text: // 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"
  
  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) {
  		fputc(',', out);
  		output_json_key_string(out, false, 5, "symbol", al->sym->name);
  
  		if (al->map && al->map->dso) {
  			const char *dso = al->map->dso->short_name;
  
  			if (dso && strlen(dso) > 0) {
  				fputc(',', out);
  				output_json_key_string(out, false, 5, "dso", dso);
  			}
  		}
  	}
  
  	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;
  	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 (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, "]");
  
  	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,
  			.tracing_data   = perf_event__process_tracing_data,
  			.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, false, &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;
  }
  