/*******************************************************************/

/*  slibtool: a skinny libtool implementation, written in C        */

/*  Copyright (C) 2016--2021  SysDeer Technologies, LLC            */

/*  Released under the Standard MIT License; see COPYING.SLIBTOOL. */

/*******************************************************************/

#include <stdio.h>

#include <limits.h>

#include <unistd.h>

#include <fcntl.h>

#include <string.h>

#include <stdlib.h>

#include <stdbool.h>

#include <sys/wait.h>

#include <slibtool/slibtool.h>

#include "slibtool_spawn_impl.h"

static void slbt_dump_machine_child(

	char *	program,

	int	fd[2])

{

	char *	compiler;

	char *	argv[3];

	close(fd[0]);

	if ((compiler = strrchr(program,'/')))

		compiler++;

	else

		compiler = program;

	argv[0] = compiler;

	argv[1] = "-dumpmachine";

	argv[2] = 0;

	if ((fd[0] = openat(AT_FDCWD,"/dev/null",O_RDONLY,0)) >= 0)

		if (dup2(fd[0],0) == 0)

			if (dup2(fd[1],1) == 1)

				execvp(program,argv);

	_exit(EXIT_FAILURE);

}

int slbt_dump_machine(

	const char *	compiler,

	char *		machine,

	size_t		buflen)

{

	ssize_t	ret;

	pid_t	pid;

	pid_t	rpid;

	int	code;

	int	fd[2];

	char *	mark;

	char	program[PATH_MAX];

	/* setup */

	if (!machine || !buflen || !--buflen) {

		errno = EINVAL;

		return -1;

	}

	if ((size_t)snprintf(program,sizeof(program),"%s",

			compiler) >= sizeof(program))

		return -1;

	/* fork */

	if (pipe(fd))

		return -1;

	if ((pid = fork()) < 0) {

		close(fd[0]);

		close(fd[1]);

		return -1;

	}

	/* child */

	if (pid == 0)

		slbt_dump_machine_child(

			program,

			fd);

	/* parent */

	close(fd[1]);

	mark = machine;

	for (; buflen; ) {

		ret = read(fd[0],mark,buflen);

		while ((ret < 0) && (errno == EINTR))

			ret = read(fd[0],mark,buflen);

		if (ret > 0) {

			buflen -= ret;

			mark   += ret;

		} else if (ret == 0) {

			close(fd[0]);

			buflen = 0;

		} else {

			close(fd[0]);

			return -1;

		}

	}

	/* execve verification */

	rpid = waitpid(

		pid,

		&code,

		0);

	if ((rpid != pid) || code) {

		errno = ESTALE;

		return -1;

	}

	/* newline verification */

	if ((mark == machine) || (*--mark != '\n')) {

		errno = ERANGE;

		return -1;

	}

	*mark = 0;

	/* portbld <--> unknown synonym? */

	if ((mark = strstr(machine,"-portbld-")))

		memcpy(mark,"-unknown",8);

	/* all done */

	return 0;

}