/* SPDX-License-Identifier: GPL-2.0+ */
/*
 * Collect variables across events.
 *
 * usage: collect [--add|--remove] <checkpoint> <id> <idlist>
 *
 * Adds ID <id> to the list governed by <checkpoint>.
 * <id> must be part of the ID list <idlist>.
 * If all IDs given by <idlist> are listed (ie collect has been
 * invoked for each ID in <idlist>) collect returns 0, the
 * number of missing IDs otherwise.
 * A negative number is returned on error.
 *
 * Copyright © 2007, Hannes Reinecke <hare@suse.de>
 *
 * 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.
 */

#include <errno.h>
#include <getopt.h>
#include <stddef.h>
#include <stdio.h>

#include "alloc-util.h"
#include "libudev-private.h"
#include "macro.h"
#include "stdio-util.h"
#include "string-util.h"
#include "udev-util.h"

#define BUFSIZE 16
#define UDEV_ALARM_TIMEOUT 180

enum collect_state {
        STATE_NONE,
        STATE_OLD,
        STATE_CONFIRMED,
};

struct _mate {
        struct udev_list_node node;
        char *name;
        enum collect_state state;
};

static struct udev_list_node bunch;
static int debug;

/* This can increase dynamically */
static size_t bufsize = BUFSIZE;

static inline struct _mate *node_to_mate(struct udev_list_node *node)
{
        return container_of(node, struct _mate, node);
}

_noreturn_ static void sig_alrm(int signo)
{
        _exit(4);
}

static void usage(void)
{
        printf("%s [options] <checkpoint> <id> <idlist>\n\n"
               "Collect variables across events.\n\n"
               "  -h --help        Print this message\n"
               "  -a --add         Add ID <id> to the list <idlist>\n"
               "  -r --remove      Remove ID <id> from the list <idlist>\n"
               "  -d --debug       Debug to stderr\n\n"
               "  Adds ID <id> to the list governed by <checkpoint>.\n"
               "  <id> must be part of the list <idlist>.\n"
               "  If all IDs given by <idlist> are listed (ie collect has been\n"
               "  invoked for each ID in <idlist>) collect returns 0, the\n"
               "  number of missing IDs otherwise.\n"
               "  On error a negative number is returned.\n\n"
               , program_invocation_short_name);
}

/*
 * prepare
 *
 * Prepares the database file
 */
static int prepare(char *dir, char *filename)
{
        char buf[PATH_MAX];
        int r, fd;

        r = mkdir(dir, 0700);
        if (r < 0 && errno != EEXIST)
                return -errno;

        snprintf(buf, sizeof buf, "%s/%s", dir, filename);

        fd = open(buf, O_RDWR|O_CREAT|O_CLOEXEC, S_IRUSR|S_IWUSR);
        if (fd < 0)
                fprintf(stderr, "Cannot open %s: %m\n", buf);

        if (lockf(fd,F_TLOCK,0) < 0) {
                if (debug)
                        fprintf(stderr, "Lock taken, wait for %d seconds\n", UDEV_ALARM_TIMEOUT);
                if (IN_SET(errno, EAGAIN, EACCES)) {
                        alarm(UDEV_ALARM_TIMEOUT);
                        lockf(fd, F_LOCK, 0);
                        if (debug)
                                fprintf(stderr, "Acquired lock on %s\n", buf);
                } else {
                        if (debug)
                                fprintf(stderr, "Could not get lock on %s: %m\n", buf);
                }
        }

        return fd;
}

/*
 * Read checkpoint file
 *
 * Tricky reading this. We allocate a buffer twice as large
 * as we're going to read. Then we read into the upper half
 * of that buffer and start parsing.
 * Once we do _not_ find end-of-work terminator (whitespace
 * character) we move the upper half to the lower half,
 * adjust the read pointer and read the next bit.
 * Quite clever methinks :-)
 * I should become a programmer ...
 *
 * Yes, one could have used fgets() for this. But then we'd
 * have to use freopen etc which I found quite tedious.
 */
static int checkout(int fd)
{
        int len;
        _cleanup_free_ char *buf = NULL;
        char *ptr, *word = NULL;
        struct _mate *him;

