tools/perf/util/data-convert-json.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * JSON export.
  *
  * Copyright (C) 2021, CodeWeavers Inc. <nfraser@codeweavers.com>
  */

 #include "data-convert.h"

 #include <fcntl.h>
 #include <inttypes.h>
 #include <sys/stat.h>
 #include <unistd.h>

 #include "linux/compiler.h"
 #include "linux/err.h"
 #include "util/auxtrace.h"
 #include "util/debug.h"
 #include "util/dso.h"
 #include "util/event.h"
 #include "util/evsel.h"
 #include "util/evlist.h"
 #include "util/header.h"
 #include "util/map.h"
 #include "util/session.h"
 #include "util/symbol.h"
 #include "util/thread.h"
 #include "util/tool.h"

 #ifdef HAVE_LIBTRACEEVENT
 #include <traceevent/event-parse.h>
 #endif

 struct convert_json {
 	struct perf_tool tool;
 	FILE *out;
 	bool first;
 	u64 events_count;
 };

 // Outputs a JSON-encoded string surrounded by quotes with characters escaped.
 static void output_json_string(FILE *out, const char *s)
 {
 	fputc('"', out);
 	while (*s) {
 		switch (*s) {

 		// required escapes with special forms as per RFC 8259
 		case '"':  fputs("\\\"", out); break;
 		case '\\': fputs("\\\\", out); break;
 		case '\b': fputs("\\b", out);  break;
 		case '\f': fputs("\\f", out);  break;
 		case '\n': fputs("\\n", out);  break;
 		case '\r': fputs("\\r", out);  break;
 		case '\t': fputs("\\t", out);  break;

 		default:
 			// all other control characters must be escaped by hex code
 			if (*s <= 0x1f)
 				fprintf(out, "\\u%04x", *s);
 			else
 				fputc(*s, out);
 			break;
 		}

 		++s;
 	}
 	fputc('"', out);
 }

 // Outputs an optional comma, newline and indentation to delimit a new value
 // from the previous one in a JSON object or array.
 static void output_json_delimiters(FILE *out, bool comma, int depth)
 {
 	int i;

 	if (comma)
 		fputc(',', out);
 	fputc('\n', out);
 	for (i = 0; i < depth; ++i)
 		fputc('\t', out);
 }

 // Outputs a printf format string (with delimiter) as a JSON value.
 __printf(4, 5)
 static void output_json_format(FILE *out, bool comma, int depth, const char *format, ...)
 {
 	va_list args;

 	output_json_delimiters(out, comma, depth);
 	va_start(args, format);
 	vfprintf(out,  format, args);
 	va_end(args);
 }

 // Outputs a JSON key-value pair where the value is a string.
 static void output_json_key_string(FILE *out, bool comma, int depth,
 		const char *key, const char *value)
 {
 	output_json_delimiters(out, comma, depth);
 	output_json_string(out, key);
 	fputs(": ", out);
 	output_json_string(out, value);
 }

 // Outputs a JSON key-value pair where the value is a printf format string.
 __printf(5, 6)
 static void output_json_key_format(FILE *out, bool comma, int depth,
 		const char *key, const char *format, ...)
 {
 	va_list args;

 	output_json_delimiters(out, comma, depth);
 	output_json_string(out, key);
 	fputs(": ", out);
 	va_start(args, format);
 	vfprintf(out,  format, args);
 	va_end(args);
 }

 static void output_sample_callchain_entry(struct perf_tool *tool,
 		u64 ip, struct addr_location *al)
 {
 	struct convert_json *c = container_of(tool, struct convert_json, tool);
 	FILE *out = c->out;

 	output_json_format(out, false, 4, "{");
 	output_json_key_format(out, false, 5, "ip", "\"0x%" PRIx64 "\"", ip);

 	if (al && al->sym && al->sym->namelen) {
 		struct dso *dso = al->map ? map__dso(al->map) : NULL;

