/* vi: set sw=4 ts=4: */
/*
 * mdev - Mini udev for busybox
 *
 * Copyright 2005 Rob Landley <rob@landley.net>
 * Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
 *
 * Licensed under GPL version 2, see file LICENSE in this tarball for details.
 */
#include "libbb.h"
#include "xregex.h"

struct globals {
        int root_major, root_minor;
        char *subsystem;
};
#define G (*(struct globals*)&bb_common_bufsiz1)
#define root_major (G.root_major)
#define root_minor (G.root_minor)
#define subsystem (G.subsystem)

/* Prevent infinite loops in /sys symlinks */
#define MAX_SYSFS_DEPTH 3

/* We use additional 64+ bytes in make_device() */
#define SCRATCH_SIZE 80

#if ENABLE_FEATURE_MDEV_RENAME
/* Builds an alias path.
 * This function potentionally reallocates the alias parameter.
 */
static char *build_alias(char *alias, const char *device_name)
{
        char *dest;

        /* ">bar/": rename to bar/device_name */
        /* ">bar[/]baz": rename to bar[/]baz */
        dest = strrchr(alias, '/');
        if (dest) { /* ">bar/[baz]" ? */
                *dest = '\0'; /* mkdir bar */
                bb_make_directory(alias, 0755, FILEUTILS_RECUR);
                *dest = '/';
                if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
                        dest = alias;
                        alias = concat_path_file(alias, device_name);
                        free(dest);
                }
        }

        return alias;
}
#endif

/* mknod in /dev based on a path like "/sys/block/hda/hda1" */
/* NB: "mdev -s" may call us many times, do not leak memory/fds! */
static void make_device(char *path, int delete)
{
#if ENABLE_FEATURE_MDEV_CONF
        parser_t *parser;
#endif
        const char *device_name;
        int major, minor, type, len;
        int mode;
        char *dev_maj_min = path + strlen(path);

        /* Force the configuration file settings exactly. */
        umask(0);

        /* Try to read major/minor string.  Note that the kernel puts \n after
         * the data, so we don't need to worry about null terminating the string
         * because sscanf() will stop at the first nondigit, which \n is.
         * We also depend on path having writeable space after it.
         */
        major = -1;
        if (!delete) {
                strcpy(dev_maj_min, "/dev");
                len = open_read_close(path, dev_maj_min + 1, 64);
                *dev_maj_min++ = '\0';
                if (len < 1) {
                        if (!ENABLE_FEATURE_MDEV_EXEC)
                                return;
                        /* no "dev" file, so just try to run script */
                        *dev_maj_min = '\0';
                } else if (sscanf(dev_maj_min, "%u:%u", &major, &minor) != 2) {
                        major = -1;
                }
        }

        /* Determine device name, type, major and minor */
        device_name = bb_basename(path);
        /* http://kernel.org/doc/pending/hotplug.txt says that only
         * "/sys/block/..." is for block devices. "/sys/bus" etc is not.
         * But since 2.6.25 block devices are also in /sys/class/block.
         * We use strstr("/block/") to forestall future surprises. */
        type = S_IFCHR;
        if (strstr(path, "/block/"))
                type = S_IFBLK;

#if !ENABLE_FEATURE_MDEV_CONF
        mode = 0660;
#else
        /* If we have config file, look up user settings */
        parser = config_open2("/etc/mdev.conf", fopen_for_read);
        while (1) {
                regmatch_t off[1 + 9*ENABLE_FEATURE_MDEV_RENAME_REGEXP];
                int keep_matching;
                char *val;
                struct bb_uidgid_t ugid;
                char *tokens[4];
# if ENABLE_FEATURE_MDEV_EXEC
                char *command = NULL;
# endif
# if ENABLE_FEATURE_MDEV_RENAME
                char *alias = NULL;
                char aliaslink = aliaslink; /* for compiler */
# endif
                /* Defaults in case we won't match any line */
                ugid.uid = ugid.gid = 0;
                keep_matching = 0;
                mode = 0660;

                if (!config_read(parser, tokens, 4, 3, "# \t", PARSE_NORMAL)) {
                        /* End of file, create dev node with default params */
                        goto line_matches;
                }

                val = tokens[0];
                keep_matching = ('-' == val[0]);
                val += keep_matching; /* swallow leading dash */

