startup-scripts.c

/*
	startup-scripts.c:
	parse and execute startup commands

	Shitty runCommands() function is garbage and definitely needs a rewrite.
*/

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>

#include "config.h"		/* imports: rcFile,
						   SERVICE_MAX_ARGS,
						   SERVICE_MAX_BUFFER,
						   MAX_SERVICES
						*/
#include "startup-scripts.h"



struct services_struct services[MAX_SERVICES];
int service_count = 0;

void runCommands()
{
	FILE *commandsFile;
	char line_buffer[SERVICE_MAX_BUFFER];

	commandsFile = fopen(rcFile, "r");
	if (commandsFile == NULL)
	{
		fprintf(stderr, "[service] Unable to read rc file %s. Does it exist?\n", rcFile);
		perror("fopen");
		return;
	}



		/*  Parse the file */
	while (fgets(line_buffer, sizeof(line_buffer), commandsFile) != NULL)
	{
			/* skip line if it begins with # or // */
		if (line_buffer[0] == '\n' || line_buffer[0] == '#' || (line_buffer[0] == '/' && line_buffer[1] == '/'))
			continue;

			// remove newline character at the end of the string
		line_buffer[strcspn(line_buffer, "\n")] = 0;


			// switching to pointer to lineBuffer for efficiency
		char *command = line_buffer;
			// skip spaces and tabs at line beginning
		while (*command == ' ' || *command == '\t')
			command++;

			// skip line if it's empty after this stage
		if (*command == '\0')
			continue;

		printf("[service] Executing %s\n", command);



			/*	tokenize and execute command	*/
		pid_t service_pid = fork();
		if (service_pid == -1)
			perror("[service] Fork failed");
		else if (service_pid == 0)	/* in child */
									/* final parsing & execution */
		{
			/* redirect stdout to not clobber TTY with useless stuff */
			/* stderr will still spit errors which is at least useful for debugging something */
			freopen("/dev/null", "w", stdout);

			char *args[SERVICE_MAX_ARGS];
			int arg_count = 0;

				// final tokenizer, parse the string into arguments
				// TODO: reinvent this shit and pull at least some of this code out of the child
			char *token = strtok(command, " ");
			while (token != NULL && arg_count < SERVICE_MAX_ARGS-1)	// null terminator must fit
			{
					/* skip line if an argument if starts with comment */
				if (token[0] == '#' || token[0] == '\n' || (token[0] == '/' && token[1] == '/'))	
					break;

				args[arg_count++] = token;
				token = strtok(NULL, " ");
			}
			args[arg_count] = NULL;				// null terminator

			/* execute final command */
			execvp(args[0], args);

			fprintf(stderr, "[service] Failed to execute\n");	// in case execvp returns (unreachable if executes)
			_exit(1);
		}
		else	/*	In parent when child forks,
					store the fork's:
						* PID
						* command (including the comment, i'll fix this)
						* status (active: 1 or dead: 0)
					for monitoring (see monitorServices(), which is triggered by killZombies).
					So-called NUTS service supervising, lol.
				*/
		{
			services[service_count].pid = service_pid;
			strncpy(services[service_count].command, command, SERVICE_MAX_BUFFER-1);
			services[service_count].command[SERVICE_MAX_BUFFER-1] = '\0';			/* to prevent error if a 255 string gets copied */
																					/* and there isn't room for terminator */
			services[service_count].is_active = 1;
			service_count++;
		}

		// small 10 ms delay between service startups (because why not? this init isn't about being the fastest)
		usleep(10000);
	}

		// close file
	fclose(commandsFile);
	return;
}



/*
void monitorServices()
{
	int status;
	pid_t result;

	for (int i = 0; i < service_count; i++)
	{
		if (!services[i].is_active)
			continue;

		result = waitpid(services[i].pid, &status, WNOHANG);

		if (result == -1)
		{
			fprintf(stderr, "[monitor] Something went wrong with service '%s' (PID %d)\n",
					services[i].command, services[i].pid);
			services[i].is_active = 0;
		}

		else if (result > 0)
		{
			if (WIFEXITED(status))
			{
				printf("[monitor] Service '%s' (PID %d) exited normally with status %d\n",
						services[i].command, services[i].pid, WEXITSTATUS(status));
			}
			else if (WIFSIGNALED(status))
			{
				printf("[monitor] Service '%s' (PID %d) was killed by signal %d\n",
						services[i].command, services[i].pid, WTERMSIG(status));
			}
			services[i].is_active = 0;
		}
	}
	return;
}
*/