 		fputc(',', out);
 		output_json_key_string(out, false, 5, "symbol", al->sym->name);

 		if (dso) {
 			const char *dso_name = dso->short_name;

 			if (dso_name && strlen(dso_name) > 0) {
 				fputc(',', out);
 				output_json_key_string(out, false, 5, "dso", dso_name);
 			}
 		}
 	}

 	output_json_format(out, false, 4, "}");
 }

 static int process_sample_event(struct perf_tool *tool,
 				union perf_event *event __maybe_unused,
 				struct perf_sample *sample,
 				struct evsel *evsel __maybe_unused,
 				struct machine *machine)
 {
 	struct convert_json *c = container_of(tool, struct convert_json, tool);
 	FILE *out = c->out;
 	struct addr_location al, tal;
 	u64 sample_type = __evlist__combined_sample_type(evsel->evlist);
 	u8 cpumode = PERF_RECORD_MISC_USER;

 	if (machine__resolve(machine, &al, sample) < 0) {
 		pr_err("Sample resolution failed!\n");
 		return -1;
 	}

 	++c->events_count;

 	if (c->first)
 		c->first = false;
 	else
 		fputc(',', out);
 	output_json_format(out, false, 2, "{");

 	output_json_key_format(out, false, 3, "timestamp", "%" PRIi64, sample->time);
 	output_json_key_format(out, true, 3, "pid", "%i", al.thread->pid_);
 	output_json_key_format(out, true, 3, "tid", "%i", al.thread->tid);

 	if ((sample_type & PERF_SAMPLE_CPU))
 		output_json_key_format(out, true, 3, "cpu", "%i", sample->cpu);
 	else if (al.thread->cpu >= 0)
 		output_json_key_format(out, true, 3, "cpu", "%i", al.thread->cpu);

 	output_json_key_string(out, true, 3, "comm", thread__comm_str(al.thread));

 	output_json_key_format(out, true, 3, "callchain", "[");
 	if (sample->callchain) {
 		unsigned int i;
 		bool ok;
 		bool first_callchain = true;

 		for (i = 0; i < sample->callchain->nr; ++i) {
 			u64 ip = sample->callchain->ips[i];

 			if (ip >= PERF_CONTEXT_MAX) {
 				switch (ip) {
 				case PERF_CONTEXT_HV:
 					cpumode = PERF_RECORD_MISC_HYPERVISOR;
 					break;
 				case PERF_CONTEXT_KERNEL:
 					cpumode = PERF_RECORD_MISC_KERNEL;
 					break;
 				case PERF_CONTEXT_USER:
 					cpumode = PERF_RECORD_MISC_USER;
 					break;
 				default:
 					pr_debug("invalid callchain context: %"
 							PRId64 "\n", (s64) ip);
 					break;
 				}
 				continue;
 			}

 			if (first_callchain)
 				first_callchain = false;
 			else
 				fputc(',', out);

 			ok = thread__find_symbol(al.thread, cpumode, ip, &tal);
 			output_sample_callchain_entry(tool, ip, ok ? &tal : NULL);
 		}
 	} else {
 		output_sample_callchain_entry(tool, sample->ip, &al);
 	}
 	output_json_format(out, false, 3, "]");

 #ifdef HAVE_LIBTRACEEVENT
 	if (sample->raw_data) {
 		int i;
 		struct tep_format_field **fields;

 		fields = tep_event_fields(evsel->tp_format);
 		if (fields) {
 			i = 0;
 			while (fields[i]) {
 				struct trace_seq s;

 				trace_seq_init(&s);
 				tep_print_field(&s, sample->raw_data, fields[i]);
 				output_json_key_string(out, true, 3, fields[i]->name, s.buffer);

 				i++;
 			}
 			free(fields);
 		}
 	}
 #endif
 	output_json_format(out, false, 2, "}");
 	return 0;
 }

