#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/sendfile.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>

#include "system.h"

int file_exists(const char *path)
{
	struct stat statbuf __attribute__((unused));
	int rc = stat(path, &statbuf);
	if (rc == 0)
		return 1;
	else if ((rc == -1) && (errno == ENOENT))
		return 0;
	fprintf(stderr, "stat: \"%s\": ", path);
	perror("");
	exit(EXIT_FAILURE);
}

void copy_file(const char *in, const char *out)
{
	int in_fd;
	int out_fd;
	int rc;
	ssize_t written_bytes;
	in_fd = open(in, O_RDONLY);
	if (in_fd == -1) {
		fprintf(stderr, "open: %s:", in);
		perror("");
		exit(EXIT_FAILURE);
	}
	out_fd = open(out, O_WRONLY | O_CREAT | O_TRUNC, 0600);
	if (out_fd == -1) {
		fprintf(stderr, "open: %s:", out);
		perror("");
		exit(EXIT_FAILURE);
	}
	while ((written_bytes = sendfile(out_fd, in_fd, NULL, 4096)) == 4096)
		;
	if (written_bytes == -1) {
		perror("sendfile");
		exit(EXIT_FAILURE);
	}
	rc = fchmod(out_fd, 0400);
	if (rc == -1) {
		fprintf(stderr, "chmod: %s: ", out);
		perror("");
		exit(EXIT_FAILURE);
	}
	close(in_fd);
	close(out_fd);
}

void
copy_file_with_encryption(const char *in, const char *out, enum encrypt encrypt)
{
	char *crypt_param;
	assert(encrypt == ENCRYPT || encrypt == DECRYPT);
	if (encrypt == ENCRYPT)
		crypt_param = "--encrypt";
	else
		crypt_param = "--decrypt";
	/* use dups to suppress "discards const qualifier" warnings */
	char *in_dup = strdup(in);
	char *out_dup = strdup(out);
	char *cmd[] = {
		"gpg",
		"--output", out_dup,
		"--yes",
		crypt_param, in_dup,
		NULL
	};
	ftag_execvp(cmd, 1);
	free(in_dup);
	free(out_dup);
}

int ftag_execvp(char *const *cmd, int can_exit)
{
	int status = 0;
	int rc = fork();
	if (rc == 0) {
		execvp(cmd[0], cmd);
		fprintf(stderr, "exec: %s: ", cmd[0]);
		perror("");
	}
	else if (rc > 0) {
		int status;
		wait(&status);
		if (!(WIFEXITED(status) && WEXITSTATUS(status) == 0)) {
			fprintf(stderr,
				"ftag: child process exited abnormally\n");
			if (can_exit)
				exit(EXIT_FAILURE);
			else
				status = -1;
		}
	}
	else {
		perror("fork");
		if (can_exit)
			exit(EXIT_FAILURE);
		else
			status = -1;
	}
	return status;
}