devices.c

Android 一些工具

            msg += 7;
            uevent->action = msg;
        } else if(!strncmp(msg, "DEVPATH=", 8)) {
            msg += 8;
            uevent->path = msg;
        } else if(!strncmp(msg, "SUBSYSTEM=", 10)) {
            msg += 10;
            uevent->subsystem = msg;
        } else if(!strncmp(msg, "FIRMWARE=", 9)) {
            msg += 9;
            uevent->firmware = msg;
        } else if(!strncmp(msg, "MAJOR=", 6)) {
            msg += 6;
            uevent->major = atoi(msg);
        } else if(!strncmp(msg, "MINOR=", 6)) {
            msg += 6;
            uevent->minor = atoi(msg);
        }

            /* advance to after the next \0 */
        while(*msg++)
            ;
    }

    log_event_print("event { '%s', '%s', '%s', '%s', %d, %d }\n",
                    uevent->action, uevent->path, uevent->subsystem,
                    uevent->firmware, uevent->major, uevent->minor);
}

static void handle_device_event(struct uevent *uevent)
{
    char devpath[96];
    char *base, *name;
    int block;

        /* if it's not a /dev device, nothing to do */
    if((uevent->major < 0) || (uevent->minor < 0))
        return;

        /* do we have a name? */
    name = strrchr(uevent->path, '/');
    if(!name)
        return;
    name++;

        /* too-long names would overrun our buffer */
    if(strlen(name) > 64)
        return;

        /* are we block or char? where should we live? */
    if(!strncmp(uevent->path, "/block", 6)) {
        block = 1;
        base = "/dev/block/";
        mkdir(base, 0755);
    } else {
        block = 0;
            /* this should probably be configurable somehow */
        if(!strncmp(uevent->path, "/class/graphics/", 16)) {
            base = "/dev/graphics/";
            mkdir(base, 0755);
        } else if (!strncmp(uevent->path, "/class/oncrpc/", 14)) {
            base = "/dev/oncrpc/";
            mkdir(base, 0755);
        } else if (!strncmp(uevent->path, "/class/adsp/", 12)) {
            base = "/dev/adsp/";
            mkdir(base, 0755);
      } else if(!strncmp(uevent->path, "/class/input/", 13)) {
            base = "/dev/input/";
            mkdir(base, 0755);
        } else if(!strncmp(uevent->path, "/class/mtd/", 11)) {
            base = "/dev/mtd/";
            mkdir(base, 0755);
        } else if(!strncmp(uevent->path, "/class/misc/", 12) &&
                    !strncmp(name, "log_", 4)) {
            base = "/dev/log/";
            mkdir(base, 0755);
            name += 4;
        } else
            base = "/dev/";
    }

    snprintf(devpath, sizeof(devpath), "%s%s", base, name);

    if(!strcmp(uevent->action, "add")) {
        make_device(devpath, block, uevent->major, uevent->minor);
        return;
    }

    if(!strcmp(uevent->action, "remove")) {
        unlink(devpath);
        return;
    }
}

static int load_firmware(int fw_fd, int loading_fd, int data_fd)
{
    struct stat st;
    long len_to_copy;
    int ret = 0;

    if(fstat(fw_fd, &st) < 0)
        return -1;
    len_to_copy = st.st_size;

    write(loading_fd, "1", 1);  /* start transfer */

    while (len_to_copy > 0) {
        char buf[PAGE_SIZE];
        ssize_t nr;

        nr = read(fw_fd, buf, sizeof(buf));
        if(!nr)
            break;
        if(nr < 0) {
            ret = -1;
            break;
        }

        len_to_copy -= nr;
        while (nr > 0) {
            ssize_t nw = 0;

            nw = write(data_fd, buf + nw, nr);
            if(nw <= 0) {
                ret = -1;
                goto out;
            }
            nr -= nw;
        }
    }

out:
    if(!ret)
        write(loading_fd, "0", 1);  /* successful end of transfer */
    else
        write(loading_fd, "-1", 2); /* abort transfer */

    return ret;
}

static void process_firmware_event(struct uevent *uevent)
{
    char *root, *loading, *data, *file;
    int l, loading_fd, data_fd, fw_fd;

