catturare l'output di processo generato a stringa

Question

Background:

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Sto lavorando su un programma che deve essere in grado di catturare l'stdout, stderr e valori di un programma di ritorno. Idealmente, mi piacerebbe catturarli in una stringa che immagazzino all'interno del mio oggetto che contiene i dettagli del processo. Al momento ho un codice che funziona salvando l'output in un file usando alcuni (a mio parere) archiico file C handle magic. Ogni volta che voglio produrre i risultati, apro quel file e stampo i contenuti.

A volte (quando un processo che spawn viene lasciato in esecuzione) la prossima esecuzione del mio eseguibile si interromperà perché non è possibile aprire il file per la scrittura.

problema dichiarazione:

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Sto cercando un modo per salvare l'output di stdout di un processo creato in Windows per una stringa e la stderr ad un altro in un più sicuro, più moderno di moda . In questo modo potrei stampare quei contenuti ogni volta che mi sembra di emettere il risultato di ogni processo creato.

mio codice brutto:

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chunk- principale

int stdoutold = _dup(_fileno(stdout)); //make a copy of stdout 
    int stderrold = _dup(_fileno(stdout)); //make a copy of stderr 
    FILE *f; 

    if(!fopen_s(&f, "name_of_my_file", "w")){ //make sure I can write to the file 
     _dup2(_fileno(f), _fileno(stdout)); //make stdout point to f 
     _dup2(_fileno(f), _fileno(stderr)); //make stderr point to f 

     fork("command_I_want_to_run", &pi); //run my fake fork (see below) 
    } 
    else{ 
     ...//error handling 
    } 
    _close(_fileno(stdout)); //close tainted stdout 
    _close(_fileno(stderr)); //close tainted stderr 
    _close(_fileno(f)); //close f 
    _dup2(stdoutold, _fileno(stdout)); //fix stdout 
    _dup2(stderrold, _fileno(stderr)); //fix stderr 

forche (si può pensare a questo come solo CreateProcess, ma solo nel caso in cui qualcuno ha bisogno di vedere cosa succede qui)

int fork(std::string s, PROCESS_INFORMATION* pi){ 
char infoBuf[INFO_BUFFER_SIZE]; 
int bufCharCount = 
    ExpandEnvironmentStrings(s.c_str(), infoBuf, INFO_BUFFER_SIZE); 
... 
    STARTUPINFO si; 
    ZeroMemory(&si, sizeof(si)); 
    si.cb = sizeof(si); 
    ZeroMemory(pi, sizeof(*pi)); 
    LPSTR str = const_cast<char *>(infoBuf); 
    if(!CreateProcess(NULL, 
     str, 
     NULL, 
     NULL, 
     TRUE, 
     0, 
     NULL, 
     NULL, 
     &si, 
     pi) 
    ){ 
     int err = GetLastError(); 
     printf("CreateProcess failed (%d).\n", err); 
     CloseHandle((*pi).hProcess); 
     CloseHandle((*pi).hThread); 
     return err; 
    } 
return 0; 
} 

Note:

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• Sto utilizzando VS 2010
• voglio rimanere con più processi, non le discussioni perché ho bisogno di quello che ho eseguito avere la libertà del proprio processo

Edit:

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Una nota in più: cerco anche di aspettare che il processo finisca subito dopo aver chiamato la funzione che esegue il codice dato, quindi i risultati di stdout e stderr sono disponibili per me in quel momento.

Answer 1

Dovrai utilizzare le pipe per acquisire il contenuto del flusso stdout del processo. C'è un esempio elaborato su MSDN su come raggiungere questo obiettivo:

MSDN: Creating a Child Process with Redirected Input and Output

Answer 2

risposta di Eddy Luten mi ha portato in una buona direzione, ma la documentazione di MSDN (mentre elaborato) aveva alcuni problemi. Principalmente, devi assicurarti di chiudere tutte le maniglie che non usi. Inoltre ha solo il codice che si aspetta che l'utente capisca.

Così, invece, ecco la mia parete del codice Mi aspetto che la gente capisca solo: D

#include <string> 
#include <iostream> 
#include <windows.h> 
#include <stdio.h> 
#pragma warning(disable : 4800) // stupid warning about bool 
#define BUFSIZE 4096 
HANDLE g_hChildStd_OUT_Rd = NULL; 
HANDLE g_hChildStd_OUT_Wr = NULL; 
HANDLE g_hChildStd_ERR_Rd = NULL; 
HANDLE g_hChildStd_ERR_Wr = NULL; 

