perf tools: Add jsmn `jasmine' JSON parser

I need a JSON parser. This adds the simplest JSON parser I could find --
Serge Zaitsev's jsmn `jasmine' -- to the perf library. I merely
converted it to (mostly) Linux style and added support for non 0
terminated input.

The parser is quite straight forward and does not copy any data, just
returns tokens with offsets into the input buffer. So it's relatively
efficient and simple to use.

The code is not fully checkpatch clean, but I didn't want to completely
fork the upstream code.

Original source: http://zserge.bitbucket.org/jsmn.html

In addition I added a simple wrapper that mmaps a json file and provides
some straight forward access functions.

Used in follow-on patches to parse event files.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/1473978296-20712-2-git-send-email-sukadev@linux.vnet.ibm.com
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
[ Use fcntl.h instead of sys/fcntl.h to fix the build on Alpine Linux 3.4/musl libc,
  use stdbool.h to avoid clashing with 'bool' typedef there ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 67 insertions, 0 deletions

diff --git a/tools/perf/pmu-events/jsmn.h b/tools/perf/pmu-events/jsmn.h
new file mode 100644
index 000000000000..d666b10cf25b
--- /dev/null
+++ b/tools/perf/pmu-events/jsmn.h
@@ -0,0 +1,67 @@
+#ifndef __JSMN_H_
+#define __JSMN_H_
+
+/*
+ * JSON type identifier. Basic types are:
+ *	o Object
+ *	o Array
+ *	o String
+ *	o Other primitive: number, boolean (true/false) or null
+ */
+typedef enum {
+	JSMN_PRIMITIVE = 0,
+	JSMN_OBJECT = 1,
+	JSMN_ARRAY = 2,
+	JSMN_STRING = 3
+} jsmntype_t;
+
+typedef enum {
+	/* Not enough tokens were provided */
+	JSMN_ERROR_NOMEM = -1,
+	/* Invalid character inside JSON string */
+	JSMN_ERROR_INVAL = -2,
+	/* The string is not a full JSON packet, more bytes expected */
+	JSMN_ERROR_PART = -3,
+	/* Everything was fine */
+	JSMN_SUCCESS = 0
+} jsmnerr_t;
+
+/*
+ * JSON token description.
+ * @param		type	type (object, array, string etc.)
+ * @param		start	start position in JSON data string
+ * @param		end		end position in JSON data string
+ */
+typedef struct {
+	jsmntype_t type;
+	int start;
+	int end;
+	int size;
+} jsmntok_t;
+
+/*
+ * JSON parser. Contains an array of token blocks available. Also stores
+ * the string being parsed now and current position in that string
+ */
+typedef struct {
+	unsigned int pos; /* offset in the JSON string */
+	int toknext; /* next token to allocate */
+	int toksuper; /* superior token node, e.g parent object or array */
+} jsmn_parser;
+
+/*
+ * Create JSON parser over an array of tokens
+ */
+void jsmn_init(jsmn_parser *parser);
+
+/*
+ * Run JSON parser. It parses a JSON data string into and array of tokens,
+ * each describing a single JSON object.
+ */
+jsmnerr_t jsmn_parse(jsmn_parser *parser, const char *js,
+		     size_t len,
+		     jsmntok_t *tokens, unsigned int num_tokens);
+
+const char *jsmn_strerror(jsmnerr_t err);
+
+#endif /* __JSMN_H_ */