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      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include <errno.h>
     18 #include <stddef.h>
     19 #include <stdio.h>
     20 #include <stdlib.h>
     21 #include <sys/stat.h>
     22 #include <sys/types.h>
     23 
     24 #include <fcntl.h>
     25 #include <dirent.h>
     26 #include <unistd.h>
     27 #include <string.h>
     28 
     29 #include <sys/socket.h>
     30 #include <sys/un.h>
     31 #include <linux/netlink.h>
     32 
     33 #include <selinux/selinux.h>
     34 #include <selinux/label.h>
     35 #include <selinux/android.h>
     36 
     37 #include <private/android_filesystem_config.h>
     38 #include <sys/time.h>
     39 #include <asm/page.h>
     40 #include <sys/wait.h>
     41 
     42 #include <cutils/list.h>
     43 #include <cutils/uevent.h>
     44 
     45 #include "devices.h"
     46 #include "util.h"
     47 #include "log.h"
     48 
     49 #define SYSFS_PREFIX    "/sys"
     50 #define FIRMWARE_DIR1   "/etc/firmware"
     51 #define FIRMWARE_DIR2   "/vendor/firmware"
     52 #define FIRMWARE_DIR3   "/firmware/image"
     53 
     54 extern struct selabel_handle *sehandle;
     55 
     56 static int device_fd = -1;
     57 
     58 struct uevent {
     59     const char *action;
     60     const char *path;
     61     const char *subsystem;
     62     const char *firmware;
     63     const char *partition_name;
     64     const char *device_name;
     65     int partition_num;
     66     int major;
     67     int minor;
     68 };
     69 
     70 struct perms_ {
     71     char *name;
     72     char *attr;
     73     mode_t perm;
     74     unsigned int uid;
     75     unsigned int gid;
     76     unsigned short prefix;
     77 };
     78 
     79 struct perm_node {
     80     struct perms_ dp;
     81     struct listnode plist;
     82 };
     83 
     84 struct platform_node {
     85     char *name;
     86     char *path;
     87     int path_len;
     88     struct listnode list;
     89 };
     90 
     91 static list_declare(sys_perms);
     92 static list_declare(dev_perms);
     93 static list_declare(platform_names);
     94 
     95 int add_dev_perms(const char *name, const char *attr,
     96                   mode_t perm, unsigned int uid, unsigned int gid,
     97                   unsigned short prefix) {
     98     struct perm_node *node = calloc(1, sizeof(*node));
     99     if (!node)
    100         return -ENOMEM;
    101 
    102     node->dp.name = strdup(name);
    103     if (!node->dp.name)
    104         return -ENOMEM;
    105 
    106     if (attr) {
    107         node->dp.attr = strdup(attr);
    108         if (!node->dp.attr)
    109             return -ENOMEM;
    110     }
    111 
    112     node->dp.perm = perm;
    113     node->dp.uid = uid;
    114     node->dp.gid = gid;
    115     node->dp.prefix = prefix;
    116 
    117     if (attr)
    118         list_add_tail(&sys_perms, &node->plist);
    119     else
    120         list_add_tail(&dev_perms, &node->plist);
    121 
    122     return 0;
    123 }
    124 
    125 void fixup_sys_perms(const char *upath)
    126 {
    127     char buf[512];
    128     struct listnode *node;
    129     struct perms_ *dp;
    130 
    131         /* upaths omit the "/sys" that paths in this list
    132          * contain, so we add 4 when comparing...
