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 <optional>
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
ReadFile(int fd)32 static std::optional<std::string> ReadFile(int fd) {
33 std::string str;
34 char buf[1024];
35 ssize_t r;
36 while ((r = read(fd, buf, sizeof(buf))) > 0) {
37 str.append(buf, r);
38 }
39 if (r != 0) {
40 return std::nullopt;
41 }
42 return std::move(str);
43 }
44
45 namespace android {
46 namespace util {
47
ExecuteBinary(const std::vector<std::string> & argv)48 ProcResult ExecuteBinary(const std::vector<std::string>& argv) {
49 int stdout[2]; // [0] read, [1] write
50 if (pipe(stdout) != 0) {
51 PLOG(ERROR) << "out pipe";
52 return ProcResult{-1};
53 }
54
55 int stderr[2]; // [0] read, [1] write
56 if (pipe(stderr) != 0) {
57 PLOG(ERROR) << "err pipe";
58 close(stdout[0]);
59 close(stdout[1]);
60 return ProcResult{-1};
61 }
62
63 auto gid = getgid();
64 auto uid = getuid();
65
66 // better keep no C++ objects going into the child here
67 auto argv0 = (char const**)malloc(sizeof(char*) * (argv.size() + 1));
68 for (size_t i = 0; i < argv.size(); i++) {
69 argv0[i] = argv[i].c_str();
70 }
71 argv0[argv.size()] = nullptr;
72 int pid = fork();
73 switch (pid) {
74 case -1: // error
75 free(argv0);
76 close(stdout[0]);
77 close(stdout[1]);
78 close(stderr[0]);
79 close(stderr[1]);
80 PLOG(ERROR) << "fork";
81 return ProcResult{-1};
82 case 0: // child
83 if (setgid(gid) != 0) {
84 PLOG(ERROR) << "setgid";
85 exit(1);
86 }
87
88 if (setuid(uid) != 0) {
89 PLOG(ERROR) << "setuid";
90 exit(1);
91 }
92
93 close(stdout[0]);
94 if (dup2(stdout[1], STDOUT_FILENO) == -1) {
95 abort();
96 }
97 close(stderr[0]);
98 if (dup2(stderr[1], STDERR_FILENO) == -1) {
99 abort();
100 }
101 execvp(argv0[0], const_cast<char* const*>(argv0));
102 PLOG(ERROR) << "execv";
103 abort();
104 default: // parent
105 free(argv0);
106 close(stdout[1]);
107 close(stderr[1]);
108 int status;
109 waitpid(pid, &status, 0);
110 if (!WIFEXITED(status)) {
111 close(stdout[0]);
112 close(stderr[0]);
113 return ProcResult{-1};
114 }
115 ProcResult result(status);
116 auto out = ReadFile(stdout[0]);
117 result.stdout_str = out ? std::move(*out) : "";
118 close(stdout[0]);
119 auto err = ReadFile(stderr[0]);
120 result.stderr_str = err ? std::move(*err) : "";
121 close(stderr[0]);
122 return std::move(result);
123 }
124 }
125
126 } // namespace util
127 } // namespace android
128 #endif
129