[PATCH v6 3/4] Implement -e status=set option
Paul Chaignon
paul.chaignon at gmail.com
Fri Jul 5 17:05:24 UTC 2019
The status qualifier enables filtering based on the return status of
syscalls. -z and -Z become aliases for -e status=successful and -e
status=failed. Staged output is only enabled when at least one status is
filtered, that is, when the set is incomplete.
* signal.c (popcount32): Move ...
* defs.h (popcount32): ... here.
(not_failing_only, failing_only): Remove.
* filter_qualify.c (status_set): New number_set variable.
(statuses): New variable for names of statuses.
(statusstr_to_uint, qualify_status): New functions.
(qual_options): Handle status qualifier.
* number_set.c (get_number_setbit, is_complete_set): New functions.
* number_set.h (is_complete_set): New prototype.
(status_t): New enumeration for statuses.
(status_set): Expose status_set variable.
* strace.1.in: Document new status qualifier.
* strace.c (not_failing_only, failing_only): Remove.
(droptcb): Handle status=detached option.
(init): Handle new status qualifier, set status_set variable on -z and -Z
options, warning on -zZ, use is_complete_set.
(maybe_switch_tcbs): Reopen memstream after tcb switch.
(print_event_exit): Handle status=unfinished option.
* syscall.c (syscall_entering_trace): Use is_complete_set.
(syscall_exiting_trace): Use is_complete_set, handle status=unavailable
option.
* NEWS: Mention this change.
Signed-off-by: Paul Chaignon <paul.chaignon at gmail.com>
---
NEWS | 2 ++
defs.h | 24 ++++++++++++++++++++++--
filter_qualify.c | 33 ++++++++++++++++++++++++++++++++
number_set.c | 17 +++++++++++++++++
number_set.h | 13 +++++++++++++
signal.c | 19 -------------------
strace.1.in | 49 ++++++++++++++++++++++++++++++++++++++++++++++++
strace.c | 45 ++++++++++++++++++++++++++++++++------------
syscall.c | 25 +++++++++++++++---------
9 files changed, 185 insertions(+), 42 deletions(-)
diff --git a/NEWS b/NEWS
index a986462d..bebc2576 100644
--- a/NEWS
+++ b/NEWS
@@ -10,6 +10,8 @@ Noteworthy changes in release ?.? (????-??-??)
* Enhanced decoding of bpf and clone syscalls.
* Updated lists of AT_*, AUDIT_*, BPF_*, CLONE_*, ETH_*, KEY_*, KVM_*, TIPC_*,
and V4L2_* constants.
+ * Added syscall return status filtering with -e status option and -Z alias
+ for failed syscalls.
Noteworthy changes in release 5.1 (2019-05-22)
==============================================
diff --git a/defs.h b/defs.h
index b9b394ec..b6140fe0 100644
--- a/defs.h
+++ b/defs.h
@@ -420,8 +420,6 @@ extern bool Tflag;
extern bool iflag;
extern bool count_wallclock;
extern unsigned int qflag;
-extern bool not_failing_only;
-extern bool failing_only;
extern unsigned int show_fd_path;
/* are we filtering traces based on paths? */
extern struct path_set {
@@ -1451,6 +1449,28 @@ truncate_kulong_to_current_wordsize(const kernel_ulong_t v)
sizeof(v) == sizeof(long) ? (long long) (long) (v) : \
(long long) (v))
+/*
+ * Computes the popcount of a vector of 32-bit values.
