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[PATCH v2] Implement output staging for failed/successful syscalls
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From: Burkhard K. <bur...@in...> - 2017-01-18 17:13:05
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With not_failing_only/failing_only flags, syscall output
is written to tcp->memf and either dropped or published
at strace_syscall_exiting
* stage_out.c strace_openmemstream(), drop_staged_out(),
publish_staged_out().
* defs.h added flags stage_out, failing only
struct tcb: new members memf, memfptr, memfloc.
* syscall.c print output depending on flags and outcome.
* strace.c add option -Z +help
modified tprintf, tprints
set stage_output in main().
* Makefile.am new: stage_out.c
* configure.ac (AC_CHECK_FUNCS): open_memstream
* strace.1 -z/-Z: description added
---
Makefile.am | 1 +
configure.ac | 1 +
defs.h | 18 +++++++++
stage_out.c | 120 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
strace.1 | 6 +++
strace.c | 107 +++++++++++++++++++++++++++++++++++++++++++++++++---
syscall.c | 18 +++++++++
7 files changed, 266 insertions(+), 5 deletions(-)
create mode 100644 stage_out.c
diff --git a/Makefile.am b/Makefile.am
index afc3dd2..4550ff2 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -226,6 +226,7 @@ strace_SOURCES = \
sockaddr.c \
socketutils.c \
sram_alloc.c \
+ stage_out.c \
stat.c \
stat.h \
stat64.c \
diff --git a/configure.ac b/configure.ac
index 793d74e..5a4212a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -285,6 +285,7 @@ AC_CHECK_FUNCS(m4_normalize([
strsignal
sync_file_range
utimensat
+ open_memstream
]))
AC_CHECK_TYPES([sig_atomic_t, struct sigcontext],,, [#include <signal.h>])
diff --git a/defs.h b/defs.h
index 09c0a5f..7494e54 100644
--- a/defs.h
+++ b/defs.h
@@ -2,6 +2,7 @@
* Copyright (c) 1991, 1992 Paul Kranenburg <pk...@cs...>
* Copyright (c) 1993 Branko Lankester <br...@ha...>
* Copyright (c) 1993, 1994, 1995, 1996 Rick Sladkey <jr...@wo...>
+ * Copyright (C) 2016-2017 Intel Deutschland GmbH
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -219,6 +220,12 @@ struct tcb {
int sys_func_rval; /* Syscall entry parser's return value */
int curcol; /* Output column for this process */
FILE *outf; /* Output file for this process */
+#if HAVE_OPEN_MEMSTREAM
+ FILE *memf; /* Staged output file for this process */
+ char *memfptr;
+ size_t memfloc;
+#endif /* if HAVE_OPEN_MEMSTREAM */
+
const char *auxstr; /* Auxiliary info from syscall (see RVAL_STR) */
void *_priv_data; /* Private data for syscall decoding functions */
void (*_free_priv_data)(void *); /* Callback for freeing priv_data */
@@ -363,6 +370,10 @@ extern bool iflag;
extern bool count_wallclock;
extern unsigned int qflag;
extern bool not_failing_only;
+#if HAVE_OPEN_MEMSTREAM
+extern bool failing_only;
+extern bool stage_output; /* allows dropping of failed/successful syscalls output */
+#endif /* if HAVE_OPEN_MEMSTREAM */
extern unsigned int show_fd_path;
/* are we filtering traces based on paths? */
extern const char **paths_selected;
@@ -736,6 +747,13 @@ extern void tabto(void);
extern void tprintf(const char *fmt, ...) ATTRIBUTE_FORMAT((printf, 1, 2));
extern void tprints(const char *str);
+/*
+ * staging output for -z/-Z (not_failing_only/failing_only)
+ */
+extern FILE *strace_openmemstream(struct tcb *tcp);
