Author: jilles
Date: Sun Nov 22 18:23:30 2009
New Revision: 199660
URL: http://svn.freebsd.org/changeset/base/199660
Log:
Fix various things about SIGINT handling:
* exception handlers are now run with interrupts disabled, which avoids
many race conditions
* fix some cases where SIGINT only aborts one command and continues the
script, in particular if a SIGINT causes an EINTR error which trumped the
interrupt.
Example:
sh -c 'echo < /some/fifo; echo This should not be printed'
The fifo should not have writers. When pressing ctrl+c to abort the open,
the shell used to continue with the next command.
Example:
sh -c '/bin/echo < /some/fifo; echo This should not be printed'
Similar. Note, however, that this particular case did not and does not work
in interactive mode with job control enabled.
Modified:
head/bin/sh/error.c
head/bin/sh/error.h
head/bin/sh/eval.c
head/bin/sh/parser.c
head/bin/sh/redir.c
head/bin/sh/var.c
Modified: head/bin/sh/error.c
==============================================================================
--- head/bin/sh/error.c Sun Nov 22 17:25:11 2009 (r199659)
+++ head/bin/sh/error.c Sun Nov 22 18:23:30 2009 (r199660)
@@ -73,11 +73,15 @@ static void exverror(int, const char *,
* Called to raise an exception. Since C doesn't include exceptions, we
* just do a longjmp to the exception handler. The type of exception is
* stored in the global variable "exception".
+ *
+ * Interrupts are disabled; they should be reenabled when the exception is
+ * caught.
*/
void
exraise(int e)
{
+ INTOFF;
if (handler == NULL)
abort();
exception = e;
@@ -138,8 +142,15 @@ onint(void)
static void
exverror(int cond, const char *msg, va_list ap)
{
- CLEAR_PENDING_INT;
- INTOFF;
+ /*
+ * An interrupt trumps an error. Certain places catch error
+ * exceptions or transform them to a plain nonzero exit code
+ * in child processes, and if an error exception can be handled,
+ * an interrupt can be handled as well.
+ *
+ * exraise() will disable interrupts for the exception handler.
+ */
+ FORCEINTON;
#ifdef DEBUG
if (msg)
Modified: head/bin/sh/error.h
==============================================================================
--- head/bin/sh/error.h Sun Nov 22 17:25:11 2009 (r199659)
+++ head/bin/sh/error.h Sun Nov 22 18:23:30 2009 (r199660)
@@ -72,6 +72,8 @@ extern volatile sig_atomic_t intpending;
#define INTOFF suppressint++
#define INTON { if (--suppressint == 0 && intpending) onint(); }
+#define is_int_on() suppressint
+#define SETINTON(s) suppressint = (s)
#define FORCEINTON {suppressint = 0; if (intpending) onint();}
#define CLEAR_PENDING_INT intpending = 0
#define int_pending() intpending
Modified: head/bin/sh/eval.c
==============================================================================
--- head/bin/sh/eval.c Sun Nov 22 17:25:11 2009 (r199659)
+++ head/bin/sh/eval.c Sun Nov 22 18:23:30 2009 (r199660)
@@ -782,7 +782,6 @@ evalcommand(union node *cmd, int flags,
savelocalvars = localvars;
localvars = NULL;
reffunc(cmdentry.u.func);
- INTON;
savehandler = handler;
if (setjmp(jmploc.loc)) {
if (exception == EXSHELLPROC)
@@ -798,6 +797,7 @@ evalcommand(union node *cmd, int flags,
longjmp(handler->loc, 1);
}
handler = &jmploc;
+ INTON;
for (sp = varlist.list ; sp ; sp = sp->next)
mklocal(sp->text);
funcnest++;
Modified: head/bin/sh/parser.c
==============================================================================
--- head/bin/sh/parser.c Sun Nov 22 17:25:11 2009 (r199659)
+++ head/bin/sh/parser.c Sun Nov 22 18:23:30 2009 (r199660)
@@ -1312,6 +1312,7 @@ parsebackq: {
int saveprompt;
const int bq_startlinno = plinno;
+ str = NULL;
if (setjmp(jmploc.loc)) {
if (str)
ckfree(str);
@@ -1323,7 +1324,6 @@ parsebackq: {
longjmp(handler->loc, 1);
}
INTOFF;
- str = NULL;
savelen = out - stackblock();
if (savelen > 0) {
str = ckmalloc(savelen);
Modified: head/bin/sh/redir.c
==============================================================================
--- head/bin/sh/redir.c Sun Nov 22 17:25:11 2009 (r199659)
+++ head/bin/sh/redir.c Sun Nov 22 18:23:30 2009 (r199660)
@@ -166,8 +166,11 @@ openredirect(union node *redir, char mem
/*
* We suppress interrupts so that we won't leave open file
- * descriptors around. This may not be such a good idea because
- * an open of a device or a fifo can block indefinitely.
+ * descriptors around. Because the signal handler remains
+ * installed and we do not use system call restart, interrupts
+ * will still abort blocking opens such as fifos (they will fail
+ * with EINTR). There is, however, a race condition if an interrupt
+ * arrives after INTOFF and before open blocks.
*/
INTOFF;
memory[fd] = 0;
Modified: head/bin/sh/var.c
==============================================================================
--- head/bin/sh/var.c Sun Nov 22 17:25:11 2009 (r199659)
+++ head/bin/sh/var.c Sun Nov 22 18:23:30 2009 (r199660)
@@ -195,7 +195,9 @@ setvarsafe(char *name, char *val, int fl
struct jmploc jmploc;
struct jmploc *const savehandler = handler;
int err = 0;
+ int inton;
+ inton = is_int_on();
if (setjmp(jmploc.loc))
err = 1;
else {
@@ -203,6 +205,7 @@ setvarsafe(char *name, char *val, int fl
setvar(name, val, flags);
}
handler = savehandler;
+ SETINTON(inton);
return err;
}
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