perf probe: Use strbuf for making strings

Replace many fixed-length char array with strbuf to stringify
perf_probe_event and probe_trace_event etc.

Signed-off-by: Masami Hiramatsu <[email protected]>
Signed-off-by: Masami Hiramatsu <[email protected]>
Cc: Ananth N Mavinakayanahalli <[email protected]>
Cc: Hemant Kumar <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/20160427183713.23446.97377.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: mhiramathitachi

tools/perf/util/probe-event.c

@@ -1673,69 +1673,51 @@ int parse_probe_trace_command(const char *cmd, struct probe_trace_event *tev)
 }
 
 /* Compose only probe arg */
-int synthesize_perf_probe_arg(struct perf_probe_arg *pa, char *buf, size_t len)
+char *synthesize_perf_probe_arg(struct perf_probe_arg *pa)
 {
 	struct perf_probe_arg_field *field = pa->field;
-	int ret;
-	char *tmp = buf;
+	struct strbuf buf;
+	char *ret;
 
+	strbuf_init(&buf, 64);
 	if (pa->name && pa->var)
-		ret = e_snprintf(tmp, len, "%s=%s", pa->name, pa->var);
+		strbuf_addf(&buf, "%s=%s", pa->name, pa->var);
 	else
-		ret = e_snprintf(tmp, len, "%s", pa->name ? pa->name : pa->var);
-	if (ret <= 0)
-		goto error;
-	tmp += ret;
-	len -= ret;
+		strbuf_addstr(&buf, pa->name ?: pa->var);
 
 	while (field) {
 		if (field->name[0] == '[')
-			ret = e_snprintf(tmp, len, "%s", field->name);
+			strbuf_addstr(&buf, field->name);
 		else
-			ret = e_snprintf(tmp, len, "%s%s",
-					 field->ref ? "->" : ".", field->name);
-		if (ret <= 0)
-			goto error;
-		tmp += ret;
-		len -= ret;
+			strbuf_addf(&buf, "%s%s", field->ref ? "->" : ".",
+				    field->name);
 		field = field->next;
 	}
 
-	if (pa->type) {
-		ret = e_snprintf(tmp, len, ":%s", pa->type);
-		if (ret <= 0)
-			goto error;
-		tmp += ret;
-		len -= ret;
-	}
+	if (pa->type)
+		strbuf_addf(&buf, ":%s", pa->type);
+
+	ret = strbuf_detach(&buf, NULL);
 
-	return tmp - buf;
-error:
-	pr_debug("Failed to synthesize perf probe argument: %d\n", ret);
 	return ret;
 }
 
 /* Compose only probe point (not argument) */
 static char *synthesize_perf_probe_point(struct perf_probe_point *pp)
 {
-	char *buf, *tmp;
-	char offs[32] = "", line[32] = "", file[32] = "";
-	int ret, len;
-
-	buf = zalloc(MAX_CMDLEN);
-	if (buf == NULL) {
-		ret = -ENOMEM;
-		goto error;
-	}
-	if (pp->offset) {
-		ret = e_snprintf(offs, 32, "+%lu", pp->offset);
-		if (ret <= 0)
-			goto error;
-	}
-	if (pp->line) {
-		ret = e_snprintf(line, 32, ":%d", pp->line);
-		if (ret <= 0)
-			goto error;
+	struct strbuf buf;
+	char *tmp;
+	int len;
+
+	strbuf_init(&buf, 64);
+	if (pp->function) {
+		strbuf_addstr(&buf, pp->function);
+		if (pp->offset)
+			strbuf_addf(&buf, "+%lu", pp->offset);
+		else if (pp->line)
+			strbuf_addf(&buf, ":%d", pp->line);
+		else if (pp->retprobe)
+			strbuf_addstr(&buf, "%return");
 	}
 	if (pp->file) {
 		tmp = pp->file;
@@ -1744,25 +1726,12 @@ static char *synthesize_perf_probe_point(struct perf_probe_point *pp)
 			tmp = strchr(pp->file + len - 30, '/');
 			tmp = tmp ? tmp + 1 : pp->file + len - 30;
 		}
-		ret = e_snprintf(file, 32, "@%s", tmp);
-		if (ret <= 0)
-			goto error;
+		strbuf_addf(&buf, "@%s", tmp);
+		if (!pp->function && pp->line)
+			strbuf_addf(&buf, ":%d", pp->line);
 	}
 
-	if (pp->function)
-		ret = e_snprintf(buf, MAX_CMDLEN, "%s%s%s%s%s", pp->function,
-				 offs, pp->retprobe ? "%return" : "", line,
-				 file);
-	else
-		ret = e_snprintf(buf, MAX_CMDLEN, "%s%s", file, line);
-	if (ret <= 0)
-		goto error;
-
-	return buf;
-error:
-	pr_debug("Failed to synthesize perf probe point: %d\n", ret);
-	free(buf);
-	return NULL;
+	return strbuf_detach(&buf, NULL);
 }
 
