util.c revision 38f368c1b3bac76d342189b6412691a217421178 
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#include <sys/stat.h>
27#include <sys/types.h>
28#include <sys/socket.h>
29#include <sys/un.h>
30
31/* for ANDROID_SOCKET_* */
32#include <cutils/sockets.h>
33
34#include <private/android_filesystem_config.h>
35
36#include "log.h"
37#include "util.h"
38
39/*
40 * android_name_to_id - returns the integer uid/gid associated with the given
41 * name, or -1U on error.
42 */
43static unsigned int android_name_to_id(const char *name)
44{
45    struct android_id_info *info = android_ids;
46    unsigned int n;
47
48    for (n = 0; n < android_id_count; n++) {
49        if (!strcmp(info[n].name, name))
50            return info[n].aid;
51    }
52
53    return -1U;
54}
55
56/*
57 * decode_uid - decodes and returns the given string, which can be either the
58 * numeric or name representation, into the integer uid or gid. Returns -1U on
59 * error.
60 */
61unsigned int decode_uid(const char *s)
62{
63    unsigned int v;
64
65    if (!s || *s == '\0')
66        return -1U;
67    if (isalpha(s[0]))
68        return android_name_to_id(s);
69
70    errno = 0;
71    v = (unsigned int) strtoul(s, 0, 0);
72    if (errno)
73        return -1U;
74    return v;
75}
76
77/*
78 * create_socket - creates a Unix domain socket in ANDROID_SOCKET_DIR
79 * ("/dev/socket") as dictated in init.rc. This socket is inherited by the
80 * daemon. We communicate the file descriptor's value via the environment
81 * variable ANDROID_SOCKET_ENV_PREFIX<name> ("ANDROID_SOCKET_foo").
82 */
83int create_socket(const char *name, int type, mode_t perm, uid_t uid, gid_t gid)
84{
85    struct sockaddr_un addr;
86    int fd, ret;
87
88    fd = socket(PF_UNIX, type, 0);
89    if (fd < 0) {
90        ERROR("Failed to open socket '%s': %s\n", name, strerror(errno));
91        return -1;
92    }
93
94    memset(&addr, 0 , sizeof(addr));
95    addr.sun_family = AF_UNIX;
96    snprintf(addr.sun_path, sizeof(addr.sun_path), ANDROID_SOCKET_DIR"/%s",
97             name);
98
99    ret = unlink(addr.sun_path);
100    if (ret != 0 && errno != ENOENT) {
101        ERROR("Failed to unlink old socket '%s': %s\n", name, strerror(errno));
102        goto out_close;
103    }
104
105    ret = bind(fd, (struct sockaddr *) &addr, sizeof (addr));
106    if (ret) {
107        ERROR("Failed to bind socket '%s': %s\n", name, strerror(errno));
108        goto out_unlink;
109    }
110
111    chown(addr.sun_path, uid, gid);
112    chmod(addr.sun_path, perm);
113
114    INFO("Created socket '%s' with mode '%o', user '%d', group '%d'\n",
115         addr.sun_path, perm, uid, gid);
116
117    return fd;
118
119out_unlink:
120    unlink(addr.sun_path);
121out_close:
122    close(fd);
123    return -1;
124}
125
126/* reads a file, making sure it is terminated with \n \0 */
127void *read_file(const char *fn, unsigned *_sz)
128{
129    char *data;
130    int sz;
131    int fd;
132    struct stat sb;
133
134    data = 0;
135    fd = open(fn, O_RDONLY);
136    if(fd < 0) return 0;
137
138    // for security reasons, disallow world-writable
139    // or group-writable files
140    if (fstat(fd, &sb) < 0) {
141        ERROR("fstat failed for '%s'\n", fn);
142        goto oops;
143    }
144    if ((sb.st_mode & (S_IWGRP | S_IWOTH)) != 0) {
145        ERROR("skipping insecure file '%s'\n", fn);
146        goto oops;
147    }
148
149    sz = lseek(fd, 0, SEEK_END);
150    if(sz < 0) goto oops;
151
152    if(lseek(fd, 0, SEEK_SET) != 0) goto oops;
153
154    data = (char*) malloc(sz + 2);
155    if(data == 0) goto oops;
156
157    if(read(fd, data, sz) != sz) goto oops;