 static void output_headers(struct perf_session *session, struct convert_json *c)
 {
 	struct stat st;
 	struct perf_header *header = &session->header;
 	int ret;
 	int fd = perf_data__fd(session->data);
 	int i;
 	FILE *out = c->out;

 	output_json_key_format(out, false, 2, "header-version", "%u", header->version);

 	ret = fstat(fd, &st);
 	if (ret >= 0) {
 		time_t stctime = st.st_mtime;
 		char buf[256];

 		strftime(buf, sizeof(buf), "%FT%TZ", gmtime(&stctime));
 		output_json_key_string(out, true, 2, "captured-on", buf);
 	} else {
 		pr_debug("Failed to get mtime of source file, not writing captured-on");
 	}

 	output_json_key_format(out, true, 2, "data-offset", "%" PRIu64, header->data_offset);
 	output_json_key_format(out, true, 2, "data-size", "%" PRIu64, header->data_size);
 	output_json_key_format(out, true, 2, "feat-offset", "%" PRIu64, header->feat_offset);

 	output_json_key_string(out, true, 2, "hostname", header->env.hostname);
 	output_json_key_string(out, true, 2, "os-release", header->env.os_release);
 	output_json_key_string(out, true, 2, "arch", header->env.arch);

 	output_json_key_string(out, true, 2, "cpu-desc", header->env.cpu_desc);
 	output_json_key_string(out, true, 2, "cpuid", header->env.cpuid);
 	output_json_key_format(out, true, 2, "nrcpus-online", "%u", header->env.nr_cpus_online);
 	output_json_key_format(out, true, 2, "nrcpus-avail", "%u", header->env.nr_cpus_avail);

 	if (header->env.clock.enabled) {
 		output_json_key_format(out, true, 2, "clockid",
 				"%u", header->env.clock.clockid);
 		output_json_key_format(out, true, 2, "clock-time",
 				"%" PRIu64, header->env.clock.clockid_ns);
 		output_json_key_format(out, true, 2, "real-time",
 				"%" PRIu64, header->env.clock.tod_ns);
 	}

 	output_json_key_string(out, true, 2, "perf-version", header->env.version);

 	output_json_key_format(out, true, 2, "cmdline", "[");
 	for (i = 0; i < header->env.nr_cmdline; i++) {
 		output_json_delimiters(out, i != 0, 3);
 		output_json_string(c->out, header->env.cmdline_argv[i]);
 	}
 	output_json_format(out, false, 2, "]");
 }

 int bt_convert__perf2json(const char *input_name, const char *output_name,
 		struct perf_data_convert_opts *opts __maybe_unused)
 {
 	struct perf_session *session;
 	int fd;
 	int ret = -1;

 	struct convert_json c = {
 		.tool = {
 			.sample         = process_sample_event,
 			.mmap           = perf_event__process_mmap,
 			.mmap2          = perf_event__process_mmap2,
 			.comm           = perf_event__process_comm,
 			.namespaces     = perf_event__process_namespaces,
 			.cgroup         = perf_event__process_cgroup,
 			.exit           = perf_event__process_exit,
 			.fork           = perf_event__process_fork,
 			.lost           = perf_event__process_lost,
 #ifdef HAVE_LIBTRACEEVENT
 			.tracing_data   = perf_event__process_tracing_data,
 #endif
 			.build_id       = perf_event__process_build_id,
 			.id_index       = perf_event__process_id_index,
 			.auxtrace_info  = perf_event__process_auxtrace_info,
 			.auxtrace       = perf_event__process_auxtrace,
 			.event_update   = perf_event__process_event_update,
 			.ordered_events = true,
 			.ordering_requires_timestamps = true,
 		},
 		.first = true,
 		.events_count = 0,
 	};

 	struct perf_data data = {
 		.mode = PERF_DATA_MODE_READ,
 		.path = input_name,
 		.force = opts->force,
 	};

