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      1 /*
      2  * Copyright (C) 2007-2014 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 <fnmatch.h>
     19 #include <stddef.h>
     20 #include <stdio.h>
     21 #include <stdlib.h>
     22 #include <sys/stat.h>
     23 #include <sys/types.h>
     24 
     25 #include <fcntl.h>
     26 #include <dirent.h>
     27 #include <unistd.h>
     28 #include <string.h>
     29 
     30 #include <sys/socket.h>
     31 #include <sys/un.h>
     32 #include <linux/netlink.h>
     33 
     34 #include <selinux/selinux.h>
     35 #include <selinux/label.h>
     36 #include <selinux/android.h>
     37 #include <selinux/avc.h>
     38 
     39 #include <private/android_filesystem_config.h>
     40 #include <sys/time.h>
     41 #include <sys/wait.h>
     42 
     43 #include <cutils/list.h>
     44 #include <cutils/uevent.h>
     45 
     46 #include "devices.h"
     47 #include "ueventd_parser.h"
     48 #include "util.h"
     49 #include "log.h"
     50 
     51 #define SYSFS_PREFIX    "/sys"
     52 static const char *firmware_dirs[] = { "/etc/firmware",
     53                                        "/vendor/firmware",
     54                                        "/firmware/image" };
     55 
     56 extern struct selabel_handle *sehandle;
     57 
     58 static int device_fd = -1;
     59 
     60 struct uevent {
     61     const char *action;
     62     const char *path;
     63     const char *subsystem;
     64     const char *firmware;
     65     const char *partition_name;
     66     const char *device_name;
     67     int partition_num;
     68     int major;
     69     int minor;
     70 };
     71 
     72 struct perms_ {
     73     char *name;
     74     char *attr;
     75     mode_t perm;
     76     unsigned int uid;
     77     unsigned int gid;
     78     unsigned short prefix;
     79     unsigned short wildcard;
     80 };
     81 
     82 struct perm_node {
     83     struct perms_ dp;
     84     struct listnode plist;
     85 };
     86 
     87 struct platform_node {
     88     char *name;
     89     char *path;
     90     int path_len;
     91     struct listnode list;
     92 };
     93 
     94 static list_declare(sys_perms);
     95 static list_declare(dev_perms);
     96 static list_declare(platform_names);
     97 
     98 int add_dev_perms(const char *name, const char *attr,
     99                   mode_t perm, unsigned int uid, unsigned int gid,
    100                   unsigned short prefix,
    101                   unsigned short wildcard) {
    102     struct perm_node *node = (perm_node*) calloc(1, sizeof(*node));
    103     if (!node)
    104         return -ENOMEM;
    105 
    106     node->dp.name = strdup(name);
    107     if (!node->dp.name)
    108         return -ENOMEM;
    109 
    110     if (attr) {
    111         node->dp.attr = strdup(attr);
    112         if (!node->dp.attr)
    113             return -ENOMEM;
    114     }
    115 
    116     node->dp.perm = perm;
    117     node->dp.uid = uid;
    118     node->dp.gid = gid;
    119     node->dp.prefix = prefix;
    120     node->dp.wildcard = wildcard;
    121 
    122     if (attr)
    123         list_add_tail(&sys_perms, &node->plist);
    124     else
    125         list_add_tail(&dev_perms, &node->plist);
    126 
    127     return 0;
    128 }
    129 
    130 void fixup_sys_perms(const char *upath)
    131 {
    132     char buf[512];
    133     struct listnode *node;
    134     struct perms_ *dp;
    135 
    136     /* upaths omit the "/sys" that paths in this list
    137      * contain, so we add 4 when comparing...