    133          */
    134     list_for_each(node, &sys_perms) {
    135         dp = &(node_to_item(node, struct perm_node, plist))->dp;
    136         if (dp->prefix) {
    137             if (strncmp(upath, dp->name + 4, strlen(dp->name + 4)))
    138                 continue;
    139         } else {
    140             if (strcmp(upath, dp->name + 4))
    141                 continue;
    142         }
    143 
    144         if ((strlen(upath) + strlen(dp->attr) + 6) > sizeof(buf))
    145             return;
    146 
    147         sprintf(buf,"/sys%s/%s", upath, dp->attr);
    148         INFO("fixup %s %d %d 0%o\n", buf, dp->uid, dp->gid, dp->perm);
    149         chown(buf, dp->uid, dp->gid);
    150         chmod(buf, dp->perm);
    151     }
    152 }
    153 
    154 static mode_t get_device_perm(const char *path, unsigned *uid, unsigned *gid)
    155 {
    156     mode_t perm;
    157     struct listnode *node;
    158     struct perm_node *perm_node;
    159     struct perms_ *dp;
    160 
    161     /* search the perms list in reverse so that ueventd.$hardware can
    162      * override ueventd.rc
    163      */
    164     list_for_each_reverse(node, &dev_perms) {
    165         perm_node = node_to_item(node, struct perm_node, plist);
    166         dp = &perm_node->dp;
    167 
    168         if (dp->prefix) {
    169             if (strncmp(path, dp->name, strlen(dp->name)))
    170                 continue;
    171         } else {
    172             if (strcmp(path, dp->name))
    173                 continue;
    174         }
    175         *uid = dp->uid;
    176         *gid = dp->gid;
    177         return dp->perm;
    178     }
    179     /* Default if nothing found. */
    180     *uid = 0;
    181     *gid = 0;
    182     return 0600;
    183 }
    184 
    185 static void make_device(const char *path,
    186                         const char *upath,
    187                         int block, int major, int minor)
    188 {
    189     unsigned uid;
    190     unsigned gid;
    191     mode_t mode;
    192     dev_t dev;
    193     char *secontext = NULL;
    194 
    195     mode = get_device_perm(path, &uid, &gid) | (block ? S_IFBLK : S_IFCHR);
    196 
    197     if (sehandle) {
    198         selabel_lookup(sehandle, &secontext, path, mode);
    199         setfscreatecon(secontext);
    200     }
    201 
    202     dev = makedev(major, minor);
    203     /* Temporarily change egid to avoid race condition setting the gid of the
    204      * device node. Unforunately changing the euid would prevent creation of
    205      * some device nodes, so the uid has to be set with chown() and is still
    206      * racy. Fixing the gid race at least fixed the issue with system_server
    207      * opening dynamic input devices under the AID_INPUT gid. */
    208     setegid(gid);
    209     mknod(path, mode, dev);
    210     chown(path, uid, -1);
    211     setegid(AID_ROOT);
    212 
    213     if (secontext) {
    214         freecon(secontext);
    215         setfscreatecon(NULL);
    216     }
    217 }
    218 
    219 static void add_platform_device(const char *path)
    220 {
    221     int path_len = strlen(path);
    222     struct listnode *node;
    223     struct platform_node *bus;
    224     const char *name = path;
    225 
    226     if (!strncmp(path, "/devices/", 9)) {
    227         name += 9;
    228         if (!strncmp(name, "platform/", 9))
    229             name += 9;
    230     }
    231 
    232     list_for_each_reverse(node, &platform_names) {
    233         bus = node_to_item(node, struct platform_node, list);
    234         if ((bus->path_len < path_len) &&
    235                 (path[bus->path_len] == '/') &&
    236                 !strncmp(path, bus->path, bus->path_len))
    237             /* subdevice of an existing platform, ignore it */
    238             return;
    239     }
    240 
    241     INFO("adding platform device %s (%s)\n", name, path);
    242 
    243     bus = calloc(1, sizeof(struct platform_node));
    244     bus->path = strdup(path);
    245     bus->path_len = path_len;
    246     bus->name = bus->path + (name - path);
    247     list_add_tail(&platform_names, &bus->list);
    248 }
    249 
    250 /*
    251  * given a path that may start with a platform device, find the length of the
    252  * platform device prefix.  If it doesn't start with a platform device, return
    253  * 0.
