util.c revision e096e36e50b4b66638ebc4d3c09c2ee35f538dfa 
1/*
2 * Copyright (C) 2008 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 <stdarg.h>
18#include <stdlib.h>
19#include <stdio.h>
20#include <string.h>
21#include <fcntl.h>
22#include <ctype.h>
23#include <errno.h>
24#include <time.h>
25
26#ifdef HAVE_SELINUX
27#include <selinux/label.h>
28#endif
29
30#include <sys/stat.h>
31#include <sys/types.h>
32#include <sys/socket.h>
33#include <sys/un.h>
34
35/* for ANDROID_SOCKET_* */
36#include <cutils/sockets.h>
37
38#include <private/android_filesystem_config.h>
39
40#include "init.h"
41#include "log.h"
42#include "util.h"
43
44/*
45 * android_name_to_id - returns the integer uid/gid associated with the given
46 * name, or -1U on error.
47 */
48static unsigned int android_name_to_id(const char *name)
49{
50    struct android_id_info *info = android_ids;
51    unsigned int n;
52
53    for (n = 0; n < android_id_count; n++) {
54        if (!strcmp(info[n].name, name))
55            return info[n].aid;
56    }
57
58    return -1U;
59}
60
61/*
62 * decode_uid - decodes and returns the given string, which can be either the
63 * numeric or name representation, into the integer uid or gid. Returns -1U on
64 * error.
65 */
66unsigned int decode_uid(const char *s)
67{
68    unsigned int v;
69
70    if (!s || *s == '\0')
71        return -1U;
72    if (isalpha(s[0]))
73        return android_name_to_id(s);
74
75    errno = 0;
76    v = (unsigned int) strtoul(s, 0, 0);
77    if (errno)
78        return -1U;
79    return v;
80}
81
82/*
83 * create_socket - creates a Unix domain socket in ANDROID_SOCKET_DIR
84 * ("/dev/socket") as dictated in init.rc. This socket is inherited by the
85 * daemon. We communicate the file descriptor's value via the environment
86 * variable ANDROID_SOCKET_ENV_PREFIX<name> ("ANDROID_SOCKET_foo").
87 */
88int create_socket(const char *name, int type, mode_t perm, uid_t uid, gid_t gid)
89{
90    struct sockaddr_un addr;
91    int fd, ret;
92#ifdef HAVE_SELINUX
93    char *secon;
94#endif
95
96    fd = socket(PF_UNIX, type, 0);
97    if (fd < 0) {
98        ERROR("Failed to open socket '%s': %s\n", name, strerror(errno));
99        return -1;
100    }
101
102    memset(&addr, 0 , sizeof(addr));
103    addr.sun_family = AF_UNIX;
104    snprintf(addr.sun_path, sizeof(addr.sun_path), ANDROID_SOCKET_DIR"/%s",
105             name);
106
107    ret = unlink(addr.sun_path);
108    if (ret != 0 && errno != ENOENT) {
109        ERROR("Failed to unlink old socket '%s': %s\n", name, strerror(errno));
110        goto out_close;
111    }
112
113#ifdef HAVE_SELINUX
114    secon = NULL;
115    if (sehandle) {
116        ret = selabel_lookup(sehandle, &secon, addr.sun_path, S_IFSOCK);
117        if (ret == 0)
118            setfscreatecon(secon);
119    }
120#endif
121
122    ret = bind(fd, (struct sockaddr *) &addr, sizeof (addr));
123    if (ret) {
124        ERROR("Failed to bind socket '%s': %s\n", name, strerror(errno));
125        goto out_unlink;
126    }
127
128#ifdef HAVE_SELINUX
129    setfscreatecon(NULL);
130    freecon(secon);
131#endif
132
133    chown(addr.sun_path, uid, gid);
134    chmod(addr.sun_path, perm);
135
136    INFO("Created socket '%s' with mode '%o', user '%d', group '%d'\n",
137         addr.sun_path, perm, uid, gid);
138
139    return fd;
140
141out_unlink:
142    unlink(addr.sun_path);
143out_close:
144    close(fd);
145    return -1;
146}
147
148/* reads a file, making sure it is terminated with \n \0 */
149void *read_file(const char *fn, unsigned *_sz)
150{
151    char *data;
152    int sz;
153    int fd;
154
155    data = 0;
156    fd = open(fn, O_RDONLY);
157    if(fd < 0) return 0;
158
159    sz = lseek(fd, 0, SEEK_END);
160    if(sz < 0) goto oops;
161
162    if(lseek(fd, 0, SEEK_SET) != 0) goto oops;
163
164    data = (char*) malloc(sz + 2);
165    if(data == 0) goto oops;
166
167    if(read(fd, data, sz) != sz) goto oops;
168    close(fd);
169    data[sz] = '\n';
170    data[sz+1] = 0;
171    if(_sz) *_sz = sz;
172    return data;
173
174oops:
175    close(fd);
176    if(data != 0) free(data);