    138      */
    139     list_for_each(node, &sys_perms) {
    140         dp = &(node_to_item(node, struct perm_node, plist))->dp;
    141         if (dp->prefix) {
    142             if (strncmp(upath, dp->name + 4, strlen(dp->name + 4)))
    143                 continue;
    144         } else if (dp->wildcard) {
    145             if (fnmatch(dp->name + 4, upath, FNM_PATHNAME) != 0)
    146                 continue;
    147         } else {
    148             if (strcmp(upath, dp->name + 4))
    149                 continue;
    150         }
    151 
    152         if ((strlen(upath) + strlen(dp->attr) + 6) > sizeof(buf))
    153             break;
    154 
    155         snprintf(buf, sizeof(buf), "/sys%s/%s", upath, dp->attr);
    156         INFO("fixup %s %d %d 0%o\n", buf, dp->uid, dp->gid, dp->perm);
    157         chown(buf, dp->uid, dp->gid);
    158         chmod(buf, dp->perm);
    159     }
    160 
    161     // Now fixup SELinux file labels
    162     int len = snprintf(buf, sizeof(buf), "/sys%s", upath);
    163     if ((len < 0) || ((size_t) len >= sizeof(buf))) {
    164         // Overflow
    165         return;
    166     }
    167     if (access(buf, F_OK) == 0) {
    168         INFO("restorecon_recursive: %s\n", buf);
    169         restorecon_recursive(buf);
    170     }
    171 }
    172 
    173 static bool perm_path_matches(const char *path, struct perms_ *dp)
    174 {
    175     if (dp->prefix) {
    176         if (strncmp(path, dp->name, strlen(dp->name)) == 0)
    177             return true;
    178     } else if (dp->wildcard) {
    179         if (fnmatch(dp->name, path, FNM_PATHNAME) == 0)
    180             return true;
    181     } else {
    182         if (strcmp(path, dp->name) == 0)
    183             return true;
    184     }
    185 
    186     return false;
    187 }
    188 
    189 static mode_t get_device_perm(const char *path, const char **links,
    190                 unsigned *uid, unsigned *gid)
    191 {
    192     struct listnode *node;
    193     struct perm_node *perm_node;
    194     struct perms_ *dp;
    195 
    196     /* search the perms list in reverse so that ueventd.$hardware can
    197      * override ueventd.rc
    198      */
    199     list_for_each_reverse(node, &dev_perms) {
    200         bool match = false;
    201 
    202         perm_node = node_to_item(node, struct perm_node, plist);
    203         dp = &perm_node->dp;
    204 
    205         if (perm_path_matches(path, dp)) {
    206             match = true;
    207         } else {
    208             if (links) {
    209                 int i;
    210                 for (i = 0; links[i]; i++) {
    211                     if (perm_path_matches(links[i], dp)) {
    212                         match = true;
    213                         break;
    214                     }
    215                 }
    216             }
    217         }
    218 
    219         if (match) {
    220             *uid = dp->uid;
    221             *gid = dp->gid;
    222             return dp->perm;
    223         }
    224     }
    225     /* Default if nothing found. */
    226     *uid = 0;
    227     *gid = 0;
    228     return 0600;
    229 }
    230 
    231 static void make_device(const char *path,
    232                         const char */*upath*/,
    233                         int block, int major, int minor,
    234                         const char **links)
    235 {
    236     unsigned uid;
    237     unsigned gid;
    238     mode_t mode;
    239     dev_t dev;
    240     char *secontext = NULL;
    241 
    242     mode = get_device_perm(path, links, &uid, &gid) | (block ? S_IFBLK : S_IFCHR);
    243 
    244     if (sehandle) {
    245         selabel_lookup_best_match(sehandle, &secontext, path, links, mode);
    246         setfscreatecon(secontext);
    247     }
    248 
    249     dev = makedev(major, minor);
    250     /* Temporarily change egid to avoid race condition setting the gid of the
    251      * device node. Unforunately changing the euid would prevent creation of
    252      * some device nodes, so the uid has to be set with chown() and is still
    253      * racy. Fixing the gid race at least fixed the issue with system_server
    254      * opening dynamic input devices under the AID_INPUT gid. */
    255     setegid(gid);
    256     mknod(path, mode, dev);
    257     chown(path, uid, -1);
    258     setegid(AID_ROOT);
    259 
    260     if (secontext) {
    261         freecon(secontext);
    262         setfscreatecon(NULL);
    263     }
    264 }
    265 
    266 static void add_platform_device(const char *path)
    267 {
    268     int path_len = strlen(path);
    269     struct platform_node *bus;
    270     const char *name = path;
    271 
    272     if (!strncmp(path, "/devices/", 9)) {
    273         name += 9;
    274         if (!strncmp(name, "platform/", 9))
    275             name += 9;
    276     }
    277 
    278     INFO("adding platform device %s (%s)\n", name, path);
    279 
    280     bus = (platform_node*) calloc(1, sizeof(struct platform_node));
    281     bus->path = strdup(path);
    282     bus->path_len = path_len;
    283     bus->name = bus->path + (name - path);
    284     list_add_tail(&platform_names, &bus->list);
    285 }
    286 
    287 /*
    288  * given a path that may start with a platform device, find the length of the
    289  * platform device prefix.  If it doesn't start with a platform device, return
    290  * 0.
