1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
|
/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include "private/android_filesystem_config.h"
#include "cutils/log.h"
void fatal(const char *msg) {
fprintf(stderr, msg);
LOG(LOG_ERROR, "logwrapper", msg);
exit(-1);
}
void usage() {
fatal(
"Usage: logwrapper BINARY [ARGS ...]\n"
"\n"
"Forks and executes BINARY ARGS, redirecting stdout and stderr to\n"
"the Android logging system. Tag is set to BINARY, priority is\n"
"always LOG_INFO.\n");
}
void parent(const char *tag, int parent_read) {
int status;
char buffer[1024];
int a = 0; // start index of unprocessed data
int b = 0; // end index of unprocessed data
int sz;
while ((sz = read(parent_read, &buffer[b], 1023 - b)) > 0) {
// Log one line at a time
for (b = a; b < sz; b++) {
if (buffer[b] == '\n') {
buffer[b] = '\0';
LOG(LOG_INFO, tag, &buffer[a]);
a = b + 1;
}
}
if (a == 0 && b == 1023) {
// buffer is full, flush
buffer[b] = '\0';
LOG(LOG_INFO, tag, &buffer[a]);
b = 0;
} else {
// Keep left-overs
b = sz - a;
memmove(buffer, &buffer[a], b);
a = 0;
}
}
// Flush remaining data
if (a != b) {
buffer[b] = '\0';
LOG(LOG_INFO, tag, &buffer[a]);
}
wait(&status); // Wait for child
}
void child(int argc, char* argv[]) {
// create null terminated argv_child array
char* argv_child[argc + 1];
memcpy(argv_child, argv, argc * sizeof(char *));
argv_child[argc] = NULL;
if (execvp(argv_child[0], argv_child)) {
LOG(LOG_ERROR, "logwrapper",
"executing %s failed: %s\n", argv_child[0], strerror(errno));
exit(-1);
}
}
int main(int argc, char* argv[]) {
pid_t pid;
int pipe_fds[2];
int *parent_read = &pipe_fds[0];
int *child_write = &pipe_fds[1];
if (argc < 2) {
usage();
}
if (pipe(pipe_fds) < 0) {
fatal("Cannot create pipe\n");
}
pid = fork();
if (pid < 0) {
fatal("Failed to fork\n");
} else if (pid == 0) {
// redirect stdout and stderr
close(*parent_read);
dup2(*child_write, 1);
dup2(*child_write, 2);
close(*child_write);
child(argc - 1, &argv[1]);
} else {
close(*child_write);
// switch user and group to "log"
// this may fail if we are not root,
// but in that case switching user/group is unnecessary
setgid(AID_LOG);
setuid(AID_LOG);
parent(argv[1], *parent_read);
}
return 0;
}
|