177    return 0;
178}
179
180#define MAX_MTD_PARTITIONS 16
181
182static struct {
183    char name[16];
184    int number;
185} mtd_part_map[MAX_MTD_PARTITIONS];
186
187static int mtd_part_count = -1;
188
189static void find_mtd_partitions(void)
190{
191    int fd;
192    char buf[1024];
193    char *pmtdbufp;
194    ssize_t pmtdsize;
195    int r;
196
197    fd = open("/proc/mtd", O_RDONLY);
198    if (fd < 0)
199        return;
200
201    buf[sizeof(buf) - 1] = '\0';
202    pmtdsize = read(fd, buf, sizeof(buf) - 1);
203    pmtdbufp = buf;
204    while (pmtdsize > 0) {
205        int mtdnum, mtdsize, mtderasesize;
206        char mtdname[16];
207        mtdname[0] = '\0';
208        mtdnum = -1;
209        r = sscanf(pmtdbufp, "mtd%d: %x %x %15s",
210                   &mtdnum, &mtdsize, &mtderasesize, mtdname);
211        if ((r == 4) && (mtdname[0] == '"')) {
212            char *x = strchr(mtdname + 1, '"');
213            if (x) {
214                *x = 0;
215            }
216            INFO("mtd partition %d, %s\n", mtdnum, mtdname + 1);
217            if (mtd_part_count < MAX_MTD_PARTITIONS) {
218                strcpy(mtd_part_map[mtd_part_count].name, mtdname + 1);
219                mtd_part_map[mtd_part_count].number = mtdnum;
220                mtd_part_count++;
221            } else {
222                ERROR("too many mtd partitions\n");
223            }
224        }
225        while (pmtdsize > 0 && *pmtdbufp != '\n') {
226            pmtdbufp++;
227            pmtdsize--;
228        }
229        if (pmtdsize > 0) {
230            pmtdbufp++;
231            pmtdsize--;
232        }
233    }
234    close(fd);
235}
236
237int mtd_name_to_number(const char *name)
238{
239    int n;
240    if (mtd_part_count < 0) {
241        mtd_part_count = 0;
242        find_mtd_partitions();
243    }
244    for (n = 0; n < mtd_part_count; n++) {
245        if (!strcmp(name, mtd_part_map[n].name)) {
246            return mtd_part_map[n].number;
247        }
248    }
249    return -1;
250}
251
252/*
253 * gettime() - returns the time in seconds of the system's monotonic clock or
254 * zero on error.
255 */
256time_t gettime(void)
257{
258    struct timespec ts;
259    int ret;
260
261    ret = clock_gettime(CLOCK_MONOTONIC, &ts);
262    if (ret < 0) {
263        ERROR("clock_gettime(CLOCK_MONOTONIC) failed: %s\n", strerror(errno));
264        return 0;
265    }
266
267    return ts.tv_sec;
268}
269
270int mkdir_recursive(const char *pathname, mode_t mode)
271{
272    char buf[128];
273    const char *slash;
274    const char *p = pathname;
275    int width;
276    int ret;
277    struct stat info;
278
279    while ((slash = strchr(p, '/')) != NULL) {
280        width = slash - pathname;
281        p = slash + 1;
282        if (width < 0)
283            break;
284        if (width == 0)
285            continue;
286        if ((unsigned int)width > sizeof(buf) - 1) {
287            ERROR("path too long for mkdir_recursive\n");
288            return -1;
289        }
290        memcpy(buf, pathname, width);
291        buf[width] = 0;
292        if (stat(buf, &info) != 0) {
293            ret = make_dir(buf, mode);
294            if (ret && errno != EEXIST)
295                return ret;
296        }
297    }
298    ret = make_dir(pathname, mode);
299    if (ret && errno != EEXIST)
300        return ret;
301    return 0;
302}
303
304void sanitize(char *s)
305{
306    if (!s)
307        return;
308    while (isalnum(*s))
309        s++;
310    *s = 0;
311}
312void make_link(const char *oldpath, const char *newpath)
313{
314    int ret;
315    char buf[256];
316    char *slash;
317    int width;
318
319    slash = strrchr(newpath, '/');
320    if (!slash)
321        return;
322    width = slash - newpath;
323    if (width <= 0 || width > (int)sizeof(buf) - 1)
324        return;
325    memcpy(buf, newpath, width);
326    buf[width] = 0;
327    ret = mkdir_recursive(buf, 0755);
328    if (ret)
329        ERROR("Failed to create directory %s: %s (%d)\n", buf, strerror(errno), errno);
330
331    ret = symlink(oldpath, newpath);
332    if (ret && errno != EEXIST)
