cdv: Find end of 'Last calls' section

This is a bug fix: the end of the 'Last calls' section is meant to be
an empty line, but in some situations this is not the case. This could
cause the complete dump to be read and stored as 'Last calls', causing
very unexpected behavior in the crashdump viewer.

This commit adds a check for ": ", which indicates that a new heading
has occured and thus the 'Last calls' section is completly read.

2 files changed, 64 insertions, 27 deletions

diff --git a/lib/observer/src/crashdump_viewer.erl b/lib/observer/src/crashdump_viewer.erl
index 9f68fee942..f7c44628cf 100644
--- a/lib/observer/src/crashdump_viewer.erl
+++ b/lib/observer/src/crashdump_viewer.erl
@@ -748,32 +748,6 @@ get_rest_of_line_1(Fd, <<>>, Acc) ->
 	eof -> {eof,lists:reverse(Acc)}
     end.
 
-get_lines_to_empty(Fd) ->
-    case get_chunk(Fd) of
-	{ok,Bin} ->
-	    get_lines_to_empty(Fd,Bin,[],[]);
-	eof ->
-	    []
-    end.
-get_lines_to_empty(Fd,<<$\n:8,Bin/binary>>,[],Lines) ->
-    put_chunk(Fd,Bin),
-    lists:reverse(Lines);
-get_lines_to_empty(Fd,<<$\n:8,Bin/binary>>,Acc,Lines) ->
-    get_lines_to_empty(Fd,Bin,[],[byte_list_to_string(lists:reverse(Acc))|Lines]);
-get_lines_to_empty(Fd,<<$\r:8,Bin/binary>>,Acc,Lines) ->
-    get_lines_to_empty(Fd,Bin,Acc,Lines);
-get_lines_to_empty(Fd,<<$\s:8,Bin/binary>>,[],Lines) ->
-    get_lines_to_empty(Fd,Bin,[],Lines);
-get_lines_to_empty(Fd,<<Char:8,Bin/binary>>,Acc,Lines) ->
-    get_lines_to_empty(Fd,Bin,[Char|Acc],Lines);
-get_lines_to_empty(Fd,<<>>,Acc,Lines) ->
-    case get_chunk(Fd) of
-	{ok,Bin} ->
-	    get_lines_to_empty(Fd,Bin,Acc,Lines);
-	eof ->
-	    lists:reverse(Lines,[byte_list_to_string(lists:reverse(Acc))])
-    end.
-
 split(Str) ->
     split($ ,Str,[]).    
 split(Char,Str) ->
@@ -1182,7 +1156,7 @@ all_procinfo(Fd,Fun,Proc,WS,LineHead) ->
 	    get_procinfo(Fd,Fun,Proc#proc{old_heap_end=bytes(Fd)},WS);
 	%% - END - moved from get_procinfo -
 	"Last calls" ->
-	    get_procinfo(Fd,Fun,Proc#proc{last_calls=get_lines_to_empty(Fd)},WS);
+	    get_procinfo(Fd,Fun,Proc#proc{last_calls=get_last_calls(Fd)},WS);
 	"Link list" ->
 	    {Links,Monitors,MonitoredBy} = parse_link_list(bytes(Fd),[],[],[]),
 	    get_procinfo(Fd,Fun,Proc#proc{links=Links,
@@ -1206,6 +1180,66 @@ all_procinfo(Fd,Fun,Proc,WS,LineHead) ->
 	    get_procinfo(Fd,Fun,Proc,WS)
     end.
 
