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
54extern struct selabel_handle *sehandle;
55
56static int device_fd = -1;
57
58struct 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
70struct 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
79struct perm_node {
80    struct perms_ dp;
81    struct listnode plist;
82};
83
84struct platform_node {
85    char *name;
86    char *path;
87    int path_len;
88    struct listnode list;
89};
90
91static list_declare(sys_perms);
92static list_declare(dev_perms);
93static list_declare(platform_names);
94
95int 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
125void fixup_sys_perms(const char *upath)
126{
127    char buf[512];
128    struct listnode *node;
129    struct perms_ *dp;
130    char *secontext;
131
132        /* upaths omit the "/sys" that paths in this list
133         * contain, so we add 4 when comparing...
134         */
135    list_for_each(node, &sys_perms) {
136        dp = &(node_to_item(node, struct perm_node, plist))->dp;
137        if (dp->prefix) {
138            if (strncmp(upath, dp->name + 4, strlen(dp->name + 4)))
139                continue;
140        } else {
141            if (strcmp(upath, dp->name + 4))
142                continue;
143        }
144
145        if ((strlen(upath) + strlen(dp->attr) + 6) > sizeof(buf))
146            return;
147
148        sprintf(buf,"/sys%s/%s", upath, dp->attr);
149        INFO("fixup %s %d %d 0%o\n", buf, dp->uid, dp->gid, dp->perm);
150        chown(buf, dp->uid, dp->gid);
151        chmod(buf, dp->perm);
152        if (sehandle) {
153            secontext = NULL;
154            selabel_lookup(sehandle, &secontext, buf, 0);
155            if (secontext) {
156                setfilecon(buf, secontext);
157                freecon(secontext);
158           }
159        }
160    }
161}
162
163static mode_t get_device_perm(const char *path, unsigned *uid, unsigned *gid)
164{
165    mode_t perm;
166    struct listnode *node;
167    struct perm_node *perm_node;
168    struct perms_ *dp;
169
170    /* search the perms list in reverse so that ueventd.$hardware can
171     * override ueventd.rc
172     */
173    list_for_each_reverse(node, &dev_perms) {
174        perm_node = node_to_item(node, struct perm_node, plist);
175        dp = &perm_node->dp;
176
177        if (dp->prefix) {
178            if (strncmp(path, dp->name, strlen(dp->name)))
179                continue;
180        } else {
181            if (strcmp(path, dp->name))
182                continue;
183        }
184        *uid = dp->uid;
185        *gid = dp->gid;
186        return dp->perm;
187    }
188    /* Default if nothing found. */
189    *uid = 0;
190    *gid = 0;
191    return 0600;
192}
193
194static void make_device(const char *path,
195                        const char *upath,
196                        int block, int major, int minor)
197{
198    unsigned uid;
199    unsigned gid;
200    mode_t mode;
201    dev_t dev;
202    char *secontext = NULL;
203
204    mode = get_device_perm(path, &uid, &gid) | (block ? S_IFBLK : S_IFCHR);
205
206    if (sehandle) {
207        selabel_lookup(sehandle, &secontext, path, mode);
208        setfscreatecon(secontext);
209    }
210
211    dev = makedev(major, minor);
212    /* Temporarily change egid to avoid race condition setting the gid of the
213     * device node. Unforunately changing the euid would prevent creation of
214     * some device nodes, so the uid has to be set with chown() and is still
215     * racy. Fixing the gid race at least fixed the issue with system_server
216     * opening dynamic input devices under the AID_INPUT gid. */
217    setegid(gid);
218    mknod(path, mode, dev);
219    chown(path, uid, -1);
220    setegid(AID_ROOT);
221
222    if (secontext) {
223        freecon(secontext);
224        setfscreatecon(NULL);
225    }
226}
227
228static void add_platform_device(const char *path)
229{
230    int path_len = strlen(path);
231    struct listnode *node;
232    struct platform_node *bus;
233    const char *name = path;
234
235    if (!strncmp(path, "/devices/", 9)) {
236        name += 9;
237        if (!strncmp(name, "platform/", 9))
238            name += 9;
239    }
240
241    list_for_each_reverse(node, &platform_names) {
242        bus = node_to_item(node, struct platform_node, list);
243        if ((bus->path_len < path_len) &&
244                (path[bus->path_len] == '/') &&
245                !strncmp(path, bus->path, bus->path_len))
246            /* subdevice of an existing platform, ignore it */
247            return;
248    }
249
250    INFO("adding platform device %s (%s)\n", name, path);
251
252    bus = calloc(1, sizeof(struct platform_node));
253    bus->path = strdup(path);
254    bus->path_len = path_len;
255    bus->name = bus->path + (name - path);
256    list_add_tail(&platform_names, &bus->list);
257}
258
259/*
260 * given a path that may start with a platform device, find the length of the
261 * platform device prefix.  If it doesn't start with a platform device, return
262 * 0.