 	if (opts->all) {
 		pr_err("--all is currently unsupported for JSON output.\n");
 		goto err;
 	}
 	if (opts->tod) {
 		pr_err("--tod is currently unsupported for JSON output.\n");
 		goto err;
 	}

 	fd = open(output_name, O_CREAT | O_WRONLY | (opts->force ? O_TRUNC : O_EXCL), 0666);
 	if (fd == -1) {
 		if (errno == EEXIST)
 			pr_err("Output file exists. Use --force to overwrite it.\n");
 		else
 			pr_err("Error opening output file!\n");
 		goto err;
 	}

 	c.out = fdopen(fd, "w");
 	if (!c.out) {
 		fprintf(stderr, "Error opening output file!\n");
 		close(fd);
 		goto err;
 	}

 	session = perf_session__new(&data, &c.tool);
 	if (IS_ERR(session)) {
 		fprintf(stderr, "Error creating perf session!\n");
 		goto err_fclose;
 	}

 	if (symbol__init(&session->header.env) < 0) {
 		fprintf(stderr, "Symbol init error!\n");
 		goto err_session_delete;
 	}

 	// The opening brace is printed manually because it isn't delimited from a
 	// previous value (i.e. we don't want a leading newline)
 	fputc('{', c.out);

 	// Version number for future-proofing. Most additions should be able to be
 	// done in a backwards-compatible way so this should only need to be bumped
 	// if some major breaking change must be made.
 	output_json_format(c.out, false, 1, "\"linux-perf-json-version\": 1");

 	// Output headers
 	output_json_format(c.out, true, 1, "\"headers\": {");
 	output_headers(session, &c);
 	output_json_format(c.out, false, 1, "}");

 	// Output samples
 	output_json_format(c.out, true, 1, "\"samples\": [");
 	perf_session__process_events(session);
 	output_json_format(c.out, false, 1, "]");
 	output_json_format(c.out, false, 0, "}");
 	fputc('\n', c.out);

 	fprintf(stderr,
 			"[ perf data convert: Converted '%s' into JSON data '%s' ]\n",
 			data.path, output_name);

 	fprintf(stderr,
 			"[ perf data convert: Converted and wrote %.3f MB (%" PRIu64 " samples) ]\n",
 			(ftell(c.out)) / 1024.0 / 1024.0, c.events_count);

 	ret = 0;
 err_session_delete:
 	perf_session__delete(session);
 err_fclose:
 	fclose(c.out);
 err:
 	return ret;
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* JSON export.
	*
	* Copyright (C) 2021, CodeWeavers Inc. <nfraser@codeweavers.com>
	*/

	#include "data-convert.h"

	#include <fcntl.h>
	#include <inttypes.h>
	#include <sys/stat.h>
	#include <unistd.h>

	#include "linux/compiler.h"
	#include "linux/err.h"
	#include "util/auxtrace.h"
	#include "util/debug.h"
	#include "util/dso.h"
	#include "util/event.h"
	#include "util/evsel.h"
	#include "util/evlist.h"
	#include "util/header.h"
	#include "util/map.h"
	#include "util/session.h"
	#include "util/symbol.h"
	#include "util/thread.h"
	#include "util/tool.h"

	#ifdef HAVE_LIBTRACEEVENT
	#include <traceevent/event-parse.h>
	#endif

	struct convert_json {
	struct perf_tool tool;
	FILE *out;
	bool first;
	u64 events_count;
	};

	// Outputs a JSON-encoded string surrounded by quotes with characters escaped.
	static void output_json_string(FILE out, const char s)
	{
	fputc('"', out);
	while (*s) {
	switch (*s) {

	// required escapes with special forms as per RFC 8259
	case '"': fputs("\\\"", out); break;
	case '\\': fputs("\\\\", out); break;
	case '\b': fputs("\\b", out); break;
	case '\f': fputs("\\f", out); break;
	case '\n': fputs("\\n", out); break;
	case '\r': fputs("\\r", out); break;
	case '\t': fputs("\\t", out); break;

	default:
	// all other control characters must be escaped by hex code
	if (*s <= 0x1f)
	fprintf(out, "\\u%04x", *s);
	else
	fputc(*s, out);
	break;
	}

