1 /*
2 * Copyright (C) 2018 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 #ifdef _WIN32
18 // nothing to see here
19 #else
20 #include <memory>
21 #include <string>
22 #include <vector>
23
24 #include <sys/types.h>
25 #include <sys/wait.h>
26 #include <unistd.h>
27
28 #include "android-base/logging.h"
29
30 #include "androidfw/PosixUtils.h"
31
32 namespace {
33
ReadFile(int fd)34 std::unique_ptr<std::string> ReadFile(int fd) {
35 std::unique_ptr<std::string> str(new std::string());
36 char buf[1024];
37 ssize_t r;
38 while ((r = read(fd, buf, sizeof(buf))) > 0) {
39 str->append(buf, r);
40 }
41 if (r != 0) {
42 return nullptr;
43 }
44 return str;
45 }
46
47 }
48
49 namespace android {
50 namespace util {
51
ExecuteBinary(const std::vector<std::string> & argv)52 std::unique_ptr<ProcResult> ExecuteBinary(const std::vector<std::string>& argv) {
53 int stdout[2]; // stdout[0] read, stdout[1] write
54 if (pipe(stdout) != 0) {
55 PLOG(ERROR) << "pipe";
56 return nullptr;
57 }
58
59 int stderr[2]; // stdout[0] read, stdout[1] write
60 if (pipe(stderr) != 0) {
61 PLOG(ERROR) << "pipe";
62 close(stdout[0]);
63 close(stdout[1]);
64 return nullptr;
65 }
66
67 auto gid = getgid();
68 auto uid = getuid();
69
70 char const** argv0 = (char const**)malloc(sizeof(char*) * (argv.size() + 1));
71 for (size_t i = 0; i < argv.size(); i++) {
72 argv0[i] = argv[i].c_str();
73 }
74 argv0[argv.size()] = nullptr;
75 switch (fork()) {
76 case -1: // error
77 free(argv0);
78 PLOG(ERROR) << "fork";
79 return nullptr;
80 case 0: // child
81 if (setgid(gid) != 0) {
82 PLOG(ERROR) << "setgid";
83 exit(1);
84 }
85
86 if (setuid(uid) != 0) {
87 PLOG(ERROR) << "setuid";
88 exit(1);
89 }
90
91 close(stdout[0]);
92 if (dup2(stdout[1], STDOUT_FILENO) == -1) {
93 abort();
94 }
95 close(stderr[0]);
96 if (dup2(stderr[1], STDERR_FILENO) == -1) {
97 abort();
98 }
99 execvp(argv0[0], const_cast<char* const*>(argv0));
100 PLOG(ERROR) << "execv";
101 abort();
102 default: // parent
103 free(argv0);
104 close(stdout[1]);
105 close(stderr[1]);
106 int status;
107 wait(&status);
108 if (!WIFEXITED(status)) {
109 return nullptr;
110 }
111 std::unique_ptr<ProcResult> result(new ProcResult());
112 result->status = status;
113 const auto out = ReadFile(stdout[0]);
114 result->stdout = out ? *out : "";
115 close(stdout[0]);
116 const auto err = ReadFile(stderr[0]);
117 result->stderr = err ? *err : "";
118 close(stderr[0]);
119 return result;
120 }
121 }
122
123 } // namespace util
124 } // namespace android
125 #endif
126