// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)

#include "commons.h"
#include "biotop.h"
#include "biotop.skel.h"
#include "trace_helpers.h"
#include "compat.h"

#define OUTPUT_ROWS_LIMIT	10240

enum SORT {
	ALL,
	IO,
	BYTES,
	TIME,
};

struct disk {
	int major;
	int minor;
	char name[256];
};

struct vector {
	size_t nr;
	size_t capacity;
	void **elems;
};

int grow_vector(struct vector *vector)
{
	if (vector->nr >= vector->capacity) {
		void **reallocated;

		if (!vector->capacity)
			vector->capacity = 1;
		else
			vector->capacity *= 2;

		reallocated = libbpf_reallocarray(vector->elems, vector->capacity, sizeof(*vector->elems));
		if (!reallocated)
			return -1;

		vector->elems = reallocated;
	}

	return 0;
}

void free_vector(struct vector vector)
{
	for (size_t i = 0; i < vector.nr; i++) {
		if (vector.elems[i] != NULL)
			free(vector.elems[i]);
	}

	free(vector.elems);
}

struct vector disks = {};

static volatile sig_atomic_t exiting;

static struct env {
	bool	clear_screen;
	int	output_rows;
	int	sort_by;
	int	interval;
	int	count;
	bool	verbose;
} env = {
	.clear_screen	= true,
	.output_rows	= 20,
	.sort_by	= ALL,
	.interval	= 1,
	.count		= 99999999,
	.verbose	= false,
};

const char *argp_program_version = "biotop 0.1";
const char *argp_program_bug_address = "Jackie Liu <liuyun01@kylinos.cn>";
const char argp_program_doc[] =
"Trace file reads/writes by process.\n"
"\n"
"USAGE: biotop [-h] [interval] [count]\n"
"\n"
"EXAMPLES:\n"
"    biotop            # file I/O top, refresh every 1s\n"
"    biotop 5 10       # 5s summaries, 10 times\n";

static const struct argp_option opts[] = {
	{ "noclear", 'c', NULL, 0, "Don't clear the screen" },
	{ "sort", 's', "SORT", 0, "Sort columns, default all [all, io, bytes, time]" },
	{ "rows", 'r', "ROWS", 0, "Maximum rows to print, default 20" },
	{ "verbose", 'v', NULL, 0, "Verbose debug output" },
	{ NULL, 'h', NULL, OPTION_HIDDEN, "Show the full help" },
	{}
};

static error_t parse_arg(int key, char *arg, struct argp_state *state)
{
	static int pos_args;

	switch (key) {
	case 'c':
		env.clear_screen = false;
		break;
	case 's':
		if (!strcmp(arg, "all")) {
			env.sort_by = ALL;
		} else if (!strcmp(arg, "io")) {
			env.sort_by = IO;
		} else if (!strcmp(arg, "bytes")) {
			env.sort_by = BYTES;
		} else if (!strcmp(arg, "time")) {
			env.sort_by = TIME;
		} else {
			warning("Invalid sort method: %s\n", arg);
			argp_usage(state);
		}
		break;
	case 'r':
		errno = 0;
		env.output_rows = strtol(arg, NULL, 10);
		if (errno || env.output_rows <= 0) {
			warning("Invalid rows: %s\n", arg);
			argp_usage(state);
		}
		if (env.output_rows > OUTPUT_ROWS_LIMIT)
			env.output_rows = OUTPUT_ROWS_LIMIT;
		break;
	case 'v':
		env.verbose = true;
		break;
	case 'h':
		argp_state_help(state, stderr, ARGP_HELP_STD_HELP);
		break;
	case ARGP_KEY_ARG:
		errno = 0;
		if (pos_args == 0) {
			env.interval = strtol(arg, NULL, 10);
			if (errno || env.interval <= 0) {
				warning("Invalid interval\n");
				argp_usage(state);
			}
		} else if (pos_args == 1) {
			env.count = strtol(arg, NULL, 10);
			if (errno || env.count <= 0) {
				warning("Invalid count\n");
				argp_usage(state);
			}
		} else {
			warning("Unrecognized positional argument: %s\n", arg);
			argp_usage(state);
		}
		pos_args++;
		break;
	default:
		return ARGP_ERR_UNKNOWN;
	}
	return 0;
}

static int libbpf_print_fn(enum libbpf_print_level level, const char *format,
			   va_list args)
{
	if (level == LIBBPF_DEBUG && !env.verbose)
		return 0;
	return vfprintf(stderr, format, args);
}

static void sig_handler(int sig)
{
	exiting = 1;
}

struct data_t {
	struct info_t key;
	struct val_t value;
};

static int sort_column(const void *obj1, const void *obj2)
{
	struct data_t *d1 = (struct data_t *)obj1;
	struct data_t *d2 = (struct data_t *)obj2;

	struct val_t *s1 = &d1->value;
	struct val_t *s2 = &d2->value;

	if (env.sort_by == IO)
		return s2->io - s1->io;
	else if (env.sort_by == BYTES)
		return s2->bytes - s1->bytes;
	else if (env.sort_by == TIME)
		return s2->us - s1->us;
	else
		return (s2->io + s2->bytes + s2->us)
			- (s1->io + s1->bytes + s1->us);
}

static void parse_disk_stat(void)
{
	FILE *fp;
	char *line;
	size_t zero = 0;

	fp = fopen("/proc/diskstats", "r");
	if (!fp)
		return;

	while (getline(&line, &zero, fp) != -1) {
		struct disk disk;

		if (sscanf(line, "%d %d %s", &disk.major, &disk.minor, disk.name) != 3)
			continue;

		if (grow_vector(&disks) == -1)
			goto err;

		disks.elems[disks.nr] = malloc(sizeof(disk));
		if (!disks.elems[disks.nr])
			goto err;

		memcpy(disks.elems[disks.nr], &disk, sizeof(disk));

		disks.nr++;
	}

	free(line);
	fclose(fp);

	return;

err:
	warning("Realloc or malloc failed\n");
	free_vector(disks);
}

static char *search_disk_name(int major, int minor)
{
	for (size_t i = 0; i < disks.nr; i++) {
		struct disk *diskp;

		if (!disks.elems[i])
			continue;

		diskp = (struct disk *)disks.elems[i];
		if (diskp->major == major && diskp->minor == minor)
			return diskp->name;
	}

	return "";
}

static int print_stat(struct biotop_bpf *obj)
{
	FILE *fp;
	struct info_t *prev_key = NULL;
	static struct data_t datas[OUTPUT_ROWS_LIMIT];
	int err = 0, rows = 0;
	int fd = bpf_map__fd(obj->maps.counts);

	fp = fopen("/proc/loadavg", "r");
	if (fp) {
		char ts[16], buf[256] = {};
		int n;

		strftime_now(ts, sizeof(ts), "%H:%M:%S");

		n = fread(buf, 1, sizeof(buf), fp);
		if (n)
			printf("%8s loadavg: %s\n", ts, buf);
		fclose(fp);
	}

	printf("%-7s %-16s %1s %-3s %-3s %-8s %5s %7s %6s\n",
	       "PID", "COMM", "D", "MAJ", "MIN", "DISK", "I/O", "Kbytes", "AVGms");

	while (1) {
		err = bpf_map_get_next_key(fd, prev_key, &datas[rows].key);
		if (err) {
			if (errno == ENOENT) {
				err = 0;
				break;
			}
			warning("bpf_map_get_next_key failed: %s\n", strerror(errno));
			return err;
		}
		prev_key = &datas[rows].key;

		err = bpf_map_lookup_elem(fd, &datas[rows].key, &datas[rows].value);
		if (err) {
			warning("bpf_map_lookup_elem failed: %s\n", strerror(errno));
			return err;
		}

		rows++;
	}

	qsort(datas, rows, sizeof(struct data_t), sort_column);
	rows = rows < env.output_rows ? rows : env.output_rows;

	for (int i = 0; i < rows; i++) {
		int major, minor;
		struct info_t *key = &datas[i].key;
		struct val_t *value = &datas[i].value;
		float avg_ms = 0;