263 */
264static struct platform_node *find_platform_device(const char *path)
265{
266    int path_len = strlen(path);
267    struct listnode *node;
268    struct platform_node *bus;
269
270    list_for_each_reverse(node, &platform_names) {
271        bus = node_to_item(node, struct platform_node, list);
272        if ((bus->path_len < path_len) &&
273                (path[bus->path_len] == '/') &&
274                !strncmp(path, bus->path, bus->path_len))
275            return bus;
276    }
277
278    return NULL;
279}
280
281static void remove_platform_device(const char *path)
282{
283    struct listnode *node;
284    struct platform_node *bus;
285
286    list_for_each_reverse(node, &platform_names) {
287        bus = node_to_item(node, struct platform_node, list);
288        if (!strcmp(path, bus->path)) {
289            INFO("removing platform device %s\n", bus->name);
290            free(bus->path);
291            list_remove(node);
292            free(bus);
293            return;
294        }
295    }
296}
297
298#if LOG_UEVENTS
299
300static inline suseconds_t get_usecs(void)
301{
302    struct timeval tv;
303    gettimeofday(&tv, 0);
304    return tv.tv_sec * (suseconds_t) 1000000 + tv.tv_usec;
305}
306
307#define log_event_print(x...) INFO(x)
308
309#else
310
311#define log_event_print(fmt, args...)   do { } while (0)
312#define get_usecs()                     0
313
314#endif
315
316static void parse_event(const char *msg, struct uevent *uevent)
317{
318    uevent->action = "";
319    uevent->path = "";
320    uevent->subsystem = "";
321    uevent->firmware = "";
322    uevent->major = -1;
323    uevent->minor = -1;
324    uevent->partition_name = NULL;
325    uevent->partition_num = -1;
326    uevent->device_name = NULL;
327
328        /* currently ignoring SEQNUM */
329    while(*msg) {
330        if(!strncmp(msg, "ACTION=", 7)) {
331            msg += 7;
332            uevent->action = msg;
333        } else if(!strncmp(msg, "DEVPATH=", 8)) {
334            msg += 8;
335            uevent->path = msg;
336        } else if(!strncmp(msg, "SUBSYSTEM=", 10)) {
337            msg += 10;
338            uevent->subsystem = msg;
339        } else if(!strncmp(msg, "FIRMWARE=", 9)) {
340            msg += 9;
341            uevent->firmware = msg;
342        } else if(!strncmp(msg, "MAJOR=", 6)) {
343            msg += 6;
344            uevent->major = atoi(msg);
345        } else if(!strncmp(msg, "MINOR=", 6)) {
346            msg += 6;
347            uevent->minor = atoi(msg);
348        } else if(!strncmp(msg, "PARTN=", 6)) {
349            msg += 6;
350            uevent->partition_num = atoi(msg);
351        } else if(!strncmp(msg, "PARTNAME=", 9)) {
352            msg += 9;
353            uevent->partition_name = msg;
354        } else if(!strncmp(msg, "DEVNAME=", 8)) {
355            msg += 8;
356            uevent->device_name = msg;
357        }
358
359        /* advance to after the next \0 */
360        while(*msg++)
361            ;
362    }
363
364    log_event_print("event { '%s', '%s', '%s', '%s', %d, %d }\n",
365                    uevent->action, uevent->path, uevent->subsystem,
366                    uevent->firmware, uevent->major, uevent->minor);
367}
368
369static char **get_character_device_symlinks(struct uevent *uevent)
370{
371    const char *parent;
372    char *slash;
373    char **links;
374    int link_num = 0;
375    int width;
376    struct platform_node *pdev;
377
378    pdev = find_platform_device(uevent->path);
379    if (!pdev)
380        return NULL;
381
382    links = malloc(sizeof(char *) * 2);
383    if (!links)
384        return NULL;
385    memset(links, 0, sizeof(char *) * 2);
386
387    /* skip "/devices/platform/<driver>" */
388    parent = strchr(uevent->path + pdev->path_len, '/');
389    if (!*parent)
