Re: [PATCH v2 5/5] perf-probe: Support escaped character in parser

[Masami Hiramatsu <mhiramat@kernel.org>]

On Fri, 8 Dec 2017 12:45:45 +0100
Thomas-Mich Richter <tmricht@linux.vnet.ibm.com> wrote:

> On 12/07/2017 08:21 AM, Masami Hiramatsu wrote:
> > Support the special characters escaped by '\' in parser.
> > This allows user to specify versions directly like below.
> > 
> >   =====
> >   # ./perf probe -x /lib64/libc-2.25.so malloc_get_state\\@GLIBC_2.2.5
> >   Added new event:
> >     probe_libc:malloc_get_state (on malloc_get_state@GLIBC_2.2.5 in /usr/lib64/libc-2.25.so)
> > 
> >   You can now use it in all perf tools, such as:
> > 
> > 	  perf record -e probe_libc:malloc_get_state -aR sleep 1
> > 
> >   =====
> > 
> > Or, you can use separators in source filename, e.g.
> > 
> >   =====
> >   # ./perf probe -x /opt/test/a.out foo+bar.c:3
> >   Semantic error :There is non-digit character in offset.
> >     Error: Command Parse Error.
> >   =====
> > 
> > Usually "+" in source file cause parser error, but
> > 
> >   =====
> >   # ./perf probe -x /opt/test/a.out foo\\+bar.c:4
> >   Added new event:
> >     probe_a:main         (on @foo+bar.c:4 in /opt/test/a.out)
> > 
> >   You can now use it in all perf tools, such as:
> > 
> > 	  perf record -e probe_a:main -aR sleep 1
> >   =====
> > 
> > escaped "\+" allows you to specify that.
> > 
> > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> > ---
> >  Changes in v2:
> >   - Add a description and samples in Documentation/perf-probe.txt
> > ---
> >  tools/perf/Documentation/perf-probe.txt |   16 +++++++++
> >  tools/perf/util/probe-event.c           |   54 +++++++++++++++++++------------
> >  tools/perf/util/string.c                |   46 ++++++++++++++++++++++++++
> >  tools/perf/util/string2.h               |    2 +
> >  4 files changed, 97 insertions(+), 21 deletions(-)
> > 
> > diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
> > index f96382692f42..b6866a05edd2 100644
> > --- a/tools/perf/Documentation/perf-probe.txt
> > +++ b/tools/perf/Documentation/perf-probe.txt
> > @@ -182,6 +182,14 @@ Note that before using the SDT event, the target binary (on which SDT events are
> >  For details of the SDT, see below.
> >  https://sourceware.org/gdb/onlinedocs/gdb/Static-Probe-Points.html
> > 
> > +ESCAPED CHARACTER
> > +-----------------
> > +
> > +In the probe syntax, '=', '@', '+', ':' and ';' are treated as a special character. You can use a backslash ('\') to escape the special characters.
> > +This is useful if you need to probe on a specific versioned symbols, like @GLIBC_... suffixes, or also you need to specify a source file which includes the special characters.
> > +Note that usually single backslash is consumed by shell, so you might need to pass double backslash (\\) or wrapping with single quotes (\'AAA\@BBB').
> > +See EXAMPLES how it is used.
> > +
> >  PROBE ARGUMENT
> >  --------------
> >  Each probe argument follows below syntax.
> > @@ -277,6 +285,14 @@ Add a USDT probe to a target process running in a different mount namespace
> > 
> >   ./perf probe --target-ns <target pid> -x /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.121-0.b13.el7_3.x86_64/jre/lib/amd64/server/libjvm.so %sdt_hotspot:thread__sleep__end
> > 
> > +Add a probe on specific versioned symbol by backslash escape
> > +
> > + ./perf probe -x /lib64/libc-2.25.so 'malloc_get_state\@GLIBC_2.2.5'
> > +
> > +Add a probe in a source file using special characters by backslash escape
> > +
> > + ./perf probe -x /opt/test/a.out 'foo\+bar.c:4'
> > +
> > 
> >  SEE ALSO
> >  --------
> > diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> > index 94acc5846e2a..c082a27982e5 100644
> > --- a/tools/perf/util/probe-event.c
> > +++ b/tools/perf/util/probe-event.c
> > @@ -1325,27 +1325,30 @@ static int parse_perf_probe_event_name(char **arg, struct perf_probe_event *pev)
> >  {
> >  	char *ptr;
> > 
> > -	ptr = strchr(*arg, ':');