		/* To avoid floating point exception. */
		if (value->io)
			avg_ms = ((float)value->us) / 1000 / value->io;

		major = key->major;
		minor = key->minor;

		printf("%-7d %-16s %1s %-3d %-3d %-8s %5d %7lld %6.2f\n",
		       key->pid, key->name, key->rwflag ? "W" : "R",
		       major, minor, search_disk_name(major, minor),
		       value->io, value->bytes / 1024, avg_ms);
	}

	printf("\n");
	prev_key = NULL;

	while (1) {
		struct info_t key;

		err = bpf_map_get_next_key(fd, prev_key, &key);
		if (err) {
			if (errno == ENOENT) {
				err = 0;
				break;
			}
			warning("bpf_map_get_next_key failed: %s\n", strerror(errno));
			return err;
		}
		err = bpf_map_delete_elem(fd, &key);
		if (err) {
			warning("bpf_map_delete_elem failed: %s\n", strerror(errno));
			return err;
		}
		prev_key = &key;
	}

	return err;
}

int main(int argc, char *argv[])
{
	static const struct argp argp = {
		.options = opts,
		.parser = parse_arg,
		.doc = argp_program_doc,
	};
	struct biotop_bpf *obj;
	struct ksyms *ksyms;
	int err;

	err = argp_parse(&argp, argc, argv, 0, NULL, NULL);
	if (err)
		return err;

	if (!bpf_is_root())
		return 1;

	libbpf_set_print(libbpf_print_fn);

	obj = biotop_bpf__open();
	if (!obj) {
		warning("Failed to open BPF object\n");
		return 1;
	}

	parse_disk_stat();

	ksyms = ksyms__load();
	if (!ksyms) {
		err = -ENOMEM;
		warning("Failed to load kallsyms\n");
		goto cleanup;
	}

	err = biotop_bpf__load(obj);
	if (err) {
		warning("Failed to load BPF object: %d\n", err);
		goto cleanup;
	}

	if (ksyms__get_symbol(ksyms, "__blk_account_io_start"))
		obj->links.blk_account_io_start =
			bpf_program__attach_kprobe(obj->progs.blk_account_io_start,
						   false, "__blk_account_io_start");
	else
		obj->links.blk_account_io_start =
			bpf_program__attach_kprobe(obj->progs.blk_account_io_start,
						   false, "blk_account_io_start");

	if (!obj->links.blk_account_io_start) {
		warning("Failed to load attach blk_account_io_start\n");
		goto cleanup;
	}

	if (ksyms__get_symbol(ksyms, "__blk_account_io_done"))
		obj->links.blk_account_io_done =
			bpf_program__attach_kprobe(obj->progs.blk_account_io_done,
						   false, "__blk_account_io_done");
	else
		obj->links.blk_account_io_done =
			bpf_program__attach_kprobe(obj->progs.blk_account_io_done,
						   false, "blk_account_io_done");

	if (!obj->links.blk_account_io_done) {
		warning("Failed to load attach blk_account_io_done");
		goto cleanup;
	}

	err = biotop_bpf__attach(obj);
	if (err) {
		warning("Failed to attach BPF programs: %d\n", err);
		goto cleanup;
	}

	if (signal(SIGINT, sig_handler) == SIG_ERR) {
		warning("Can't set signal handler: %s\n", strerror(errno));
		err =  1;
		goto cleanup;
	}

	while (1) {
		sleep(env.interval);

		if (env.clear_screen) {
			err = system("clear");
			if (err)
				goto cleanup;
		}

		err = print_stat(obj);
		if (err)
			goto cleanup;

		if (exiting || !env.count--)
			goto cleanup;
	}

cleanup:
	ksyms__free(ksyms);
	free_vector(disks);
	biotop_bpf__destroy(obj);

	return err != 0;
}