    291  */
    292 static struct platform_node *find_platform_device(const char *path)
    293 {
    294     int path_len = strlen(path);
    295     struct listnode *node;
    296     struct platform_node *bus;
    297 
    298     list_for_each_reverse(node, &platform_names) {
    299         bus = node_to_item(node, struct platform_node, list);
    300         if ((bus->path_len < path_len) &&
    301                 (path[bus->path_len] == '/') &&
    302                 !strncmp(path, bus->path, bus->path_len))
    303             return bus;
    304     }
    305 
    306     return NULL;
    307 }
    308 
    309 static void remove_platform_device(const char *path)
    310 {
    311     struct listnode *node;
    312     struct platform_node *bus;
    313 
    314     list_for_each_reverse(node, &platform_names) {
    315         bus = node_to_item(node, struct platform_node, list);
    316         if (!strcmp(path, bus->path)) {
    317             INFO("removing platform device %s\n", bus->name);
    318             free(bus->path);
    319             list_remove(node);
    320             free(bus);
    321             return;
    322         }
    323     }
    324 }
    325 
    326 /* Given a path that may start with a PCI device, populate the supplied buffer
    327  * with the PCI domain/bus number and the peripheral ID and return 0.
    328  * If it doesn't start with a PCI device, or there is some error, return -1 */
    329 static int find_pci_device_prefix(const char *path, char *buf, ssize_t buf_sz)
    330 {
    331     const char *start, *end;
    332 
    333     if (strncmp(path, "/devices/pci", 12))
    334         return -1;
    335 
    336     /* Beginning of the prefix is the initial "pci" after "/devices/" */
    337     start = path + 9;
    338 
    339     /* End of the prefix is two path '/' later, capturing the domain/bus number
    340      * and the peripheral ID. Example: pci0000:00/0000:00:1f.2 */
    341     end = strchr(start, '/');
    342     if (!end)
    343         return -1;
    344     end = strchr(end + 1, '/');
    345     if (!end)
    346         return -1;
    347 
    348     /* Make sure we have enough room for the string plus null terminator */
    349     if (end - start + 1 > buf_sz)
    350         return -1;
    351 
    352     strncpy(buf, start, end - start);
    353     buf[end - start] = '\0';
    354     return 0;
    355 }
    356 
    357 static void parse_event(const char *msg, struct uevent *uevent)
    358 {
    359     uevent->action = "";
    360     uevent->path = "";
    361     uevent->subsystem = "";
    362     uevent->firmware = "";
    363     uevent->major = -1;
    364     uevent->minor = -1;
    365     uevent->partition_name = NULL;
    366     uevent->partition_num = -1;
    367     uevent->device_name = NULL;
    368 
    369         /* currently ignoring SEQNUM */
    370     while(*msg) {
    371         if(!strncmp(msg, "ACTION=", 7)) {
    372             msg += 7;
    373             uevent->action = msg;
    374         } else if(!strncmp(msg, "DEVPATH=", 8)) {
    375             msg += 8;
    376             uevent->path = msg;
    377         } else if(!strncmp(msg, "SUBSYSTEM=", 10)) {
    378             msg += 10;
    379             uevent->subsystem = msg;
    380         } else if(!strncmp(msg, "FIRMWARE=", 9)) {
    381             msg += 9;
    382             uevent->firmware = msg;
    383         } else if(!strncmp(msg, "MAJOR=", 6)) {
    384             msg += 6;
    385             uevent->major = atoi(msg);
    386         } else if(!strncmp(msg, "MINOR=", 6)) {
    387             msg += 6;
    388             uevent->minor = atoi(msg);
    389         } else if(!strncmp(msg, "PARTN=", 6)) {
    390             msg += 6;
    391             uevent->partition_num = atoi(msg);
    392         } else if(!strncmp(msg, "PARTNAME=", 9)) {
    393             msg += 9;
    394             uevent->partition_name = msg;
    395         } else if(!strncmp(msg, "DEVNAME=", 8)) {
    396             msg += 8;
    397             uevent->device_name = msg;
    398         }
    399 
    400         /* advance to after the next \0 */
    401         while(*msg++)
    402             ;
    403     }
    404 
    405     if (LOG_UEVENTS) {
    406         INFO("event { '%s', '%s', '%s', '%s', %d, %d }\n",
    407              uevent->action, uevent->path, uevent->subsystem,
    408              uevent->firmware, uevent->major, uevent->minor);
    409     }
    410 }
    411 
    412 static char **get_character_device_symlinks(struct uevent *uevent)
