utils: adding subprocess utility

CMakeLists.txt

@@ -9,7 +9,7 @@
  ##############################################################################
 
 cmake_minimum_required(VERSION 3.11)
-project(mwr VERSION 2025.02.28 LANGUAGES CXX)
+project(mwr VERSION 2025.02.28 LANGUAGES C CXX)
 
 set(MWR_LINTER "" CACHE STRING "Code linter to use")
 set(MWR_COVERAGE OFF CACHE BOOL "Collect code coverage data")
@@ -67,6 +67,7 @@ if(MSVC)
     target_sources(mwr PRIVATE ${src}/mwr/utils/library_win32.cpp)
     target_sources(mwr PRIVATE ${src}/mwr/utils/memory_win32.cpp)
     target_sources(mwr PRIVATE ${src}/mwr/utils/socket_win32.cpp)
+    target_sources(mwr PRIVATE ${src}/mwr/utils/subprocess_win32.cpp)
     target_link_options(mwr PUBLIC /OPT:NOREF)
     target_link_libraries(mwr PUBLIC Dbghelp.lib)
     target_link_libraries(mwr PUBLIC ws2_32)
@@ -75,6 +76,7 @@ else()
     target_sources(mwr PRIVATE ${src}/mwr/utils/library_posix.cpp)
     target_sources(mwr PRIVATE ${src}/mwr/utils/memory_posix.cpp)
     target_sources(mwr PRIVATE ${src}/mwr/utils/socket_posix.cpp)
+    target_sources(mwr PRIVATE ${src}/mwr/utils/subprocess_posix.cpp)
     target_link_libraries(mwr PUBLIC -rdynamic)
     if(NOT APPLE)
         target_link_libraries(mwr PUBLIC rt stdc++fs)

include/mwr.h

@@ -44,6 +44,7 @@
 #include "mwr/utils/socket.h"
 #include "mwr/utils/srec.h"
 #include "mwr/utils/ihex.h"
+#include "mwr/utils/subprocess.h"
 #include "mwr/utils/terminal.h"
 #include "mwr/utils/uimage.h"
 

include/mwr/utils/subprocess.h

@@ -0,0 +1,66 @@
+/******************************************************************************
+ *                                                                            *
+ * Copyright (C) 2025 MachineWare GmbH                                        *
+ * All Rights Reserved                                                        *
+ *                                                                            *
+ * This is work is licensed under the terms described in the LICENSE file     *
+ * found in the root directory of this source tree.                           *
+ *                                                                            *
+ ******************************************************************************/
+
+#ifndef MWR_UTILS_SUBPROCESS_H
+#define MWR_UTILS_SUBPROCESS_H
+
+#include "mwr/core/types.h"
+#include "mwr/core/report.h"
+#include "mwr/core/compiler.h"
+#include "mwr/core/utils.h"
+
+#include "mwr/stl/strings.h"
+#include "mwr/stl/containers.h"
+
+namespace mwr {
+
+class subprocess
+{
+private:
+#ifdef MWR_WINDOWS
+    void* m_handle;
+    void* m_stdin;
+    void* m_stdout;
+    void* m_stderr;
+    unsigned long m_pid;
+#else
+    int m_pid;
+    int m_stdin;
+    int m_stdout;
+    int m_stderr;
+#endif
+
+public:
+    map<string, string> env;
+
+#ifdef MWR_WINDOWS
+    unsigned long pid() const { return m_pid; }
+    void* native_handle() const { return m_handle; }
+#else
+    int pid() const { return m_pid; }
+    int native_handle() const { return m_pid; }
+#endif
+
+    subprocess();
+    virtual ~subprocess();
+
+    bool run(const string& path,
+             const vector<string>& args = vector<string>());
+
+    bool terminate();
+
+    bool write(const string& str);
+    bool read(char* buf, size_t buflen, bool use_stderr = false);
+    string read(bool use_stderr = false); // non-blocking
+};
+
+} // namespace mwr
+
+#endif