    254  */
    255 static struct platform_node *find_platform_device(const char *path)
    256 {
    257     int path_len = strlen(path);
    258     struct listnode *node;
    259     struct platform_node *bus;
    260 
    261     list_for_each_reverse(node, &platform_names) {
    262         bus = node_to_item(node, struct platform_node, list);
    263         if ((bus->path_len < path_len) &&
    264                 (path[bus->path_len] == '/') &&
    265                 !strncmp(path, bus->path, bus->path_len))
    266             return bus;
    267     }
    268 
    269     return NULL;
    270 }
    271 
    272 static void remove_platform_device(const char *path)
    273 {
    274     struct listnode *node;
    275     struct platform_node *bus;
    276 
    277     list_for_each_reverse(node, &platform_names) {
    278         bus = node_to_item(node, struct platform_node, list);
    279         if (!strcmp(path, bus->path)) {
    280             INFO("removing platform device %s\n", bus->name);
    281             free(bus->path);
    282             list_remove(node);
    283             free(bus);
    284             return;
    285         }
    286     }
    287 }
    288 
    289 #if LOG_UEVENTS
    290 
    291 static inline suseconds_t get_usecs(void)
    292 {
    293     struct timeval tv;
    294     gettimeofday(&tv, 0);
    295     return tv.tv_sec * (suseconds_t) 1000000 + tv.tv_usec;
    296 }
    297 
    298 #define log_event_print(x...) INFO(x)
    299 
    300 #else
    301 
    302 #define log_event_print(fmt, args...)   do { } while (0)
    303 #define get_usecs()                     0
    304 
    305 #endif
    306 
    307 static void parse_event(const char *msg, struct uevent *uevent)
    308 {
    309     uevent->action = "";
    310     uevent->path = "";
    311     uevent->subsystem = "";
    312     uevent->firmware = "";
    313     uevent->major = -1;
    314     uevent->minor = -1;
    315     uevent->partition_name = NULL;
    316     uevent->partition_num = -1;
    317     uevent->device_name = NULL;
    318 
    319         /* currently ignoring SEQNUM */
    320     while(*msg) {
    321         if(!strncmp(msg, "ACTION=", 7)) {
    322             msg += 7;
    323             uevent->action = msg;
    324         } else if(!strncmp(msg, "DEVPATH=", 8)) {
    325             msg += 8;
    326             uevent->path = msg;
    327         } else if(!strncmp(msg, "SUBSYSTEM=", 10)) {
    328             msg += 10;
    329             uevent->subsystem = msg;
    330         } else if(!strncmp(msg, "FIRMWARE=", 9)) {
    331             msg += 9;
    332             uevent->firmware = msg;
    333         } else if(!strncmp(msg, "MAJOR=", 6)) {
    334             msg += 6;
    335             uevent->major = atoi(msg);
    336         } else if(!strncmp(msg, "MINOR=", 6)) {
    337             msg += 6;
    338             uevent->minor = atoi(msg);
    339         } else if(!strncmp(msg, "PARTN=", 6)) {
    340             msg += 6;
    341             uevent->partition_num = atoi(msg);
    342         } else if(!strncmp(msg, "PARTNAME=", 9)) {
    343             msg += 9;
    344             uevent->partition_name = msg;
    345         } else if(!strncmp(msg, "DEVNAME=", 8)) {
    346             msg += 8;
    347             uevent->device_name = msg;
    348         }
    349 
    350         /* advance to after the next \0 */
    351         while(*msg++)
    352             ;
    353     }
    354 
    355     log_event_print("event { '%s', '%s', '%s', '%s', %d, %d }\n",
    356                     uevent->action, uevent->path, uevent->subsystem,
    357                     uevent->firmware, uevent->major, uevent->minor);
    358 }
    359 
    360 static char **get_character_device_symlinks(struct uevent *uevent)
    361 {
    362     const char *parent;
    363     char *slash;
    364     char **links;
    365     int link_num = 0;
    366     int width;
    367     struct platform_node *pdev;
    368 
    369     pdev = find_platform_device(uevent->path);
    370     if (!pdev)
    371         return NULL;
    372 
    373     links = malloc(sizeof(char *) * 2);
    374     if (!links)
    375         return NULL;
    376     memset(links, 0, sizeof(char *) * 2);
    377 
    378     /* skip "/devices/platform/<driver>" */
    379     parent = strchr(uevent->path + pdev->path_len, '/');
    380     if (!*parent)
    381         goto err;
    382 
    383     if (!strncmp(parent, "/usb", 4)) {
    384         /* skip root hub name and device. use device interface */
    385         while (*++parent && *parent != '/');
    386         if (*parent)
    387             while (*++parent && *parent != '/');
    388         if (!*parent)
    389             goto err;
    390         slash = strchr(++parent, '/');
    391         if (!slash)
    392             goto err;
    393         width = slash - parent;
    394         if (width <= 0)
    395             goto err;
    396 
    397         if (asprintf(&links[link_num], "/dev/usb/%s%.*s", uevent->subsystem, width, parent) > 0)
    398             link_num++;
    399         else
    400             links[link_num] = NULL;
    401         mkdir("/dev/usb", 0755);
    402     }
    403     else {
    404         goto err;
    405     }
    406 
    407     return links;
    408 err:
    409     free(links);
    410     return NULL;
    411 }
    412 
    413 static char **parse_platform_block_device(struct uevent *uevent)
    414 {
    415     const char *device;
    416     struct platform_node *pdev;
    417     char *slash;
