __init__(self, readonly=False):
     self.vars = {}  # string -> runtime.cell
     self.readonly = readonly
 
+  def Dump(self):
+    vars_ = {}
+    for name, cell in self.vars.iteritems():
+      # NOTE: We're using the ASDL representation.  Need to dump it as JSON too.
+      vars_[name] = str(cell)
+    return {
+        'vars': vars_,
+        'readonly': self.readonly
+    }
+
   def __repr__(self):
     f = cStringIO.StringIO()
     f.write('<_StackFrame readonly:%s' % self.readonly)
@@ -409,6 +425,11 @@ def __repr__(self):
     parts.append('>')
     return '\n'.join(parts) + '\n'
 
+  def Dump(self):
+    var_stack = [frame.Dump() for frame in self.var_stack]
+    argv_stack = [frame.Dump() for frame in self.argv_stack]
+    return var_stack, argv_stack, list(self.func_name_stack)
+
   def _InitDefaults(self):
     # Default value; user may unset it.
     # $ echo -n "$IFS" | python -c 'import sys;print repr(sys.stdin.read())'

spec/introspect.test.sh

@@ -86,18 +86,20 @@ f  # line 9
 ## END
 
 #### $LINENO is the current line, not line of function call
+echo $LINENO  # first line
 g() {
-  argv.py $LINENO  # line 2
+  argv.py $LINENO  # line 3
 }
 f() {
-  argv.py $LINENO  # line 5
+  argv.py $LINENO  # line 6
   g
-  argv.py $LINENO  # line 7
+  argv.py $LINENO  # line 8
 }
 f
 ## STDOUT: 
-['5']
-['2']
-['7']
+1
+['6']
+['3']
+['8']
 ## END