/*

 * Copyright (C) 2018  ABRT team

 * Copyright (C) 2018  RedHat Inc

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program 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.

 */

#include <stdio.h>

#include <unistd.h>

#include <sys/types.h>

#include <string.h>

#define INIT_PROC_STDERR_FD_PATH "/proc/1/fd/2"

#define DEFAULT_TAG "container-exception-logger"

int main(int argc, char *argv[])

{

    const char *program_usage_string =

        "Usage: container-exception-logger [--no-tag | --tag STRING | --help]"

        "\n"

        "\nThe tool reads from standard input and writes to '"INIT_PROC_STDERR_FD_PATH"'";

    int opt_notag = 0;

    const char * opt_tag = NULL;

    if (argc > 1)

    {

        for (int i = 1; i < argc; ++i)

        {

            if (strcmp(argv[i], "--help") == 0 || strcmp(argv[i], "-h") == 0)

            {

                fprintf(stderr, "%s\n", program_usage_string);

                return 1;

            }

            else if (strcmp(argv[i], "--no-tag") == 0)

            {

                opt_notag = 1;

            }

            else if (strcmp(argv[i], "--tag") == 0

                     && i + 1 < argc

                     && argv[i + 1][0] != '-')

            {

                opt_tag = argv[++i];

            }

            else

            {

                fprintf(stderr, "%s\n", program_usage_string);

                return 1;

            }

        }

    }

    FILE *f = fopen(INIT_PROC_STDERR_FD_PATH, "w");

    if (f == NULL)

    {

        perror("Failed to open '"INIT_PROC_STDERR_FD_PATH"' as root");

        /* Try to open the 'INIT_PROC_STDERR_FD_PATH' as normal user because of

           https://github.com/minishift/minishift/issues/2058

        */

        if (seteuid(getuid()) == 0)

        {

            f = fopen(INIT_PROC_STDERR_FD_PATH, "w");

            if (f == NULL)

            {

                perror("Failed to open '"INIT_PROC_STDERR_FD_PATH"' as user");

                return 2;

            }

        }

        else

        {

            perror("Failed to setuid");

            return 3;

        }

    }

    setvbuf (f, NULL, _IONBF, 0);

    if (!opt_notag)

        fprintf(f, "%s - ", opt_tag ? opt_tag : DEFAULT_TAG);

    char buffer[BUFSIZ];

    ssize_t bytes_read = 0;

    while (1)

    {

        bytes_read = read(0, buffer, sizeof buffer);

        if (bytes_read <= 0)

            break;

        if (fwrite(buffer, bytes_read, 1, f) != 1)

        {

            perror("Failed to write to '"INIT_PROC_STDERR_FD_PATH"'");

            fclose(f);

            return 4;

        }

    }

    fclose(f);

    return 0;

}