158    close(fd);
159    data[sz] = '\n';
160    data[sz+1] = 0;
161    if(_sz) *_sz = sz;
162    return data;
163
164oops:
165    close(fd);
166    if(data != 0) free(data);
167    return 0;
168}
169
170#define MAX_MTD_PARTITIONS 16
171
172static struct {
173    char name[16];
174    int number;
175} mtd_part_map[MAX_MTD_PARTITIONS];
176
177static int mtd_part_count = -1;
178
179static void find_mtd_partitions(void)
180{
181    int fd;
182    char buf[1024];
183    char *pmtdbufp;
184    ssize_t pmtdsize;
185    int r;
186
187    fd = open("/proc/mtd", O_RDONLY);
188    if (fd < 0)
189        return;
190
191    buf[sizeof(buf) - 1] = '\0';
192    pmtdsize = read(fd, buf, sizeof(buf) - 1);
193    pmtdbufp = buf;
194    while (pmtdsize > 0) {
195        int mtdnum, mtdsize, mtderasesize;
196        char mtdname[16];
197        mtdname[0] = '\0';
198        mtdnum = -1;
199        r = sscanf(pmtdbufp, "mtd%d: %x %x %15s",
200                   &mtdnum, &mtdsize, &mtderasesize, mtdname);
201        if ((r == 4) && (mtdname[0] == '"')) {
202            char *x = strchr(mtdname + 1, '"');
203            if (x) {
204                *x = 0;
205            }
206            INFO("mtd partition %d, %s\n", mtdnum, mtdname + 1);
207            if (mtd_part_count < MAX_MTD_PARTITIONS) {
208                strcpy(mtd_part_map[mtd_part_count].name, mtdname + 1);
209                mtd_part_map[mtd_part_count].number = mtdnum;
210                mtd_part_count++;
211            } else {
212                ERROR("too many mtd partitions\n");
213            }
214        }
215        while (pmtdsize > 0 && *pmtdbufp != '\n') {
216            pmtdbufp++;
217            pmtdsize--;
218        }
219        if (pmtdsize > 0) {
220            pmtdbufp++;
221            pmtdsize--;
222        }
223    }
224    close(fd);
225}
226
227int mtd_name_to_number(const char *name)
228{
229    int n;
230    if (mtd_part_count < 0) {
231        mtd_part_count = 0;
232        find_mtd_partitions();
233    }
234    for (n = 0; n < mtd_part_count; n++) {
235        if (!strcmp(name, mtd_part_map[n].name)) {
236            return mtd_part_map[n].number;
237        }
238    }
239    return -1;
240}
241
242/*
243 * gettime() - returns the time in seconds of the system's monotonic clock or
244 * zero on error.
245 */
246time_t gettime(void)
247{
248    struct timespec ts;
249    int ret;
250
251    ret = clock_gettime(CLOCK_MONOTONIC, &ts);
252    if (ret < 0) {
253        ERROR("clock_gettime(CLOCK_MONOTONIC) failed: %s\n", strerror(errno));
254        return 0;
255    }
256
257    return ts.tv_sec;
258}
259
260int mkdir_recursive(const char *pathname, mode_t mode)
261{
262    char buf[128];
263    const char *slash;
264    const char *p = pathname;
265    int width;
266    int ret;
267    struct stat info;
268
269    while ((slash = strchr(p, '/')) != NULL) {
270        width = slash - pathname;
271        p = slash + 1;
272        if (width < 0)
273            break;
274        if (width == 0)
275            continue;
276        if ((unsigned int)width > sizeof(buf) - 1) {
277            ERROR("path too long for mkdir_recursive\n");
278            return -1;
279        }
280        memcpy(buf, pathname, width);
281        buf[width] = 0;
282        if (stat(buf, &info) != 0) {
283            ret = mkdir(buf, mode);
284            if (ret && errno != EEXIST)
285                return ret;
286        }
287    }
288    ret = mkdir(pathname, mode);
289    if (ret && errno != EEXIST)
290        return ret;
291    return 0;
292}
293
294void sanitize(char *s)
295{
296    if (!s)
297        return;
298    while (isalnum(*s))
