309 lines
13 KiB
C++
309 lines
13 KiB
C++
#include "libclpex_tty.h"
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/**
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* @brief Safely prints a message and exits the program
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*
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* @param msg The message to print
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* @param ttyOrig A pointer to a struct termios representing the original terminal settings
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*
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* This function takes a message `msg` and a pointer to a struct termios `ttyOrig` as input.
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* The function first prints the `msg` to `stderr`.
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* Then, it calls `ttyResetExit()` with `ttyOrig` as its argument to reset the terminal settings.
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* Finally, the function exits the program with exit code 1.
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*/
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void safe_perror( const char * msg, struct termios * ttyOrig )
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{
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std::cerr << msg << std::endl;
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ttyResetExit( ttyOrig );
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exit(1);
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}
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/**
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* @brief Executes the child process
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*
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* @param fd_child_stderr_pipe A file descriptor array for the child process's stderr pipe
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* @param processed_command An array of char pointers representing the command and its arguments to be executed
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* @param ttyOrig A pointer to a struct termios representing the original terminal settings
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* @param context_override A flag indicating whether to override the process's execution context
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* @param context_user The username to use for the execution context if `context_override` is `true`
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* @param context_group The group name to use for the execution context if `context_override` is `true`
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*
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* This function takes an array of file descriptors `fd_child_stderr_pipe` for the child process's stderr pipe,
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* an array of char pointers `processed_command` representing the command and its arguments to be executed,
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* a pointer to a struct termios `ttyOrig` representing the original terminal settings,
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* a flag `context_override` indicating whether to override the process's execution context,
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* a string `context_user` representing the username to use for the execution context if `context_override` is `true`,
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* and a string `context_group` representing the group name to use for the execution context if `context_override` is `true`.
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*
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* The function first redirects the child process's stderr to the write end of the stderr pipe.
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* If `context_override` is `true`, the function sets the process's execution context using `set_identity_context()`.
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* If `context_override` is `false`, the function does nothing.
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* Finally, the function executes the command specified in `processed_command` using `execvp()`.
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* If the execution of `execvp()` fails, the function calls `safe_perror()` to print a message and exit the program.
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*/
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void run_child_process( int fd_child_stderr_pipe[2], char * processed_command[], struct termios * ttyOrig, bool context_override, std::string context_user, std::string context_group )
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{
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// redirect stderr to the write end of the stderr pipe
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// close the file descriptor STDERR_FILENO if it was previously open, then (re)open it as a copy of
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while ((dup2(fd_child_stderr_pipe[WRITE_END], STDERR_FILENO) == -1) && (errno == EINTR)) {}
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// close the write end of the stderr pipe
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close( fd_child_stderr_pipe[WRITE_END] );
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// if the user has specified a context override, set the context
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if ( context_override )
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{
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int context_result = set_identity_context(context_user, context_group);
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switch (context_result) {
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case IDENTITY_CONTEXT_ERRORS::ERROR_NONE:
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break;
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case IDENTITY_CONTEXT_ERRORS::ERROR_NO_SUCH_USER:
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std::cerr << "lcpex: Aborting: context user not found: " << context_user << std::endl;
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exit(1);
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break;
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case IDENTITY_CONTEXT_ERRORS::ERROR_NO_SUCH_GROUP:
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std::cerr << "lcpex: Aborting: context group not found: " << context_group << std::endl;
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exit(1);
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break;
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case IDENTITY_CONTEXT_ERRORS::ERROR_SETGID_FAILED:
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std::cerr << "lcpex: Aborting: Setting GID failed: " << context_user << "/" << context_group << std::endl;
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exit(1);
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break;
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case IDENTITY_CONTEXT_ERRORS::ERROR_SETUID_FAILED:
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std::cerr << "lcpex: Aborting: Setting UID failed: " << context_user << "/" << context_group << std::endl;
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exit(1);
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break;
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default:
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std::cerr << "lcpex: Aborting: Unknown error while setting identity context." << std::endl;
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exit(1);
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break;
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}
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}
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// execute the dang command, print to stdout, stderr (of parent), and dump to file for each!!!!