+ */
+static inline unsigned int
+popcount32(const uint32_t *a, unsigned int size)
+{
+ unsigned int count = 0;
+
+ for (; size; ++a, --size) {
+ uint32_t x = *a;
+
+#ifdef HAVE___BUILTIN_POPCOUNT
+ count += __builtin_popcount(x);
+#else
+ for (; x; ++count)
+ x &= x - 1;
+#endif
+ }
+
+ return count;
+}
+
extern const char *const errnoent[];
extern const char *const signalent[];
extern const unsigned int nerrnos;
diff --git a/filter_qualify.c b/filter_qualify.c
index 4a05f1b2..e5e3728a 100644
--- a/filter_qualify.c
+++ b/filter_qualify.c
@@ -12,10 +12,12 @@
#include "filter.h"
#include "delay.h"
#include "retval.h"
+#include "static_assert.h"
struct number_set *read_set;
struct number_set *write_set;
struct number_set *signal_set;
+struct number_set *status_set;
static struct number_set *abbrev_set;
static struct number_set *inject_set;
@@ -57,6 +59,28 @@ sigstr_to_uint(const char *s)
return -1;
}
+static const char *statuses[] = {
+ "successful",
+ "failed",
+ "unfinished",
+ "unavailable",
+ "detached",
+};
+static_assert(ARRAY_SIZE(statuses) == NUMBER_OF_STATUSES,
+ "statuses array and status_t enum mismatch");
+
+static int
+statusstr_to_uint(const char *str)
+{
+ unsigned int i;
+
+ for (i = 0; i < NUMBER_OF_STATUSES; ++i)
+ if (strcasecmp(str, statuses[i]) == 0)
+ return i;
+
+ return -1;
+}
+
static int
find_errno_by_name(const char *name)
{
@@ -275,6 +299,14 @@ qualify_signals(const char *const str)
qualify_tokens(str, signal_set, sigstr_to_uint, "signal");
}
+static void
+qualify_status(const char *const str)
+{
+ if (!status_set)
+ status_set = alloc_number_set_array(1);
+ qualify_tokens(str, status_set, statusstr_to_uint, "status");
+}
+
static void
qualify_trace(const char *const str)
{
@@ -421,6 +453,7 @@ static const struct qual_options {
{ "x", qualify_raw },
{ "signal", qualify_signals },
{ "signals", qualify_signals },
+ { "status", qualify_status },
{ "s", qualify_signals },
{ "read", qualify_read },
{ "reads", qualify_read },
diff --git a/number_set.c b/number_set.c
index 4092ffda..70727eee 100644
--- a/number_set.c
+++ b/number_set.c
@@ -12,7 +12,9 @@
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
+#include "defs.h"
#include "number_set.h"
+#include "static_assert.h"
#include "xmalloc.h"
typedef unsigned int number_slot_t;
@@ -47,6 +49,14 @@ reallocate_number_set(struct number_set *const set, const unsigned int new_nslot
set->nslots = new_nslots;
}
+static unsigned int
+get_number_setbit(const struct number_set *const set)
+{
+ static_assert(sizeof(number_slot_t) == sizeof(uint32_t),
+ "number_slot_t is not 32-bit long");
+ return popcount32(set->vec, set->nslots);
+}
+
bool
number_set_array_is_empty(const struct number_set *const set,
const unsigned int idx)
@@ -69,6 +79,13 @@ is_number_in_set_array(const unsigned int number, const struct number_set *const
&& number_isset(number, set[idx].vec)) ^ set[idx].not;
}
+bool
+is_complete_set(const struct number_set *const set, const unsigned int max_numbers)
+{
+ return set && ((set->not && !set->nslots) ||
+ (get_number_setbit(set) == max_numbers));
+}
+
void
add_number_to_set(const unsigned int number, struct number_set *const set)
{
diff --git a/number_set.h b/number_set.h
index 77dc3a9c..b6399cc8 100644
--- a/number_set.h
+++ b/number_set.h
@@ -21,6 +21,9 @@ is_number_in_set(unsigned int number, const struct number_set *);
extern bool
is_number_in_set_array(unsigned int number, const struct number_set *, unsigned int idx);
+extern bool
+is_complete_set(const struct number_set *, unsigned int max_numbers);
+
extern void
add_number_to_set(unsigned int number, struct number_set *);
@@ -39,8 +42,18 @@ alloc_number_set_array(unsigned int nmemb) ATTRIBUTE_MALLOC;
extern void
free_number_set_array(struct number_set *, unsigned int nmemb);
+enum status_t {
+ STATUS_SUCCESSFUL,
+ STATUS_FAILED,
+ STATUS_UNFINISHED,
+ STATUS_UNAVAILABLE,
+ STATUS_DETACHED,
+ NUMBER_OF_STATUSES
+};
+
extern struct number_set *read_set;
extern struct number_set *write_set;
extern struct number_set *signal_set;
+extern struct number_set *status_set;
#endif /* !STRACE_NUMBER_SET_H */
diff --git a/signal.c b/signal.c
index fcaf9d4f..3cb54bb3 100644
--- a/signal.c
+++ b/signal.c
@@ -138,25 +138,6 @@ sprintsigname(const int sig)
return buf;
}
-static unsigned int
-popcount32(const uint32_t *a, unsigned int size)
-{
- unsigned int count = 0;
-
- for (; size; ++a, --size) {
- uint32_t x = *a;
-
-#ifdef HAVE___BUILTIN_POPCOUNT
- count += __builtin_popcount(x);
-#else
- for (; x; ++count)
- x &= x - 1;
-#endif
- }
-
- return count;
-}
-
const char *
sprintsigmask_n(const char *prefix, const void *sig_mask, unsigned int bytes)
{
diff --git a/strace.1.in b/strace.1.in
index e1090a0f..b9938ca0 100644
--- a/strace.1.in
+++ b/strace.1.in
@@ -409,6 +409,7 @@ is one of
.BR write ,
.BR fault ,
.BR inject ,
+.BR status ,
or
.B kvm
and
@@ -613,6 +614,54 @@ Note that this is independent from the normal tracing of the
system call which is controlled by the option
.BR -e "\ " trace = write .
