/**
* Reads file content by specified file path.
*
* <p>TODO: add file size checking, note that size checking and file content reading should be
* done in an atomic way, which means that two separate instance processes is not the case.
*
* @param filePath path to file on machine instance
* @param startFrom line number to start reading from
* @param limit limitation on line
* @return if {@code limit} and {@code startFrom} grater than 0 content from {@code startFrom} to
* {@code startFrom + limit} will be returned, if file contains less lines than {@code
* startFrom} empty content will be returned
* @throws MachineException if any error occurs with file reading
*/
@Override
public String readFileContent(String filePath, int startFrom, int limit) throws MachineException {
if (limit <= 0 || startFrom <= 0) {
throw new MachineException(
"Impossible to read file " + limit + " lines from " + startFrom + " line");
}
// command sed getting file content from startFrom line to (startFrom + limit)
String bashCommand =
format("sed -n \'%1$2s, %2$2sp\' %3$2s", startFrom, startFrom + limit, filePath);
final String[] command = {"/bin/bash", "-c", bashCommand};
ListLineConsumer lines = new ListLineConsumer();
try {
Exec exec = docker.createExec(container, false, command);
docker.startExec(exec.getId(), new LogMessagePrinter(lines, LogMessage::getContent));
} catch (IOException e) {
throw new MachineException(
format(
"Error occurs while initializing command %s in docker container %s: %s",
Arrays.toString(command), container, e.getLocalizedMessage()),
e);
}
String content = lines.getText();
if (content.contains("sed: can't read " + filePath + ": No such file or directory")
|| content.contains("cat: " + filePath + ": No such file or directory")) {
throw new MachineException("File with path " + filePath + " not found");
}
return content;
}
private String execAndGetOutput(String command)
throws JSchException, MachineException, IOException {
ChannelExec exec = (ChannelExec) session.openChannel("exec");
exec.setCommand(command);
try (BufferedReader reader = new BufferedReader(new InputStreamReader(exec.getInputStream()));
InputStream erStream = exec.getErrStream()) {
exec.connect(connectionTimeout);
ListLineConsumer listLineConsumer = new ListLineConsumer();
String line;
while ((line = reader.readLine()) != null) {
listLineConsumer.writeLine(line);
}
// read stream to wait until command finishes its work
IoUtil.readStream(erStream);
if (exec.getExitStatus() != 0) {
throw new MachineException(
format(
"Error code: %s. Error: %s",
exec.getExitStatus(), IoUtil.readAndCloseQuietly(exec.getErrStream())));
}
return listLineConsumer.getText();
} finally {
exec.disconnect();
}
}