os_win32/popen_win32.cpp

   1 /*
   2  * os_win32/popen_win32.cpp
   3  *
   4  * Home page of code is: https://www.smartmontools.org
   5  *
   6  * Copyright (C) 2018 Christian Franke
   7  *
   8  * SPDX-License-Identifier: GPL-2.0-or-later
   9  */
  10
  11 #include "popen.h"
  12
  13 const char * popen_win32_cpp_cvsid = "$Id: popen_win32.cpp 4818 2018-10-17 05:32:17Z chrfranke $"
  14   POPEN_H_CVSID;
  15
  16 #include <errno.h>
  17 #include <fcntl.h>
  18 #include <io.h> // _open_osfhandle()
  19 #include <signal.h> // SIGSEGV
  20 #include <stdlib.h>
  21 #include <string.h>
  22
  23 #define WIN32_LEAN_AND_MEAN
  24 #include <windows.h>
  25
  26 static FILE * s_popen_file;
  27 static HANDLE s_popen_process;
  28
  29 extern "C"
  30 FILE * popen(const char * command, const char * mode)
  31 {
  32   // Fail if previous run is still in progress
  33   if (s_popen_file) {
  34     errno = EEXIST;
  35     return (FILE *)0;
  36   }
  37
  38   // mode "w" is not implemented
  39   if (!(mode[0] == 'r' && (!mode[1] || !mode[2]))) {
  40     errno = EINVAL;
  41     return (FILE *)0;
  42   }
  43
  44   // Set flags for text or binary mode
  45   // Note: _open_osfhandle() ignores _fmode and defaults to O_BINARY
  46   int oflags; const char * fomode;
  47   switch (mode[1]) {
  48     case 0:
  49     case 't':
  50       oflags = O_RDONLY|O_TEXT;
  51       fomode = "rt";
  52       break;
  53     case 'b':
  54       oflags = O_RDONLY|O_BINARY;
  55       fomode = "rb";
  56       break;
  57     default:
  58       errno = EINVAL;
  59       return (FILE *)0;
  60   }
  61
  62   // Create stdout pipe with inheritable write end
  63   HANDLE pipe_out_r, pipe_out_w;
  64   if (!CreatePipe(&pipe_out_r, &pipe_out_w, (SECURITY_ATTRIBUTES *)0, 1024)) {
  65     errno = EMFILE;
  66     return (FILE *)0;
  67   }
  68   if (!SetHandleInformation(pipe_out_w, HANDLE_FLAG_INHERIT, HANDLE_FLAG_INHERIT)) {
  69     CloseHandle(pipe_out_r); CloseHandle(pipe_out_w);
  70     errno = EMFILE;
  71     return (FILE *)0;
  72   }
  73
  74   // Connect pipe read end to new FD
  75   int fd = _open_osfhandle((intptr_t)pipe_out_r, oflags);
  76   if (fd < 0) {
  77     CloseHandle(pipe_out_r); CloseHandle(pipe_out_w);
  78     return (FILE *)0;
  79   }
  80
  81   // Connect FD to new FILE
  82   FILE * f = fdopen(fd, fomode);
  83   if (!f) {
  84     int err = errno;
  85     close(fd); // CloseHandle(pipe_out_r)
  86     CloseHandle(pipe_out_w);
  87     errno = err;
  88     return (FILE *)0;
  89   }
  90
  91   // Build command line "cmd /c COMMAND"
  92   int cmdlen = strlen(command);
  93   char * shellcmd = (char *)malloc(7 + cmdlen + 1);
  94   if (!shellcmd) {
  95     fclose(f); // CloseHandle(pipe_out_r)
  96     CloseHandle(pipe_out_w);
  97     errno = ENOMEM;
  98     return (FILE *)0;
  99   }
 100   memcpy(shellcmd, "cmd /c ", 7);
 101   memcpy(shellcmd + 7, command, cmdlen + 1);
 102
 103   // Redirect stdin stderr to null device
 104   // Don't inherit parent's stdin, script may hang if parent has no console.
 105   SECURITY_ATTRIBUTES sa_inherit = { sizeof(sa_inherit), (SECURITY_DESCRIPTOR *)0, TRUE };
 106   HANDLE null_in  = CreateFile("nul", GENERIC_READ , 0, &sa_inherit, OPEN_EXISTING, 0, (HANDLE)0);
 107   HANDLE null_err = CreateFile("nul", GENERIC_WRITE, 0, &sa_inherit, OPEN_EXISTING, 0, (HANDLE)0);
 108
 109   // Set stdio handles
 110   STARTUPINFO si; memset(&si, 0, sizeof(si)); si.cb = sizeof(si);
 111   si.hStdInput  = null_in;
 112   si.hStdOutput = pipe_out_w;
 113   si.hStdError  = null_err;
 114   si.dwFlags = STARTF_USESTDHANDLES;
 115
 116   // Create process
 117   PROCESS_INFORMATION pi;
 118   BOOL ok = CreateProcessA(
 119     getenv("COMSPEC"), // "C:\WINDOWS\system32\cmd.exe" or nullptr
 120     shellcmd, // "cmd /c COMMAND" ("cmd" searched in PATH if COMSPEC not set)
 121     (SECURITY_ATTRIBUTES *)0, (SECURITY_ATTRIBUTES *)0,
 122     TRUE, // inherit
 123     CREATE_NO_WINDOW, // DETACHED_PROCESS would open new console(s)
 124     (void *)0, (char *)0, &si, &pi
 125   );
 126   free(shellcmd);
 127
 128   // Close inherited handles
 129   CloseHandle(null_err);
 130   CloseHandle(null_in);
 131   CloseHandle(pipe_out_w);
 132
 133   if (!ok) {
 134     fclose(f); // CloseHandle(pipe_out_r)
 135     errno = ENOENT;
 136     return (FILE *)0;
 137   }
 138
 139   // Store process and FILE for pclose()
 140   CloseHandle(pi.hThread);
 141   s_popen_process = pi.hProcess;
 142   s_popen_file = f;
 143
 144   return f;
 145 }
 146
 147 extern "C"
 148 int pclose(FILE * f)
 149 {
 150   if (f != s_popen_file) {
 151     errno = EBADF;
 152     return -1;
 153   }
 154
 155   fclose(f);
 156   s_popen_file = 0;
 157
 158   // Wait for process exitcode
 159   DWORD exitcode = 42;
 160   bool ok = (   WaitForSingleObject(s_popen_process, INFINITE) == WAIT_OBJECT_0
 161              && GetExitCodeProcess(s_popen_process, &exitcode));
 162
 163   CloseHandle(s_popen_process);
 164   s_popen_process = 0;
 165
 166   if (!ok) {
 167     errno = ECHILD;
 168     return -1;
 169   }
 170
 171   // Modify exitcode for wait(3) macros
 172   if (exitcode >> 23)
 173     return ((exitcode << 9) >> 1) | SIGSEGV;
 174   else
 175     return exitcode << 8;
 176 }