#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include "util.h"
#include "interfere.h"

const char *progname="redirectfd";

struct private
{
	int fd;
	int targetfd;
	char *filename;
};

int redirectfd(struct process *proc, struct private *priv)
{
	PROC_BEGIN(proc);

	proc_open(proc, priv->filename, 
		O_RDWR|O_CREAT|O_APPEND, 0666);
	if (proc->last_error)
	{
		warn("open(pid %li, file %s): %s\n", 
			(long)proc->pid, priv->filename,
			strerror(proc->last_error));
		goto out;
	}
	priv->fd=proc->retval;

	if (priv->fd != priv->targetfd)
	{
		proc_dup2(proc, priv->fd, priv->targetfd);
		if (proc->last_error)
		{
			warn("dup2(pid %li): %s\n", 
				(long)proc->pid, strerror(proc->last_error));
			goto out;
		}
	}
	printf("pid %li: Redirected fd %i -> %s\n", 
		(long)proc->pid, priv->targetfd, priv->filename);
		
	if (priv->fd != priv->targetfd)
	{
		proc_close(proc, priv->fd);
		if (proc->last_error)
		{
			warn("close(pid %li): %s\n", 
				(long)proc->pid, strerror(proc->last_error));
			goto out;
		}
	}

 out:
	PROC_END(proc);
}

int main(int argc, char *argv[])
{
	pid_t pid;
	int status;
	struct process proc;
	struct private priv;
	char cwd[PATH_MAX];
	char *filename;

	if (argc>0) setprogname(argv[0]);
	if (argc<4) die("Usage: %s pid fd filename\n", progname);

	pid=str_to_pid(argv[1]);
	priv.targetfd=str_to_fd(argv[2]);
	filename=argv[3];

	if (filename[0] != '/')
	{
		char *newname;
		if (!getcwd(cwd, sizeof(cwd)))
			die("getcwd: %s\n", strerror(errno));
		if (!strcmp(cwd, "/")) *cwd=0;
		newname=malloc(strlen(cwd)+1+strlen(filename)+1);
		if (!newname) die("malloc: %s\n", strerror(errno));
		sprintf(newname, "%s/%s", cwd, filename);
		filename=newname;
	}

	priv.filename=filename;

	if (pid==0) die("Invalid pid: 0\n");

	proc_init(&proc);
	proc_attach(&proc, pid);
		
	while (1)
	{
		pid=waitpid(proc.pid, &status, 0);
		if (pid==-1)
		{
			if (errno==EINTR) continue;
			if (errno==ECHILD) break;
			die("waitpid: %s\n", strerror(errno));
		}
		redirectfd(&proc, &priv);
	}
	return 0;
}