 restart:
        len = bufsize >> 1;
        buf = malloc(bufsize + 1);
        if (!buf)
                return log_oom();
        memset(buf, ' ', bufsize);
        buf[bufsize] = '\0';

        ptr = buf + len;
        while ((read(fd, buf + len, len)) > 0) {
                while (ptr && *ptr) {
                        word = ptr;
                        ptr = strpbrk(word," \n\t\r");
                        if (!ptr && word < (buf + len)) {
                                bufsize = bufsize << 1;
                                if (debug)
                                        fprintf(stderr, "ID overflow, restarting with size %zu\n", bufsize);
                                lseek(fd, 0, SEEK_SET);
                                goto restart;
                        }
                        if (ptr) {
                                *ptr = '\0';
                                ptr++;
                                if (isempty(word))
                                        continue;

                                if (debug)
                                        fprintf(stderr, "Found word %s\n", word);
                                him = malloc(sizeof (struct _mate));
                                if (!him)
                                        return log_oom();
                                him->name = strdup(word);
                                if (!him->name) {
                                        free(him);
                                        return log_oom();
                                }
                                him->state = STATE_OLD;
                                udev_list_node_append(&him->node, &bunch);
                                word = NULL;
                        }
                }
                memcpy(buf, buf + len, len);
                memset(buf + len, ' ', len);

                if (!ptr)
                        ptr = word;
                ptr -= len;
        }

        return 0;
}

/*
 * invite
 *
 * Adds a new ID 'us' to the internal list,
 * marks it as confirmed.
 */
static void invite(char *us)
{
        struct udev_list_node *him_node;
        struct _mate *who = NULL;

        if (debug)
                fprintf(stderr, "Adding ID '%s'\n", us);

        udev_list_node_foreach(him_node, &bunch) {
                struct _mate *him = node_to_mate(him_node);

                if (streq(him->name, us)) {
                        him->state = STATE_CONFIRMED;
                        who = him;
                }
        }
        if (debug && !who)
                fprintf(stderr, "ID '%s' not in database\n", us);

}

/*
 * reject
 *
 * Marks the ID 'us' as invalid,
 * causing it to be removed when the
 * list is written out.
 */
static void reject(char *us)
{
        struct udev_list_node *him_node;
        struct _mate *who = NULL;

        if (debug)
                fprintf(stderr, "Removing ID '%s'\n", us);

        udev_list_node_foreach(him_node, &bunch) {
                struct _mate *him = node_to_mate(him_node);

                if (streq(him->name, us)) {
                        him->state = STATE_NONE;
                        who = him;
                }
        }
        if (debug && !who)
                fprintf(stderr, "ID '%s' not in database\n", us);
}

/*
 * kickout
 *
 * Remove all IDs in the internal list which are not part
 * of the list passed via the command line.
 */
static void kickout(void)
{
        struct udev_list_node *him_node;
        struct udev_list_node *tmp;

        udev_list_node_foreach_safe(him_node, tmp, &bunch) {
                struct _mate *him = node_to_mate(him_node);

                if (him->state == STATE_OLD) {
                        udev_list_node_remove(&him->node);
                        free(him->name);
                        free(him);
                }
        }
}

/*
 * missing
 *
 * Counts all missing IDs in the internal list.
 */
static int missing(int fd)
{
        char *buf;
        int ret = 0;
        struct udev_list_node *him_node;

        buf = malloc(bufsize);
        if (!buf)
                return log_oom();

        udev_list_node_foreach(him_node, &bunch) {
                struct _mate *him = node_to_mate(him_node);

                if (him->state == STATE_NONE) {
                        ret++;
                } else {
                        while (strlen(him->name)+1 >= bufsize) {
                                char *tmpbuf;