    413 {
    414     const char *parent;
    415     char *slash;
    416     char **links;
    417     int link_num = 0;
    418     int width;
    419     struct platform_node *pdev;
    420 
    421     pdev = find_platform_device(uevent->path);
    422     if (!pdev)
    423         return NULL;
    424 
    425     links = (char**) malloc(sizeof(char *) * 2);
    426     if (!links)
    427         return NULL;
    428     memset(links, 0, sizeof(char *) * 2);
    429 
    430     /* skip "/devices/platform/<driver>" */
    431     parent = strchr(uevent->path + pdev->path_len, '/');
    432     if (!parent)
    433         goto err;
    434 
    435     if (!strncmp(parent, "/usb", 4)) {
    436         /* skip root hub name and device. use device interface */
    437         while (*++parent && *parent != '/');
    438         if (*parent)
    439             while (*++parent && *parent != '/');
    440         if (!*parent)
    441             goto err;
    442         slash = strchr(++parent, '/');
    443         if (!slash)
    444             goto err;
    445         width = slash - parent;
    446         if (width <= 0)
    447             goto err;
    448 
    449         if (asprintf(&links[link_num], "/dev/usb/%s%.*s", uevent->subsystem, width, parent) > 0)
    450             link_num++;
    451         else
    452             links[link_num] = NULL;
    453         mkdir("/dev/usb", 0755);
    454     }
    455     else {
    456         goto err;
    457     }
    458 
    459     return links;
    460 err:
    461     free(links);
    462     return NULL;
    463 }
    464 
    465 static char **get_block_device_symlinks(struct uevent *uevent)
    466 {
    467     const char *device;
    468     struct platform_node *pdev;
    469     char *slash;
    470     const char *type;
    471     char buf[256];
    472     char link_path[256];
    473     int link_num = 0;
    474     char *p;
    475 
    476     pdev = find_platform_device(uevent->path);
    477     if (pdev) {
    478         device = pdev->name;
    479         type = "platform";
    480     } else if (!find_pci_device_prefix(uevent->path, buf, sizeof(buf))) {
    481         device = buf;
    482         type = "pci";
    483     } else {
    484         return NULL;
    485     }
    486 
    487     char **links = (char**) malloc(sizeof(char *) * 4);
    488     if (!links)
    489         return NULL;
    490     memset(links, 0, sizeof(char *) * 4);
    491 
    492     INFO("found %s device %s\n", type, device);
    493 
    494     snprintf(link_path, sizeof(link_path), "/dev/block/%s/%s", type, device);
    495 
    496     if (uevent->partition_name) {
    497         p = strdup(uevent->partition_name);
    498         sanitize(p);
    499         if (strcmp(uevent->partition_name, p))
    500             NOTICE("Linking partition '%s' as '%s'\n", uevent->partition_name, p);
    501         if (asprintf(&links[link_num], "%s/by-name/%s", link_path, p) > 0)
    502             link_num++;
    503         else
    504             links[link_num] = NULL;
    505         free(p);
    506     }
    507 
    508     if (uevent->partition_num >= 0) {
    509         if (asprintf(&links[link_num], "%s/by-num/p%d", link_path, uevent->partition_num) > 0)
    510             link_num++;
    511         else
    512             links[link_num] = NULL;
    513     }
    514 
    515     slash = strrchr(uevent->path, '/');
    516     if (asprintf(&links[link_num], "%s/%s", link_path, slash + 1) > 0)
    517         link_num++;
    518     else
    519         links[link_num] = NULL;
    520 
    521     return links;
    522 }
    523 
    524 static void handle_device(const char *action, const char *devpath,
    525         const char *path, int block, int major, int minor, char **links)
    526 {
    527     int i;
    528 
    529     if(!strcmp(action, "add")) {
    530         make_device(devpath, path, block, major, minor, (const char **)links);
    531         if (links) {
    532             for (i = 0; links[i]; i++)
    533                 make_link_init(devpath, links[i]);
    534         }
    535     }
    536 
    537     if(!strcmp(action, "remove")) {
    538         if (links) {
    539             for (i = 0; links[i]; i++)
    540                 remove_link(devpath, links[i]);
    541         }
    542         unlink(devpath);
    543     }
    544 
    545     if (links) {
    546         for (i = 0; links[i]; i++)
    547             free(links[i]);
    548         free(links);
    549     }