+extern void drop_staged_out(struct tcb *tcp);
+extern void publish_staged_out(struct tcb *tcp);
+
#if SUPPORTED_PERSONALITIES > 1
extern void set_personality(int personality);
extern unsigned current_personality;
diff --git a/stage_out.c b/stage_out.c
new file mode 100644
index 0000000..88af3b8
--- /dev/null
+++ b/stage_out.c
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2016-2017 Intel Deutschland GmbH
+
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * Output staging is based on the "open_memstream()" function, see:
+ * http://man7.org/linux/man-pages/man3/open_memstream.3.html
+ * Requires glibc version 2.7 mininal
+ *
+ * open_memstream returns a FILE stream that allows writing to a
+ * dynamically growing buffer, that can be either copied to
+ * tcp->outf (syscall successful) or dropped (syscall failed)
+ */
+
+#include "defs.h"
+#if HAVE_OPEN_MEMSTREAM
+
+FILE *
+strace_openmemstream(struct tcb *tcp)
+{
+ FILE *fp = NULL; // to be returned
+
+ if(debug_flag) {
+ ; /* error_msg("stage_openmemstream working on tcp %p", tcp); */
+ }
+ if (NULL != tcp) {
+ tcp->memfptr = NULL;
+ fp = open_memstream(&(tcp->memfptr), &(tcp->memfloc));
+ if (NULL == fp)
+ perror_msg_and_die("error during open_memstream");
+ else
+ /* call to fflush required to update tcp->memfptr, see open_memstream man page */
+ fflush(fp);
+ tcp->memf = fp;
+ if(debug_flag) {
+ ; /* error_msg("stage_openmemstream for tcp: %p (opened memf: %p, memfptr: %p, size: %zu)", tcp, tcp->memf, tcp->memfptr, tcp->memfloc); */
+ }
+ }
+
+ return fp;
+}
+
+void
+drop_staged_out(struct tcb *tcp)
+{
+ if (NULL != tcp->memf) {
+ if(debug_flag) {
+ ; /* error_msg("drop_stage_out (before flcose): for tcp: %p (opened memf: %p, memfptr: %p, size: %zu)", tcp, tcp->memf, tcp->memfptr, tcp->memfloc); */
+ }
+
+ if (fclose(tcp->memf)) {
+ perror_msg("flose on tcp->memf");
+ }
+ if (NULL != tcp->memfptr) {
+ if(debug_flag) {
+ error_msg("syscall output dropped: %s ...", tcp->memfptr);
+ }
+
+ free(tcp->memfptr);
+ tcp->memfptr = NULL;
+ }
+
+ /* reopen tcp->memf for subsequent use */
+ strace_openmemstream(tcp);
+ }
+}
+
+void
+publish_staged_out(struct tcb *tcp)
+{
+ if (NULL != tcp->memf) {
+ if(debug_flag) {
+ ; /* error_msg("publish_staged_out (before fclose): for tcp: %p (opened memf: %p, memfptr: %p, size: %zu)", tcp, tcp->memf, tcp->memfptr, tcp->memfloc); */
+ }
+
+ if (fclose(tcp->memf)) {
+ perror_msg("flose on tcp->memf");
+ }
+ if (NULL != tcp->memfptr) {
+ if (0 > fprintf(tcp->outf, "%s", tcp->memfptr)) {
+ /* ToDo: print suitable error msg */
+ }
+
+ if (debug_flag) {
+ ; /* error_msg("publish_staged_out (after free): for tcp: %p (opened memf: %p, memfptr: %p, size: %zu)", tcp, tcp->memf, tcp->memfptr, tcp->memfloc); */
+ }
+
+ free(tcp->memfptr);
+ tcp->memfptr = NULL;
+ }
+
+ /* reopen tcp->memf for subsequent use */
+ strace_openmemstream(tcp);
+ }
+}
+#endif /* if HAVE_OPEN_MEMSTREAM */
diff --git a/strace.1 b/strace.1
index 0356c2d..08739c0 100644
--- a/strace.1
+++ b/strace.1
@@ -581,6 +581,12 @@ Print unabbreviated versions of environment, stat, termios, etc.
calls. These structures are very common in calls and so the default
behavior displays a reasonable subset of structure members. Use
this option to get all of the gory details.
+.TP
+.B \-z
+Print successful syscalls only.
+.TP
+.B \-Z
+Print failed syscalls only.
