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 <errno.h>
18 #include <stdio.h>
19 #include <stdlib.h>
20 #include <sys/wait.h>
21 #include <unistd.h>
22 
23 #include <logwrap/logwrap.h>
24 #include <cutils/klog.h>
25 
26 #include "cutils/log.h"
27 
fatal(const char * msg)28 void fatal(const char *msg) {
29     fprintf(stderr, "%s", msg);
30     ALOG(LOG_ERROR, "logwrapper", "%s", msg);
31     exit(-1);
32 }
33 
usage()34 void usage() {
35     fatal(
36         "Usage: logwrapper [-a] [-d] [-k] BINARY [ARGS ...]\n"
37         "\n"
38         "Forks and executes BINARY ARGS, redirecting stdout and stderr to\n"
39         "the Android logging system. Tag is set to BINARY, priority is\n"
40         "always LOG_INFO.\n"
41         "\n"
42         "-a: Causes logwrapper to do abbreviated logging.\n"
43         "    This logs up to the first 4K and last 4K of the command\n"
44         "    being run, and logs the output when the command exits\n"
45         "-d: Causes logwrapper to SIGSEGV when BINARY terminates\n"
46         "    fault address is set to the status of wait()\n"
47         "-k: Causes logwrapper to log to the kernel log instead of\n"
48         "    the Android system log\n");
49 }
50 
main(int argc,char * argv[])51 int main(int argc, char* argv[]) {
52     int seg_fault_on_exit = 0;
53     int log_target = LOG_ALOG;
54     bool abbreviated = false;
55     int ch;
56     int status = 0xAAAA;
57     int rc;
58 
59     while ((ch = getopt(argc, argv, "adk")) != -1) {
60         switch (ch) {
61             case 'a':
62                 abbreviated = true;
63                 break;
64             case 'd':
65                 seg_fault_on_exit = 1;
66                 break;
67             case 'k':
68                 log_target = LOG_KLOG;
69                 klog_set_level(6);
70                 break;
71             case '?':
72             default:
73               usage();
74         }
75     }
76     argc -= optind;
77     argv += optind;
78 
79     if (argc < 1) {
80         usage();
81     }
82 
83     rc = android_fork_execvp_ext(argc, &argv[0], &status, true,
84                                  log_target, abbreviated, NULL, NULL, 0);
85     if (!rc) {
86         if (WIFEXITED(status))
87             rc = WEXITSTATUS(status);
88         else
89             rc = -ECHILD;
90     }
91 
92     if (seg_fault_on_exit) {
93         uintptr_t fault_address = (uintptr_t) status;
94         *(int *) fault_address = 0;  // causes SIGSEGV with fault_address = status
95     }
96 
97     return rc;
98 }
99