	++s;
	}
	fputc('"', out);
	}

	// Outputs an optional comma, newline and indentation to delimit a new value
	// from the previous one in a JSON object or array.
	static void output_json_delimiters(FILE *out, bool comma, int depth)
	{
	int i;

	if (comma)
	fputc(',', out);
	fputc('\n', out);
	for (i = 0; i < depth; ++i)
	fputc('\t', out);
	}

	// Outputs a printf format string (with delimiter) as a JSON value.
	__printf(4, 5)
	static void output_json_format(FILE out, bool comma, int depth, const char format, ...)
	{
	va_list args;

	output_json_delimiters(out, comma, depth);
	va_start(args, format);
	vfprintf(out, format, args);
	va_end(args);
	}

	// Outputs a JSON key-value pair where the value is a string.
	static void output_json_key_string(FILE *out, bool comma, int depth,
	const char key, const char value)
	{
	output_json_delimiters(out, comma, depth);
	output_json_string(out, key);
	fputs(": ", out);
	output_json_string(out, value);
	}

	// Outputs a JSON key-value pair where the value is a printf format string.
	__printf(5, 6)
	static void output_json_key_format(FILE *out, bool comma, int depth,
	const char key, const char format, ...)
	{
	va_list args;

	output_json_delimiters(out, comma, depth);
	output_json_string(out, key);
	fputs(": ", out);
	va_start(args, format);
	vfprintf(out, format, args);
	va_end(args);
	}

	static void output_sample_callchain_entry(struct perf_tool *tool,
	u64 ip, struct addr_location *al)
	{
	struct convert_json *c = container_of(tool, struct convert_json, tool);
	FILE *out = c->out;

	output_json_format(out, false, 4, "{");
	output_json_key_format(out, false, 5, "ip", "\"0x%" PRIx64 "\"", ip);

	if (al && al->sym && al->sym->namelen) {
	struct dso *dso = al->map ? map__dso(al->map) : NULL;

	fputc(',', out);
	output_json_key_string(out, false, 5, "symbol", al->sym->name);

	if (dso) {
	const char *dso_name = dso->short_name;

	if (dso_name && strlen(dso_name) > 0) {
	fputc(',', out);
	output_json_key_string(out, false, 5, "dso", dso_name);
	}
	}
	}

	output_json_format(out, false, 4, "}");
	}

	static int process_sample_event(struct perf_tool *tool,
	union perf_event *event __maybe_unused,
	struct perf_sample *sample,
	struct evsel *evsel __maybe_unused,
	struct machine *machine)
	{
	struct convert_json *c = container_of(tool, struct convert_json, tool);
	FILE *out = c->out;
	struct addr_location al, tal;
	u64 sample_type = __evlist__combined_sample_type(evsel->evlist);
	u8 cpumode = PERF_RECORD_MISC_USER;

	if (machine__resolve(machine, &al, sample) < 0) {
	pr_err("Sample resolution failed!\n");
	return -1;
	}

	++c->events_count;

	if (c->first)
	c->first = false;
	else
	fputc(',', out);
	output_json_format(out, false, 2, "{");

	output_json_key_format(out, false, 3, "timestamp", "%" PRIi64, sample->time);
	output_json_key_format(out, true, 3, "pid", "%i", al.thread->pid_);
	output_json_key_format(out, true, 3, "tid", "%i", al.thread->tid);

	if ((sample_type & PERF_SAMPLE_CPU))
	output_json_key_format(out, true, 3, "cpu", "%i", sample->cpu);
	else if (al.thread->cpu >= 0)
	output_json_key_format(out, true, 3, "cpu", "%i", al.thread->cpu);

	output_json_key_string(out, true, 3, "comm", thread__comm_str(al.thread));