.SS Tracing
.TP 12
.TP
diff --git a/strace.c b/strace.c
index da6b165..78fcffe 100644
--- a/strace.c
+++ b/strace.c
@@ -3,6 +3,7 @@
* Copyright (c) 1993 Branko Lankester <br...@ha...>
* Copyright (c) 1993, 1994, 1995, 1996 Rick Sladkey <jr...@wo...>
* Copyright (c) 1996-1999 Wichert Akkerman <wi...@ci...>
+ * Copyright (C) 2016-2017 Intel Deutschland GmbH
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -121,8 +122,12 @@ static int post_attach_sigstop = TCB_IGNORE_ONE_SIGSTOP;
# define use_seize 0
#endif
-/* Sometimes we want to print only succeeding syscalls. */
-bool not_failing_only = 0;
+/* Sometimes we want to print succeeding/failing syscalls only. */
+bool not_failing_only = false;
+#if HAVE_OPEN_MEMSTREAM
+bool failing_only = false;
+bool stage_output = false;
+#endif /* #if HAVE_OPEN_MEMSTREAM */
/* Show path associated with fd arguments */
unsigned int show_fd_path = 0;
@@ -239,7 +244,13 @@ Filtering:\n\
-e expr a qualifying expression: option=[!]all or option=[!]val1[,val2]...\n\
options: trace, abbrev, verbose, raw, signal, read, write, fault\n\
-P path trace accesses to path\n\
-\n\
+"
+#if HAVE_OPEN_MEMSTREAM
+" -z print only succeeding syscalls\n\
+ -Z print only failing syscalls\n\
+"
+#endif /* #if HAVE_OPEN_MEMSTREAM */
+"\n\
Tracing:\n\
-b execve detach on execve syscall\n\
-D run tracer process as a detached grandchild, not as parent\n\
@@ -267,9 +278,11 @@ Miscellaneous:\n\
/* ancient, no one should use it
-F -- attempt to follow vforks (deprecated, use -f)\n\
*/
+#if HAVE_OPEN_MEMSTREAM == 0
/* this is broken, so don't document it
-z -- print only succeeding syscalls\n\
*/
+#endif /* #if HAVE_OPEN_MEMSTREAM */
, DEFAULT_ACOLUMN, DEFAULT_STRLEN, DEFAULT_SORTBY);
exit(0);
}
@@ -573,16 +586,43 @@ void
tprintf(const char *fmt, ...)
{
va_list args;
+ int n = 0;
va_start(args, fmt);
+#if HAVE_OPEN_MEMSTREAM
+ if (current_tcp) {
+ if (stage_output) {
+ if (NULL == current_tcp->memf) {
+ error_msg("tprintf: No file opened for current_tcp->memf\n");
+ goto ret;
+ }
+ n = vfprintf(current_tcp->memf, fmt, args);
+ if (n < 0) {
+ perror_msg("printing to memf");
+ }
+ } else {
+ n = vfprintf(current_tcp->outf, fmt, args);
+ if (n < 0) {
+ if (current_tcp->outf != stderr)
+ perror_msg("%s", outfname);
+ }
+ }
+ }
+
+ if (n >= 0) {
+ current_tcp->curcol += n;
+ }
+ret:
+#else
if (current_tcp) {
- int n = vfprintf(current_tcp->outf, fmt, args);
+ n = vfprintf(current_tcp->outf, fmt, args);
if (n < 0) {
if (current_tcp->outf != stderr)
perror_msg("%s", outfname);
} else
current_tcp->curcol += n;
}
+#endif /* #if HAVE_OPEN_MEMSTREAM */
va_end(args);
}
@@ -594,7 +634,21 @@ void
tprints(const char *str)
{
if (current_tcp) {
- int n = fputs_unlocked(str, current_tcp->outf);
+ int n;
+
+#if HAVE_OPEN_MEMSTREAM
+ if (stage_output) {
+ if (NULL == current_tcp->memf) {
+ error_msg("tprints: No file opened for current_tcp->memf\n");
+ return;
+ }
+ n = fputs_unlocked(str, current_tcp->memf);
+ } else {
+ n = fputs_unlocked(str, current_tcp->outf);
+ }
+#else
+ n = fputs_unlocked(str, current_tcp->outf);
+#endif /* #if HAVE_OPEN_MEMSTREAM */
if (n >= 0) {
current_tcp->curcol += strlen(str);
return;
@@ -700,6 +754,11 @@ newoutf(struct tcb *tcp)
sprintf(name, "%.512s.%u", outfname, tcp->pid);
tcp->outf = strace_fopen(name);
}
+#if HAVE_OPEN_MEMSTREAM
+ if (not_failing_only || failing_only) {
+ strace_openmemstream(tcp);
+ }
+#endif /* #if HAVE_OPEN_MEMSTREAM */
}
static void
@@ -1606,7 +1665,11 @@ init(int argc, char *argv[])
#endif
qualify("signal=all");
while ((c = getopt(argc, argv,
+#if HAVE_OPEN_MEMSTREAM
+ "+b:cCdfFhiqrtTvVwxyzZ"
+#else
"+b:cCdfFhiqrtTvVwxyz"
+#endif /* HAVE_OPEN_MEMSTREAM */