390        goto err;
391
392    if (!strncmp(parent, "/usb", 4)) {
393        /* skip root hub name and device. use device interface */
394        while (*++parent && *parent != '/');
395        if (*parent)
396            while (*++parent && *parent != '/');
397        if (!*parent)
398            goto err;
399        slash = strchr(++parent, '/');
400        if (!slash)
401            goto err;
402        width = slash - parent;
403        if (width <= 0)
404            goto err;
405
406        if (asprintf(&links[link_num], "/dev/usb/%s%.*s", uevent->subsystem, width, parent) > 0)
407            link_num++;
408        else
409            links[link_num] = NULL;
410        mkdir("/dev/usb", 0755);
411    }
412    else {
413        goto err;
414    }
415
416    return links;
417err:
418    free(links);
419    return NULL;
420}
421
422static char **parse_platform_block_device(struct uevent *uevent)
423{
424    const char *device;
425    struct platform_node *pdev;
426    char *slash;
427    int width;
428    char buf[256];
429    char link_path[256];
430    int fd;
431    int link_num = 0;
432    int ret;
433    char *p;
434    unsigned int size;
435    struct stat info;
436
437    pdev = find_platform_device(uevent->path);
438    if (!pdev)
439        return NULL;
440    device = pdev->name;
441
442    char **links = malloc(sizeof(char *) * 4);
443    if (!links)
444        return NULL;
445    memset(links, 0, sizeof(char *) * 4);
446
447    INFO("found platform device %s\n", device);
448
449    snprintf(link_path, sizeof(link_path), "/dev/block/platform/%s", device);
450
451    if (uevent->partition_name) {
452        p = strdup(uevent->partition_name);
453        sanitize(p);
454        if (strcmp(uevent->partition_name, p))
455            NOTICE("Linking partition '%s' as '%s'\n", uevent->partition_name, p);
456        if (asprintf(&links[link_num], "%s/by-name/%s", link_path, p) > 0)
457            link_num++;
458        else
459            links[link_num] = NULL;
460        free(p);
461    }
462
463    if (uevent->partition_num >= 0) {
464        if (asprintf(&links[link_num], "%s/by-num/p%d", link_path, uevent->partition_num) > 0)
465            link_num++;
466        else
467            links[link_num] = NULL;
468    }
469
470    slash = strrchr(uevent->path, '/');
471    if (asprintf(&links[link_num], "%s/%s", link_path, slash + 1) > 0)
472        link_num++;
473    else
474        links[link_num] = NULL;
475
476    return links;
477}
478
479static void handle_device(const char *action, const char *devpath,
480        const char *path, int block, int major, int minor, char **links)
481{
482    int i;
483
484    if(!strcmp(action, "add")) {
485        make_device(devpath, path, block, major, minor);
486        if (links) {
487            for (i = 0; links[i]; i++)
488                make_link(devpath, links[i]);
489        }
490    }
491
492    if(!strcmp(action, "remove")) {
493        if (links) {
494            for (i = 0; links[i]; i++)
495                remove_link(devpath, links[i]);
496        }
497        unlink(devpath);
498    }
499
500    if (links) {
501        for (i = 0; links[i]; i++)
502            free(links[i]);
503        free(links);
504    }
505}
506
507static void handle_platform_device_event(struct uevent *uevent)
508{
509    const char *path = uevent->path;
510
511    if (!strcmp(uevent->action, "add"))
512        add_platform_device(path);
513    else if (!strcmp(uevent->action, "remove"))
514        remove_platform_device(path);
515}
516
517static const char *parse_device_name(struct uevent *uevent, unsigned int len)
518{
519    const char *name;
520
521    /* if it's not a /dev device, nothing else to do */
522    if((uevent->major < 0) || (uevent->minor < 0))
523        return NULL;
524
525    /* do we have a name? */
