diff options
| -rw-r--r-- | include/mts/MTS_System.h | 84 | ||||
| -rw-r--r-- | src/MTS_System.cpp | 200 |
2 files changed, 284 insertions, 0 deletions
diff --git a/include/mts/MTS_System.h b/include/mts/MTS_System.h index bd5fa53..d51a5ea 100644 --- a/include/mts/MTS_System.h +++ b/include/mts/MTS_System.h @@ -31,6 +31,7 @@ #include <mts/MTS_NonConstructable.h> #include <mts/MTS_Stdint.h> #include <string> +#include <vector> namespace MTS { @@ -38,6 +39,17 @@ namespace MTS { public: + //! Type of the pipe to be opened in executeBackground + enum class PipeType { + READ, WRITE + }; + + //! Utility structure with information about the child process + struct ChildHandle { + pid_t pid; + FILE* stream; + }; + //UTC (Coordinated Universal Time) : This is the standard international time or the Greenwich Mean Time. //EPOCH : number of seconds elapsed since 00:00:00 on January 1, 1970, Coordinated Universal Time. @@ -53,6 +65,78 @@ namespace MTS { static int32_t cmd(const std::string& cmd, std::string& result); static int32_t readFile(const std::string& path, std::string& result); + + //! Execute application with specified arguments. + /*! + * A safer alternative to System::cmd that allows to execute applications with controlled + * list of arguments bypasing the system shell. + * + * \param cmd name of the application to be executed + * \param argv vector of arguments (excluding argument zero) + * \param result stdout output from the application is stored here + * \return result code as for std::system and UNIX pclose + */ + static int32_t execute(const std::string& cmd, const std::vector<std::string>& argv, std::string& result); + + //! Spawn a process and open pipe with the specified type (READ or WRITE) + /*! + * A safer alternative to POSIX popen that allows to execute applications with controlled + * list of arguments bypasing the system shell. If succeded, information about the spawned + * process is written to the \p child structure. + * + * \param cmd name of the application to be executed + * \param argv vector of arguments (excluding argument zero) + * \param type open pipe for read from child or write to child + * \param child on success is populated with child process information, on failure is not defined + * \return true on success, false on failure + */ + static bool executeBackground(const std::string& cmd, const std::vector<std::string>& argv, PipeType type, ChildHandle& child); + + //! Close the pipe and wait for a child to finish execution + /*! + * \param child structure with child process information as populated by executeBackground + * \return result code as for std::system and UNIX pclose + */ + static int closeBackground(ChildHandle& child); + + private: + + //! Spawn a process and open pipe with the specified type (READ or WRITE) + static bool executeBackground(const std::string& cmd, char* const argv[], PipeType type, ChildHandle& child); + + //! Utility method. Cast argument to a C pointer required by some C-style functions. + static inline char* castArgument(const std::string& arg); + + //! Utility method. Convert argument vector to a format required by execve and posix_spawn. + static std::vector<char*> castArgVector(const std::string& cmd, const std::vector<std::string>& argv); + + //! Lightweight C++ wrapper with auto-close for file descriptors + class FdWrapper { + + public: + static const int FD_NOT_READY = -1; + + explicit FdWrapper(int fd = FD_NOT_READY); + ~FdWrapper(); + + inline int get() const; + int release(); + void reset(int fd = FD_NOT_READY); + + private: + int m_fd; + + }; + + //! Utility structure, used by popen wrapper + struct Pipe { + FdWrapper parent; + FdWrapper child; + }; + + //! Initialize UNIX pipe + static int initPipe(Pipe& pipe, PipeType type); + }; } diff --git a/src/MTS_System.cpp b/src/MTS_System.cpp index abed817..31976e1 100644 --- a/src/MTS_System.cpp +++ b/src/MTS_System.cpp @@ -22,6 +22,9 @@ #include <fstream> #include <sstream> #include <cassert> +#include <spawn.h> +#include <sys/wait.h> +#include <unistd.h> #ifdef WIN32 #include <windows.h> @@ -169,3 +172,200 @@ int32_t System::readFile(const std::string& path, std::string& result) { return 0; } +int32_t System::execute(const std::string& cmd, const std::vector<std::string>& argv, std::string& result) { + // Ported directly from System::cmd + std::string output; + const