    418     int width;
    419     char buf[256];
    420     char link_path[256];
    421     int fd;
    422     int link_num = 0;
    423     int ret;
    424     char *p;
    425     unsigned int size;
    426     struct stat info;
    427 
    428     pdev = find_platform_device(uevent->path);
    429     if (!pdev)
    430         return NULL;
    431     device = pdev->name;
    432 
    433     char **links = malloc(sizeof(char *) * 4);
    434     if (!links)
    435         return NULL;
    436     memset(links, 0, sizeof(char *) * 4);
    437 
    438     INFO("found platform device %s\n", device);
    439 
    440     snprintf(link_path, sizeof(link_path), "/dev/block/platform/%s", device);
    441 
    442     if (uevent->partition_name) {
    443         p = strdup(uevent->partition_name);
    444         sanitize(p);
    445         if (asprintf(&links[link_num], "%s/by-name/%s", link_path, p) > 0)
    446             link_num++;
    447         else
    448             links[link_num] = NULL;
    449         free(p);
    450     }
    451 
    452     if (uevent->partition_num >= 0) {
    453         if (asprintf(&links[link_num], "%s/by-num/p%d", link_path, uevent->partition_num) > 0)
    454             link_num++;
    455         else
    456             links[link_num] = NULL;
    457     }
    458 
    459     slash = strrchr(uevent->path, '/');
    460     if (asprintf(&links[link_num], "%s/%s", link_path, slash + 1) > 0)
    461         link_num++;
    462     else
    463         links[link_num] = NULL;
    464 
    465     return links;
    466 }
    467 
    468 static void handle_device(const char *action, const char *devpath,
    469         const char *path, int block, int major, int minor, char **links)
    470 {
    471     int i;
    472 
    473     if(!strcmp(action, "add")) {
    474         make_device(devpath, path, block, major, minor);
    475         if (links) {
    476             for (i = 0; links[i]; i++)
    477                 make_link(devpath, links[i]);
    478         }
    479     }
    480 
    481     if(!strcmp(action, "remove")) {
    482         if (links) {
    483             for (i = 0; links[i]; i++)
    484                 remove_link(devpath, links[i]);
    485         }
    486         unlink(devpath);
    487     }
    488 
    489     if (links) {
    490         for (i = 0; links[i]; i++)
    491             free(links[i]);
    492         free(links);
    493     }
    494 }
    495 
    496 static void handle_platform_device_event(struct uevent *uevent)
    497 {
    498     const char *path = uevent->path;
    499 
    500     if (!strcmp(uevent->action, "add"))
    501         add_platform_device(path);
    502     else if (!strcmp(uevent->action, "remove"))
    503         remove_platform_device(path);
    504 }
    505 
    506 static const char *parse_device_name(struct uevent *uevent, unsigned int len)
    507 {
    508     const char *name;
    509 
    510     /* if it's not a /dev device, nothing else to do */
    511     if((uevent->major < 0) || (uevent->minor < 0))
    512         return NULL;
    513 
    514     /* do we have a name? */
    515     name = strrchr(uevent->path, '/');
    516     if(!name)
    517         return NULL;
    518     name++;
    519 
    520     /* too-long names would overrun our buffer */
    521     if(strlen(name) > len)
    522         return NULL;
    523 
    524     return name;
    525 }
    526 
    527 static void handle_block_device_event(struct uevent *uevent)
    528 {
    529     const char *base = "/dev/block/";
    530     const char *name;
    531     char devpath[96];
    532     char **links = NULL;
    533 
    534     name = parse_device_name(uevent, 64);
    535     if (!name)
    536         return;
    537 
    538     snprintf(devpath, sizeof(devpath), "%s%s", base, name);
    539     make_dir(base, 0755);
    540 
    541     if (!strncmp(uevent->path, "/devices/", 9))
    542         links = parse_platform_block_device(uevent);
    543 
    544     handle_device(uevent->action, devpath, uevent->path, 1,
    545             uevent->major, uevent->minor, links);
    546 }
    547 
    548 static void handle_generic_device_event(struct uevent *uevent)
    549 {
    550     char *base;
    551     const char *name;
    552     char devpath[96] = {0};
    553     char **links = NULL;
    554 
    555     name = parse_device_name(uevent, 64);
    556     if (!name)
    557         return;
    558 
    559     if (!strncmp(uevent->subsystem, "usb", 3)) {
    560          if (!strcmp(uevent->subsystem, "usb")) {
    561             if (uevent->device_name) {
    562                 /*
    563                  * create device node provided by kernel if present
    564                  * see drivers/base/core.c
    565                  */
    566                 char *p = devpath;
    567                 snprintf(devpath, sizeof(devpath), "/dev/%s", uevent->device_name);
    568                 /* skip leading /dev/ */
    569                 p += 5;
    570                 /* build directories */
    571                 while (*p) {
    572                     if (*p == '/') {
    573                         *p = 0;
    574                         make_dir(devpath, 0755);
    575                         *p = '/';
    576                     }
    577                     p++;
    578                 }
    579              }
    580              else {
    581                  /* This imitates the file system that would be created
    582                   * if we were using devfs instead.