 #if 0
@@ -1791,106 +1760,72 @@ char *synthesize_perf_probe_command(struct perf_probe_event *pev)
 #endif
 
 static int __synthesize_probe_trace_arg_ref(struct probe_trace_arg_ref *ref,
-					     char **buf, size_t *buflen,
-					     int depth)
+					    struct strbuf *buf, int depth)
 {
-	int ret;
 	if (ref->next) {
 		depth = __synthesize_probe_trace_arg_ref(ref->next, buf,
-							 buflen, depth + 1);
+							 depth + 1);
 		if (depth < 0)
 			goto out;
 	}
-
-	ret = e_snprintf(*buf, *buflen, "%+ld(", ref->offset);
-	if (ret < 0)
-		depth = ret;
-	else {
-		*buf += ret;
-		*buflen -= ret;
-	}
+	strbuf_addf(buf, "%+ld(", ref->offset);
 out:
 	return depth;
-
 }
 
 static int synthesize_probe_trace_arg(struct probe_trace_arg *arg,
-				       char *buf, size_t buflen)
+				      struct strbuf *buf)
 {
 	struct probe_trace_arg_ref *ref = arg->ref;
-	int ret, depth = 0;
-	char *tmp = buf;
+	int depth = 0;
 
 	/* Argument name or separator */
 	if (arg->name)
-		ret = e_snprintf(buf, buflen, " %s=", arg->name);
+		strbuf_addf(buf, " %s=", arg->name);
 	else
-		ret = e_snprintf(buf, buflen, " ");
-	if (ret < 0)
-		return ret;
-	buf += ret;
-	buflen -= ret;
+		strbuf_addch(buf, ' ');
 
 	/* Special case: @XXX */
 	if (arg->value[0] == '@' && arg->ref)
 			ref = ref->next;
 
 	/* Dereferencing arguments */
 	if (ref) {
-		depth = __synthesize_probe_trace_arg_ref(ref, &buf,
-							  &buflen, 1);
+		depth = __synthesize_probe_trace_arg_ref(ref, buf, 1);
 		if (depth < 0)
 			return depth;
 	}
 
 	/* Print argument value */
 	if (arg->value[0] == '@' && arg->ref)
-		ret = e_snprintf(buf, buflen, "%s%+ld", arg->value,
-				 arg->ref->offset);
+		strbuf_addf(buf, "%s%+ld", arg->value, arg->ref->offset);
 	else
-		ret = e_snprintf(buf, buflen, "%s", arg->value);
-	if (ret < 0)
-		return ret;
-	buf += ret;
-	buflen -= ret;
+		strbuf_addstr(buf, arg->value);
 
 	/* Closing */
-	while (depth--) {
-		ret = e_snprintf(buf, buflen, ")");
-		if (ret < 0)
-			return ret;
-		buf += ret;
-		buflen -= ret;
-	}
+	while (depth--)
+		strbuf_addch(buf, ')');
 	/* Print argument type */
-	if (arg->type) {
-		ret = e_snprintf(buf, buflen, ":%s", arg->type);
-		if (ret <= 0)
-			return ret;
-		buf += ret;
-	}
+	if (arg->type)
+		strbuf_addf(buf, ":%s", arg->type);
 
-	return buf - tmp;
+	return 0;
 }
 
 char *synthesize_probe_trace_command(struct probe_trace_event *tev)
 {
 	struct probe_trace_point *tp = &tev->point;
-	char *buf;
-	int i, len, ret;
-
-	buf = zalloc(MAX_CMDLEN);
-	if (buf == NULL)
-		return NULL;
-
-	len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s ", tp->retprobe ? 'r' : 'p',
-			 tev->group, tev->event);
-	if (len <= 0)
-		goto error;
+	struct strbuf buf;
+	char *ret = NULL;
+	int i;
 
 	/* Uprobes must have tp->module */
 	if (tev->uprobes && !tp->module)
-		goto error;
+		return NULL;
+
+	strbuf_init(&buf, 32);
+	strbuf_addf(&buf, "%c:%s/%s ", tp->retprobe ? 'r' : 'p',
+		    tev->group, tev->event);
 	/*
 	 * If tp->address == 0, then this point must be a
 	 * absolute address uprobe.
@@ -1904,34 +1839,23 @@ char *synthesize_probe_trace_command(struct probe_trace_event *tev)
 