> > +	ptr = strpbrk_esc(*arg, ":");
> >  	if (ptr) {
> >  		*ptr = '\0';
> >  		if (!pev->sdt && !is_c_func_name(*arg))
> >  			goto ng_name;
> > -		pev->group = strdup(*arg);
> > +		pev->group = strdup_esc(*arg);
> >  		if (!pev->group)
> >  			return -ENOMEM;
> >  		*arg = ptr + 1;
> >  	} else
> >  		pev->group = NULL;
> > -	if (!pev->sdt && !is_c_func_name(*arg)) {
> > +
> > +	pev->event = strdup_esc(*arg);
> > +	if (pev->event == NULL)
> > +		return -ENOMEM;
> > +
> > +	if (!pev->sdt && !is_c_func_name(pev->event)) {
> > +		zfree(&pev->event);
> >  ng_name:
> > +		zfree(&pev->group);
> >  		semantic_error("%s is bad for event name -it must "
> >  			       "follow C symbol-naming rule.\n", *arg);
> >  		return -EINVAL;
> >  	}
> > -	pev->event = strdup(*arg);
> > -	if (pev->event == NULL)
> > -		return -ENOMEM;
> > -
> >  	return 0;
> >  }
> > 
> > @@ -1373,7 +1376,7 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
> >  			arg++;
> >  	}
> > 
> > -	ptr = strpbrk(arg, ";=@+%");
> > +	ptr = strpbrk_esc(arg, ";=@+%");
> >  	if (pev->sdt) {
> >  		if (ptr) {
> >  			if (*ptr != '@') {
> > @@ -1387,7 +1390,7 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
> >  				pev->target = build_id_cache__origname(tmp);
> >  				free(tmp);
> >  			} else
> > -				pev->target = strdup(ptr + 1);
> > +				pev->target = strdup_esc(ptr + 1);
> >  			if (!pev->target)
> >  				return -ENOMEM;
> >  			*ptr = '\0';
> > @@ -1421,13 +1424,14 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
> >  	 *
> >  	 * Otherwise, we consider arg to be a function specification.
> >  	 */
> > -	if (!strpbrk(arg, "+@%") && (ptr = strpbrk(arg, ";:")) != NULL) {
> > +	if (!strpbrk_esc(arg, "+@%")) {
> > +		ptr = strpbrk_esc(arg, ";:");
> >  		/* This is a file spec if it includes a '.' before ; or : */
> > -		if (memchr(arg, '.', ptr - arg))
> > +		if (ptr && memchr(arg, '.', ptr - arg))
> >  			file_spec = true;
> >  	}
> > 
> > -	ptr = strpbrk(arg, ";:+@%");
> > +	ptr = strpbrk_esc(arg, ";:+@%");
> >  	if (ptr) {
> >  		nc = *ptr;
> >  		*ptr++ = '\0';
> > @@ -1436,7 +1440,7 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
> >  	if (arg[0] == '\0')
> >  		tmp = NULL;
> >  	else {
> > -		tmp = strdup(arg);
> > +		tmp = strdup_esc(arg);
> >  		if (tmp == NULL)
> >  			return -ENOMEM;
> >  	}
> > @@ -1469,12 +1473,12 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
> >  		arg = ptr;
> >  		c = nc;
> >  		if (c == ';') {	/* Lazy pattern must be the last part */
> > -			pp->lazy_line = strdup(arg);
> > +			pp->lazy_line = strdup(arg); /* let leave escapes */
> >  			if (pp->lazy_line == NULL)
> >  				return -ENOMEM;
> >  			break;
> >  		}
> > -		ptr = strpbrk(arg, ";:+@%");
> > +		ptr = strpbrk_esc(arg, ";:+@%");
> >  		if (ptr) {
> >  			nc = *ptr;
> >  			*ptr++ = '\0';
> > @@ -1501,7 +1505,7 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
> >  				semantic_error("SRC@SRC is not allowed.\n");
> >  				return -EINVAL;
> >  			}
> > -			pp->file = strdup(arg);
> > +			pp->file = strdup_esc(arg);
> >  			if (pp->file == NULL)
> >  				return -ENOMEM;
> >  			break;
> > @@ -2803,21 +2807,29 @@ static int find_probe_functions(struct map *map, char *name,
> >  	struct rb_node *tmp;
> >  	const char *norm, *ver;
> >  	char *buf = NULL;
> > +	bool cut_version = true;
> > 
> >  	if (map__load(map) < 0)
> >  		return 0;
> > 
> > +	/* If user gives a version, don't cut off the version from symbols */
> > +	if (strchr(name, '@'))
> > +		cut_version = false;
> > +
> >  	map__for_each_symbol(map, sym, tmp) {
> >  		norm = arch__normalize_symbol_name(sym->name);
> 
> Same as before (patch 4)
> 
> >  		if (!norm)
> >  			continue;
> > 
> > -		/* We don't care about default symbol or not */
> > -		ver = strchr(norm, '@');
> > -		if (ver) {
> > -			buf = strndup(norm, ver - norm);
> > -			norm = buf;
> 
> Again strndup() may return a NULL ptr and then strglobmatch() / strchr() below
> dereferences it.

