eval: Only restore exit status on exit/return

[Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>]

Martijn Dekker <martijn@xxxxxxxx> wrote:
> Big bad bug: it appears that subshells always return status 0 in traps.
> 
> Bug found in dash 0.5.9 and later.
> 
> $ src/dash -c 'trap "(false) && echo BUG" INT; kill -s INT $$'
> BUG
> $ src/dash -c 'trap "(false) && echo BUG" EXIT'
> BUG
> $ src/dash -c 'trap "(false); echo \$?" EXIT'
> 0
> 
> Workaround: if an explicit 'exit' is given, it works as expected.
> 
> $ src/dash -c 'trap "(false; exit \$?); echo \$?" EXIT'
> 1

Thanks for the report.  This patch should fix the problem:

---8<---
We unconditionally restore the saved status in exitreset, which
is incorrect as we only want to do it for exitcmd and returncmd.
This patch fixes the problem by introducing EXEND.

Reported-by: Martijn Dekker <martijn@xxxxxxxx>
Fixes: da30b4b78769 ("[BUILTIN] Exit without arguments in a trap...")
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

diff --git a/src/error.h b/src/error.h
index 9630b56..94e30a2 100644
--- a/src/error.h
+++ b/src/error.h
@@ -66,7 +66,8 @@ extern int exception;
 /* exceptions */
 #define EXINT 0		/* SIGINT received */
 #define EXERROR 1	/* a generic error */
-#define EXEXIT 4	/* exit the shell */
+#define EXEND 3		/* exit the shell */
+#define EXEXIT 4	/* exit the shell via exitcmd */
 
 
 /*
diff --git a/src/eval.c b/src/eval.c
index 546ee1b..3cea2a3 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -114,12 +114,13 @@ STATIC const struct builtincmd bltin = {
 INCLUDE "eval.h"
 
 EXITRESET {
-	evalskip = 0;
-	loopnest = 0;
 	if (savestatus >= 0) {
-		exitstatus = savestatus;
+		if (exception == EXEXIT || evalskip == SKIPFUNCDEF)
+			exitstatus = savestatus;
 		savestatus = -1;
 	}
+	evalskip = 0;
+	loopnest = 0;
 }
 #endif
 
@@ -314,7 +315,7 @@ out:
 
 	if (flags & EV_EXIT) {
 exexit:
-		exraise(EXEXIT);
+		exraise(EXEND);
 	}
 
 	return exitstatus;
diff --git a/src/exec.c b/src/exec.c
index 9d0215a..87354d4 100644
--- a/src/exec.c
+++ b/src/exec.c
@@ -143,7 +143,7 @@ shellexec(char **argv, const char *path, int idx)
 	exitstatus = exerrno;
 	TRACE(("shellexec failed for %s, errno %d, suppressint %d\n",
 		argv[0], e, suppressint ));
-	exerror(EXEXIT, "%s: %s", argv[0], errmsg(e, E_EXEC));
+	exerror(EXEND, "%s: %s", argv[0], errmsg(e, E_EXEC));
 	/* NOTREACHED */
 }
 
diff --git a/src/main.c b/src/main.c
index 6d53e00..6b3a090 100644
--- a/src/main.c
+++ b/src/main.c
@@ -111,7 +111,7 @@ main(int argc, char **argv)
 		e = exception;
 
 		s = state;
-		if (e == EXEXIT || s == 0 || iflag == 0 || shlvl)
+		if (e == EXEND || e == EXEXIT || s == 0 || iflag == 0 || shlvl)
 			exitshell();
 
 		reset();
-- 
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt