micro-utils/include/proc_parser.h

#ifndef _PROC_PARSER
#define _PROC_PARSER

#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <limits.h>
#include <errno.h>
#include <ctype.h>
#include <pwd.h>
#include <grp.h>

struct mu_proc {
	/* from status */
	char prog[PATH_MAX + 1];
	uid_t uid;
	gid_t gid;

	/* from stat */
	pid_t pid;
	char cmdline[PATH_MAX + 1];
	char state;
	int ppid;
	int pgrp;
	int sid;
	int tty;
	int tpgid;
	unsigned flags;
	unsigned long minflt;
	unsigned long cminflt;
	unsigned long majflt;
	unsigned long cmajflt;
	unsigned long utime;
	unsigned long stime;
	long cutime;
	long cstime;
	long priority;
	long nice;
	long num_threads;
	long itrealvalue;
	unsigned long long starttime;
	unsigned long vsize;
	long rss;
	long rsslim;
};

static int mu_proc_status(const char *prog_name, const pid_t pid, struct mu_proc *proc_s) {
	proc_s->uid = -1;
	proc_s->gid = -1;

	/* Proccess file */
	char path[PATH_MAX + 1];
	snprintf(path, sizeof(path), "/proc/%d/status", pid);

	int fd = open(path, O_RDONLY);
	if (fd < 0) {
		if (prog_name)
			fprintf(stderr, "%s: %s: %s\n", prog_name, path, strerror(errno));

		return 1;
	}

	char status[2048];
	ssize_t n = read(fd, status, sizeof(status) - 1);
	status[n] = '\0';
	close(fd);

	char *token = strtok(status, "\n");
	while (token) {
		char *val = strchr(token, ':');
		if (val == NULL) {
			fprintf(stderr, "ps: incorrect %s file\n", path);
			return 1;
		}

		*val = '\0';
		val++;

		/* Strip */
		while (isspace(*val))
			val++;

		/* Write values */
		if (!strncmp(token, "Name", 4))
			strcpy(proc_s->prog, val);

		else if (!strncmp(token, "Uid", 3))
			proc_s->uid = strtoul(val, 0L, 10);

		else if (!strncmp(token, "Gid", 3))
			proc_s->gid = strtoul(val, 0L, 10);

		token = strtok(NULL, "\n");
	}

	return 0;
}

static int mu_proc_stat(const char *prog_name, const pid_t pid, struct mu_proc *proc_s) {
	char path[PATH_MAX + 1];
	snprintf(path, sizeof(path), "/proc/%d/stat", pid);

	FILE *fp = fopen(path, "r");
	if (fp == NULL) {
		if (prog_name)
			fprintf(stderr, "%s: %s: %s\n", prog_name, path, strerror(errno));

		return 1;
	}

	fscanf(fp, "%d %s %c %d %d %d %d %d %u %lu %lu %lu %lu %lu %lu", &proc_s->pid, proc_s->cmdline, &proc_s->state, &proc_s->ppid, &proc_s->pgrp, &proc_s->sid, &proc_s->tty, &proc_s->tpgid, &proc_s->flags, &proc_s->minflt, &proc_s->cminflt, &proc_s->majflt, &proc_s->cmajflt, &proc_s->utime, &proc_s->stime);
	fscanf(fp, "%ld %ld %ld %ld %ld %ld %llu %lu %ld %ld", &proc_s->cutime, &proc_s->cstime, &proc_s->priority, &proc_s->nice, &proc_s->num_threads, &proc_s->itrealvalue, &proc_s->starttime, &proc_s->vsize, &proc_s->rss, &proc_s->rsslim);
	fclose(fp);

	return 0;
}

int mu_proc_parser(const char *prog_name, const pid_t pid, struct mu_proc *proc_s) {
	memset(proc_s, 0, sizeof(struct mu_proc));

	int ret = 0;

	/* STAT */
	if (mu_proc_stat(prog_name, pid, proc_s))
		ret = 1;

	/* STATUS */
	if (mu_proc_status(prog_name, pid, proc_s))
		ret = 1;

	return ret;
}

#endif