Hi,
Bug reported by miod@, how to reproduce:
$ command -v r
alias r='fc -s'
$ sleep 5
$ r sleep
^C # abort sleep before finishing
$ r sleep
ksh: fc: history function called recursively
The c_fc() function has some internal state used to prevent recursive
invocations that gets out of sync when the re-executed command is
aborted by SIGINT. My proposal is to temporarily register a SIGINT
handler before re-executing the command in order to reset the call depth
counter upon signal delivery.
Comments? OK?
Index: history.c
===================================================================
RCS file: /cvs/src/bin/ksh/history.c,v
retrieving revision 1.80
diff -u -p -r1.80 history.c
--- history.c 15 Jan 2018 22:30:38 -0000 1.80
+++ history.c 28 Oct 2018 19:10:54 -0000
@@ -36,6 +36,8 @@ static char **hist_get(const char *, i
static char **hist_get_oldest(void);
static void histbackup(void);
+static void hist_sigint(int);
+
static FILE *histfh;
static char **histbase; /* actual start of the history[] allocation */
static char **current; /* current position in history[] */
@@ -46,6 +48,8 @@ static int ignorespace; /* ditch lines s
static Source *hist_source;
static uint32_t line_co;
+static volatile sig_atomic_t fc_depth;
+
static struct stat last_sb;
int
@@ -58,9 +62,8 @@ c_fc(char **wp)
int optc, ret;
char *first = NULL, *last = NULL;
char **hfirst, **hlast, **hp;
- static int depth;
- if (depth != 0) {
+ if (fc_depth != 0) {
bi_errorf("history function called recursively");
return 1;
}
@@ -70,6 +73,8 @@ c_fc(char **wp)
return 1;
}
+ setsig(&sigtraps[SIGINT], hist_sigint, SS_ONESHOT);
+
while ((optc = ksh_getopt(wp, &builtin_opt,
"e:glnrs0,1,2,3,4,5,6,7,8,9,")) != -1)
switch (optc) {
@@ -146,9 +151,9 @@ c_fc(char **wp)
hist_get_newest(false);
if (!hp)
return 1;
- depth++;
+ fc_depth++;
ret = hist_replace(hp, pat, rep, gflag);
- depth--;
+ fc_depth--;
return ret;
}
@@ -268,9 +273,9 @@ c_fc(char **wp)
shf_close(shf);
*xp = '\0';
strip_nuls(Xstring(xs, xp), Xlength(xs, xp));
- depth++;
+ fc_depth++;
ret = hist_execute(Xstring(xs, xp));
- depth--;
+ fc_depth--;
return ret;
}
}
@@ -852,4 +857,10 @@ void
hist_finish(void)
{
history_close();
+}
+
+static void
+hist_sigint(int signo)
+{
+ fc_depth = 0;
}
Index: sh.h
===================================================================
RCS file: /cvs/src/bin/ksh/sh.h,v
retrieving revision 1.73
diff -u -p -r1.73 sh.h
--- sh.h 18 May 2018 13:25:20 -0000 1.73
+++ sh.h 28 Oct 2018 19:10:54 -0000
@@ -230,6 +230,7 @@ typedef struct trap {
#define TF_TTY_INTR BIT(7) /* tty generated signal (see j_waitj) */
#define TF_CHANGED BIT(8) /* used by runtrap() to detect trap changes */
#define TF_FATAL BIT(9) /* causes termination if not trapped */
+#define TF_ONESHOT BIT(10) /* temporary trap handler registered */
/* values for setsig()/setexecsig() flags argument */
#define SS_RESTORE_MASK 0x3 /* how to restore a signal before an
exec() */
@@ -240,6 +241,7 @@ typedef struct trap {
#define SS_FORCE BIT(3) /* set signal even if original signal ignored */
#define SS_USER BIT(4) /* user is doing the set (ie, trap
command) */
#define SS_SHTRAP BIT(5) /* trap for internal use (CHLD,ALRM,WINCH) */
+#define SS_ONESHOT BIT(6) /* register temporary trap handler */
#define SIGEXIT_ 0 /* for trap EXIT */
#define SIGERR_ NSIG /* for trap ERR */
Index: trap.c
===================================================================
RCS file: /cvs/src/bin/ksh/trap.c,v
retrieving revision 1.32
diff -u -p -r1.32 trap.c
--- trap.c 15 Mar 2018 16:51:29 -0000 1.32
+++ trap.c 28 Oct 2018 19:10:54 -0000
@@ -13,6 +13,8 @@
Trap sigtraps[NSIG + 1];
+static sig_t traphandler(Trap *);
+
static struct sigaction Sigact_ign, Sigact_trap;
void
@@ -117,6 +119,7 @@ void
trapsig(int i)
{
Trap *p = &sigtraps[i];
+ sig_t f;
int errno_ = errno;
trap = p->set = 1;
@@ -126,8 +129,9 @@ trapsig(int i)
fatal_trap = 1;
intrsig = 1;
}
- if (p->shtrap)
- (*p->shtrap)(i);
+ f = traphandler(p);
+ if (f)
+ (*f)(i);
errno = errno_;
}
@@ -200,10 +204,13 @@ runtraps(int flag)
intrsig = 0;
if (flag & TF_FATAL)
fatal_trap = 0;
- for (p = sigtraps, i = NSIG+1; --i >= 0; p++)
+ for (p = sigtraps, i = NSIG+1; --i >= 0; p++) {
+ (void)traphandler(p); /* clear one shot handler */
+
if (p->set && (!flag ||
((p->flags & flag) && p->trap == NULL)))
runtrap(p);
+ }
}
void
@@ -354,6 +361,14 @@ setsig(Trap *p, sig_t f, int flags)
if (p->signal == SIGEXIT_ || p->signal == SIGERR_)
return 1;
+ if ((flags & SS_ONESHOT) == SS_ONESHOT) {
+ if (p->shtrap != NULL)
+ return 0;
+ p->flags |= TF_ONESHOT;
+ p->shtrap = f;
+ return 1;
+ }
+
/* First time setting this signal? If so, get and note the current
* setting.
*/
@@ -420,4 +435,21 @@ setexecsig(Trap *p, int restore)
p->flags |= TF_EXEC_IGN;
break;
}
+}
+
+/*
+ * Returns the signal handler associated with the given trap.
+ * If the handler is registered as a one shot, it's disassociated with the
trap.
+ */
+static sig_t
+traphandler(Trap *p)
+{
+ sig_t f;
+
+ f = p->shtrap;
+ if (p->flags & TF_ONESHOT) {
+ p->flags &= ~TF_ONESHOT;
+ p->shtrap = NULL;
+ }
+ return f;
}