    583                   * Minors are broken up into groups of 128, starting at "001"
    584                   */
    585                  int bus_id = uevent->minor / 128 + 1;
    586                  int device_id = uevent->minor % 128 + 1;
    587                  /* build directories */
    588                  make_dir("/dev/bus", 0755);
    589                  make_dir("/dev/bus/usb", 0755);
    590                  snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d", bus_id);
    591                  make_dir(devpath, 0755);
    592                  snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d/%03d", bus_id, device_id);
    593              }
    594          } else {
    595              /* ignore other USB events */
    596              return;
    597          }
    598      } else if (!strncmp(uevent->subsystem, "graphics", 8)) {
    599          base = "/dev/graphics/";
    600          make_dir(base, 0755);
    601      } else if (!strncmp(uevent->subsystem, "drm", 3)) {
    602          base = "/dev/dri/";
    603          make_dir(base, 0755);
    604      } else if (!strncmp(uevent->subsystem, "oncrpc", 6)) {
    605          base = "/dev/oncrpc/";
    606          make_dir(base, 0755);
    607      } else if (!strncmp(uevent->subsystem, "adsp", 4)) {
    608          base = "/dev/adsp/";
    609          make_dir(base, 0755);
    610      } else if (!strncmp(uevent->subsystem, "msm_camera", 10)) {
    611          base = "/dev/msm_camera/";
    612          make_dir(base, 0755);
    613      } else if(!strncmp(uevent->subsystem, "input", 5)) {
    614          base = "/dev/input/";
    615          make_dir(base, 0755);
    616      } else if(!strncmp(uevent->subsystem, "mtd", 3)) {
    617          base = "/dev/mtd/";
    618          make_dir(base, 0755);
    619      } else if(!strncmp(uevent->subsystem, "sound", 5)) {
    620          base = "/dev/snd/";
    621          make_dir(base, 0755);
    622      } else if(!strncmp(uevent->subsystem, "misc", 4) &&
    623                  !strncmp(name, "log_", 4)) {
    624          base = "/dev/log/";
    625          make_dir(base, 0755);
    626          name += 4;
    627      } else
    628          base = "/dev/";
    629      links = get_character_device_symlinks(uevent);
    630 
    631      if (!devpath[0])
    632          snprintf(devpath, sizeof(devpath), "%s%s", base, name);
    633 
    634      handle_device(uevent->action, devpath, uevent->path, 0,
    635              uevent->major, uevent->minor, links);
    636 }
    637 
    638 static void handle_device_event(struct uevent *uevent)
    639 {
    640     if (!strcmp(uevent->action,"add") || !strcmp(uevent->action, "change"))
    641         fixup_sys_perms(uevent->path);
    642 
    643     if (!strncmp(uevent->subsystem, "block", 5)) {
    644         handle_block_device_event(uevent);
    645     } else if (!strncmp(uevent->subsystem, "platform", 8)) {
    646         handle_platform_device_event(uevent);
    647     } else {
    648         handle_generic_device_event(uevent);
    649     }
    650 }
    651 
    652 static int load_firmware(int fw_fd, int loading_fd, int data_fd)
    653 {