526    name = strrchr(uevent->path, '/');
527    if(!name)
528        return NULL;
529    name++;
530
531    /* too-long names would overrun our buffer */
532    if(strlen(name) > len)
533        return NULL;
534
535    return name;
536}
537
538static void handle_block_device_event(struct uevent *uevent)
539{
540    const char *base = "/dev/block/";
541    const char *name;
542    char devpath[96];
543    char **links = NULL;
544
545    name = parse_device_name(uevent, 64);
546    if (!name)
547        return;
548
549    snprintf(devpath, sizeof(devpath), "%s%s", base, name);
550    make_dir(base, 0755);
551
552    if (!strncmp(uevent->path, "/devices/", 9))
553        links = parse_platform_block_device(uevent);
554
555    handle_device(uevent->action, devpath, uevent->path, 1,
556            uevent->major, uevent->minor, links);
557}
558
559static void handle_generic_device_event(struct uevent *uevent)
560{
561    char *base;
562    const char *name;
563    char devpath[96] = {0};
564    char **links = NULL;
565
566    name = parse_device_name(uevent, 64);
567    if (!name)
568        return;
569
570    if (!strncmp(uevent->subsystem, "usb", 3)) {
571         if (!strcmp(uevent->subsystem, "usb")) {
572            if (uevent->device_name) {
573                /*
574                 * create device node provided by kernel if present
575                 * see drivers/base/core.c
576                 */
577                char *p = devpath;
578                snprintf(devpath, sizeof(devpath), "/dev/%s", uevent->device_name);
579                /* skip leading /dev/ */
580                p += 5;
581                /* build directories */
582                while (*p) {
583                    if (*p == '/') {
584                        *p = 0;
585                        make_dir(devpath, 0755);
586                        *p = '/';
587                    }
588                    p++;
589                }
590             }
591             else {
592                 /* This imitates the file system that would be created
593                  * if we were using devfs instead.
594                  * Minors are broken up into groups of 128, starting at "001"
595                  */
596                 int bus_id = uevent->minor / 128 + 1;
597                 int device_id = uevent->minor % 128 + 1;
598                 /* build directories */
599                 make_dir("/dev/bus", 0755);
600                 make_dir("/dev/bus/usb", 0755);
601                 snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d", bus_id);
602                 make_dir(devpath, 0755);
603                 snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d/%03d", bus_id, device_id);
604             }
605         } else {
606             /* ignore other USB events */
607             return;
608         }
609     } else if (!strncmp(uevent->subsystem, "graphics", 8)) {
610         base = "/dev/graphics/";
611         make_dir(base, 0755);
612     } else if (!strncmp(uevent->subsystem, "drm", 3)) {
613         base = "/dev/dri/";
614         make_dir(base, 0755);
615     } else if (!strncmp(uevent->subsystem, "oncrpc", 6)) {
616         base = "/dev/oncrpc/";
617         make_dir(base, 0755);
618     } else if (!strncmp(uevent->subsystem, "adsp", 4)) {
619         base = "/dev/adsp/";
620         make_dir(base, 0755);
621     } else if (!strncmp(uevent->subsystem, "msm_camera", 10)) {
622         base = "/dev/msm_camera/";
623         make_dir(base, 0755);
624     } else if(!strncmp(uevent->subsystem, "input", 5)) {
625         base = "/dev/input/";
626         make_dir(base, 0755);
627     } else if(!strncmp(uevent->subsystem, "mtd", 3)) {
628         base = "/dev/mtd/";
629         make_dir(base, 0755);
630     } else if(!strncmp(uevent->subsystem, "sound", 5)) {
631         base = "/dev/snd/";