                                bufsize = bufsize << 1;
                                tmpbuf = realloc(buf, bufsize);
                                if (!tmpbuf) {
                                        free(buf);
                                        return log_oom();
                                }
                                buf = tmpbuf;
                        }
                        snprintf(buf, strlen(him->name)+2, "%s ", him->name);
                        if (write(fd, buf, strlen(buf)) < 0) {
                                free(buf);
                                return -1;
                        }
                }
        }

        free(buf);
        return ret;
}

/*
 * everybody
 *
 * Prints out the status of the internal list.
 */
static void everybody(void)
{
        struct udev_list_node *him_node;
        const char *state = "";

        udev_list_node_foreach(him_node, &bunch) {
                struct _mate *him = node_to_mate(him_node);

                switch (him->state) {
                case STATE_NONE:
                        state = "none";
                        break;
                case STATE_OLD:
                        state = "old";
                        break;
                case STATE_CONFIRMED:
                        state = "confirmed";
                        break;
                }
                fprintf(stderr, "ID: %s=%s\n", him->name, state);
        }
}

int main(int argc, char **argv) {
        static const struct option options[] = {
                { "add", no_argument, NULL, 'a' },
                { "remove", no_argument, NULL, 'r' },
                { "debug", no_argument, NULL, 'd' },
                { "help", no_argument, NULL, 'h' },
                {}
        };
        int argi;
        char *checkpoint, *us;
        int fd;
        int i;
        int ret = EXIT_SUCCESS;
        int prune = 0;
        char tmpdir[UTIL_PATH_SIZE];

        log_set_target(LOG_TARGET_AUTO);
        udev_parse_config();
        log_parse_environment();
        log_open();

        for (;;) {
                int option;

                option = getopt_long(argc, argv, "ardh", options, NULL);
                if (option == -1)
                        break;

                switch (option) {
                case 'a':
                        prune = 0;
                        break;
                case 'r':
                        prune = 1;
                        break;
                case 'd':
                        debug = 1;
                        break;
                case 'h':
                        usage();
                        return 0;
                default:
                        return 1;
                }
        }

        argi = optind;
        if (argi + 2 > argc) {
                printf("Missing parameter(s)\n");
                return 1;
        }
        checkpoint = argv[argi++];
        us = argv[argi++];

        if (signal(SIGALRM, sig_alrm) == SIG_ERR) {
                fprintf(stderr, "Cannot set SIGALRM: %m\n");
                return 2;
        }

        udev_list_node_init(&bunch);

        if (debug)
                fprintf(stderr, "Using checkpoint '%s'\n", checkpoint);

        strscpyl(tmpdir, sizeof(tmpdir), "/run/udev/collect", NULL);
        fd = prepare(tmpdir, checkpoint);
        if (fd < 0) {
                ret = 3;
                goto out;
        }

        if (checkout(fd) < 0) {
                ret = 2;
                goto out;
        }

        for (i = argi; i < argc; i++) {
                struct udev_list_node *him_node;
                struct _mate *who;

                who = NULL;
                udev_list_node_foreach(him_node, &bunch) {
                        struct _mate *him = node_to_mate(him_node);

                        if (streq(him->name, argv[i]))
                                who = him;
                }
                if (!who) {
                        struct _mate *him;

                        if (debug)
                                fprintf(stderr, "ID %s: not in database\n", argv[i]);
                        him = new(struct _mate, 1);
                        if (!him) {
                                ret = ENOMEM;
                                goto out;
                        }

                        him->name = strdup(argv[i]);
                        if (!him->name) {
                                free(him);
                                ret = ENOMEM;
                                goto out;
                        }

                        him->state = STATE_NONE;
                        udev_list_node_append(&him->node, &bunch);
                } else {
                        if (debug)
                                fprintf(stderr, "ID %s: found in database\n", argv[i]);
                        who->state = STATE_CONFIRMED;
                }
        }

        if (prune)
                reject(us);
        else
                invite(us);

        if (debug) {
                everybody();
                fprintf(stderr, "Prune lists\n");
        }
        kickout();

        lseek(fd, 0, SEEK_SET);
        ftruncate(fd, 0);
        ret = missing(fd);

        lockf(fd, F_ULOCK, 0);
        close(fd);
out:
        if (debug)
                everybody();
        if (ret >= 0)
                printf("COLLECT_%s=%d\n", checkpoint, ret);
        return ret;
}