    log_event_print("firmware event { '%s', '%s' }\n",
                    uevent->path, uevent->firmware);

    l = asprintf(&root, SYSFS_PREFIX"%s/", uevent->path);
    if (l == -1)
        return;

    l = asprintf(&loading, "%sloading", root);
    if (l == -1)
        goto root_free_out;

    l = asprintf(&data, "%sdata", root);
    if (l == -1)
        goto loading_free_out;

    l = asprintf(&file, FIRMWARE_DIR"/%s", uevent->firmware);
    if (l == -1)
        goto data_free_out;

    loading_fd = open(loading, O_WRONLY);
    if(loading_fd < 0)
        goto file_free_out;

    data_fd = open(data, O_WRONLY);
    if(data_fd < 0)
        goto loading_close_out;

    fw_fd = open(file, O_RDONLY);
    if(fw_fd < 0)
        goto data_close_out;

    if(!load_firmware(fw_fd, loading_fd, data_fd))
        log_event_print("firmware copy success { '%s', '%s' }\n", root, file);
    else
        log_event_print("firmware copy failure { '%s', '%s' }\n", root, file);

    close(fw_fd);
data_close_out:
    close(data_fd);
loading_close_out:
    close(loading_fd);
file_free_out:
    free(file);
data_free_out:
    free(data);
loading_free_out:
    free(loading);
root_free_out:
    free(root);
}

static void handle_firmware_event(struct uevent *uevent)
{
    pid_t pid;

    if(strcmp(uevent->subsystem, "firmware"))
        return;

    if(strcmp(uevent->action, "add"))
        return;

    /* we fork, to avoid making large memory allocations in init proper */
    pid = fork();
    if (!pid) {
        process_firmware_event(uevent);
        exit(EXIT_SUCCESS);
    }
}

#define UEVENT_MSG_LEN  1024
void handle_device_fd(int fd)
{
    char msg[UEVENT_MSG_LEN+2];
    int n;

    while((n = recv(fd, msg, UEVENT_MSG_LEN, 0)) > 0) {
        struct uevent uevent;

        if(n == UEVENT_MSG_LEN)   /* overflow -- discard */
            continue;

        msg[n] = '\0';
        msg[n+1] = '\0';

        parse_event(msg, &uevent);

        handle_device_event(&uevent);
        handle_firmware_event(&uevent);
    }
}

/* Coldboot walks parts of the /sys tree and pokes the uevent files
** to cause the kernel to regenerate device add events that happened
** before init's device manager was started
**
** We drain any pending events from the netlink socket every time
** we poke another uevent file to make sure we don't overrun the
** socket's buffer.  
*/

static void do_coldboot(int event_fd, DIR *d)
{
    struct dirent *de;
    int dfd, fd;

    dfd = dirfd(d);

    fd = openat(dfd, "uevent", O_WRONLY);
    if(fd >= 0) {
        write(fd, "add\n", 4);
        close(fd);
        handle_device_fd(event_fd);
    }

    while((de = readdir(d))) {
        DIR *d2;

        if(de->d_type != DT_DIR || de->d_name[0] == '.')
            continue;

        fd = openat(dfd, de->d_name, O_RDONLY | O_DIRECTORY);
        if(fd < 0)
            continue;

        d2 = fdopendir(fd);
        if(d2 == 0)
            close(fd);
        else {
            do_coldboot(event_fd, d2);
            closedir(d2);
        }
    }
}

static void coldboot(int event_fd, const char *path)
{
    DIR *d = opendir(path);
    if(d) {
        do_coldboot(event_fd, d);
        closedir(d);
    }
}

int device_init(void)
{
    suseconds_t t0, t1;
    int fd;

    fd = open_uevent_socket();
    if(fd < 0)
        return -1;

    fcntl(fd, F_SETFD, FD_CLOEXEC);
    fcntl(fd, F_SETFL, O_NONBLOCK);

    t0 = get_usecs();
    coldboot(fd, "/sys/class");
    coldboot(fd, "/sys/block");
    coldboot(fd, "/sys/devices");
    t1 = get_usecs();

    log_event_print("coldboot %ld uS\n", ((long) (t1 - t0)));

    return fd;
}