	output_json_key_format(out, true, 3, "callchain", "[");
	if (sample->callchain) {
	unsigned int i;
	bool ok;
	bool first_callchain = true;

	for (i = 0; i < sample->callchain->nr; ++i) {
	u64 ip = sample->callchain->ips[i];

	if (ip >= PERF_CONTEXT_MAX) {
	switch (ip) {
	case PERF_CONTEXT_HV:
	cpumode = PERF_RECORD_MISC_HYPERVISOR;
	break;
	case PERF_CONTEXT_KERNEL:
	cpumode = PERF_RECORD_MISC_KERNEL;
	break;
	case PERF_CONTEXT_USER:
	cpumode = PERF_RECORD_MISC_USER;
	break;
	default:
	pr_debug("invalid callchain context: %"
	PRId64 "\n", (s64) ip);
	break;
	}
	continue;
	}

	if (first_callchain)
	first_callchain = false;
	else
	fputc(',', out);

	ok = thread__find_symbol(al.thread, cpumode, ip, &tal);
	output_sample_callchain_entry(tool, ip, ok ? &tal : NULL);
	}
	} else {
	output_sample_callchain_entry(tool, sample->ip, &al);
	}
	output_json_format(out, false, 3, "]");

	#ifdef HAVE_LIBTRACEEVENT
	if (sample->raw_data) {
	int i;
	struct tep_format_field **fields;

	fields = tep_event_fields(evsel->tp_format);
	if (fields) {
	i = 0;
	while (fields[i]) {
	struct trace_seq s;

	trace_seq_init(&s);
	tep_print_field(&s, sample->raw_data, fields[i]);
	output_json_key_string(out, true, 3, fields[i]->name, s.buffer);

	i++;
	}
	free(fields);
	}
	}
	#endif
	output_json_format(out, false, 2, "}");
	return 0;
	}

	static void output_headers(struct perf_session session, struct convert_json c)
	{
	struct stat st;
	struct perf_header *header = &session->header;
	int ret;
	int fd = perf_data__fd(session->data);
	int i;
	FILE *out = c->out;

	output_json_key_format(out, false, 2, "header-version", "%u", header->version);

	ret = fstat(fd, &st);
	if (ret >= 0) {
	time_t stctime = st.st_mtime;
	char buf[256];

	strftime(buf, sizeof(buf), "%FT%TZ", gmtime(&stctime));
	output_json_key_string(out, true, 2, "captured-on", buf);
	} else {
	pr_debug("Failed to get mtime of source file, not writing captured-on");
	}

	output_json_key_format(out, true, 2, "data-offset", "%" PRIu64, header->data_offset);
	output_json_key_format(out, true, 2, "data-size", "%" PRIu64, header->data_size);
	output_json_key_format(out, true, 2, "feat-offset", "%" PRIu64, header->feat_offset);

	output_json_key_string(out, true, 2, "hostname", header->env.hostname);
	output_json_key_string(out, true, 2, "os-release", header->env.os_release);
	output_json_key_string(out, true, 2, "arch", header->env.arch);

	output_json_key_string(out, true, 2, "cpu-desc", header->env.cpu_desc);
	output_json_key_string(out, true, 2, "cpuid", header->env.cpuid);
	output_json_key_format(out, true, 2, "nrcpus-online", "%u", header->env.nr_cpus_online);
	output_json_key_format(out, true, 2, "nrcpus-avail", "%u", header->env.nr_cpus_avail);

	if (header->env.clock.enabled) {
	output_json_key_format(out, true, 2, "clockid",
	"%u", header->env.clock.clockid);
	output_json_key_format(out, true, 2, "clock-time",
	"%" PRIu64, header->env.clock.clockid_ns);
	output_json_key_format(out, true, 2, "real-time",
	"%" PRIu64, header->env.clock.tod_ns);
	}

	output_json_key_string(out, true, 2, "perf-version", header->env.version);