    654     struct stat st;
    655     long len_to_copy;
    656     int ret = 0;
    657 
    658     if(fstat(fw_fd, &st) < 0)
    659         return -1;
    660     len_to_copy = st.st_size;
    661 
    662     write(loading_fd, "1", 1);  /* start transfer */
    663 
    664     while (len_to_copy > 0) {
    665         char buf[PAGE_SIZE];
    666         ssize_t nr;
    667 
    668         nr = read(fw_fd, buf, sizeof(buf));
    669         if(!nr)
    670             break;
    671         if(nr < 0) {
    672             ret = -1;
    673             break;
    674         }
    675 
    676         len_to_copy -= nr;
    677         while (nr > 0) {
    678             ssize_t nw = 0;
    679 
    680             nw = write(data_fd, buf + nw, nr);
    681             if(nw <= 0) {
    682                 ret = -1;
    683                 goto out;
    684             }
    685             nr -= nw;
    686         }
    687     }
    688 
    689 out:
    690     if(!ret)
    691         write(loading_fd, "0", 1);  /* successful end of transfer */
    692     else
    693         write(loading_fd, "-1", 2); /* abort transfer */
    694 
    695     return ret;
    696 }
    697 
    698 static int is_booting(void)
    699 {
    700     return access("/dev/.booting", F_OK) == 0;
    701 }
    702 
    703 static void process_firmware_event(struct uevent *uevent)
    704 {
    705     char *root, *loading, *data, *file1 = NULL, *file2 = NULL, *file3 = NULL;
    706     int l, loading_fd, data_fd, fw_fd;
    707     int booting = is_booting();
    708 
    709     INFO("firmware: loading '%s' for '%s'\n",
    710          uevent->firmware, uevent->path);
    711 
    712     l = asprintf(&root, SYSFS_PREFIX"%s/", uevent->path);
    713     if (l == -1)
    714         return;
    715 
    716     l = asprintf(&loading, "%sloading", root);
    717     if (l == -1)
    718         goto root_free_out;
    719 
    720     l = asprintf(&data, "%sdata", root);
    721     if (l == -1)
    722         goto loading_free_out;
    723 
    724     l = asprintf(&file1, FIRMWARE_DIR1"/%s", uevent->firmware);
    725     if (l == -1)
    726         goto data_free_out;
    727 
    728     l = asprintf(&file2, FIRMWARE_DIR2"/%s", uevent->firmware);
    729     if (l == -1)
    730         goto data_free_out;
    731 
    732     l = asprintf(&file3, FIRMWARE_DIR3"/%s", uevent->firmware);
    733     if (l == -1)
    734         goto data_free_out;
    735 
    736     loading_fd = open(loading, O_WRONLY);
    737     if(loading_fd < 0)
    738         goto file_free_out;
    739 
    740     data_fd = open(data, O_WRONLY);
    741     if(data_fd < 0)
    742         goto loading_close_out;
    743 
    744 try_loading_again:
    745     fw_fd = open(file1, O_RDONLY);
    746     if(fw_fd < 0) {
    747         fw_fd = open(file2, O_RDONLY);
    748         if (fw_fd < 0) {
    749             fw_fd = open(file3, O_RDONLY);
    750             if (fw_fd < 0) {
    751                 if (booting) {
    752                         /* If we're not fully booted, we may be missing
    753                          * filesystems needed for firmware, wait and retry.