299        s++;
300    *s = 0;
301}
302void make_link(const char *oldpath, const char *newpath)
303{
304    int ret;
305    char buf[256];
306    char *slash;
307    int width;
308
309    slash = strrchr(newpath, '/');
310    if (!slash)
311        return;
312    width = slash - newpath;
313    if (width <= 0 || width > (int)sizeof(buf) - 1)
314        return;
315    memcpy(buf, newpath, width);
316    buf[width] = 0;
317    ret = mkdir_recursive(buf, 0755);
318    if (ret)
319        ERROR("Failed to create directory %s: %s (%d)\n", buf, strerror(errno), errno);
320
321    ret = symlink(oldpath, newpath);
322    if (ret && errno != EEXIST)
323        ERROR("Failed to symlink %s to %s: %s (%d)\n", oldpath, newpath, strerror(errno), errno);
324}
325
326void remove_link(const char *oldpath, const char *newpath)
327{
328    char path[256];
329    ssize_t ret;
330    ret = readlink(newpath, path, sizeof(path) - 1);
331    if (ret <= 0)
332        return;
333    path[ret] = 0;
334    if (!strcmp(path, oldpath))
335        unlink(newpath);
336}
337
338int wait_for_file(const char *filename, int timeout)
339{
340    struct stat info;
341    time_t timeout_time = gettime() + timeout;
342    int ret = -1;
343
344    while (gettime() < timeout_time && ((ret = stat(filename, &info)) < 0))
345        usleep(10000);
346
347    return ret;
348}
349
350void open_devnull_stdio(void)
351{
352    int fd;
353    static const char *name = "/dev/__null__";
354    if (mknod(name, S_IFCHR | 0600, (1 << 8) | 3) == 0) {
355        fd = open(name, O_RDWR);
356        unlink(name);
357        if (fd >= 0) {
358            dup2(fd, 0);
359            dup2(fd, 1);
360            dup2(fd, 2);
361            if (fd > 2) {
362                close(fd);
363            }
364            return;
365        }
366    }
367
368    exit(1);
369}
370
371void get_hardware_name(char *hardware, unsigned int *revision)
372{
373    char data[1024];
374    int fd, n;
375    char *x, *hw, *rev;
376
377    /* Hardware string was provided on kernel command line */
378    if (hardware[0])
379        return;
380
381    fd = open("/proc/cpuinfo", O_RDONLY);
382    if (fd < 0) return;
383
384    n = read(fd, data, 1023);
385    close(fd);
386    if (n < 0) return;
387
388    data[n] = 0;
389    hw = strstr(data, "\nHardware");
390    rev = strstr(data, "\nRevision");
391
392    if (hw) {
393        x = strstr(hw, ": ");
394        if (x) {
395            x += 2;
396            n = 0;
397            while (*x && *x != '\n') {
398                if (!isspace(*x))
399                    hardware[n++] = tolower(*x);
400                x++;
401                if (n == 31) break;
402            }
403            hardware[n] = 0;
404        }
405    }
406
407    if (rev) {
408        x = strstr(rev, ": ");
409        if (x) {
410            *revision = strtoul(x + 2, 0, 16);
411        }
412    }
413}
414
415void import_kernel_cmdline(int in_qemu,
416                           void (*import_kernel_nv)(char *name, int in_qemu))
417{
418    char cmdline[1024];
419    char *ptr;
420    int fd;
421
422    fd = open("/proc/cmdline", O_RDONLY);
423    if (fd >= 0) {
424        int n = read(fd, cmdline, 1023);
425        if (n < 0) n = 0;
426
427        /* get rid of trailing newline, it happens */
428        if (n > 0 && cmdline[n-1] == '\n') n--;
429
430        cmdline[n] = 0;
431        close(fd);
432    } else {
433        cmdline[0] = 0;
434    }
435
436    ptr = cmdline;
437    while (ptr && *ptr) {
438        char *x = strchr(ptr, ' ');
439        if (x != 0) *x++ = 0;
440        import_kernel_nv(ptr, in_qemu);
441        ptr = x;
442    }
443}
444