+%% The end of the 'Last calls' section is meant to be an empty line,
+%% but in some cases this is not the case, so we also need to look for
+%% the next heading which currently (OTP-20.1) can be "Link list: ",
+%% "Dictionary: " or "Reductions: ". We do this by looking for ": "
+%% and when found, pushing the heading back into the saved chunk.
+%%
+%% Note that the 'Last calls' section is only present if the
+%% 'save_calls' process flag is set.
+get_last_calls(Fd) ->
+    case get_chunk(Fd) of
+	{ok,Bin} ->
+	    get_last_calls(Fd,Bin,[],[]);
+	eof ->
+	    []
+    end.
+get_last_calls(Fd,<<$\n:8,Bin/binary>>,[],Lines) ->
+    %% Empty line - we're done
+    put_chunk(Fd,Bin),
+    lists:reverse(Lines);
+get_last_calls(Fd,<<$::8>>,Acc,Lines) ->
+    case get_chunk(Fd) of
+	{ok,Bin} ->
+            %% Could be a colon followed by a space - see next function clause
+	    get_last_calls(Fd,<<$::8,Bin/binary>>,Acc,Lines);
+	eof ->
+            %% Truncated here - either we've got the next heading, or
+            %% it was truncated in a last call function, in which case
+            %% we note that it was truncated
+            case byte_list_to_string(lists:reverse(Acc)) of
+                NextHeading when NextHeading=="Link list";
+                                 NextHeading=="Dictionary";
+                                 NextHeading=="Reductions" ->
+                    put_chunk(Fd,list_to_binary(NextHeading++":")),
+                    lists:reverse(Lines);
+                LastCallFunction->
+                    lists:reverse(Lines,[LastCallFunction++":...(truncated)"])
+            end
+    end;
+get_last_calls(Fd,<<$\::8,$\s:8,Bin/binary>>,Acc,Lines) ->
+    %% ": " - means we have the next heading in Acc - save it back
+    %% into the chunk and return the lines we've found
+    HeadingBin = list_to_binary(lists:reverse(Acc,[$:])),
+    put_chunk(Fd,<<HeadingBin/binary,Bin/binary>>),
+    lists:reverse(Lines);
+get_last_calls(Fd,<<$\n:8,Bin/binary>>,Acc,Lines) ->
+    get_last_calls(Fd,Bin,[],[byte_list_to_string(lists:reverse(Acc))|Lines]);
+get_last_calls(Fd,<<$\r:8,Bin/binary>>,Acc,Lines) ->
+    get_last_calls(Fd,Bin,Acc,Lines);
+get_last_calls(Fd,<<$\s:8,Bin/binary>>,[],Lines) ->
+    get_last_calls(Fd,Bin,[],Lines);
+get_last_calls(Fd,<<Char:8,Bin/binary>>,Acc,Lines) ->
+    get_last_calls(Fd,Bin,[Char|Acc],Lines);
+get_last_calls(Fd,<<>>,Acc,Lines) ->
+    case get_chunk(Fd) of
+	{ok,Bin} ->
+	    get_last_calls(Fd,Bin,Acc,Lines);
+	eof ->
+	    lists:reverse(Lines,[byte_list_to_string(lists:reverse(Acc))])
+    end.
+
 parse_link_list([SB|Str],Links,Monitors,MonitoredBy) when SB==$[; SB==$] ->
     parse_link_list(Str,Links,Monitors,MonitoredBy);
 parse_link_list("#Port"++_=Str,Links,Monitors,MonitoredBy) ->
diff --git a/lib/observer/test/crashdump_viewer_SUITE.erl b/lib/observer/test/crashdump_viewer_SUITE.erl
index 77cf086d4b..4b0127bcfb 100644
--- a/lib/observer/test/crashdump_viewer_SUITE.erl
+++ b/lib/observer/test/crashdump_viewer_SUITE.erl
@@ -364,6 +364,9 @@ special(File,Procs) ->
 		crashdump_viewer:expand_binary({SOffset,SSize,SPos}),
 	    io:format("  expand binary ok",[]),
 
+	    #proc{last_calls=LastCalls} = ProcDetails,
+            true = length(LastCalls) =< 4,
+
 	    ['#CDVPid',X1,Y1,Z1] = proplists:get_value(ext_pid,Dict),
 	    ChannelStr1 = integer_to_list(X1),
 	    ExtPid =