.TP
+\fB\-e\ status\fR=\,\fIset\fR
+Trace only system calls with the specified return status. The default is
+.BR status = all .
+When using the
+.B status
+qualifier, because
+.B strace
+waits for system calls to return before deciding if they should be printed, the
+order of events may not be preserved anymore. If two system calls are executed
+by concurrent threads,
+.B strace
+will first print both the entry and exit of the first system call to exit,
+regardless of their respective entry time. The entry and exit of the second
+system call to exit will be printed afterwards. Here is an example when
+.BR select (2)
+is called, but a different thread calls
+.BR clock_gettime (2)
+before
+.BR select (2)
+finishes:
+.CW
+[pid 28779] clock_gettime(CLOCK_REALTIME, {1130322148, 939977000}) = 0
+[pid 28772] select(4, [3], NULL, NULL, NULL <unfinished ...>
+[pid 28772] <... select resumed> ) = 1 (in [3])
+.CE
+.TP
+.BR "\-e\ status" = successful
+Trace system calls that returned without an error code. The
+.B -z
+option has the effect of
+.BR status=successful .
+.TP
+.BR "\-e\ status" = failed
+Trace system calls that returned with an error code. The
+.B -Z
+option has the effect of
+.BR status=failed .
+.TP
+.BR "\-e\ status" = unfinished
+Trace system calls that did not return. This might happen, for example, due to
+an execve call in a neighbour thread.
+.TP
+.BR "\-e\ status" = unavailable
+Trace system calls that returned but strace failed to fetch the error status.
+.TP
+.BR "\-e\ status" = detached
+Trace system calls for which strace detached before the return.
+.TP
\fB\-e\ inject\fR=\,\fIset\/\fR[:\fBerror\fR=\,\fIerrno\/\fR|:\fBretval\fR=\,\fIvalue\/\fR][:\fBsignal\fR=\,\fIsig\/\fR][:\fBsyscall\fR=\fIsyscall\fR][:\fBdelay_enter\fR=\,\fIusecs\/\fR][:\fBdelay_exit\fR=\,\fIusecs\/\fR][:\fBwhen\fR=\,\fIexpr\/\fR]
Perform syscall tampering for the specified set of syscalls.
diff --git a/strace.c b/strace.c
index cb1d1840..a2fc2036 100644
--- a/strace.c
+++ b/strace.c
@@ -109,10 +109,6 @@ static bool daemonized_tracer;
static int post_attach_sigstop = TCB_IGNORE_ONE_SIGSTOP;
#define use_seize (post_attach_sigstop == 0)
-/* Sometimes we want to print succeeding/failing syscalls only. */
-bool not_failing_only;
-bool failing_only;
-
/* Show path associated with fd arguments */
unsigned int show_fd_path;
@@ -273,7 +269,7 @@ Statistics:\n\
\n\
Filtering:\n\
-e expr a qualifying expression: option=[!]all or option=[!]val1[,val2]...\n\
- options: trace, abbrev, verbose, raw, signal, read, write, fault, inject, kvm\n\
+ options: trace, abbrev, verbose, raw, signal, read, write, fault, inject, status, kvm\n\
-P path trace accesses to path\n\
-z print only syscalls that returned without an error code\n\
-Z print only syscalls that returned with an error code\n\
@@ -812,12 +808,18 @@ droptcb(struct tcb *tcp)
debug_msg("dropped tcb for pid %d, %d remain", tcp->pid, nprocs);
if (tcp->outf) {
+ bool publish = true;
+ if (!is_complete_set(status_set, NUMBER_OF_STATUSES)) {
+ publish = is_number_in_set(STATUS_DETACHED, status_set);
+ strace_close_memstream(tcp, publish);
+ }
+
if (followfork >= 2) {
- if (tcp->curcol != 0)
+ if (tcp->curcol != 0 && publish)
fprintf(tcp->outf, " <detached ...>\n");
fclose(tcp->outf);
} else {
- if (printing_tcp == tcp && tcp->curcol != 0)
+ if (printing_tcp == tcp && tcp->curcol != 0 && publish)
fprintf(tcp->outf, " <detached ...>\n");
flush_tcp_output(tcp);
}
@@ -1553,7 +1555,7 @@ static void ATTRIBUTE_NOINLINE
init(int argc, char *argv[])