                /* Fields: regex uid:gid mode [alias] [cmd] */

                /* 1st field: @<numeric maj,min>... */
                if (val[0] == '@') {
                        /* @major,minor[-last] */
                        /* (useful when name is ambiguous:
                         * "/sys/class/usb/lp0" and
                         * "/sys/class/printer/lp0") */
                        int cmaj, cmin0, cmin1, sc;
                        if (major < 0)
                                continue; /* no dev, no match */
                        sc = sscanf(val, "@%u,%u-%u", &cmaj, &cmin0, &cmin1);
                        if (sc < 1 || major != cmaj
                         || (sc == 2 && minor != cmin0)
                         || (sc == 3 && (minor < cmin0 || minor > cmin1))
                        ) {
                                continue; /* this line doesn't match */
                        }
                } else { /* ... or regex to match device name */
                        regex_t match;
                        int result;
                        const char *dev_name_or_subsystem = device_name;
                        if ('/' == val[0] && subsystem) {
                                dev_name_or_subsystem = subsystem;
                                val++;
                        }

                        /* Is this it? */
                        xregcomp(&match, val, REG_EXTENDED);
                        result = regexec(&match, dev_name_or_subsystem, ARRAY_SIZE(off), off, 0);
                        regfree(&match);

                        //bb_error_msg("matches:");
                        //for (int i = 0; i < ARRAY_SIZE(off); i++) {
                        //      if (off[i].rm_so < 0) continue;
                        //      bb_error_msg("match %d: '%.*s'\n", i,
                        //              (int)(off[i].rm_eo - off[i].rm_so),
                        //              device_name + off[i].rm_so);
                        //}

                        /* If not this device, skip rest of line */
                        /* (regexec returns whole pattern as "range" 0) */
                        if (result || off[0].rm_so
                         || ((int)off[0].rm_eo != (int)strlen(dev_name_or_subsystem))
                        ) {
                                continue; /* this line doesn't match */
                        }
                }

                /* This line matches: stop parsing the file after parsing
                 * the rest of fields unless keep_matching == 1 */

                /* 2nd field: uid:gid - device ownership */
                if (get_uidgid(&ugid, tokens[1], 1) == 0)
                        bb_error_msg("unknown user/group %s", tokens[1]);

                /* 3rd field: mode - device permissions */
                mode = strtoul(tokens[2], NULL, 8);

                val = tokens[3];
                /* 4th field (opt): >|=alias */
# if ENABLE_FEATURE_MDEV_RENAME
                if (!val)
                        goto line_matches;
                aliaslink = val[0];
                if (aliaslink == '>' || aliaslink == '=') {
                        char *a, *s, *st;
#  if ENABLE_FEATURE_MDEV_RENAME_REGEXP
                        char *p;
                        unsigned i, n;
#  endif
                        a = val;
                        s = strchrnul(val, ' ');
                        st = strchrnul(val, '\t');
                        if (st < s)
                                s = st;
                        val = (s[0] && s[1]) ? s+1 : NULL;
                        s[0] = '\0';

#  if ENABLE_FEATURE_MDEV_RENAME_REGEXP
                        /* substitute %1..9 with off[1..9], if any */
                        n = 0;
                        s = a;
                        while (*s)
                                if (*s++ == '%')
                                        n++;

                        p = alias = xzalloc(strlen(a) + n * strlen(device_name));
                        s = a + 1;
                        while (*s) {
                                *p = *s;
                                if ('%' == *s) {
                                        i = (s[1] - '0');
                                        if (i <= 9 && off[i].rm_so >= 0) {
                                                n = off[i].rm_eo - off[i].rm_so;
                                                strncpy(p, device_name + off[i].rm_so, n);
                                                p += n - 1;
                                                s++;
                                        }
                                }
                                p++;
                                s++;
                        }
#  else
                        alias = xstrdup(a + 1);
#  endif
                }
# endif /* ENABLE_FEATURE_MDEV_RENAME */

# if ENABLE_FEATURE_MDEV_EXEC
                /* The rest (opt): @|$|*command */
                if (!val)
                        goto line_matches;
                {
                        const char *s = "@$*";
                        const char *s2 = strchr(s, val[0]);

                        if (!s2)
                                bb_error_msg_and_die("bad line %u", parser->lineno);

                        /* Correlate the position in the "@$*" with the delete
                         * step so that we get the proper behavior:
                         * @cmd: run on create
                         * $cmd: run on delete
                         * *cmd: run on both
                         */
                        if ((s2 - s + 1) /*1/2/3*/ & /*1/2*/ (1 + delete)) {
                                command = xstrdup(val + 1);
                        }
                }
# endif
                /* End of field parsing */
 line_matches:
#endif /* ENABLE_FEATURE_MDEV_CONF */

