filters.c

// This file is part of Snownews - A lightweight console RSS newsreader
//
// Copyright (c) 2003-2004 Oliver Feiler <kiza@kcore.de>
//
// Snownews is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License version 3
// as published by the Free Software Foundation.
//
// Snownews is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty
// of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Snownews. If not, see http://www.gnu.org/licenses/.

#include "filters.h"
#include "uiutil.h"
#include "conv.h"

//----------------------------------------------------------------------

static int pipe_command_buf (const char* command, char** argv, const void* inbuf, size_t inbuf_size, char** outbuf, unsigned* outbuf_size);

//----------------------------------------------------------------------

// Load output of local script. Must be valid RSS.
int FilterExecURL (struct feed* cur_ptr)
{
    char* command = strdup (cur_ptr->feedurl);
    char* freeme = command;

    strsep (&command, ":");

    char buf[BUFSIZ];
    snprintf (buf, sizeof (buf), _("Loading \"%s\""), command);
    UIStatus (buf, 0, 0);

    FILE* scriptoutput = popen (command, "r");
    free (freeme);
    if (!scriptoutput)
	return -1;

    cur_ptr->content_length = 0;
    cur_ptr->xmltext = realloc (cur_ptr->xmltext, cur_ptr->content_length + 1);
    cur_ptr->xmltext[cur_ptr->content_length] = '\0';

    while (!feof (scriptoutput) && fgets (buf, sizeof (buf), scriptoutput)) {
	size_t br = strlen (buf);
	cur_ptr->xmltext = realloc (cur_ptr->xmltext, cur_ptr->content_length + br + 1);
	memcpy (&cur_ptr->xmltext[cur_ptr->content_length], buf, br + 1);
	cur_ptr->content_length += br;
    }
    pclose (scriptoutput);

    // Set title and link structure to something.
    // To the feedurl in this case so the program shows something
    // as placeholder instead of crash.
    if (cur_ptr->title == NULL)
	cur_ptr->title = strdup (cur_ptr->feedurl);
    if (cur_ptr->link == NULL)
	cur_ptr->link = strdup (cur_ptr->feedurl);
    return 0;
}

int FilterPipeNG (struct feed* cur_ptr)
{
    if (cur_ptr->perfeedfilter == NULL)
	return -1;

    char* data = malloc (cur_ptr->content_length + 1);
    memcpy (data, cur_ptr->xmltext, cur_ptr->content_length);
    data[cur_ptr->content_length] = 0;

    free (cur_ptr->xmltext);
    cur_ptr->xmltext = NULL;
    cur_ptr->content_length = 0;

    char* filter = strdup (cur_ptr->perfeedfilter);
    char* command = strsep (&filter, " ");

    char** options = malloc (sizeof (char*));
    size_t nopts = 0;
    options[nopts++] = command;

    for (;;) {
	options = realloc (options, sizeof (char*) * (nopts + 1));
	if (!(options[nopts++] = strsep (&filter, " ")))
	    break;
    }

    int rc = pipe_command_buf (command, options,
			       data, cur_ptr->content_length,
			       &cur_ptr->xmltext, &cur_ptr->content_length);

    free (data);
    free (command);
    free (options);	       // options[i] contains only pointers!
    return rc;
}

static int pipe_command_buf (const char* command, char** argv, const void* inbuf, size_t inbuf_size, char** outbuf, unsigned* outbuf_size)
{
    enum { READ_END, WRITE_END, N_ENDS };

    int input_pipe[N_ENDS], output_pipe[N_ENDS];
    if (0 != pipe (input_pipe)) {
	perror ("Couldn't create input pipe");
	return -1;
    }
    if (0 != pipe (output_pipe)) {
	close (input_pipe[READ_END]);
	close (input_pipe[WRITE_END]);
	perror ("Couldn't create output pipe");
	return -1;
    }

    int result = fork();
    if (result < 0) {
	close (input_pipe[READ_END]);
	close (input_pipe[WRITE_END]);
	close (output_pipe[READ_END]);
	close (output_pipe[WRITE_END]);
	perror ("fork");
	return -1;
    } else if (result == 0) {
	close (output_pipe[WRITE_END]);
	close (input_pipe[READ_END]);

	if (0 > dup2 (output_pipe[READ_END], STDIN_FILENO)) {
	    perror ("dup2 error on output_pipe");
	    exit (EXIT_FAILURE);
	}
	close (output_pipe[READ_END]);

	if (0 > dup2 (input_pipe[WRITE_END], STDOUT_FILENO)) {
	    perror ("dup2 error on input_pipe");
	    exit (EXIT_FAILURE);
	}
	close (input_pipe[WRITE_END]);

	if (0 > execvp (command, argv)) {
	    char tmp[PATH_MAX];
	    snprintf (tmp, sizeof (tmp), "Exec of \"%s\" failed", command);
	    perror (tmp);
	}
	exit (EXIT_FAILURE);
    } else {
	close (output_pipe[READ_END]);
	close (input_pipe[WRITE_END]);

	write (output_pipe[WRITE_END], inbuf, inbuf_size);
	close (output_pipe[WRITE_END]);

	char* buf = NULL, *buf_cur = NULL;
	int buf_size = 0, bytes_read = 0;
	do {
	    buf_size += BUFSIZ;
	    buf = realloc (buf, buf_size + 1);
	    buf_cur = buf + buf_size - BUFSIZ;
	    result = read (input_pipe[READ_END], buf_cur, BUFSIZ);
	    if (result > 0) {
		bytes_read += result;
		if (result < BUFSIZ) {
		    buf_size -= (BUFSIZ - result);
		    buf = realloc (buf, buf_size + 1);
		    break;
		}
	    } else if (result < 0) {
		free (buf);
		buf = NULL;
		return -1;
	    }
	} while (result > 0);
	close (input_pipe[READ_END]);

	if (bytes_read == 0) {
	    free (buf);
	    return -1;
	} else {
	    buf[buf_size] = '\0';
	    *outbuf = buf;
	    *outbuf_size = buf_size;
	}
    }
    return 0;
}