OK, but those will be fixed in patch 4/5.
(Of course below block should be updated)

Anyway, Thank you!

> 
> > +		if (cut_version) {
> > +			/* We don't care about default symbol or not */
> > +			ver = strchr(norm, '@');
> > +			if (ver) {
> > +				buf = strndup(norm, ver - norm);
> > +				norm = buf;
> > +			}
> >  		}
> > +
> >  		if (strglobmatch(norm, name)) {
> >  			found++;
> >  			if (syms && found < probe_conf.max_probes)
> > diff --git a/tools/perf/util/string.c b/tools/perf/util/string.c
> > index aaa08ee8c717..d8bfd0c4d2cb 100644
> > --- a/tools/perf/util/string.c
> > +++ b/tools/perf/util/string.c
> > @@ -396,3 +396,49 @@ char *asprintf_expr_inout_ints(const char *var, bool in, size_t nints, int *ints
> >  	free(expr);
> >  	return NULL;
> >  }
> > +
> > +/* Like strpbrk(), but not break if it is right after a backslash (escaped) */
> > +char *strpbrk_esc(char *str, const char *stopset)
> > +{
> > +	char *ptr;
> > +
> > +	do {
> > +		ptr = strpbrk(str, stopset);
> > +		if (ptr == str ||
> > +		    (ptr == str + 1 && *(ptr - 1) != '\\'))
> > +			break;
> > +		str = ptr + 1;
> > +	} while (ptr && *(ptr - 1) == '\\' && *(ptr - 2) != '\\');
> > +
> > +	return ptr;
> > +}
> > +
> > +/* Like strdup, but do not copy a single backslash */
> > +char *strdup_esc(const char *str)
> > +{
> > +	char *s, *d, *p, *ret = strdup(str);
> > +
> > +	if (!ret)
> > +		return NULL;
> > +
> > +	d = strchr(ret, '\\');
> > +	if (!d)
> > +		return ret;
> > +
> > +	s = d + 1;
> > +	do {
> > +		if (*s == '\0') {
> > +			*d = '\0';
> > +			break;
> > +		}
> > +		p = strchr(s + 1, '\\');
> > +		if (p) {
> > +			memmove(d, s, p - s);
> > +			d += p - s;
> > +			s = p + 1;
> > +		} else
> > +			memmove(d, s, strlen(s) + 1);
> > +	} while (p);
> > +
> > +	return ret;
> > +}
> > diff --git a/tools/perf/util/string2.h b/tools/perf/util/string2.h
> > index ee14ca5451ab..4c68a09b97e8 100644
> > --- a/tools/perf/util/string2.h
> > +++ b/tools/perf/util/string2.h
> > @@ -39,5 +39,7 @@ static inline char *asprintf_expr_not_in_ints(const char *var, size_t nints, int
> >  	return asprintf_expr_inout_ints(var, false, nints, ints);
> >  }
> > 
> > +char *strpbrk_esc(char *str, const char *stopset);
> > +char *strdup_esc(const char *str);
> > 
> >  #endif /* PERF_STRING_H */
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-perf-users" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > 
> 
> 
> -- 
> Thomas Richter, Dept 3303, IBM LTC Boeblingen Germany
> --
> Vorsitzende des Aufsichtsrats: Martina Koederitz 
> Geschäftsführung: Dirk Wittkopp
> Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294
> 


-- 
Masami Hiramatsu <mhiramat@kernel.org>