    754                          */
    755                     usleep(100000);
    756                     booting = is_booting();
    757                     goto try_loading_again;
    758                 }
    759                 INFO("firmware: could not open '%s' %d\n", uevent->firmware, errno);
    760                 write(loading_fd, "-1", 2);
    761                 goto data_close_out;
    762             }
    763         }
    764     }
    765 
    766     if(!load_firmware(fw_fd, loading_fd, data_fd))
    767         INFO("firmware: copy success { '%s', '%s' }\n", root, uevent->firmware);
    768     else
    769         INFO("firmware: copy failure { '%s', '%s' }\n", root, uevent->firmware);
    770 
    771     close(fw_fd);
    772 data_close_out:
    773     close(data_fd);
    774 loading_close_out:
    775     close(loading_fd);
    776 file_free_out:
    777     free(file1);
    778     free(file2);
    779     free(file3);
    780 data_free_out:
    781     free(data);
    782 loading_free_out:
    783     free(loading);
    784 root_free_out:
    785     free(root);
    786 }
    787 
    788 static void handle_firmware_event(struct uevent *uevent)
    789 {
    790     pid_t pid;
    791     int ret;
    792 
    793     if(strcmp(uevent->subsystem, "firmware"))
    794         return;
    795 
    796     if(strcmp(uevent->action, "add"))
    797         return;
    798 
    799     /* we fork, to avoid making large memory allocations in init proper */
    800     pid = fork();
    801     if (!pid) {
    802         process_firmware_event(uevent);
    803         exit(EXIT_SUCCESS);
    804     }
    805 }
    806 
    807 #define UEVENT_MSG_LEN  1024
    808 void handle_device_fd()
    809 {
    810     char msg[UEVENT_MSG_LEN+2];
    811     int n;
    812     while ((n = uevent_kernel_multicast_recv(device_fd, msg, UEVENT_MSG_LEN)) > 0) {
    813         if(n >= UEVENT_MSG_LEN)   /* overflow -- discard */
    814             continue;
    815 
    816         msg[n] = '\0';
    817         msg[n+1] = '\0';
    818 
    819         struct uevent uevent;
    820         parse_event(msg, &uevent);
    821 
    822         handle_device_event(&uevent);
    823         handle_firmware_event(&uevent);
    824     }
    825 }
    826 
    827 /* Coldboot walks parts of the /sys tree and pokes the uevent files
    828 ** to cause the kernel to regenerate device add events that happened
    829 ** before init's device manager was started
    830 **
    831 ** We drain any pending events from the netlink socket every time
    832 ** we poke another uevent file to make sure we don't overrun the
    833 ** socket's buffer.
    834 */
    835 
    836 static void do_coldboot(DIR *d)
    837 {
    838     struct dirent *de;
    839     int dfd, fd;
    840 
    841     dfd = dirfd(d);
    842 
    843     fd = openat(dfd, "uevent", O_WRONLY);
    844     if(fd >= 0) {
    845         write(fd, "add\n", 4);
    846         close(fd);
    847         handle_device_fd();
    848     }
    849 
    850     while((de = readdir(d))) {
    851         DIR *d2;
    852 
    853         if(de->d_type != DT_DIR || de->d_name[0] == '.')
    854             continue;
    855 
    856         fd = openat(dfd, de->d_name, O_RDONLY | O_DIRECTORY);
    857         if(fd < 0)
    858             continue;
    859 
    860         d2 = fdopendir(fd);
    861         if(d2 == 0)
    862             close(fd);
    863         else {
    864             do_coldboot(d2);
    865             closedir(d2);
    866         }
    867     }
    868 }
    869 
    870 static void coldboot(const char *path)
    871 {
    872     DIR *d = opendir(path);
    873     if(d) {
    874         do_coldboot(d);
    875         closedir(d);
    876     }
    877 }
    878 
    879 void device_init(void)
    880 {
    881     suseconds_t t0, t1;
    882     struct stat info;
    883     int fd;
    884 
    885     sehandle = NULL;
    886     if (is_selinux_enabled() > 0) {
    887         sehandle = selinux_android_file_context_handle();
    888     }
    889 
    890     /* is 256K enough? udev uses 16MB! */
    891     device_fd = uevent_open_socket(256*1024, true);
    892     if(device_fd < 0)
    893         return;
    894 
    895     fcntl(device_fd, F_SETFD, FD_CLOEXEC);
    896     fcntl(device_fd, F_SETFL, O_NONBLOCK);
    897 
    898     if (stat(coldboot_done, &info) < 0) {
    899         t0 = get_usecs();
    900         coldboot("/sys/class");
    901         coldboot("/sys/block");
    902         coldboot("/sys/devices");
    903         t1 = get_usecs();
    904         fd = open(coldboot_done, O_WRONLY|O_CREAT, 0000);
    905         close(fd);
    906         log_event_print("coldboot %ld uS\n", ((long) (t1 - t0)));
    907     } else {
    908         log_event_print("skipping coldboot, already done\n");
    909     }
    910 }
    911 
    912 int get_device_fd()
    913 {
    914     return device_fd;
    915 }
    916