632         make_dir(base, 0755);
633     } else if(!strncmp(uevent->subsystem, "misc", 4) &&
634                 !strncmp(name, "log_", 4)) {
635         base = "/dev/log/";
636         make_dir(base, 0755);
637         name += 4;
638     } else
639         base = "/dev/";
640     links = get_character_device_symlinks(uevent);
641
642     if (!devpath[0])
643         snprintf(devpath, sizeof(devpath), "%s%s", base, name);
644
645     handle_device(uevent->action, devpath, uevent->path, 0,
646             uevent->major, uevent->minor, links);
647}
648
649static void handle_device_event(struct uevent *uevent)
650{
651    if (!strcmp(uevent->action,"add") || !strcmp(uevent->action, "change"))
652        fixup_sys_perms(uevent->path);
653
654    if (!strncmp(uevent->subsystem, "block", 5)) {
655        handle_block_device_event(uevent);
656    } else if (!strncmp(uevent->subsystem, "platform", 8)) {
657        handle_platform_device_event(uevent);
658    } else {
659        handle_generic_device_event(uevent);
660    }
661}
662
663static int load_firmware(int fw_fd, int loading_fd, int data_fd)
664{
665    struct stat st;
666    long len_to_copy;
667    int ret = 0;
668
669    if(fstat(fw_fd, &st) < 0)
670        return -1;
671    len_to_copy = st.st_size;
672
673    write(loading_fd, "1", 1);  /* start transfer */
674
675    while (len_to_copy > 0) {
676        char buf[PAGE_SIZE];
677        ssize_t nr;
678
679        nr = read(fw_fd, buf, sizeof(buf));
680        if(!nr)
681            break;
682        if(nr < 0) {
683            ret = -1;
684            break;
685        }
686
687        len_to_copy -= nr;
688        while (nr > 0) {
689            ssize_t nw = 0;
690
691            nw = write(data_fd, buf + nw, nr);
692            if(nw <= 0) {
693                ret = -1;
694                goto out;
695            }
696            nr -= nw;
697        }
698    }
699
700out:
701    if(!ret)
702        write(loading_fd, "0", 1);  /* successful end of transfer */
703    else
704        write(loading_fd, "-1", 2); /* abort transfer */
705
706    return ret;
707}
708
709static int is_booting(void)
710{
711    return access("/dev/.booting", F_OK) == 0;
712}
713
714static void process_firmware_event(struct uevent *uevent)
715{
716    char *root, *loading, *data, *file1 = NULL, *file2 = NULL, *file3 = NULL;
717    int l, loading_fd, data_fd, fw_fd;
718    int booting = is_booting();
719
720    INFO("firmware: loading '%s' for '%s'\n",
721         uevent->firmware, uevent->path);
722
723    l = asprintf(&root, SYSFS_PREFIX"%s/", uevent->path);
724    if (l == -1)
725        return;
726
727    l = asprintf(&loading, "%sloading", root);
728    if (l == -1)
729        goto root_free_out;
730
731    l = asprintf(&data, "%sdata", root);
732    if (l == -1)
733        goto loading_free_out;
734
735    l = asprintf(&file1, FIRMWARE_DIR1"/%s", uevent->firmware);
736    if (l == -1)
737        goto data_free_out;
738
739    l = asprintf(&file2, FIRMWARE_DIR2"/%s", uevent->firmware);
740    if (l == -1)
741        goto data_free_out;
742
743    l = asprintf(&file3, FIRMWARE_DIR3"/%s", uevent->firmware);
744    if (l == -1)
745        goto data_free_out;
746
747    loading_fd = open(loading, O_WRONLY);
748    if(loading_fd < 0)
749        goto file_free_out;
750
751    data_fd = open(data, O_WRONLY);
752    if(data_fd < 0)
753        goto loading_close_out;
754
755try_loading_again:
756    fw_fd = open(file1, O_RDONLY);
757    if(fw_fd < 0) {
758        fw_fd = open(file2, O_RDONLY);
759        if (fw_fd < 0) {
760            fw_fd = open(file3, O_RDONLY);
761            if (fw_fd < 0) {
762                if (booting) {
763                        /* If we're not fully booted, we may be missing
764                         * filesystems needed for firmware, wait and retry.