src/mwr/utils/subprocess_posix.cpp

@@ -0,0 +1,157 @@
+/******************************************************************************
+ *                                                                            *
+ * Copyright (C) 2025 MachineWare GmbH                                        *
+ * All Rights Reserved                                                        *
+ *                                                                            *
+ * This is work is licensed under the terms described in the LICENSE file     *
+ * found in the root directory of this source tree.                           *
+ *                                                                            *
+ ******************************************************************************/
+
+#include "mwr/utils/subprocess.h"
+
+#include <errno.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+namespace mwr {
+
+subprocess::subprocess():
+    m_pid(-1), m_stdin(-1), m_stdout(-1), m_stderr(-1), env() {
+}
+
+subprocess::~subprocess() {
+    terminate();
+}
+
+static void set_o_nonblock(int fd, bool set) {
+    int flags = fcntl(fd, F_GETFL, 0);
+    if (set)
+        flags |= O_NONBLOCK;
+    else
+        flags &= ~O_NONBLOCK;
+    fcntl(fd, F_SETFL, flags);
+}
+
+bool subprocess::run(const string& path, const vector<string>& args) {
+    int stdin_pipe[2];
+    int stdout_pipe[2];
+    int stderr_pipe[2];
+
+    if (pipe(stdin_pipe) < 0)
+        MWR_ERROR("error creating pipe: %s", strerror(errno));
+    if (pipe(stdout_pipe) < 0)
+        MWR_ERROR("error creating pipe: %s", strerror(errno));
+    if (pipe(stderr_pipe) < 0)
+        MWR_ERROR("error creating pipe: %s", strerror(errno));
+
+    int pid = fork();
+    if (pid < 0)
+        return false;
+
+    if (pid == 0) { // child process
+        dup2(stdin_pipe[0], STDIN_FILENO);
+        dup2(stdout_pipe[1], STDOUT_FILENO);
+        dup2(stderr_pipe[1], STDERR_FILENO);
+        close(stdin_pipe[0]);
+        close(stdin_pipe[1]);
+        close(stdout_pipe[0]);
+        close(stdout_pipe[1]);
+        close(stderr_pipe[0]);
+        close(stderr_pipe[1]);
+
+        vector<char*> argv;
+        argv.push_back(const_cast<char*>(path.c_str()));
+        for (auto& arg : args)
+            argv.push_back(const_cast<char*>(arg.c_str()));
+        argv.push_back(nullptr);
+
+        vector<char*> envp;
+        if (env.empty()) {
+            execv(path.c_str(), argv.data());
+        } else {
+            vector<string> env_strings(env.size());
+            for (auto& [name, value] : env)
+                env_strings.push_back(strcat(name, "=", value));
+            for (auto& s : env_strings)
+                envp.push_back(const_cast<char*>(s.c_str()));
+            envp.push_back(nullptr);
+            execve(path.c_str(), argv.data(), envp.data());
+        }
+
+        _exit(1);
+    } else { // parent process
+        close(stdout_pipe[1]);
+        close(stdin_pipe[0]);
+        m_stdin = stdin_pipe[1];
+        m_stdout = stdout_pipe[0];
+        m_stderr = stderr_pipe[0];
+        m_pid = pid;
+        return true;
+    }
+}
+
+bool subprocess::terminate() {
+    if (m_pid < 0)
+        return false;
+
+    if (kill(m_pid, SIGTERM))
+        return false;
+
+    int status;
+    waitpid(m_pid, &status, 0);
+
+    m_stdin = -1;
+    m_stdout = -1;
+    m_stderr = -1;
+    m_pid = -1;
+
+    return true;
+}
+
+bool subprocess::write(const string& s) {
+    if (m_stdin < 0)
+        return false;
+    if (s.empty())
+        return true;
+
+    ssize_t n = ::write(m_stdin, s.data(), s.length());
+    return n < 0 ? false : (size_t)n == s.length();
+}
+
+bool subprocess::read(char* buf, size_t buflen, bool use_stderr) {
+    int fd = use_stderr ? m_stderr : m_stdout;
+    if (fd < 0)
+        return false;
+
+    set_o_nonblock(fd, false);
+
+    size_t nread = 0;
+    while (nread < buflen) {
+        ssize_t res = ::read(fd, buf + nread, buflen - nread);
+        if (res < 0)
+            return false;
+        if (res == 0)
+            return false; // EOF
+        nread += (ssize_t)res;
+    }
+
+    return true;
+}
+
+string subprocess::read(bool use_stderr) {
+    int fd = use_stderr ? m_stderr : m_stdout;
+    if (fd < 0)
+        return "";
+
+    set_o_nonblock(fd, true);
+
+    char buf[1024] = {};
+    ssize_t n = ::read(fd, buf, sizeof(buf) - 1);
+    return n < 0 ? "" : buf;
+}
+
+} // namespace mwr