	output_json_key_format(out, true, 2, "cmdline", "[");
	for (i = 0; i < header->env.nr_cmdline; i++) {
	output_json_delimiters(out, i != 0, 3);
	output_json_string(c->out, header->env.cmdline_argv[i]);
	}
	output_json_format(out, false, 2, "]");
	}

	int bt_convert__perf2json(const char input_name, const char output_name,
	struct perf_data_convert_opts *opts __maybe_unused)
	{
	struct perf_session *session;
	int fd;
	int ret = -1;

	struct convert_json c = {
	.tool = {
	.sample = process_sample_event,
	.mmap = perf_event__process_mmap,
	.mmap2 = perf_event__process_mmap2,
	.comm = perf_event__process_comm,
	.namespaces = perf_event__process_namespaces,
	.cgroup = perf_event__process_cgroup,
	.exit = perf_event__process_exit,
	.fork = perf_event__process_fork,
	.lost = perf_event__process_lost,
	#ifdef HAVE_LIBTRACEEVENT
	.tracing_data = perf_event__process_tracing_data,
	#endif
	.build_id = perf_event__process_build_id,
	.id_index = perf_event__process_id_index,
	.auxtrace_info = perf_event__process_auxtrace_info,
	.auxtrace = perf_event__process_auxtrace,
	.event_update = perf_event__process_event_update,
	.ordered_events = true,
	.ordering_requires_timestamps = true,
	},
	.first = true,
	.events_count = 0,
	};

	struct perf_data data = {
	.mode = PERF_DATA_MODE_READ,
	.path = input_name,
	.force = opts->force,
	};

	if (opts->all) {
	pr_err("--all is currently unsupported for JSON output.\n");
	goto err;
	}
	if (opts->tod) {
	pr_err("--tod is currently unsupported for JSON output.\n");
	goto err;
	}

	fd = open(output_name, O_CREAT \| O_WRONLY \| (opts->force ? O_TRUNC : O_EXCL), 0666);
	if (fd == -1) {
	if (errno == EEXIST)
	pr_err("Output file exists. Use --force to overwrite it.\n");
	else
	pr_err("Error opening output file!\n");
	goto err;
	}

	c.out = fdopen(fd, "w");
	if (!c.out) {
	fprintf(stderr, "Error opening output file!\n");
	close(fd);
	goto err;
	}

	session = perf_session__new(&data, &c.tool);
	if (IS_ERR(session)) {
	fprintf(stderr, "Error creating perf session!\n");
	goto err_fclose;
	}

	if (symbol__init(&session->header.env) < 0) {
	fprintf(stderr, "Symbol init error!\n");
	goto err_session_delete;
	}

	// The opening brace is printed manually because it isn't delimited from a
	// previous value (i.e. we don't want a leading newline)
	fputc('{', c.out);

	// Version number for future-proofing. Most additions should be able to be
	// done in a backwards-compatible way so this should only need to be bumped
	// if some major breaking change must be made.
	output_json_format(c.out, false, 1, "\"linux-perf-json-version\": 1");

	// Output headers
	output_json_format(c.out, true, 1, "\"headers\": {");
	output_headers(session, &c);
	output_json_format(c.out, false, 1, "}");

	// Output samples
	output_json_format(c.out, true, 1, "\"samples\": [");
	perf_session__process_events(session);
	output_json_format(c.out, false, 1, "]");
	output_json_format(c.out, false, 0, "}");
	fputc('\n', c.out);

	fprintf(stderr,
	"[ perf data convert: Converted '%s' into JSON data '%s' ]\n",
	data.path, output_name);

	fprintf(stderr,
	"[ perf data convert: Converted and wrote %.3f MB (%" PRIu64 " samples) ]\n",
	(ftell(c.out)) / 1024.0 / 1024.0, c.events_count);

	ret = 0;
	err_session_delete:
	perf_session__delete(session);
	err_fclose:
	fclose(c.out);
	err:
	return ret;
	}