{
int c, i;
- int optF = 0;
+ int optF = 0, zflags = 0;
if (!program_invocation_name || !*program_invocation_name) {
static char name[] = "strace";
@@ -1571,6 +1573,7 @@ init(int argc, char *argv[])
qualify("trace=all");
qualify("abbrev=all");
qualify("verbose=all");
+ qualify("status=all");
#if DEFAULT_QUAL_FLAGS != (QUAL_TRACE | QUAL_ABBREV | QUAL_VERBOSE)
# error Bug in DEFAULT_QUAL_FLAGS
#endif
@@ -1708,10 +1711,14 @@ init(int argc, char *argv[])
show_fd_path++;
break;
case 'z':
- not_failing_only = 1;
+ clear_number_set_array(status_set, 1);
+ add_number_to_set(STATUS_SUCCESSFUL, status_set);
+ zflags++;
break;
case 'Z':
- failing_only = 1;
+ clear_number_set_array(status_set, 1);
+ add_number_to_set(STATUS_FAILED, status_set);
+ zflags++;
break;
default:
error_msg_and_help(NULL);
@@ -1764,10 +1771,14 @@ init(int argc, char *argv[])
}
#ifndef HAVE_OPEN_MEMSTREAM
- if (not_failing_only || failing_only)
- error_msg_and_help("open_memstream is required to use -z or -Z");
+ if (!is_complete_set(status_set, NUMBER_OF_STATUSES))
+ error_msg_and_help("open_memstream is required to use -z, -Z, or -e status");
#endif
+ if (zflags > 1)
+ error_msg("Only the last of -z/-Z options will take effect. "
+ "See status qualifier for more complex filters.");
+
acolumn_spaces = xmalloc(acolumn + 1);
memset(acolumn_spaces, ' ', acolumn);
acolumn_spaces[acolumn] = '\0';
@@ -2093,6 +2104,12 @@ maybe_switch_tcbs(struct tcb *tcp, const int pid)
printleader(tcp);
tprintf("+++ superseded by execve in pid %lu +++\n", old_pid);
line_ended();
+ /*
+ * Need to reopen memstream for thread
+ * as we closed it in droptcb.
+ */
+ if (!is_complete_set(status_set, NUMBER_OF_STATUSES))
+ strace_open_memstream(tcp);
tcp->flags |= TCB_REPRINT;
}
@@ -2208,6 +2225,10 @@ print_event_exit(struct tcb *tcp)
tprints(") ");
tabto();
tprints("= ?\n");
+ if (!is_complete_set(status_set, NUMBER_OF_STATUSES)) {
+ bool publish = is_number_in_set(STATUS_UNFINISHED, status_set);
+ strace_close_memstream(tcp, publish);
+ }
line_ended();
}
diff --git a/syscall.c b/syscall.c
index 4121b7ae..d106967d 100644
--- a/syscall.c
+++ b/syscall.c
@@ -656,7 +656,7 @@ syscall_entering_trace(struct tcb *tcp, unsigned int *sig)
}
#endif
- if (not_failing_only || failing_only)
+ if (!is_complete_set(status_set, NUMBER_OF_STATUSES))
strace_open_memstream(tcp);
printleader(tcp);
@@ -751,6 +751,11 @@ syscall_exiting_trace(struct tcb *tcp, struct timespec *ts, int res)
tprints(") ");
tabto();
tprints("= ? <unavailable>\n");
+ if (!is_complete_set(status_set, NUMBER_OF_STATUSES)) {
+ bool publish = is_number_in_set(STATUS_UNAVAILABLE,
+ status_set);
+ strace_close_memstream(tcp, publish);
+ }
line_ended();
return res;
}
@@ -766,14 +771,16 @@ syscall_exiting_trace(struct tcb *tcp, struct timespec *ts, int res)
sys_res = tcp_sysent(tcp)->sys_func(tcp);
}
- if ((not_failing_only && syserror(tcp)) ||
- (failing_only && !syserror(tcp))) {
- strace_close_memstream(tcp, false);
- line_ended();
- return 0; /* ignore failed/successful
- * syscalls */
- } else if (not_failing_only || failing_only) {
- strace_close_memstream(tcp, true);
+ if (!is_complete_set(status_set, NUMBER_OF_STATUSES)) {
+ bool publish = syserror(tcp)
+ && is_number_in_set(STATUS_FAILED, status_set);
+ publish |= !syserror(tcp)
+ && is_number_in_set(STATUS_SUCCESSFUL, status_set);
+ strace_close_memstream(tcp, publish);
+ if (!publish) {
+ line_ended();
+ return 0;
+ }
}
tprints(") ");
--
2.17.1
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