    550 }
    551 
    552 static void handle_platform_device_event(struct uevent *uevent)
    553 {
    554     const char *path = uevent->path;
    555 
    556     if (!strcmp(uevent->action, "add"))
    557         add_platform_device(path);
    558     else if (!strcmp(uevent->action, "remove"))
    559         remove_platform_device(path);
    560 }
    561 
    562 static const char *parse_device_name(struct uevent *uevent, unsigned int len)
    563 {
    564     const char *name;
    565 
    566     /* if it's not a /dev device, nothing else to do */
    567     if((uevent->major < 0) || (uevent->minor < 0))
    568         return NULL;
    569 
    570     /* do we have a name? */
    571     name = strrchr(uevent->path, '/');
    572     if(!name)
    573         return NULL;
    574     name++;
    575 
    576     /* too-long names would overrun our buffer */
    577     if(strlen(name) > len) {
    578         ERROR("DEVPATH=%s exceeds %u-character limit on filename; ignoring event\n",
    579                 name, len);
    580         return NULL;
    581     }
    582 
    583     return name;
    584 }
    585 
    586 static void handle_block_device_event(struct uevent *uevent)
    587 {
    588     const char *base = "/dev/block/";
    589     const char *name;
    590     char devpath[96];
    591     char **links = NULL;
    592 
    593     name = parse_device_name(uevent, 64);
    594     if (!name)
    595         return;
    596 
    597     snprintf(devpath, sizeof(devpath), "%s%s", base, name);
    598     make_dir(base, 0755);
    599 
    600     if (!strncmp(uevent->path, "/devices/", 9))
    601         links = get_block_device_symlinks(uevent);
    602 
    603     handle_device(uevent->action, devpath, uevent->path, 1,
    604             uevent->major, uevent->minor, links);
    605 }
    606 
    607 #define DEVPATH_LEN 96
    608 
    609 static bool assemble_devpath(char *devpath, const char *dirname,
    610         const char *devname)
    611 {
    612     int s = snprintf(devpath, DEVPATH_LEN, "%s/%s", dirname, devname);
    613     if (s < 0) {
    614         ERROR("failed to assemble device path (%s); ignoring event\n",
    615                 strerror(errno));
    616         return false;
    617     } else if (s >= DEVPATH_LEN) {
    618         ERROR("%s/%s exceeds %u-character limit on path; ignoring event\n",
    619                 dirname, devname, DEVPATH_LEN);
    620         return false;
    621     }
    622     return true;
    623 }
    624 
    625 static void mkdir_recursive_for_devpath(const char *devpath)
    626 {
    627     char dir[DEVPATH_LEN];
    628     char *slash;
    629 
    630     strcpy(dir, devpath);
    631     slash = strrchr(dir, '/');
    632     *slash = '\0';
    633     mkdir_recursive(dir, 0755);
    634 }
    635 
    636 static void handle_generic_device_event(struct uevent *uevent)
    637 {
    638     const char *base;
    639     const char *name;
    640     char devpath[DEVPATH_LEN] = {0};
    641     char **links = NULL;
    642 
    643     name = parse_device_name(uevent, 64);
    644     if (!name)
    645         return;
    646 
    647     struct ueventd_subsystem *subsystem =
    648             ueventd_subsystem_find_by_name(uevent->subsystem);
    649 
    650     if (subsystem) {
    651         const char *devname;
    652 
    653         switch (subsystem->devname_src) {
    654         case DEVNAME_UEVENT_DEVNAME:
    655             devname = uevent->device_name;
    656             break;
    657 
    658         case DEVNAME_UEVENT_DEVPATH:
    659             devname = name;
    660             break;
    661 
    662         default:
    663             ERROR("%s subsystem's devpath option is not set; ignoring event\n",
    664                     uevent->subsystem);
    665             return;
    666         }
    667 
    668         if (!assemble_devpath(devpath, subsystem->dirname, devname))
    669             return;
    670         mkdir_recursive_for_devpath(devpath);
    671     } else if (!strncmp(uevent->subsystem, "usb", 3)) {
    672          if (!strcmp(uevent->subsystem, "usb")) {
    673             if (uevent->device_name) {
    674                 if (!assemble_devpath(devpath, "/dev", uevent->device_name))
    675                     return;
    676                 mkdir_recursive_for_devpath(devpath);
    677              }
    678              else {
    679                  /* This imitates the file system that would be created
    680                   * if we were using devfs instead.