 	/* Use the tp->address for uprobes */
 	if (tev->uprobes)
-		ret = e_snprintf(buf + len, MAX_CMDLEN - len, "%s:0x%lx",
-				 tp->module, tp->address);
+		strbuf_addf(&buf, "%s:0x%lx", tp->module, tp->address);
 	else if (!strncmp(tp->symbol, "0x", 2))
 		/* Absolute address. See try_to_find_absolute_address() */
-		ret = e_snprintf(buf + len, MAX_CMDLEN - len, "%s%s0x%lx",
-				 tp->module ?: "", tp->module ? ":" : "",
-				 tp->address);
+		strbuf_addf(&buf, "%s%s0x%lx", tp->module ?: "",
+			    tp->module ? ":" : "", tp->address);
 	else
-		ret = e_snprintf(buf + len, MAX_CMDLEN - len, "%s%s%s+%lu",
-				 tp->module ?: "", tp->module ? ":" : "",
-				 tp->symbol, tp->offset);
-
-	if (ret <= 0)
-		goto error;
-	len += ret;
+		strbuf_addf(&buf, "%s%s%s+%lu", tp->module ?: "",
+			    tp->module ? ":" : "", tp->symbol, tp->offset);
 
-	for (i = 0; i < tev->nargs; i++) {
-		ret = synthesize_probe_trace_arg(&tev->args[i], buf + len,
-						  MAX_CMDLEN - len);
-		if (ret <= 0)
+	for (i = 0; i < tev->nargs; i++)
+		if (synthesize_probe_trace_arg(&tev->args[i], &buf) < 0)
 			goto error;
-		len += ret;
-	}
 
-	return buf;
+	ret = strbuf_detach(&buf, NULL);
 error:
-	free(buf);
-	return NULL;
+	strbuf_release(&buf);
+	return ret;
 }
 
 static int find_perf_probe_point_from_map(struct probe_trace_point *tp,
@@ -2013,7 +1937,7 @@ static int convert_to_perf_probe_point(struct probe_trace_point *tp,
 static int convert_to_perf_probe_event(struct probe_trace_event *tev,
 			       struct perf_probe_event *pev, bool is_kprobe)
 {
-	char buf[64] = "";
+	struct strbuf buf = STRBUF_INIT;
 	int i, ret;
 
 	/* Convert event/group name */
@@ -2036,9 +1960,9 @@ static int convert_to_perf_probe_event(struct probe_trace_event *tev,
 		if (tev->args[i].name)
 			pev->args[i].name = strdup(tev->args[i].name);
 		else {
-			ret = synthesize_probe_trace_arg(&tev->args[i],
-							  buf, 64);
-			pev->args[i].name = strdup(buf);
+			strbuf_init(&buf, 32);
+			ret = synthesize_probe_trace_arg(&tev->args[i], &buf);
+			pev->args[i].name = strbuf_detach(&buf, NULL);
 		}
 		if (pev->args[i].name == NULL && ret >= 0)
 			ret = -ENOMEM;
@@ -2216,37 +2140,37 @@ static int perf_probe_event__sprintf(const char *group, const char *event,
 				     const char *module,
 				     struct strbuf *result)
 {
-	int i, ret;
-	char buf[128];
-	char *place;
+	int i;
+	char *buf;
 
-	/* Synthesize only event probe point */
-	place = synthesize_perf_probe_point(&pev->point);
-	if (!place)
-		return -EINVAL;
+	if (asprintf(&buf, "%s:%s", group, event) < 0)
+		return -errno;
+	strbuf_addf(result, "  %-20s (on ", buf);
+	free(buf);
 
-	ret = e_snprintf(buf, 128, "%s:%s", group, event);
-	if (ret < 0)
-		goto out;
+	/* Synthesize only event probe point */
+	buf = synthesize_perf_probe_point(&pev->point);
+	if (!buf)
+		return -ENOMEM;
+	strbuf_addstr(result, buf);
+	free(buf);
 
-	strbuf_addf(result, "  %-20s (on %s", buf, place);
 	if (module)
 		strbuf_addf(result, " in %s", module);
 
 	if (pev->nargs > 0) {
 		strbuf_add(result, " with", 5);
 		for (i = 0; i < pev->nargs; i++) {
-			ret = synthesize_perf_probe_arg(&pev->args[i],
-							buf, 128);
-			if (ret < 0)
-				goto out;
+			buf = synthesize_perf_probe_arg(&pev->args[i]);
+			if (!buf)
+				return -ENOMEM;
 			strbuf_addf(result, " %s", buf);
+			free(buf);
 		}
 	}
 	strbuf_addch(result, ')');
-out:
-	free(place);
-	return ret;
+
+	return 0;
 }
 
 /* Show an event */

tools/perf/util/probe-event.h

@@ -120,7 +120,7 @@ int parse_probe_trace_command(const char *cmd, struct probe_trace_event *tev);
 /* Events to command string */
 char *synthesize_perf_probe_command(struct perf_probe_event *pev);
 char *synthesize_probe_trace_command(struct probe_trace_event *tev);
-int synthesize_perf_probe_arg(struct perf_probe_arg *pa, char *buf, size_t len);
+char *synthesize_perf_probe_arg(struct perf_probe_arg *pa);
 
 /* Check the perf_probe_event needs debuginfo */
 bool perf_probe_event_need_dwarf(struct perf_probe_event *pev);