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 int pid = fork();
76 switch (pid) {
77 case -1: // error
78 free(argv0);
79 PLOG(ERROR) << "fork";
80 return nullptr;
81 case 0: // child
82 if (setgid(gid) != 0) {
83 PLOG(ERROR) << "setgid";
84 exit(1);
85 }
86
87 if (setuid(uid) != 0) {
88 PLOG(ERROR) << "setuid";
89 exit(1);
90 }
91
92 close(stdout[0]);
93 if (dup2(stdout[1], STDOUT_FILENO) == -1) {
94 abort();
95 }
96 close(stderr[0]);
97 if (dup2(stderr[1], STDERR_FILENO) == -1) {
98 abort();
99 }
100 execvp(argv0[0], const_cast<char* const*>(argv0));
101 PLOG(ERROR) << "execv";
102 abort();
103 default: // parent
104 free(argv0);
105 close(stdout[1]);
106 close(stderr[1]);
107 int status;
108 waitpid(pid, &status, 0);
109 if (!WIFEXITED(status)) {
110 close(stdout[0]);
111 close(stderr[0]);
112 return nullptr;
113 }
114 std::unique_ptr<ProcResult> result(new ProcResult());
115 result->status = status;
116 const auto out = ReadFile(stdout[0]);
117 result->stdout = out ? *out : "";
118 close(stdout[0]);
119 const auto err = ReadFile(stderr[0]);
120 result->stderr = err ? *err : "";
121 close(stderr[0]);
122 return result;
123 }
124 }
125
126 } // namespace util
127 } // namespace android
128 #endif
129