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Commit 28416d6d authored by Elliott Hughes's avatar Elliott Hughes
Browse files

Fix adb shell escape handling. 

Start of input is, by definition, the start of a line. Give the states
names to make the error clearer. We should also swallow the escape
character until/unless it's proven not to have been part of an escape
sequence. Finally, implement an ssh(1)-like -e option so the user can
choose -- or, more importantly, disable -- escape character handling.

Change-Id: I28a91db47e15f3e7de96303c0b9a98d302b9c92e
parent 892f0e93

adb/commandline.cpp

+45 −26
Original line number Diff line number Diff line
@@ -467,6 +467,7 @@ struct StdinReadArgs { 
    int stdin_fd, write_fd;

    bool raw_stdin;

    std::unique_ptr<ShellProtocol> protocol;

    char escape_char;

};



// Loops to read from stdin and push the data to the given FD.
@@ -474,7 +475,6 @@ struct StdinReadArgs { 
// will take ownership of the object and delete it when finished.

static void* stdin_read_thread_loop(void* x) {

    std::unique_ptr<StdinReadArgs> args(reinterpret_cast<StdinReadArgs*>(x));

    int state = 0;



#if !defined(_WIN32)

    // Mask SIGTTIN in case we're in a backgrounded process.
@@ -496,7 +496,7 @@ static void* stdin_read_thread_loop(void* x) { 
    // Set up the initial window size.

    send_window_size_change(args->stdin_fd, args->protocol);



    char raw_buffer[1024];

    char raw_buffer[BUFSIZ];

    char* buffer_ptr = raw_buffer;

    size_t buffer_size = sizeof(raw_buffer);

    if (args->protocol != nullptr) {
@@ -504,6 +504,14 @@ static void* stdin_read_thread_loop(void* x) { 
        buffer_size = args->protocol->data_capacity();

    }



    // If we need to parse escape sequences, make life easy.

    if (args->raw_stdin && args->escape_char != '\0') {

        buffer_size = 1;

    }



    enum EscapeState { kMidFlow, kStartOfLine, kInEscape };

    EscapeState state = kStartOfLine;



    while (true) {

        // Use unix_read() rather than adb_read() for stdin.

        D("stdin_read_thread_loop(): pre unix_read(fdi=%d,...)", args->stdin_fd);
@@ -529,36 +537,36 @@ static void* stdin_read_thread_loop(void* x) { 
            }

            break;

        }

        // If we made stdin raw, check input for the "~." escape sequence. In

        // If we made stdin raw, check input for escape sequences. In

        // this situation signals like Ctrl+C are sent remotely rather than

        // interpreted locally so this provides an emergency out if the remote

        // process starts ignoring the signal. SSH also does this, see the

        // "escape characters" section on the ssh man page for more info.

        if (args->raw_stdin) {

            for (int n = 0; n < r; n++) {

                switch (buffer_ptr[n]) {

                case '\n':

                    state = 1;

                    break;

                case '\r':

                    state = 1;

                    break;

                case '~':

                    if (state == 1) {

                        state++;

        if (args->raw_stdin && args->escape_char != '\0') {

            char ch = buffer_ptr[0];

            if (ch == args->escape_char) {

                if (state == kStartOfLine) {

                    state = kInEscape;

                    // Swallow the escape character.

                    continue;

                } else {

                        state = 0;

                    state = kMidFlow;

                }

                    break;

                case '.':

                    if (state == 2) {

                        fprintf(stderr,"\r\n* disconnect *\r\n");

            } else {

                if (state == kInEscape) {

                    if (ch == '.') {

                        fprintf(stderr,"\r\n[ disconnected ]\r\n");

                        stdin_raw_restore();

                        exit(0);

                    } else {

                        // We swallowed an escape character that wasn't part of

                        // a valid escape sequence; time to cough it up.

                        buffer_ptr[0] = args->escape_char;

                        buffer_ptr[1] = ch;

                        ++r;

                    }

                default:

                    state = 0;

                }

                state = (ch == '\n' || ch == '\r') ? kStartOfLine : kMidFlow;

            }

        }

        if (args->protocol) {
@@ -603,6 +611,7 @@ static std::string ShellServiceString(bool use_shell_protocol, 
// On success returns the remote exit code if |use_shell_protocol| is true,

// 0 otherwise. On failure returns 1.

static int RemoteShell(bool use_shell_protocol, const std::string& type_arg,

                       char escape_char,

                       const std::string& command) {

    std::string service_string = ShellServiceString(use_shell_protocol,

                                                    type_arg, command);
@@ -628,6 +637,7 @@ static int RemoteShell(bool use_shell_protocol, const std::string& type_arg, 
    args->stdin_fd = STDIN_FILENO;

    args->write_fd = fd;

    args->raw_stdin = raw_stdin;

    args->escape_char = escape_char;

    if (use_shell_protocol) {

        args->protocol.reset(new ShellProtocol(args->write_fd));

    }
@@ -689,8 +699,17 @@ static int adb_shell(int argc, const char** argv, 
    --argc;

    ++argv;

    int t_arg_count = 0;

    char escape_char = '~';

    while (argc) {

        if (!strcmp(argv[0], "-T") || !strcmp(argv[0], "-t")) {

        if (!strcmp(argv[0], "-e")) {

            if (argc < 2 || !(strlen(argv[1]) == 1 || strcmp(argv[1], "none") == 0)) {

                fprintf(stderr, "error: -e requires a single-character argument or 'none'\n");

                return 1;

            }

            escape_char = (strcmp(argv[1], "none") == 0) ? 0 : argv[1][0];

            argc -= 2;

            argv += 2;

        } else if (!strcmp(argv[0], "-T") || !strcmp(argv[0], "-t")) {

            if (!CanUseFeature(features, kFeatureShell2)) {

                fprintf(stderr, "error: target doesn't support PTY args -Tt\n");

                return 1;
@@ -746,7 +765,7 @@ static int adb_shell(int argc, const char** argv, 
        command = android::base::Join(std::vector<const char*>(argv, argv + argc), ' ');

    }



    return RemoteShell(use_shell_protocol, shell_type_arg, command);

    return RemoteShell(use_shell_protocol, shell_type_arg, escape_char, command);

}



static int adb_download_buffer(const char *service, const char *fn, const void* data, unsigned sz,