watchprops.c revision dd7bc3319deb2b77c5d07a51b7d6cd7e11b5beb0 
1#include <stdio.h>
2#include <stdlib.h>
3#include <time.h>
4
5#include <cutils/properties.h>
6
7#include <sys/atomics.h>
8
9#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
10#include <sys/_system_properties.h>
11
12
13extern prop_area *__system_property_area__;
14
15typedef struct pwatch pwatch;
16
17struct pwatch
18{
19    const prop_info *pi;
20    unsigned serial;
21};
22
23static pwatch watchlist[1024];
24
25static void announce(const prop_info *pi)
26{
27    char name[PROP_NAME_MAX];
28    char value[PROP_VALUE_MAX];
29    char *x;
30
31    __system_property_read(pi, name, value);
32
33    for(x = value; *x; x++) {
34        if((*x < 32) || (*x > 127)) *x = '.';
35    }
36
37    fprintf(stderr,"%10d %s = '%s'\n", (int) time(0), name, value);
38}
39
40int watchprops_main(int argc, char *argv[])
41{
42    prop_area *pa = __system_property_area__;
43    unsigned serial = pa->serial;
44    unsigned count = pa->count;
45    unsigned n;
46
47    if(count >= 1024) exit(1);
48
49    for(n = 0; n < count; n++) {
50        watchlist[n].pi = __system_property_find_nth(n);
51        watchlist[n].serial = watchlist[n].pi->serial;
52    }
53
54    for(;;) {
55        do {
56            __futex_wait(&pa->serial, serial, 0);
57        } while(pa->serial == serial);
58
59        while(count < pa->count){
60            watchlist[count].pi = __system_property_find_nth(count);
61            watchlist[count].serial = watchlist[n].pi->serial;
62            announce(watchlist[count].pi);
63            count++;
64            if(count == 1024) exit(1);
65        }
66
67        for(n = 0; n < count; n++){
68            unsigned tmp = watchlist[n].pi->serial;
69            if(watchlist[n].serial != tmp) {
70                announce(watchlist[n].pi);
71                watchlist[n].serial = tmp;
72            }
73        }
74    }
75    return 0;
76}
77