1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
|
%
% (c) The University of Glasgow 2006
% (c) The GRASP Project, Glasgow University, 1992-2000
%
Defines basic funtions for printing error messages.
It's hard to put these functions anywhere else without causing
some unnecessary loops in the module dependency graph.
\begin{code}
module Panic
(
GhcException(..), showGhcException, throwGhcException, handleGhcException,
ghcError, progName,
pgmError,
panic, panicFastInt, assertPanic, trace,
Exception.Exception(..), showException, try, tryMost, throwTo,
installSignalHandlers, interruptTargetThread
) where
#include "HsVersions.h"
import Config
import FastTypes
#ifndef mingw32_HOST_OS
import System.Posix.Signals
#endif /* mingw32_HOST_OS */
#if defined(mingw32_HOST_OS)
import GHC.ConsoleHandler
#endif
import Exception
import Control.Concurrent ( MVar, ThreadId, withMVar, newMVar )
import Data.Dynamic
import Debug.Trace ( trace )
import System.IO.Unsafe ( unsafePerformIO )
import System.Exit
import System.Environment
\end{code}
GHC's own exception type.
\begin{code}
ghcError :: GhcException -> a
ghcError e = Exception.throw e
-- error messages all take the form
--
-- <location>: <error>
--
-- If the location is on the command line, or in GHC itself, then
-- <location>="ghc". All of the error types below correspond to
-- a <location> of "ghc", except for ProgramError (where the string is
-- assumed to contain a location already, so we don't print one).
data GhcException
= PhaseFailed String -- name of phase
ExitCode -- an external phase (eg. cpp) failed
| Interrupted -- someone pressed ^C
| UsageError String -- prints the short usage msg after the error
| CmdLineError String -- cmdline prob, but doesn't print usage
| Panic String -- the `impossible' happened
| InstallationError String -- an installation problem
| ProgramError String -- error in the user's code, probably
deriving Eq
instance Exception GhcException
progName :: String
progName = unsafePerformIO (getProgName)
{-# NOINLINE progName #-}
short_usage :: String
short_usage = "Usage: For basic information, try the `--help' option."
showException :: Exception e => e -> String
showException = show
instance Show GhcException where
showsPrec _ e@(ProgramError _) = showGhcException e
showsPrec _ e@(CmdLineError _) = showString "<command line>: " . showGhcException e
showsPrec _ e = showString progName . showString ": " . showGhcException e
showGhcException :: GhcException -> String -> String
showGhcException (UsageError str)
= showString str . showChar '\n' . showString short_usage
showGhcException (PhaseFailed phase code)
= showString "phase `" . showString phase .
showString "' failed (exitcode = " . shows int_code .
showString ")"
where
int_code =
case code of
ExitSuccess -> (0::Int)
ExitFailure x -> x
showGhcException (CmdLineError str)
= showString str
showGhcException (ProgramError str)
= showString str
showGhcException (InstallationError str)
= showString str
showGhcException (Interrupted)
= showString "interrupted"
showGhcException (Panic s)
= showString ("panic! (the 'impossible' happened)\n"
++ " (GHC version " ++ cProjectVersion ++ " for " ++ TargetPlatform_NAME ++ "):\n\t"
++ s ++ "\n\n"
++ "Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug\n")
throwGhcException :: GhcException -> a
throwGhcException = Exception.throw
handleGhcException :: ExceptionMonad m => (GhcException -> m a) -> m a -> m a
handleGhcException = ghandle
ghcExceptionTc :: TyCon
ghcExceptionTc = mkTyCon "GhcException"
{-# NOINLINE ghcExceptionTc #-}
instance Typeable GhcException where
typeOf _ = mkTyConApp ghcExceptionTc []
\end{code}
Panics and asserts.
\begin{code}
panic, pgmError :: String -> a
panic x = throwGhcException (Panic x)
pgmError x = throwGhcException (ProgramError x)
-- #-versions because panic can't return an unboxed int, and that's
-- what TAG_ is with GHC at the moment. Ugh. (Simon)
-- No, man -- Too Beautiful! (Will)
panicFastInt :: String -> FastInt
panicFastInt s = case (panic s) of () -> _ILIT(0)
assertPanic :: String -> Int -> a
assertPanic file line =
Exception.throw (Exception.AssertionFailed
("ASSERT failed! file " ++ file ++ ", line " ++ show line))
\end{code}
\begin{code}
-- | tryMost is like try, but passes through Interrupted and Panic
-- exceptions. Used when we want soft failures when reading interface
-- files, for example.
-- XXX I'm not entirely sure if this is catching what we really want to catch
tryMost :: IO a -> IO (Either SomeException a)
tryMost action = do r <- try action
case r of
Left se ->
case fromException se of
-- Some GhcException's we rethrow,
Just Interrupted -> throwIO se
Just (Panic _) -> throwIO se
-- others we return
Just _ -> return (Left se)
Nothing ->
case fromException se of
-- All IOExceptions are returned
Just (_ :: IOException) ->
return (Left se)
-- Anything else is rethrown
Nothing -> throwIO se
Right v -> return (Right v)
\end{code}
Standard signal handlers for catching ^C, which just throw an
exception in the target thread. The current target thread is
the thread at the head of the list in the MVar passed to
installSignalHandlers.
\begin{code}
installSignalHandlers :: IO ()
installSignalHandlers = do
let
interrupt_exn = (toException Interrupted)
interrupt = do
withMVar interruptTargetThread $ \targets ->
case targets of
[] -> return ()
(thread:_) -> throwTo thread interrupt_exn
--
#if !defined(mingw32_HOST_OS)
_ <- installHandler sigQUIT (Catch interrupt) Nothing
_ <- installHandler sigINT (Catch interrupt) Nothing
return ()
#else
-- GHC 6.3+ has support for console events on Windows
-- NOTE: running GHCi under a bash shell for some reason requires
-- you to press Ctrl-Break rather than Ctrl-C to provoke
-- an interrupt. Ctrl-C is getting blocked somewhere, I don't know
-- why --SDM 17/12/2004
let sig_handler ControlC = interrupt
sig_handler Break = interrupt
sig_handler _ = return ()
_ <- installHandler (Catch sig_handler)
return ()
#endif
{-# NOINLINE interruptTargetThread #-}
interruptTargetThread :: MVar [ThreadId]
interruptTargetThread = unsafePerformIO (newMVar [])
\end{code}
|
