/* sshc, ssh command
   written by Sam Watkins, 2007 - 2009
   this program is public domain
*/

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#include <limits.h>

#ifdef __MINGW32_MAJOR_VERSION
#define WIFEXITED(x) 1
#define WEXITSTATUS(x) x
#else
#include <sys/wait.h>
#endif

/* sshc - ssh command */

/* special exit codes: 123 - system call failed. 124 - remote cd failed */

static void arcs_error(char *error)
{
	fprintf(stderr, "Error: %s\n", error);
	exit(EXIT_FAILURE);
}

#ifndef __MINGW32_MAJOR_VERSION
/* Quoting arguments for the shell */
/* The "to" buffer must have enough space, allow 2 * strlen(from)+1. */
/* It adds a null and returns the address of the null. */
static char *sh_quote(const char *from, char *to)
{
	char c;
	while (1) {
		c = *from;
		if (c == '\0')
			break;
		if ((c >= 'A' && c <= 'Z') ||
		    (c >= 'a' && c <= 'z') ||
		    (c >= '0' && c <= '9') || strchr("-_./", c) != NULL) {
			// doesn't need escaping
			*to = c;
			++to;
		} else {
			to[0] = '\\';
			to[1] = c;
			to += 2;
		}
		++from;
	}
	*to = '\0';
	return to;
}
#else
static char *sh_quote(const char *from, char *to)
{
	int quote = strchr(from, ' ') ? 1 : 0;
	if (quote)
		*to++ = '"';
	strcpy(to, from);
	to += strlen(from);
	if (quote)
		*to++ = '"';
	return to;
}
#endif

static char *sh_quote_malloc(const char *from)
{
	char *to = malloc(strlen(from)*2+3);
	sh_quote(from, to);
	return to;
}

char *current_dir_home_relative(void)
{
	char *dir = NULL;
	char buf[PATH_MAX];
	char *home = getenv("HOME");
	int l;
	if (!getcwd(buf, sizeof(buf)))
		arcs_error("directory path too long");
	if (home && (l = strlen(home)) && strncmp(home, buf, l) == 0) {
		if (buf[l] == '\0')
			dir = ".";
		else if (buf[l] == '/')
			dir = buf+l+1;
	}
	if (!dir)
		dir = buf;
	return strdup(dir);
}

/* -------------------------------------------------------- */

int main(int argc, char **argv)
{
	char *user_host_dir;
	char *user_host;
	char *dir;
	char *delim;
	char command[4096];
	char ssh_command[8192];
	char *out;
	int count;
	char *ssh_prog;

	ssh_prog = getenv("ARCS_SSH");
	if (!ssh_prog) { ssh_prog = getenv("SSH"); }
	if (ssh_prog == NULL)
		ssh_prog = "ssh";

	if (argc < 2) {
		arcs_error("usage: sshc user@host:dir command arg1...");
	}

	user_host_dir = argv[1];

	user_host = user_host_dir;
	delim = strchr(user_host_dir, ':');
	if (delim && delim[1] != '\0') {
		*delim = '\0';
		dir = delim + 1;
	} else if ((delim = strchr(user_host_dir, '=')) && delim[1] == '\0') {
		*delim = '\0';
		dir = current_dir_home_relative();
	} else {
		dir = ".";
	}

	argv += 2;

	out = command;

	while (*argv != NULL) {
		if (out - command + strlen(*argv)*2 + 4 > sizeof(command)) {
			arcs_error("arguments too long");
		}
		out = sh_quote(*argv, out);
		*out = ' '; ++out;
		++argv;
	}
	if (out > command)
		--out;

	*out = '\0';

	char *dir_q = sh_quote_malloc(dir);
	char *dir_qq = sh_quote_malloc(dir_q);
	char *command_q = sh_quote_malloc(command);

	// TODO could do this with a temp file shell script

#ifdef __MINGW32_MAJOR_VERSION
	count = snprintf(ssh_command, sizeof(ssh_command), "%s -- %s \"umask 0002 ; mkdir -p %s ; cd %s || exit 124 ; %s\"", ssh_prog, user_host, dir, dir, command);
#else
	count = snprintf(ssh_command, sizeof(ssh_command), "%s -- %s umask\\ 0002\\ \\;\\ mkdir -p\\ %s\\ \\;\\ \\cd\\ %s\\ \\|\\| exit 124 \\;\\ %s", ssh_prog, user_host, dir_qq, dir_qq, command_q);
#endif
	if (count >= (int)sizeof(ssh_command)) {
		arcs_error("arguments too long");
	}

	int status = system(ssh_command);
	if (status == -1) {
		status = 123;
	} else if (WIFEXITED(status)) {
		status = WEXITSTATUS(status);
	}

	free(dir_q);
	free(dir_qq);
	free(command_q);

	exit(status);
}