    681                   * Minors are broken up into groups of 128, starting at "001"
    682                   */
    683                  int bus_id = uevent->minor / 128 + 1;
    684                  int device_id = uevent->minor % 128 + 1;
    685                  /* build directories */
    686                  make_dir("/dev/bus", 0755);
    687                  make_dir("/dev/bus/usb", 0755);
    688                  snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d", bus_id);
    689                  make_dir(devpath, 0755);
    690                  snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d/%03d", bus_id, device_id);
    691              }
    692          } else {
    693              /* ignore other USB events */
    694              return;
    695          }
    696      } else if (!strncmp(uevent->subsystem, "graphics", 8)) {
    697          base = "/dev/graphics/";
    698          make_dir(base, 0755);
    699      } else if (!strncmp(uevent->subsystem, "drm", 3)) {
    700          base = "/dev/dri/";
    701          make_dir(base, 0755);
    702      } else if (!strncmp(uevent->subsystem, "oncrpc", 6)) {
    703          base = "/dev/oncrpc/";
    704          make_dir(base, 0755);
    705      } else if (!strncmp(uevent->subsystem, "adsp", 4)) {
    706          base = "/dev/adsp/";
    707          make_dir(base, 0755);
    708      } else if (!strncmp(uevent->subsystem, "msm_camera", 10)) {
    709          base = "/dev/msm_camera/";
    710          make_dir(base, 0755);
    711      } else if(!strncmp(uevent->subsystem, "input", 5)) {
    712          base = "/dev/input/";
    713          make_dir(base, 0755);
    714      } else if(!strncmp(uevent->subsystem, "mtd", 3)) {
    715          base = "/dev/mtd/";
    716          make_dir(base, 0755);
    717      } else if(!strncmp(uevent->subsystem, "sound", 5)) {
    718          base = "/dev/snd/";
    719          make_dir(base, 0755);
    720      } else if(!strncmp(uevent->subsystem, "misc", 4) &&
    721                  !strncmp(name, "log_", 4)) {
    722          INFO("kernel logger is deprecated\n");
    723          base = "/dev/log/";
    724          make_dir(base, 0755);
    725          name += 4;
    726      } else
    727          base = "/dev/";
    728      links = get_character_device_symlinks(uevent);
    729 
    730      if (!devpath[0])
    731          snprintf(devpath, sizeof(devpath), "%s%s", base, name);
    732 
    733      handle_device(uevent->action, devpath, uevent->path, 0,
    734              uevent->major, uevent->minor, links);
    735 }
    736 
    737 static void handle_device_event(struct uevent *uevent)
    738 {
    739     if (!strcmp(uevent->action,"add") || !strcmp(uevent->action, "change") || !strcmp(uevent->action, "online"))
    740         fixup_sys_perms(uevent->path);
    741 
    742     if (!strncmp(uevent->subsystem, "block", 5)) {
    743         handle_block_device_event(uevent);
    744     } else if (!strncmp(uevent->subsystem, "platform", 8)) {
    745         handle_platform_device_event(uevent);
    746     } else {
    747         handle_generic_device_event(uevent);
    748     }
    749 }
    750 
    751 static int load_firmware(int fw_fd, int loading_fd, int data_fd)
