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Date: Fri, 11 Sep 2015 19:00:03 +0300
From: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To: Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Ingo Molnar <mingo@...hat.com>
Cc: linux-kernel@...r.kernel.org, vince@...ter.net, eranian@...gle.com,
johannes@...solutions.net,
Arnaldo Carvalho de Melo <acme@...radead.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Subject: [PATCH RFC v3 4/6] perf tools: Add a simple JSON parser
In order to process kernel's extended syscall error reports, we need a
JSON parser. This one I wrote myself, it should be very simple and
straightforward and extensible when/if somebody needs more features from
it.
Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
---
tools/include/tools/json.h | 40 ++++++++
tools/lib/util/json.c | 250 +++++++++++++++++++++++++++++++++++++++++++++
tools/perf/util/Build | 5 +
3 files changed, 295 insertions(+)
create mode 100644 tools/include/tools/json.h
create mode 100644 tools/lib/util/json.c
diff --git a/tools/include/tools/json.h b/tools/include/tools/json.h
new file mode 100644
index 0000000000..a1684574c2
--- /dev/null
+++ b/tools/include/tools/json.h
@@ -0,0 +1,40 @@
+/*
+ * A simple JSON parser
+ * Copyright (c) 2015, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ */
+
+#ifndef _TOOLS_JSON_H
+#define _TOOLS_JSON_H
+
+#define JSON_DEPTH 8
+
+struct json_member {
+ const char *key;
+ char *value;
+ unsigned int size;
+};
+
+struct json_parser {
+ const char *buffer;
+ const char *end;
+ const char *cursor;
+ unsigned int state;
+ unsigned int level;
+ unsigned char stack[JSON_DEPTH];
+ struct json_member *schema;
+ unsigned int schema_strict;
+ int key;
+};
+
+int parse_json(struct json_parser *p);
+
+#endif /* _TOOLS_JSON_H */
diff --git a/tools/lib/util/json.c b/tools/lib/util/json.c
new file mode 100644
index 0000000000..029c244d0e
--- /dev/null
+++ b/tools/lib/util/json.c
@@ -0,0 +1,250 @@
+/*
+ * A simple JSON parser
+ * Copyright (c) 2015, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ */
+
+#include <string.h>
+#include <errno.h>
+#include <ctype.h>
+
+#include "tools/json.h"
+
+enum {
+ JS_VALUE = 0,
+ JS_SEPARATOR,
+ JS_KEY,
+ JS_END,
+};
+
+enum {
+ OBJECT = 0,
+ ARRAY,
+ LITERAL,
+};
+
+static int got_key(struct json_parser *p, unsigned int back)
+{
+ const char *key = p->cursor - back;
+ int i;
+
+ for (i = 0; p->schema[i].key; i++) {
+ struct json_member *m = &p->schema[i];
+
+ if (!strncmp(key, m->key, strlen(m->key))) {
+ p->key = i;
+ return 0;
+ }
+ }
+
+ p->key = -1;
+ return p->schema_strict ? -EINVAL : 0;
+}
+
+static int got_value(struct json_parser *p, unsigned int back)
+{
+ unsigned int len = back;
+
+ if (p->key < 0)
+ return p->schema_strict ? -EINVAL : 0;
+
+ if (len > p->schema[p->key].size)
+ len = p->schema[p->key].size;
+
+ memcpy(p->schema[p->key].value, p->cursor - back, len);
+ p->schema[p->key].value[len] = 0;
+ p->key = -1;
+ return 0;
+}
+
+static int consume_string(struct json_parser *p)
+{
+ int ret = 0;
+
+ for (p->cursor++; p->cursor < p->end;
+ p->cursor++, ret++) {
+ switch(*p->cursor) {
+ case '"':
+ goto done;
+ case '\\':
+ p->cursor++;
+ ret++;
+ default:
+ continue;
+ }
+ }
+
+ return -EINVAL;
+
+done:
+ if (p->state == JS_KEY)
+ ret = got_key(p, ret);
+ else if (p->state == JS_VALUE)
+ ret = got_value(p, ret);
+
+ return ret;
+}
+