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// (and capture exit code in parent)
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int exit_code = execvp( processed_command[0], processed_command );
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safe_perror("failed on execvp in child", ttyOrig );
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exit(exit_code);
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}
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// this does three things:
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// - execute a dang string as a subprocess command
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// - capture child stdout/stderr to respective log files
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// - TEE child stdout/stderr to parent stdout/stderr
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int exec_pty(
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std::string command,
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FILE * stdout_log_fh,
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FILE * stderr_log_fh,
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bool context_override,
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std::string context_user,
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std::string context_group,
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bool environment_supplied
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) {
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// initialize the terminal settings obj
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struct termios ttyOrig;
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// if the user chose to supply the environment, then we need to clear the environment
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// before we fork the process, so that the child process will inherit the environment
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// from the parent process
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if ( environment_supplied ) {
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//clearenv();
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}
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// turn our command string into something execvp can consume
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char ** processed_command = expand_env( command );
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if ( stdout_log_fh == NULL ) {
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safe_perror( "Error opening STDOUT log file. Aborting.", &ttyOrig );
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exit( 1 );
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}
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if ( stderr_log_fh == NULL ) {
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safe_perror( "Error opening STDERR log file. Aborting.", &ttyOrig );
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exit( 1 );
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}
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// create the pipes for the child process to write and read from using its stderr
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int fd_child_stderr_pipe[2];
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if ( pipe( fd_child_stderr_pipe ) == -1 ) {
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safe_perror( "child stderr pipe", &ttyOrig );
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exit( 1 );
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}
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// using O_CLOEXEC to ensure that the child process closes the file descriptors
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if ( fcntl( fd_child_stderr_pipe[READ_END], F_SETFD, FD_CLOEXEC ) == -1 ) { perror("fcntl"); exit(1); }
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// // same for stderr write
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if ( fcntl( fd_child_stderr_pipe[WRITE_END], F_SETFD, FD_CLOEXEC ) == -1 ) { perror("fcntl"); exit(1); }
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// status result basket for the parent process to capture the child's exit status
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int status = 616;
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// start ptyfork integration
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char slaveName[MAX_SNAME];
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int masterFd;
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struct winsize ws;
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/* Retrieve the attributes of terminal on which we are started */
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if (tcgetattr(STDIN_FILENO, &ttyOrig) == -1)
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safe_perror("tcgetattr", &ttyOrig);
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if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) < 0)
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safe_perror("ioctl-TIOCGWINSZ", &ttyOrig );
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pid_t pid = ptyFork( &masterFd, slaveName, MAX_SNAME, &ttyOrig, &ws );
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switch( pid ) {
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case -1:
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{
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// fork failed
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safe_perror("ptyfork failure", &ttyOrig );
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exit(1);
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}
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case 0:
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{
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// child process
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run_child_process( fd_child_stderr_pipe, processed_command, &ttyOrig, context_override, context_user, context_group );
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}
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default:
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{
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// parent process
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// start ptyfork integration
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ttySetRaw(STDIN_FILENO, &ttyOrig);
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// The parent process has no need to access the entrance to the pipe
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close(fd_child_stderr_pipe[WRITE_END]);
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// attempt to write to stdout,stderr from child as well as to write each to file
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char buf[BUFFER_SIZE];
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// contains the byte count of the last read from the pipe
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ssize_t byte_count;
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// watched_fds for poll() to wait on
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struct pollfd watched_fds[3];
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// populate the watched_fds array
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// child in to parent
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watched_fds[0].fd = STDIN_FILENO;
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watched_fds[0].events = POLLIN;
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// child pty to parent (stdout)
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watched_fds[1].fd = masterFd;
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watched_fds[1].events = POLLIN;
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// child stderr to parent
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watched_fds[2].fd = fd_child_stderr_pipe[READ_END];
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watched_fds[2].events = POLLIN;
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// number of files poll() reports as ready
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int num_files_readable;
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// loop flag
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bool break_out = false;
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// loop until we've read all the data from the child process
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while ( ! break_out ) {
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num_files_readable = poll(watched_fds, sizeof(watched_fds) / sizeof(watched_fds[0]), -1);
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// after the poll() call, add a check to see if both pipes are closed
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if (!(watched_fds[1].events & POLLIN) &&
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!(watched_fds[2].events & POLLIN)) {
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break_out = true;
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}
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if (num_files_readable == -1) {
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// error occurred in poll()
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safe_perror("poll", &ttyOrig );
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exit(1);
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}
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if (num_files_readable == 0) {
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// poll reports no files readable
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break_out = true;
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break;
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}
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for (int this_fd = 0; this_fd < 3; this_fd++) {
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if (watched_fds[this_fd].revents & POLLIN) {
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// this pipe is readable
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byte_count = read(watched_fds[this_fd].fd, buf, BUFFER_SIZE);
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if (byte_count == -1) {
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if (errno == EAGAIN) { continue; } else {
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// error reading from pipe
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safe_perror("read", &ttyOrig );
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exit(EXIT_FAILURE);
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}
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} else if (byte_count == 0) {
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// reached EOF on one of the streams but not a HUP
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// we've read all we can this cycle, so go to the next fd in the for loop
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continue;
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} else {
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// byte count was sane
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// write to stdout,stderr
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if (this_fd == 0) {
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// parent stdin received, write to child pty (stdin)
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write_all(masterFd, buf, byte_count);
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} else if (this_fd == 1 ) {
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// child pty sent some stuff, write to parent stdout and log
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write_all(stdout_log_fh->_fileno, buf, byte_count);
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write_all(STDOUT_FILENO, buf, byte_count);
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} else if ( this_fd == 2 ){
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//the child's stderr pipe sent some stuff, write to parent stderr and log
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write_all(stderr_log_fh->_fileno, buf, byte_count);
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write_all(STDERR_FILENO, buf, byte_count);
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} else {
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// this should never happen
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perror("Logic error!");
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exit(EXIT_FAILURE);
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}
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}
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}
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if (watched_fds[this_fd].revents & POLLERR) {
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//close(watched_fds[this_fd].fd);
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break_out = true;
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//continue;
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}
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// if (watched_fds[this_fd].revents & POLLHUP) {
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// // this pipe has hung up
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// close(watched_fds[this_fd].fd);
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// break_out = true;
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// break;
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// }
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if (watched_fds[this_fd].revents & POLLHUP) {
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// this pipe has hung up
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// don't close the file descriptor yet, there might still be data to read
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// instead, remove the POLLIN event to avoid getting a POLLHUP event in the next poll() call
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watched_fds[this_fd].events &= ~POLLIN;
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}
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}
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}
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// wait for child to exit, capture status
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waitpid(pid, &status, 0);
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while ((byte_count = read(watched_fds[1].fd, buf, BUFFER_SIZE)) > 0) {
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write_all(stdout_log_fh->_fileno, buf, byte_count);
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write_all(STDOUT_FILENO, buf, byte_count);
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}
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while ((byte_count = read(fd_child_stderr_pipe[READ_END], buf, BUFFER_SIZE)) > 0) {
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write_all(stderr_log_fh->_fileno, buf, byte_count);
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write_all(STDERR_FILENO, buf, byte_count);
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}
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ttyResetExit( &ttyOrig);
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if WIFEXITED(status) {
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return WEXITSTATUS(status);
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} else {
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return -617;
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}
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}
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}
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} |