                /* "Execute" the line we found */

                if (!delete && major >= 0) {
                        if (ENABLE_FEATURE_MDEV_RENAME)
                                unlink(device_name);
                        if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
                                bb_perror_msg_and_die("mknod %s", device_name);
                        if (major == root_major && minor == root_minor)
                                symlink(device_name, "root");
#if ENABLE_FEATURE_MDEV_CONF
                        chown(device_name, ugid.uid, ugid.gid);
# if ENABLE_FEATURE_MDEV_RENAME
                        if (alias) {
                                alias = build_alias(alias, device_name);
                                /* move the device, and optionally
                                 * make a symlink to moved device node */
                                if (rename(device_name, alias) == 0 && aliaslink == '>')
                                        symlink(alias, device_name);
                                free(alias);
                        }
# endif
#endif
                }
#if ENABLE_FEATURE_MDEV_EXEC
                if (command) {
                        /* setenv will leak memory, use putenv/unsetenv/free */
                        char *s = xasprintf("%s=%s", "MDEV", device_name);
                        char *s1 = xasprintf("%s=%s", "SUBSYSTEM", subsystem);
                        putenv(s);
                        putenv(s1);
                        if (system(command) == -1)
                                bb_perror_msg_and_die("can't run '%s'", command);
                        unsetenv("SUBSYSTEM");
                        free(s1);
                        unsetenv("MDEV");
                        free(s);
                        free(command);
                }
#endif
                if (delete) {
                        unlink(device_name);
                        /* At creation time, device might have been moved
                         * and a symlink might have been created. Undo that. */
#if ENABLE_FEATURE_MDEV_RENAME
                        if (alias) {
                                alias = build_alias(alias, device_name);
                                unlink(alias);
                                free(alias);
                        }
#endif
                }

#if ENABLE_FEATURE_MDEV_CONF
                /* We found matching line.
                 * Stop unless it was prefixed with '-' */
                if (!keep_matching)
                        break;
        } /* end of "while line is read from /etc/mdev.conf" */

        config_close(parser);
#endif /* ENABLE_FEATURE_MDEV_CONF */
}

/* File callback for /sys/ traversal */
static int FAST_FUNC fileAction(const char *fileName,
                struct stat *statbuf UNUSED_PARAM,
                void *userData,
                int depth UNUSED_PARAM)
{
        size_t len = strlen(fileName) - 4; /* can't underflow */
        char *scratch = userData;

        /* len check is for paranoid reasons */
        if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX)
                return FALSE;

        strcpy(scratch, fileName);
        scratch[len] = '\0';
        make_device(scratch, 0);

        return TRUE;
}

/* Directory callback for /sys/ traversal */
static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
                struct stat *statbuf UNUSED_PARAM,
                void *userData UNUSED_PARAM,
                int depth)
{
        /* Extract device subsystem -- the name of the directory
         * under /sys/class/ */
        if (1 == depth) {
                free(subsystem);
                subsystem = strrchr(fileName, '/');
                if (subsystem)
                        subsystem = xstrdup(subsystem + 1);
        }

        return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
}

/* For the full gory details, see linux/Documentation/firmware_class/README
 *
 * Firmware loading works like this:
 * - kernel sets FIRMWARE env var
 * - userspace checks /lib/firmware/$FIRMWARE
 * - userspace waits for /sys/$DEVPATH/loading to appear
 * - userspace writes "1" to /sys/$DEVPATH/loading
 * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 * - kernel loads firmware into device
 */
static void load_firmware(const char *const firmware, const char *const sysfs_path)
{
        int cnt;
        int firmware_fd, loading_fd, data_fd;

        /* check for /lib/firmware/$FIRMWARE */
        xchdir("/lib/firmware");
        firmware_fd = xopen(firmware, O_RDONLY);

        /* in case we goto out ... */
        data_fd = -1;

        /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
        xchdir(sysfs_path);
        for (cnt = 0; cnt < 30; ++cnt) {
                loading_fd = open("loading", O_WRONLY);
                if (loading_fd != -1)
                        goto loading;
                sleep(1);
        }
        goto out;

 loading:
        /* tell kernel we're loading by "echo 1 > /sys/$DEVPATH/loading" */
        if (full_write(loading_fd, "1", 1) != 1)
                goto out;

        /* load firmware into /sys/$DEVPATH/data */
        data_fd = open("data", O_WRONLY);
        if (data_fd == -1)
                goto out;
        cnt = bb_copyfd_eof(firmware_fd, data_fd);

