1 /*
2 * Copyright (C) 2016 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include "linker_logger.h"
30
31 #include <string.h>
32 #include <sys/prctl.h>
33 #include <unistd.h>
34
35 #include <string>
36 #include <vector>
37
38 #include <async_safe/log.h>
39
40 #include "android-base/strings.h"
41 #include "private/CachedProperty.h"
42
43 LinkerLogger g_linker_logger;
44
ParseProperty(const std::string & value)45 static uint32_t ParseProperty(const std::string& value) {
46 if (value.empty()) {
47 return 0;
48 }
49
50 std::vector<std::string> options = android::base::Split(value, ",");
51
52 uint32_t flags = 0;
53
54 for (const auto& o : options) {
55 if (o == "dlerror") {
56 flags |= kLogErrors;
57 } else if (o == "dlopen") {
58 flags |= kLogDlopen;
59 } else if (o == "dlsym") {
60 flags |= kLogDlsym;
61 } else {
62 async_safe_format_log(ANDROID_LOG_WARN, "linker", "Ignoring unknown debug.ld option \"%s\"",
63 o.c_str());
64 }
65 }
66
67 return flags;
68 }
69
GetAppSpecificProperty(char * buffer)70 static void GetAppSpecificProperty(char* buffer) {
71 // Get process basename.
72 const char* process_name_start = basename(g_argv[0]);
73
74 // Remove ':' and everything after it. This is the naming convention for
75 // services: https://developer.android.com/guide/components/services.html
76 const char* process_name_end = strchr(process_name_start, ':');
77
78 std::string process_name = (process_name_end != nullptr) ?
79 std::string(process_name_start, (process_name_end - process_name_start)) :
80 std::string(process_name_start);
81
82 std::string property_name = std::string("debug.ld.app.") + process_name;
83 __system_property_get(property_name.c_str(), buffer);
84 }
85
ResetState()86 void LinkerLogger::ResetState() {
87 // The most likely scenario app is not debuggable and
88 // is running on a user build, in which case logging is disabled.
89 if (prctl(PR_GET_DUMPABLE, 0, 0, 0, 0) == 0) {
90 return;
91 }
92
93 flags_ = 0;
94
95 // For logging, check the flag applied to all processes first.
96 static CachedProperty debug_ld_all("debug.ld.all");
97 flags_ |= ParseProperty(debug_ld_all.Get());
98
99 // Safeguard against a NULL g_argv. Ignore processes started without argv (http://b/33276926).
100 if (g_argv == nullptr || g_argv[0] == nullptr) {
101 return;
102 }
103
104 // Otherwise check the app-specific property too.
105 // We can't easily cache the property here because argv[0] changes.
106 char debug_ld_app[PROP_VALUE_MAX] = {};
107 GetAppSpecificProperty(debug_ld_app);
108 flags_ |= ParseProperty(debug_ld_app);
109 }
110
Log(const char * format,...)111 void LinkerLogger::Log(const char* format, ...) {
112 va_list ap;
113 va_start(ap, format);
114 async_safe_format_log_va_list(ANDROID_LOG_DEBUG, "linker", format, ap);
115 va_end(ap);
116 }
117