765                         */
766                    usleep(100000);
767                    booting = is_booting();
768                    goto try_loading_again;
769                }
770                INFO("firmware: could not open '%s' %d\n", uevent->firmware, errno);
771                write(loading_fd, "-1", 2);
772                goto data_close_out;
773            }
774        }
775    }
776
777    if(!load_firmware(fw_fd, loading_fd, data_fd))
778        INFO("firmware: copy success { '%s', '%s' }\n", root, uevent->firmware);
779    else
780        INFO("firmware: copy failure { '%s', '%s' }\n", root, uevent->firmware);
781
782    close(fw_fd);
783data_close_out:
784    close(data_fd);
785loading_close_out:
786    close(loading_fd);
787file_free_out:
788    free(file1);
789    free(file2);
790    free(file3);
791data_free_out:
792    free(data);
793loading_free_out:
794    free(loading);
795root_free_out:
796    free(root);
797}
798
799static void handle_firmware_event(struct uevent *uevent)
800{
801    pid_t pid;
802    int ret;
803
804    if(strcmp(uevent->subsystem, "firmware"))
805        return;
806
807    if(strcmp(uevent->action, "add"))
808        return;
809
810    /* we fork, to avoid making large memory allocations in init proper */
811    pid = fork();
812    if (!pid) {
813        process_firmware_event(uevent);
814        exit(EXIT_SUCCESS);
815    }
816}
817
818#define UEVENT_MSG_LEN  1024
819void handle_device_fd()
820{
821    char msg[UEVENT_MSG_LEN+2];
822    int n;
823    while ((n = uevent_kernel_multicast_recv(device_fd, msg, UEVENT_MSG_LEN)) > 0) {
824        if(n >= UEVENT_MSG_LEN)   /* overflow -- discard */
825            continue;
826
827        msg[n] = '\0';
828        msg[n+1] = '\0';
829
830        struct uevent uevent;
831        parse_event(msg, &uevent);
832
833        handle_device_event(&uevent);
834        handle_firmware_event(&uevent);
835    }
836}
837
838/* Coldboot walks parts of the /sys tree and pokes the uevent files
839** to cause the kernel to regenerate device add events that happened
840** before init's device manager was started
841**
842** We drain any pending events from the netlink socket every time
843** we poke another uevent file to make sure we don't overrun the
844** socket's buffer.
845*/
846
847static void do_coldboot(DIR *d)
848{
849    struct dirent *de;
850    int dfd, fd;
851
852    dfd = dirfd(d);
853
854    fd = openat(dfd, "uevent", O_WRONLY);
855    if(fd >= 0) {
856        write(fd, "add\n", 4);
857        close(fd);
858        handle_device_fd();
859    }
860
861    while((de = readdir(d))) {
862        DIR *d2;
863
864        if(de->d_type != DT_DIR || de->d_name[0] == '.')
865            continue;
866
867        fd = openat(dfd, de->d_name, O_RDONLY | O_DIRECTORY);
868        if(fd < 0)
869            continue;
870
871        d2 = fdopendir(fd);
872        if(d2 == 0)
873            close(fd);
874        else {
875            do_coldboot(d2);
876            closedir(d2);
877        }
878    }
879}
880
881static void coldboot(const char *path)
882{
883    DIR *d = opendir(path);
884    if(d) {
885        do_coldboot(d);
886        closedir(d);
887    }
888}
889
890void device_init(void)
891{
892    suseconds_t t0, t1;
893    struct stat info;
894    int fd;
895
896    sehandle = NULL;
897    if (is_selinux_enabled() > 0) {
898        sehandle = selinux_android_file_context_handle();
899    }
900
901    /* is 256K enough? udev uses 16MB! */
902    device_fd = uevent_open_socket(256*1024, true);
903    if(device_fd < 0)
904        return;
905
906    fcntl(device_fd, F_SETFD, FD_CLOEXEC);
907    fcntl(device_fd, F_SETFL, O_NONBLOCK);
908
909    if (stat(coldboot_done, &info) < 0) {
910        t0 = get_usecs();
911        coldboot("/sys/class");
912        coldboot("/sys/block");
913        coldboot("/sys/devices");
914        t1 = get_usecs();
915        fd = open(coldboot_done, O_WRONLY|O_CREAT, 0000);
916        close(fd);
917        log_event_print("coldboot %ld uS\n", ((long) (t1 - t0)));
918    } else {
919        log_event_print("skipping coldboot, already done\n");
920    }
921}
922
923int get_device_fd()
924{
925    return device_fd;
926}
927