        /* tell kernel result by "echo [0|-1] > /sys/$DEVPATH/loading" */
        if (cnt > 0)
                full_write(loading_fd, "0", 1);
        else
                full_write(loading_fd, "-1", 2);

 out:
        if (ENABLE_FEATURE_CLEAN_UP) {
                close(firmware_fd);
                close(loading_fd);
                close(data_fd);
        }
}

int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int mdev_main(int argc UNUSED_PARAM, char **argv)
{
        RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);

        /* We can be called as hotplug helper */
        /* Kernel cannot provide suitable stdio fds for us, do it ourself */
#if 1
        bb_sanitize_stdio();
#else
        /* Debug code */
        /* Replace LOGFILE by other file or device name if you need */
#define LOGFILE "/dev/console"
        /* Just making sure fd 0 is not closed,
         * we don't really intend to read from it */
        xmove_fd(xopen("/", O_RDONLY), STDIN_FILENO);
        xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDOUT_FILENO);
        xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDERR_FILENO);
#endif

        xchdir("/dev");

        if (argv[1] && strcmp(argv[1], "-s") == 0) {
                /* Scan:
                 * mdev -s
                 */
                struct stat st;

                xstat("/", &st);
                root_major = major(st.st_dev);
                root_minor = minor(st.st_dev);

                /* ACTION_FOLLOWLINKS is needed since in newer kernels
                 * /sys/block/loop* (for example) are symlinks to dirs,
                 * not real directories.
                 * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
                 * but we can't enforce that on users)
                 */
                if (access("/sys/class/block", F_OK) != 0) {
                        /* Scan obsolete /sys/block only if /sys/class/block
                         * doesn't exist. Otherwise we'll have dupes.
                         * Also, do not complain if it doesn't exist.
                         * Some people configure kernel to have no blockdevs.
                         */
                        recursive_action("/sys/block",
                                ACTION_RECURSE | ACTION_FOLLOWLINKS | ACTION_QUIET,
                                fileAction, dirAction, temp, 0);
                }
                recursive_action("/sys/class",
                        ACTION_RECURSE | ACTION_FOLLOWLINKS,
                        fileAction, dirAction, temp, 0);
        } else {
                char *fw;
                char *seq;
                char *action;
                char *env_path;

                /* Hotplug:
                 * env ACTION=... DEVPATH=... SUBSYSTEM=... [SEQNUM=...] mdev
                 * ACTION can be "add" or "remove"
                 * DEVPATH is like "/block/sda" or "/class/input/mice"
                 */
                action = getenv("ACTION");
                env_path = getenv("DEVPATH");
                subsystem = getenv("SUBSYSTEM");
                if (!action || !env_path /*|| !subsystem*/)
                        bb_show_usage();
                fw = getenv("FIRMWARE");

                /* If it exists, does /dev/mdev.seq match $SEQNUM?
                 * If it does not match, earlier mdev is running
                 * in parallel, and we need to wait */
                seq = getenv("SEQNUM");
                if (seq) {
                        int timeout = 2000 / 32; /* 2000 msec */
                        do {
                                int seqlen;
                                char seqbuf[sizeof(int)*3 + 2];

                                seqlen = open_read_close("mdev.seq", seqbuf, sizeof(seqbuf-1));
                                if (seqlen < 0) {
                                        seq = NULL;
                                        break;
                                }
                                seqbuf[seqlen] = '\0';
                                if (seqbuf[0] == '\n' /* seed file? */
                                 || strcmp(seq, seqbuf) == 0 /* correct idx? */
                                ) {
                                        break;
                                }
                                usleep(32*1000);
                        } while (--timeout);
                }

                snprintf(temp, PATH_MAX, "/sys%s", env_path);
                if (strcmp(action, "remove") == 0) {
                        /* Ignoring "remove firmware". It was reported
                         * to happen and to cause erroneous deletion
                         * of device nodes. */
                        if (!fw)
                                make_device(temp, 1);
                }
                else if (strcmp(action, "add") == 0) {
                        make_device(temp, 0);
                        if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
                                if (fw)
                                        load_firmware(fw, temp);
                        }
                }

                if (seq) {
                        xopen_xwrite_close("mdev.seq", utoa(xatou(seq) + 1));
                }
        }

        if (ENABLE_FEATURE_CLEAN_UP)
                RELEASE_CONFIG_BUFFER(temp);

        return EXIT_SUCCESS;
}