PROCESS_INFORMATION CreateChildProcess(void); 
void ReadFromPipe(PROCESS_INFORMATION); 

int main(int argc, char *argv[]){ 
    SECURITY_ATTRIBUTES sa; 
    printf("\n->Start of parent execution.\n"); 
    // Set the bInheritHandle flag so pipe handles are inherited. 
    sa.nLength = sizeof(SECURITY_ATTRIBUTES); 
    sa.bInheritHandle = TRUE; 
    sa.lpSecurityDescriptor = NULL; 
    // Create a pipe for the child process's STDERR. 
    if (! CreatePipe(&g_hChildStd_ERR_Rd, &g_hChildStd_ERR_Wr, &sa, 0)) { 
     exit(1); 
    } 
    // Ensure the read handle to the pipe for STDERR is not inherited. 
    if (! SetHandleInformation(g_hChildStd_ERR_Rd, HANDLE_FLAG_INHERIT, 0)){ 
     exit(1); 
    } 
    // Create a pipe for the child process's STDOUT. 
    if (! CreatePipe(&g_hChildStd_OUT_Rd, &g_hChildStd_OUT_Wr, &sa, 0)) { 
     exit(1); 
    } 
    // Ensure the read handle to the pipe for STDOUT is not inherited 
    if (! SetHandleInformation(g_hChildStd_OUT_Rd, HANDLE_FLAG_INHERIT, 0)){ 
     exit(1); 
    } 
    // Create the child process. 
    PROCESS_INFORMATION piProcInfo = CreateChildProcess(); 

    // Read from pipe that is the standard output for child process. 
    printf("\n->Contents of child process STDOUT:\n\n", argv[1]); 
    ReadFromPipe(piProcInfo); 

    printf("\n->End of parent execution.\n"); 

    // The remaining open handles are cleaned up when this process terminates. 
    // To avoid resource leaks in a larger application, 
    // close handles explicitly. 
    return 0; 
} 

// Create a child process that uses the previously created pipes 
// for STDERR and STDOUT. 
PROCESS_INFORMATION CreateChildProcess(){ 
    // Set the text I want to run 
    char szCmdline[]="test --log_level=all --report_level=detailed"; 
    PROCESS_INFORMATION piProcInfo; 
    STARTUPINFO siStartInfo; 
    bool bSuccess = FALSE; 

    // Set up members of the PROCESS_INFORMATION structure. 
    ZeroMemory(&piProcInfo, sizeof(PROCESS_INFORMATION)); 

    // Set up members of the STARTUPINFO structure. 
    // This structure specifies the STDERR and STDOUT handles for redirection. 
    ZeroMemory(&siStartInfo, sizeof(STARTUPINFO)); 
    siStartInfo.cb = sizeof(STARTUPINFO); 
    siStartInfo.hStdError = g_hChildStd_ERR_Wr; 
    siStartInfo.hStdOutput = g_hChildStd_OUT_Wr; 
    siStartInfo.dwFlags |= STARTF_USESTDHANDLES; 

    // Create the child process. 
    bSuccess = CreateProcess(NULL, 
     szCmdline,  // command line 
     NULL,   // process security attributes 
     NULL,   // primary thread security attributes 
     TRUE,   // handles are inherited 
     0,    // creation flags 
     NULL,   // use parent's environment 
     NULL,   // use parent's current directory 
     &siStartInfo, // STARTUPINFO pointer 
     &piProcInfo); // receives PROCESS_INFORMATION 
    CloseHandle(g_hChildStd_ERR_Wr); 
    CloseHandle(g_hChildStd_OUT_Wr); 
    // If an error occurs, exit the application. 
    if (! bSuccess) { 
     exit(1); 
    } 
    return piProcInfo; 
} 

// Read output from the child process's pipe for STDOUT 
// and write to the parent process's pipe for STDOUT. 
// Stop when there is no more data. 
void ReadFromPipe(PROCESS_INFORMATION piProcInfo) { 
    DWORD dwRead; 
    CHAR chBuf[BUFSIZE]; 
    bool bSuccess = FALSE; 
    std::string out = "", err = ""; 
    for (;;) { 
     bSuccess=ReadFile(g_hChildStd_OUT_Rd, chBuf, BUFSIZE, &dwRead, NULL); 
     if(! bSuccess || dwRead == 0) break; 

     std::string s(chBuf, dwRead); 
     out += s; 
    } 
    dwRead = 0; 
    for (;;) { 
     bSuccess=ReadFile(g_hChildStd_ERR_Rd, chBuf, BUFSIZE, &dwRead, NULL); 
     if(! bSuccess || dwRead == 0) break; 

     std::string s(chBuf, dwRead); 
     err += s; 

    } 
    std::cout << "stdout:" << out << std::endl; 
    std::cout << "stderr:" << err << std::endl; 
} 

Answer 3

codice

Shawn Blakesley è buona rilavorazione di Microsoft codice di esempio, ma è un po 'un problema quando non v'è enorme stdout e stderr flussi interlacciati che sono fuori uso. E alcune maniglie sono trapelate (che è OK per il codice di esempio). Avendo thread in background e PeekNamedPipe() chiama fa che il codice si comportano più simile a POSIX chiamata di sistema:

#include <windows.h> 
#include <stdio.h> 
#include <malloc.h> 

#ifdef __cplusplus 
#define BEGIN_C extern "C" { 
#define END_C } // extern "C" 
#define null nullptr 
#else 
#define BEGIN_C 
#define END_C 
#define null ((void*)0) 
#endif 

BEGIN_C 

int system_np(const char* command, int timeout_milliseconds, 
       char* stdout_data, int stdout_data_size, 
       char* stderr_data, int stderr_data_size, int* exit_code); 

typedef struct system_np_s { 
    HANDLE child_stdout_read; 
    HANDLE child_stderr_read; 
    HANDLE reader; 
    PROCESS_INFORMATION pi; 
    const char* command; 
    char* stdout_data; 
    int stdout_data_size; 
    char* stderr_data; 
    int stderr_data_size; 
    int* exit_code; 
    int timeout; // timeout in milliseconds or -1 for INIFINTE 
} system_np_t; 

static char stdout_data[16 * 1024 * 1024]; 
static char stderr_data[16 * 1024 * 1024]; 

int main(int argc, char *argv[]) { 
    int bytes = 1; 
    for (int i = 1; i < argc; i++) { 
     bytes += (int)strlen(argv[i]) + 1; 
    } 
    char* command = (char*)alloca(bytes); 
    command[0] = 0; 
    char* p = command; 
    for (int i = 1; i < argc; i++) { 
     int n = (int)strlen(argv[i]); 
     memcpy(p, argv[i], n); p += n; 
     *p = (i == argc - 1) ? 0x00 : 0x20; 
     p++; 
    } 
    int exit_code = 0; 
    if (command[0] == 0) { 
     command = (char*)"cmd.exe /c \"dir /w /b\""; 
    } 
    int r = system_np(command, 100 * 1000, stdout_data, sizeof(stdout_data), stderr_data, sizeof(stderr_data), &exit_code); 
    if (r != 0) { 
     fprintf(stderr, "system_np failed: %d 0x%08x %s", r, r, strerror(r)); 
     return r; 
    } else { 
     fwrite(stdout_data, strlen(stdout_data), 1, stdout); 
     fwrite(stderr_data, strlen(stderr_data), 1, stderr); 
     return exit_code; 
    } 
} 

static int peek_pipe(HANDLE pipe, char* data, int size) {   
    char buffer[4 * 1024]; 
    DWORD read = 0; 
    DWORD available = 0; 
    bool b = PeekNamedPipe(pipe, null, sizeof(data), null, &available, null); 
    if (!b) { 
     return -1; 
    } else if (available > 0) { 
     int bytes = min(sizeof(buffer), available); 
     b = ReadFile(pipe, buffer, bytes, &read, null); 
     if (!b) { 
      return -1; 
     } 
     if (data != null && size > 0) { 
      int n = min(size - 1, (int)read); 
      memcpy(data, buffer, n); 
      data[n + 1] = 0; // always zero terminated 
      return n; 
     } 
    } 
    return 0; 
} 

static DWORD WINAPI read_from_all_pipes_fully(void* p) { 
    system_np_t* system = (system_np_t*)p; 
    unsigned long long milliseconds = GetTickCount64(); // since boot time 
    char* out = system->stdout_data != null && system->stdout_data_size > 0 ? system->stdout_data : null; 
    char* err = system->stderr_data != null && system->stderr_data_size > 0 ? system->stderr_data : null; 
    int out_bytes = system->stdout_data != null && system->stdout_data_size > 0 ? system->stdout_data_size - 1 : 0; 
    int err_bytes = system->stderr_data != null && system->stderr_data_size > 0 ? system->stderr_data_size - 1 : 0; 
    for (;;) { 
     int read_stdout = peek_pipe(system->child_stdout_read, out, out_bytes); 
     if (read_stdout > 0 && out != null) { out += read_stdout; out_bytes -= read_stdout; } 
     int read_stderr = peek_pipe(system->child_stderr_read, err, err_bytes); 
     if (read_stderr > 0 && err != null) { err += read_stderr; err_bytes -= read_stderr; } 
     if (read_stdout < 0 && read_stderr < 0) { break; } // both pipes are closed 
     unsigned long long time_spent_in_milliseconds = GetTickCount64() - milliseconds; 
     if (system->timeout > 0 && time_spent_in_milliseconds > system->timeout) { break; } 
     if (read_stdout == 0 && read_stderr == 0) { // nothing has been read from both pipes 
      HANDLE handles[2] = {system->child_stdout_read, system->child_stderr_read}; 
      WaitForMultipleObjects(2, handles, false, 1); // wait for at least 1 millisecond (more likely 16) 
     } 
    } 
    if (out != null) { *out = 0; } 
    if (err != null) { *err = 0; } 
    return 0; 
} 