333        ERROR("Failed to symlink %s to %s: %s (%d)\n", oldpath, newpath, strerror(errno), errno);
334}
335
336void remove_link(const char *oldpath, const char *newpath)
337{
338    char path[256];
339    ssize_t ret;
340    ret = readlink(newpath, path, sizeof(path) - 1);
341    if (ret <= 0)
342        return;
343    path[ret] = 0;
344    if (!strcmp(path, oldpath))
345        unlink(newpath);
346}
347
348int wait_for_file(const char *filename, int timeout)
349{
350    struct stat info;
351    time_t timeout_time = gettime() + timeout;
352    int ret = -1;
353
354    while (gettime() < timeout_time && ((ret = stat(filename, &info)) < 0))
355        usleep(10000);
356
357    return ret;
358}
359
360void open_devnull_stdio(void)
361{
362    int fd;
363    static const char *name = "/dev/__null__";
364    if (mknod(name, S_IFCHR | 0600, (1 << 8) | 3) == 0) {
365        fd = open(name, O_RDWR);
366        unlink(name);
367        if (fd >= 0) {
368            dup2(fd, 0);
369            dup2(fd, 1);
370            dup2(fd, 2);
371            if (fd > 2) {
372                close(fd);
373            }
374            return;
375        }
376    }
377
378    exit(1);
379}
380
381void get_hardware_name(char *hardware, unsigned int *revision)
382{
383    char data[1024];
384    int fd, n;
385    char *x, *hw, *rev;
386
387    /* Hardware string was provided on kernel command line */
388    if (hardware[0])
389        return;
390
391    fd = open("/proc/cpuinfo", O_RDONLY);
392    if (fd < 0) return;
393
394    n = read(fd, data, 1023);
395    close(fd);
396    if (n < 0) return;
397
398    data[n] = 0;
399    hw = strstr(data, "\nHardware");
400    rev = strstr(data, "\nRevision");
401
402    if (hw) {
403        x = strstr(hw, ": ");
404        if (x) {
405            x += 2;
406            n = 0;
407            while (*x && *x != '\n') {
408                if (!isspace(*x))
409                    hardware[n++] = tolower(*x);
410                x++;
411                if (n == 31) break;
412            }
413            hardware[n] = 0;
414        }
415    }
416
417    if (rev) {
418        x = strstr(rev, ": ");
419        if (x) {
420            *revision = strtoul(x + 2, 0, 16);
421        }
422    }
423}
424
425void import_kernel_cmdline(int in_qemu,
426                           void (*import_kernel_nv)(char *name, int in_qemu))
427{
428    char cmdline[1024];
429    char *ptr;
430    int fd;
431
432    fd = open("/proc/cmdline", O_RDONLY);
433    if (fd >= 0) {
434        int n = read(fd, cmdline, 1023);
435        if (n < 0) n = 0;
436
437        /* get rid of trailing newline, it happens */
438        if (n > 0 && cmdline[n-1] == '\n') n--;
439
440        cmdline[n] = 0;
441        close(fd);
442    } else {
443        cmdline[0] = 0;
444    }
445
446    ptr = cmdline;
447    while (ptr && *ptr) {
448        char *x = strchr(ptr, ' ');
449        if (x != 0) *x++ = 0;
450        import_kernel_nv(ptr, in_qemu);
451        ptr = x;
452    }
453}
454
455int make_dir(const char *path, mode_t mode)
456{
457    int rc;
458
459#ifdef HAVE_SELINUX
460    char *secontext = NULL;
461
462    if (sehandle) {
463        selabel_lookup(sehandle, &secontext, path, mode);
464        setfscreatecon(secontext);
465    }
466#endif
467
468    rc = mkdir(path, mode);
469
470#ifdef HAVE_SELINUX
471    if (secontext) {
472        int save_errno = errno;
473        freecon(secontext);
474        setfscreatecon(NULL);
475        errno = save_errno;
476    }
477#endif
478    return rc;
479}
480
481int restorecon(const char *pathname)
482{
483#ifdef HAVE_SELINUX
484    char *secontext = NULL;
485    struct stat sb;
486    int i;
487
488    if (is_selinux_enabled() <= 0 || !sehandle)
489        return 0;
490
491    if (lstat(pathname, &sb) < 0)
492        return -errno;
493    if (selabel_lookup(sehandle, &secontext, pathname, sb.st_mode) < 0)
494        return -errno;
495    if (lsetfilecon(pathname, secontext) < 0) {
496        freecon(secontext);
497        return -errno;
498    }
499    freecon(secontext);
500#endif
501    return 0;
502}
503