1 // termux-api.c - helper binary for calling termux api classes
2 // Usage: termux-api ${API_METHOD} ${ADDITIONAL_FLAGS}
4 // am broadcast com.termux.api/.TermuxApiReceiver --es socket_input ${INPUT_SOCKET}
5 // --es socket_output ${OUTPUT_SOCKET}
8 // where ${INPUT_SOCKET} and ${OUTPUT_SOCKET} are addresses to linux abstract namespace sockets,
9 // used to pass on stdin to the java implementation and pass back output from java to stdout.
19 #include <sys/socket.h>
21 #include <sys/types.h>
26 // Function which execs "am broadcast ..".
27 void exec_am_broadcast(int argc
, char** argv
, char* input_address_string
, char* output_address_string
)
29 // Redirect stdout to /dev/null (but leave stderr open):
31 open("/dev/null", O_RDONLY
);
35 char const* const file
= "/system/bin/am";
36 // Avoid the system am binary from linking to wrong libraries:
37 unsetenv("LD_LIBRARY_PATH");
38 // Ensure /system/bin/app_process is in path, which is needed by am in some systems:
39 putenv("PATH=/system/bin");
41 // The user is calculated from the uid in android.os.UserHandle#getUserId(int uid) as "uid / 100000", so we do the same:
42 uid_t current_uid
= getuid();
43 int android_user_id
= current_uid
/ 100000;
44 char* android_user_id_string
;
45 if (asprintf(&android_user_id_string
, "%d", android_user_id
) == -1) {
46 fprintf(stderr
, "asprintf() error");
50 int const extra_args
= 15; // Including ending NULL.
51 char** child_argv
= malloc((sizeof(char*)) * (argc
+ extra_args
));
54 child_argv
[1] = "broadcast";
55 child_argv
[2] = "--user";
56 child_argv
[3] = android_user_id_string
;
58 child_argv
[5] = "com.termux.api/.TermuxApiReceiver";
59 child_argv
[6] = "--es";
60 // Input/output are reversed for the java process (our output is its input):
61 child_argv
[7] = "socket_input";
62 child_argv
[8] = output_address_string
;
63 child_argv
[9] = "--es";
64 child_argv
[10] = "socket_output";
65 child_argv
[11] = input_address_string
;
66 child_argv
[12] = "--es";
67 child_argv
[13] = "api_method";
68 child_argv
[14] = argv
[1];
70 // Copy the remaining arguments -2 for first binary and second api name:
71 memcpy(child_argv
+ extra_args
, argv
+ 2, (argc
-1) * sizeof(char*));
74 child_argv
[argc
+ extra_args
] = NULL
;
76 execv(file
, child_argv
);
77 perror("execv(\"/system/bin/am\")");
81 void generate_uuid(char* str
) {
82 sprintf(str
, "%x%x-%x-%x-%x-%x%x%x",
83 rand(), rand(), // Generates a 64-bit Hex number
84 (uint32_t) getpid(), // Generates a 32-bit Hex number
85 ((rand() & 0x0fff) | 0x4000), // Generates a 32-bit Hex number of the form 4xxx (4 indicates the UUID version)
86 rand() % 0x3fff + 0x8000, // Generates a 32-bit Hex number in the range [0x8000, 0xbfff]
87 rand(), rand(), rand()); // Generates a 96-bit Hex number
90 // Thread function which reads from stdin and writes to socket.
91 void* transmit_stdin_to_socket(void* arg
) {
92 int output_server_socket
= *((int*) arg
);
93 struct sockaddr_un remote_addr
;
94 socklen_t addrlen
= sizeof(remote_addr
);
95 int output_client_socket
= accept(output_server_socket
, (struct sockaddr
*) &remote_addr
, &addrlen
);
99 while (len
= read(STDIN_FILENO
, &buffer
, sizeof(buffer
)-1), len
> 0) {
100 if (write(output_client_socket
, buffer
, len
) < 0) break;
102 // Close output socket on end of input:
103 close(output_client_socket
);
107 // Main thread function which reads from input socket and writes to stdout.
108 void transmit_socket_to_stdout(int input_socket_fd
) {
111 while ((len
= read(input_socket_fd
, &buffer
, sizeof(buffer
)-1)) > 0) {
113 write(STDOUT_FILENO
, buffer
, len
);
115 if (len
< 0) perror("read()");
118 int main(int argc
, char** argv
) {
119 // Do not transform children into zombies when they terminate:
120 struct sigaction sigchld_action
= { .sa_handler
= SIG_DFL
, .sa_flags
= SA_RESTART
| SA_NOCLDSTOP
| SA_NOCLDWAIT
};
121 sigaction(SIGCHLD
, &sigchld_action
, NULL
);
123 char input_address_string
[100]; // This program reads from it.
124 char output_address_string
[100]; // This program writes to it.
126 // Seed the random number generator:
128 gettimeofday(&time
,NULL
);
129 srand((time
.tv_sec
* 1000) + (time
.tv_usec
/ 1000));
131 generate_uuid(input_address_string
);
132 generate_uuid(output_address_string
);
134 struct sockaddr_un input_address
= { .sun_family
= AF_UNIX
};
135 struct sockaddr_un output_address
= { .sun_family
= AF_UNIX
};
136 // Leave struct sockaddr_un.sun_path[0] as 0 and use the UUID string as abstract linux namespace:
137 strncpy(&input_address
.sun_path
[1], input_address_string
, strlen(input_address_string
));
138 strncpy(&output_address
.sun_path
[1], output_address_string
, strlen(output_address_string
));
140 int input_server_socket
= socket(AF_UNIX
, SOCK_STREAM
|SOCK_CLOEXEC
, 0);
141 if (input_server_socket
== -1) { perror("socket()"); return 1; }
142 int output_server_socket
= socket(AF_UNIX
, SOCK_STREAM
|SOCK_CLOEXEC
, 0);
143 if (output_server_socket
== -1) { perror("socket()"); return 1; }
145 if (bind(input_server_socket
, (struct sockaddr
*) &input_address
, sizeof(sa_family_t
) + strlen(input_address_string
) + 1) == -1) {
146 perror("bind(input)");
149 if (bind(output_server_socket
, (struct sockaddr
*) &output_address
, sizeof(sa_family_t
) + strlen(output_address_string
) + 1) == -1) {
150 perror("bind(output)");
154 if (listen(input_server_socket
, 1) == -1) { perror("listen()"); return 1; }
155 if (listen(output_server_socket
, 1) == -1) { perror("listen()"); return 1; }
157 pid_t fork_result
= fork();
158 switch (fork_result
) {
159 case -1: perror("fork()"); return 1;
160 case 0: exec_am_broadcast(argc
, argv
, input_address_string
, output_address_string
); return 0;
163 struct sockaddr_un remote_addr
;
164 socklen_t addrlen
= sizeof(remote_addr
);
165 int input_client_socket
= accept(input_server_socket
, (struct sockaddr
*) &remote_addr
, &addrlen
);
167 pthread_t transmit_thread
;
168 pthread_create(&transmit_thread
, NULL
, transmit_stdin_to_socket
, &output_server_socket
);
170 transmit_socket_to_stdout(input_client_socket
);