    752 {
    753     struct stat st;
    754     long len_to_copy;
    755     int ret = 0;
    756 
    757     if(fstat(fw_fd, &st) < 0)
    758         return -1;
    759     len_to_copy = st.st_size;
    760 
    761     write(loading_fd, "1", 1);  /* start transfer */
    762 
    763     while (len_to_copy > 0) {
    764         char buf[PAGE_SIZE];
    765         ssize_t nr;
    766 
    767         nr = read(fw_fd, buf, sizeof(buf));
    768         if(!nr)
    769             break;
    770         if(nr < 0) {
    771             ret = -1;
    772             break;
    773         }
    774 
    775         len_to_copy -= nr;
    776         while (nr > 0) {
    777             ssize_t nw = 0;
    778 
    779             nw = write(data_fd, buf + nw, nr);
    780             if(nw <= 0) {
    781                 ret = -1;
    782                 goto out;
    783             }
    784             nr -= nw;
    785         }
    786     }
    787 
    788 out:
    789     if(!ret)
    790         write(loading_fd, "0", 1);  /* successful end of transfer */
    791     else
    792         write(loading_fd, "-1", 2); /* abort transfer */
    793 
    794     return ret;
    795 }
    796 
    797 static int is_booting(void)
    798 {
    799     return access("/dev/.booting", F_OK) == 0;
    800 }
    801 
    802 static void process_firmware_event(struct uevent *uevent)
    803 {
    804     char *root, *loading, *data;
    805     int l, loading_fd, data_fd, fw_fd;
    806     size_t i;
    807     int booting = is_booting();
    808 
    809     INFO("firmware: loading '%s' for '%s'\n",
    810          uevent->firmware, uevent->path);
    811 
    812     l = asprintf(&root, SYSFS_PREFIX"%s/", uevent->path);
    813     if (l == -1)
    814         return;
    815 
    816     l = asprintf(&loading, "%sloading", root);
    817     if (l == -1)
    818         goto root_free_out;
    819 
    820     l = asprintf(&data, "%sdata", root);
    821     if (l == -1)
    822         goto loading_free_out;
    823 
    824     loading_fd = open(loading, O_WRONLY|O_CLOEXEC);
    825     if(loading_fd < 0)
    826         goto data_free_out;
    827 
    828     data_fd = open(data, O_WRONLY|O_CLOEXEC);
    829     if(data_fd < 0)
    830         goto loading_close_out;
    831 
    832 try_loading_again:
    833     for (i = 0; i < ARRAY_SIZE(firmware_dirs); i++) {
    834         char *file = NULL;
    835         l = asprintf(&file, "%s/%s", firmware_dirs[i], uevent->firmware);
    836         if (l == -1)
    837             goto data_free_out;
    838         fw_fd = open(file, O_RDONLY|O_CLOEXEC);
    839         free(file);
    840         if (fw_fd >= 0) {
    841             if(!load_firmware(fw_fd, loading_fd, data_fd))
    842                 INFO("firmware: copy success { '%s', '%s' }\n", root, uevent->firmware);
    843             else
    844                 INFO("firmware: copy failure { '%s', '%s' }\n", root, uevent->firmware);
    845             break;
    846         }
    847     }
    848     if (fw_fd < 0) {
    849         if (booting) {
    850             /* If we're not fully booted, we may be missing
    851              * filesystems needed for firmware, wait and retry.