+static int consume_number(struct json_parser *p)
+{
+ unsigned int hex = 0;
+ int ret = 0;
+
+ for (; p->cursor < p->end;
+ p->cursor++, ret++) {
+ switch (*p->cursor) {
+ case '.': /* float */
+ if (!ret)
+ return -EINVAL;
+ continue;
+ case 'x': /* hex */
+ if (ret != 1 || *(p->cursor - 1) != '0')
+ return -EINVAL;
+ hex = 1;
+ continue;
+ case '-': /* negative */
+ if (ret)
+ return -EINVAL;
+ continue;
+ default:
+ if (!hex && !isdigit(*p->cursor))
+ goto done;
+ if (hex && !isxdigit(*p->cursor))
+ goto done;
+
+ continue;
+ }
+ }
+
+ return -EINVAL;
+
+done:
+ if (p->state == JS_KEY)
+ return -EINVAL;
+ else if (p->state == JS_VALUE)
+ ret = got_value(p, ret);
+
+ p->cursor--;
+
+ return ret;
+}
+
+int parse_json(struct json_parser *p)
+{
+ int ret;
+
+ p->key = -1;
+ p->level = 0;
+ p->stack[0] = ARRAY;
+
+ for (p->cursor = p->buffer, p->state = JS_VALUE;
+ p->cursor < p->end; p->cursor++) {
+ switch (*p->cursor) {
+ case ' ':
+ case '\t':
+ case '\n':
+ /* doesn't change state */
+ continue;
+ case '{':
+ if (p->state != JS_VALUE)
+ return -EINVAL;
+
+ p->stack[++p->level] = OBJECT;
+ p->state = JS_KEY;
+ break;
+ case '}':
+ if ((p->state != JS_END && p->state != JS_KEY) ||
+ !p->level)
+ return -EINVAL;
+
+ p->level--;
+ p->state = JS_END;
+ break;
+ case ':':
+ if (p->state != JS_SEPARATOR)
+ return -EINVAL;
+
+ p->state = JS_VALUE;
+ break;
+ case '[':
+ if (p->state != JS_VALUE)
+ return -EINVAL;
+
+ p->stack[++p->level] = OBJECT;
+ p->state = JS_VALUE;
+ break;
+ case ']':
+ if ((p->state != JS_END && p->state != JS_VALUE) ||
+ !p->level)
+ return -EINVAL;
+
+ p->level--;
+ /* still JS_END */
+ break;
+ case '"':
+ /* consume everything up to the matching quote */
+ ret = consume_string(p);
+ if (ret < 0)
+ return ret;
+
+ switch (p->state) {
+ case JS_KEY:
+ p->state = JS_SEPARATOR;
+ break;
+ case JS_VALUE:
+ p->state = JS_END;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ continue;
+ case ',':
+ if (p->state != JS_END)
+ return -EINVAL;
+
+ if (p->stack[p->level] == ARRAY)
+ p->state = JS_VALUE;
+ else /* OBJECT */
+ p->state = JS_KEY;
+ break;
+ default:
+ if (p->state != JS_VALUE)
+ return -EINVAL;
+
+ if (isdigit(*p->cursor) || *p->cursor == '-') {
+ ret = consume_number(p);
+ if (ret < 0)
+ return ret;
+ } else if (!strncasecmp(p->cursor, "null", 4)) {
+ p->cursor += 3;
+ got_value(p, 4);
+ } else if (!strncasecmp(p->cursor, "true", 4)) {
+ p->cursor += 3;
+ got_value(p, 4);
+ } else if (!strncasecmp(p->cursor, "false", 5)) {
+ p->cursor += 4;
+ got_value(p, 5);
+ } else {
+ return -EINVAL;
+ }
+
+ p->state = JS_END;
+ break;
+ }
+ }
+
+ if (p->level || p->state != JS_END)
+ return -EINVAL;
+
+ return 0;
+}
+
diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index 349bc96ca1..af5acb9a02 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -12,6 +12,7 @@ libperf-y += evsel.o
libperf-y += exec_cmd.o
libperf-y += find_next_bit.o
libperf-y += help.o
+libperf-y += json.o
libperf-y += kallsyms.o
libperf-y += levenshtein.o
libperf-y += llvm-utils.o
@@ -147,6 +148,10 @@ $(OUTPUT)util/find_next_bit.o: ../lib/util/find_next_bit.c FORCE
$(call rule_mkdir)
$(call if_changed_dep,cc_o_c)
+$(OUTPUT)util/json.o: ../lib/util/json.c FORCE
+ $(call rule_mkdir)
+ $(call if_changed_dep,cc_o_c)
+
$(OUTPUT)util/rbtree.o: ../lib/rbtree.c FORCE
$(call rule_mkdir)
$(call if_changed_dep,cc_o_c)
--
2.5.1
--
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