int max_buffer = 256; + char buffer[max_buffer]; + int32_t code = -1; + ChildHandle child; + + if (executeBackground(cmd, argv, PipeType::READ, child)) { + while (!feof(child.stream)) { + if (fgets(buffer, max_buffer, child.stream) != NULL) { + output.append(buffer); + } + } + code = closeBackground(child); + } + + result = output; + + return code; +} + +bool System::executeBackground(const std::string& cmd, const std::vector<std::string>& argv, System::PipeType type, System::ChildHandle& child) { + std::vector<char*> arguments = castArgVector(cmd, argv); + return executeBackground(cmd, arguments.data(), type, child); +} + +int System::closeBackground(System::ChildHandle& child) { + int pstat; + pid_t pid; + + fclose(child.stream); + + do { + pid = waitpid(child.pid, &pstat, 0); + } while (pid == -1 && errno == EINTR); + + return pstat; +} + +bool System::executeBackground(const std::string& cmd, char* const argv[], System::PipeType type, ChildHandle& child) { + pid_t childPid; + FILE* stream = NULL; + posix_spawn_file_actions_t actions; + int childTargetFd; + const char* parentMode = nullptr; + bool bActionsInitialized = false; + bool bSuccess = false; + + do { + + Pipe pipe; + if (initPipe(pipe, type) != 0) { + // failed to create pipe + break; + } + + if (type == PipeType::READ) { + childTargetFd = STDOUT_FILENO; + parentMode = "r"; + } else if (type == PipeType::WRITE) { + childTargetFd = STDIN_FILENO; + parentMode = "w"; + } else { + break; // unreachable, unknown mode + } + + // Define how child process should handle pipes + if (posix_spawn_file_actions_init(&actions) != 0) { + // failed to initialize file actions + break; + } + + bActionsInitialized = true; + + if (posix_spawn_file_actions_addclose(&actions, pipe.parent.get()) != 0) { + // failed to add action to close parent pipe fd + break; + } + + if (posix_spawn_file_actions_adddup2(&actions, pipe.child.get(), childTargetFd) != 0) { + // failed to add an action to use child pipe fd for output + break; + } + + if (posix_spawn_file_actions_addclose(&actions, pipe.child.get()) != 0) { + // failed to add an action to close dupped child pipe fd + break; + } + + if (posix_spawnp(&childPid, cmd.c_str(), &actions, NULL, argv, NULL) != 0) { + // failed to spawn the process + break; + } + + // Close child-specific file descriptor + pipe.child.reset(); + + // Convert parent fd to FILE pointer + stream = fdopen(pipe.parent.release(), parentMode); + + // Save data about child + child.pid = childPid; + child.stream = stream; + + bSuccess = true; + + } while (false); + + if (bActionsInitialized) { + posix_spawn_file_actions_destroy(&actions); + } + + return bSuccess; +} + +char* System::castArgument(const std::string& arg) { + // Casting const away is required only to be compatible with some C-style system functions. + // Arguments are not actually modified in such functions. + return const_cast<char*>(arg.c_str()); +} + +std::vector<char*> System::castArgVector(const std::string& cmd, const std::vector<std::string>& argv) { + std::vector<char*> result; + + // Append application name as argument zero + result.push_back(castArgument(cmd)); + + // Append all other arguments + for (const std::string& arg : argv) { + result.push_back(castArgument(arg)); + } + + // Terminate with NULL + result.push_back(NULL); + return result; +} + +int System::initPipe(System::Pipe& pipe, System::PipeType type) { + const int READ_END_IDX = 0; + const int WRITE_END_IDX = 1; + + int holder[2]; + int parentIndex; + int childIndex; + int ret = -1; + + do { + + if (type == PipeType::READ) { + parentIndex = READ_END_IDX; + childIndex = WRITE_END_IDX; + } else if (type == PipeType::WRITE) { + parentIndex = WRITE_END_IDX; + childIndex = READ_END_IDX; + } else { + // unreachable, unknown mode + break; // error + } + + ret = ::pipe(holder); + if (ret != 0) { + break; + } + + pipe.parent.reset(holder[parentIndex]); + pipe.child.reset(holder[childIndex]); + + } while (false); + + return ret; +} + +System::FdWrapper::FdWrapper(int fd) + : m_fd(fd) +{} + +System::FdWrapper::~FdWrapper() { + reset(); +} + +int System::FdWrapper::get() const { + return m_fd; +} + +int System::FdWrapper::release() { + int fd = m_fd; + m_fd = FD_NOT_READY; + return fd; +} + +void System::FdWrapper::reset(int fd) { + if (FD_NOT_READY != m_fd) { + ::close(m_fd); + } + m_fd = fd; +} |