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, 162 insertions, 0 deletions

diff --git a/tools/perf/pmu-events/json.c b/tools/perf/pmu-events/json.c
new file mode 100644
index 000000000000..f67bbb0aa36e
--- /dev/null
+++ b/tools/perf/pmu-events/json.c
@@ -0,0 +1,162 @@
+/* Parse JSON files using the JSMN parser. */
+
+/*
+ * Copyright (c) 2014, Intel Corporation
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "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
+ * COPYRIGHT HOLDER OR CONTRIBUTORS 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.
+*/
+
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <errno.h>
+#include <unistd.h>
+#include "jsmn.h"
+#include "json.h"
+#include <linux/kernel.h>
+
+
+static char *mapfile(const char *fn, size_t *size)
+{
+	unsigned ps = sysconf(_SC_PAGESIZE);
+	struct stat st;
+	char *map = NULL;
+	int err;
+	int fd = open(fn, O_RDONLY);
+
+	if (fd < 0 && verbose && fn) {
+		pr_err("Error opening events file '%s': %s\n", fn,
+				strerror(errno));
+	}
+
+	if (fd < 0)
+		return NULL;
+	err = fstat(fd, &st);
+	if (err < 0)
+		goto out;
+	*size = st.st_size;
+	map = mmap(NULL,
+		   (st.st_size + ps - 1) & ~(ps - 1),
+		   PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
+	if (map == MAP_FAILED)
+		map = NULL;
+out:
+	close(fd);
+	return map;
+}
+
+static void unmapfile(char *map, size_t size)
+{
+	unsigned ps = sysconf(_SC_PAGESIZE);
+	munmap(map, roundup(size, ps));
+}
+
+/*
+ * Parse json file using jsmn. Return array of tokens,
+ * and mapped file. Caller needs to free array.
+ */
+jsmntok_t *parse_json(const char *fn, char **map, size_t *size, int *len)
+{
+	jsmn_parser parser;
+	jsmntok_t *tokens;
+	jsmnerr_t res;
+	unsigned sz;
+
+	*map = mapfile(fn, size);
+	if (!*map)
+		return NULL;
+	/* Heuristic */
+	sz = *size * 16;
+	tokens = malloc(sz);
+	if (!tokens)
+		goto error;
+	jsmn_init(&parser);
+	res = jsmn_parse(&parser, *map, *size, tokens,
+			 sz / sizeof(jsmntok_t));
+	if (res != JSMN_SUCCESS) {
+		pr_err("%s: json error %s\n", fn, jsmn_strerror(res));
+		goto error_free;
+	}
+	if (len)
+		*len = parser.toknext;
+	return tokens;
+error_free:
+	free(tokens);
+error:
+	unmapfile(*map, *size);
+	return NULL;
+}
+
+void free_json(char *map, size_t size, jsmntok_t *tokens)
+{
+	free(tokens);
+	unmapfile(map, size);
+}
+
+static int countchar(char *map, char c, int end)
+{
+	int i;
+	int count = 0;
+	for (i = 0; i < end; i++)
+		if (map[i] == c)
+			count++;
+	return count;
+}
+
+/* Return line number of a jsmn token */
+int json_line(char *map, jsmntok_t *t)
+{
+	return countchar(map, '\n', t->start) + 1;
+}
+
+static const char * const jsmn_types[] = {
+	[JSMN_PRIMITIVE] = "primitive",
+	[JSMN_ARRAY] = "array",
+	[JSMN_OBJECT] = "object",
+	[JSMN_STRING] = "string"
+};
+
+#define LOOKUP(a, i) ((i) < (sizeof(a)/sizeof(*(a))) ? ((a)[i]) : "?")
+
+/* Return type name of a jsmn token */
+const char *json_name(jsmntok_t *t)
+{
+	return LOOKUP(jsmn_types, t->type);
+}
+
+int json_len(jsmntok_t *t)
+{
+	return t->end - t->start;
+}
+
+/* Is string t equal to s? */
+int json_streq(char *map, jsmntok_t *t, const char *s)
+{
+	unsigned len = json_len(t);
+	return len == strlen(s) && !strncasecmp(map + t->start, s, len);
+}