#ifdef USE_LIBUNWIND
"k"
#endif
@@ -1680,6 +1743,11 @@ init(int argc, char *argv[])
case 'z':
not_failing_only = 1;
break;
+#if HAVE_OPEN_MEMSTREAM
+ case 'Z':
+ failing_only = 1;
+ break;
+#endif /* HAVE_OPEN_MEMSTREAM */
case 'a':
acolumn = string_to_uint(optarg);
if (acolumn < 0)
@@ -2132,6 +2200,11 @@ print_signalled(struct tcb *tcp, const int pid, int status)
static void
print_exited(struct tcb *tcp, const int pid, int status)
{
+#if HAVE_OPEN_MEMSTREAM
+ bool saved_stage_output_flag = stage_output;
+
+ stage_output = false;
+#endif /* #if HAVE_OPEN_MEMSTREAM */
if (pid == strace_child) {
exit_code = WEXITSTATUS(status);
strace_child = 0;
@@ -2143,11 +2216,19 @@ print_exited(struct tcb *tcp, const int pid, int status)
tprintf("+++ exited with %d +++\n", WEXITSTATUS(status));
line_ended();
}
+#if HAVE_OPEN_MEMSTREAM
+ stage_output = saved_stage_output_flag;
+#endif /* #if HAVE_OPEN_MEMSTREAM */
}
static void
print_stopped(struct tcb *tcp, const siginfo_t *si, const unsigned int sig)
{
+#if HAVE_OPEN_MEMSTREAM
+ bool saved_stage_output_flag = stage_output;
+
+ stage_output = false;
+#endif /* #if HAVE_OPEN_MEMSTREAM */
if (cflag != CFLAG_ONLY_STATS
&& !hide_log(tcp)
&& is_number_in_set(sig, &signal_set)) {
@@ -2160,6 +2241,9 @@ print_stopped(struct tcb *tcp, const siginfo_t *si, const unsigned int sig)
tprintf("--- stopped by %s ---\n", signame(sig));
line_ended();
}
+#if HAVE_OPEN_MEMSTREAM
+ stage_output = saved_stage_output_flag;
+#endif /* #if HAVE_OPEN_MEMSTREAM */
}
static void
@@ -2488,13 +2572,26 @@ restart_tracee:
int
main(int argc, char *argv[])
{
+#if HAVE_OPEN_MEMSTREAM
+
+ /* during init don't print to internal memf stream */
+ stage_output = false;
+#endif /* #if HAVE_OPEN_MEMSTREAM */
+
init(argc, argv);
exit_code = !nprocs;
+#if HAVE_OPEN_MEMSTREAM
+ stage_output = not_failing_only || failing_only;
+#endif /* #if HAVE_OPEN_MEMSTREAM */
while (trace())
;
+#if HAVE_OPEN_MEMSTREAM
+ /* during cleanup and shutdown don't print to internal memf stream */
+ stage_output = false;
+#endif /* #if HAVE_OPEN_MEMSTREAM */
cleanup();
fflush(NULL);
if (shared_log != stderr)
diff --git a/syscall.c b/syscall.c
index 9de3056..a9be536 100644
--- a/syscall.c
+++ b/syscall.c
@@ -6,6 +6,7 @@
* Copyright (c) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Linux for s390 port by D.J. Barrow
* <bar...@ma...,djb...@de...>
+ * Copyright (C) 2016-2017 Intel Deutschland GmbH
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -796,6 +797,17 @@ trace_syscall_exiting(struct tcb *tcp)
if (tcp->qual_flg & QUAL_RAW) {
/* sys_res = printargs(tcp); - but it's nop on sysexit */
} else {
+#if HAVE_OPEN_MEMSTREAM
+ if (stage_output) {
+ if ( (not_failing_only && syserror(tcp) ) || (failing_only && !syserror(tcp)) ) {
+ drop_staged_out(tcp);
+ line_ended();
+ goto ret; /* ignore failed/successful syscalls */
+ }
+ } else {
+ /* publish staged output later */
+ }
+#else
/* FIXME: not_failing_only (IOW, option -z) is broken:
* failure of syscall is known only after syscall return.
* Thus we end up with something like this on, say, ENOENT:
@@ -806,6 +818,7 @@ trace_syscall_exiting(struct tcb *tcp)
*/
if (not_failing_only && tcp->u_error)
goto ret; /* ignore failed syscalls */
+#endif /* #if HAVE_OPEN_MEMSTREAM */
if (tcp->sys_func_rval & RVAL_DECODED)
sys_res = tcp->sys_func_rval;
else
@@ -952,6 +965,11 @@ trace_syscall_exiting(struct tcb *tcp)
}
tprints("\n");
dumpio(tcp);
+#if HAVE_OPEN_MEMSTREAM
+ if (stage_output) {
+ publish_staged_out(tcp);
+ }
+#endif /* #if HAVE_OPEN_MEMSTREAM */
line_ended();
#ifdef USE_LIBUNWIND
--
1.9.1
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