    852              */
    853             usleep(100000);
    854             booting = is_booting();
    855             goto try_loading_again;
    856         }
    857         INFO("firmware: could not open '%s': %s\n", uevent->firmware, strerror(errno));
    858         write(loading_fd, "-1", 2);
    859         goto data_close_out;
    860     }
    861 
    862     close(fw_fd);
    863 data_close_out:
    864     close(data_fd);
    865 loading_close_out:
    866     close(loading_fd);
    867 data_free_out:
    868     free(data);
    869 loading_free_out:
    870     free(loading);
    871 root_free_out:
    872     free(root);
    873 }
    874 
    875 static void handle_firmware_event(struct uevent *uevent)
    876 {
    877     pid_t pid;
    878 
    879     if(strcmp(uevent->subsystem, "firmware"))
    880         return;
    881 
    882     if(strcmp(uevent->action, "add"))
    883         return;
    884 
    885     /* we fork, to avoid making large memory allocations in init proper */
    886     pid = fork();
    887     if (!pid) {
    888         process_firmware_event(uevent);
    889         _exit(EXIT_SUCCESS);
    890     } else if (pid < 0) {
    891         ERROR("could not fork to process firmware event: %s\n", strerror(errno));
    892     }
    893 }
    894 
    895 #define UEVENT_MSG_LEN  2048
    896 void handle_device_fd()
    897 {
    898     char msg[UEVENT_MSG_LEN+2];
    899     int n;
    900     while ((n = uevent_kernel_multicast_recv(device_fd, msg, UEVENT_MSG_LEN)) > 0) {
    901         if(n >= UEVENT_MSG_LEN)   /* overflow -- discard */
    902             continue;
    903 
    904         msg[n] = '\0';
    905         msg[n+1] = '\0';
    906 
    907         struct uevent uevent;
    908         parse_event(msg, &uevent);
    909 
    910         if (sehandle && selinux_status_updated() > 0) {
    911             struct selabel_handle *sehandle2;
    912             sehandle2 = selinux_android_file_context_handle();
    913             if (sehandle2) {
    914                 selabel_close(sehandle);
    915                 sehandle = sehandle2;
    916             }
    917         }
    918 
    919         handle_device_event(&uevent);
    920         handle_firmware_event(&uevent);
    921     }
    922 }
    923 
    924 /* Coldboot walks parts of the /sys tree and pokes the uevent files
    925 ** to cause the kernel to regenerate device add events that happened
    926 ** before init's device manager was started
    927 **
    928 ** We drain any pending events from the netlink socket every time
    929 ** we poke another uevent file to make sure we don't overrun the
    930 ** socket's buffer.
    931 */
    932 
    933 static void do_coldboot(DIR *d)
    934 {
    935     struct dirent *de;
    936     int dfd, fd;
    937 
    938     dfd = dirfd(d);
    939 
    940     fd = openat(dfd, "uevent", O_WRONLY);
    941     if(fd >= 0) {
    942         write(fd, "add\n", 4);
    943         close(fd);
    944         handle_device_fd();
    945     }
    946 
    947     while((de = readdir(d))) {
    948         DIR *d2;
    949 
    950         if(de->d_type != DT_DIR || de->d_name[0] == '.')
    951             continue;
    952 
    953         fd = openat(dfd, de->d_name, O_RDONLY | O_DIRECTORY);
    954         if(fd < 0)
    955             continue;
    956 
    957         d2 = fdopendir(fd);
    958         if(d2 == 0)
    959             close(fd);
    960         else {
    961             do_coldboot(d2);
    962             closedir(d2);
    963         }
    964     }
    965 }
    966 
    967 static void coldboot(const char *path)
    968 {
    969     DIR *d = opendir(path);
    970     if(d) {
    971         do_coldboot(d);
    972         closedir(d);
    973     }
    974 }
    975 
    976 void device_init() {
    977     sehandle = NULL;
    978     if (is_selinux_enabled() > 0) {
    979         sehandle = selinux_android_file_context_handle();
    980         selinux_status_open(true);
    981     }
    982 
    983     /* is 256K enough? udev uses 16MB! */
    984     device_fd = uevent_open_socket(256*1024, true);
    985     if (device_fd == -1) {
    986         return;
    987     }
    988     fcntl(device_fd, F_SETFL, O_NONBLOCK);
    989 
    990     if (access(COLDBOOT_DONE, F_OK) == 0) {
    991         NOTICE("Skipping coldboot, already done!\n");
    992         return;
    993     }
    994 
    995     Timer t;
    996     coldboot("/sys/class");
    997     coldboot("/sys/block");
    998     coldboot("/sys/devices");
    999     close(open(COLDBOOT_DONE, O_WRONLY|O_CREAT|O_CLOEXEC, 0000));
   1000     NOTICE("Coldboot took %.2fs.\n", t.duration());
   1001 }
   1002 
   1003 int get_device_fd()
   1004 {
   1005     return device_fd;
   1006 }
   1007