static int create_child_process(system_np_t* system) { 
    SECURITY_ATTRIBUTES sa = {0}; 
    sa.nLength = sizeof(SECURITY_ATTRIBUTES); 
    sa.bInheritHandle = true; 
    sa.lpSecurityDescriptor = null; 
    HANDLE child_stdout_write = INVALID_HANDLE_VALUE; 
    HANDLE child_stderr_write = INVALID_HANDLE_VALUE; 
    if (!CreatePipe(&system->child_stderr_read, &child_stderr_write, &sa, 0)) { 
     return GetLastError(); 
    } 
    if (!SetHandleInformation(system->child_stderr_read, HANDLE_FLAG_INHERIT, 0)){ 
     return GetLastError(); 
    } 
    if (!CreatePipe(&system->child_stdout_read, &child_stdout_write, &sa, 0)) { 
     return GetLastError(); 
    } 
    if (!SetHandleInformation(system->child_stdout_read, HANDLE_FLAG_INHERIT, 0)){ 
     return GetLastError(); 
    } 
    // Set the text I want to run 
    STARTUPINFO siStartInfo = {0}; 
    siStartInfo.cb = sizeof(STARTUPINFO); 
    siStartInfo.hStdError = child_stderr_write; 
    siStartInfo.hStdOutput = child_stdout_write; 
    siStartInfo.dwFlags |= STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW; 
    siStartInfo.wShowWindow = SW_HIDE; 
    bool b = CreateProcessA(null, 
     (char*)system->command, 
     null,    // process security attributes 
     null,    // primary thread security attributes 
     true,    // handles are inherited 
     CREATE_NO_WINDOW, // creation flags 
     null,    // use parent's environment 
     null,    // use parent's current directory 
     &siStartInfo,  // STARTUPINFO pointer 
     &system->pi);  // receives PROCESS_INFORMATION 
    int err = GetLastError(); 
    CloseHandle(child_stderr_write); 
    CloseHandle(child_stdout_write); 
    if (!b) { 
     CloseHandle(system->child_stdout_read); system->child_stdout_read = INVALID_HANDLE_VALUE; 
     CloseHandle(system->child_stderr_read); system->child_stderr_read = INVALID_HANDLE_VALUE; 
    } 
    return b ? 0 : err; 
} 

int system_np(const char* command, int timeout_milliseconds, 
       char* stdout_data, int stdout_data_size, 
       char* stderr_data, int stderr_data_size, int* exit_code) { 
    system_np_t system = {0}; 
    if (exit_code != null) { *exit_code = 0; } 
    if (stdout_data != null && stdout_data_size > 0) { stdout_data[0] = 0; } 
    if (stderr_data != null && stderr_data_size > 0) { stderr_data[0] = 0; } 
    system.timeout = timeout_milliseconds > 0 ? timeout_milliseconds : -1; 
    system.command = command; 
    system.stdout_data = stdout_data; 
    system.stderr_data = stderr_data; 
    system.stdout_data_size = stdout_data_size; 
    system.stderr_data_size = stderr_data_size; 
    int r = create_child_process(&system); 
    if (r == 0) { 
     system.reader = CreateThread(null, 0, read_from_all_pipes_fully, &system, 0, null); 
     if (system.reader == null) { // in theory should rarely happen only when system super low on resources 
      r = GetLastError(); 
      TerminateProcess(system.pi.hProcess, ECANCELED); 
     } else { 
      bool thread_done = WaitForSingleObject(system.pi.hThread, timeout_milliseconds) == 0; 
      bool process_done = WaitForSingleObject(system.pi.hProcess, timeout_milliseconds) == 0; 
      if (!thread_done || !process_done) { 
       TerminateProcess(system.pi.hProcess, ETIME); 
      } 
      if (exit_code != null) { 
       GetExitCodeProcess(system.pi.hProcess, (DWORD*)exit_code); 
      }   
      CloseHandle(system.pi.hThread); 
      CloseHandle(system.pi.hProcess); 
      CloseHandle(system.child_stdout_read); system.child_stdout_read = INVALID_HANDLE_VALUE; 
      CloseHandle(system.child_stderr_read); system.child_stderr_read = INVALID_HANDLE_VALUE; 
      WaitForSingleObject(system.reader, INFINITE); // join thread 
      CloseHandle(system.reader); 
     } 
    } 
    if (stdout_data != null && stdout_data_size > 0) { stdout_data[stdout_data_size - 1] = 0; } 
    if (stderr_data != null && stderr_data_size > 0) { stderr_data[stderr_data_size - 1] = 0; } 
    return r; 
} 

END_C