Is there a way to get the environment block of a process created with CreateProcess ? More precisely I would like to use CreateProcess to call vcvarsall.bat and then being able to call cl.exe in another CreateProcess. I found this "solution" but it's more of a hack than a real solution.
This question is related to this 4coder thread.
This question is related to this 4coder thread.
Edited by Simon Anciaux
on
Reason: Initial post
You can invoke "cmd.exe /c set" process which will print out its env variables. Capture stdout and store these values. Then when you want to launch new process, pass all of them to environment vars. There is no way to pass "environment block" between processes. Otherwise - what would happen if one would modify it? Other process could crash or read garbage data if variable is not available anymore and it is keeping pointer to it (from the time variable existed).
Edited by Mārtiņš Možeiko
on
That's what was suggested on stackoverflow. I was hoping there was a more direct way to get a copy.
Here is the code that does it with some notes about the issues I ran into.
Here is the code that does it with some notes about the issues I ran into.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 | /* NOTE: build command: cl main.c -nologo -Zi -Od */ #include <windows.h> #include <stdio.h> #include <assert.h> typedef enum Error { error_none, error_create_process, error_wait_for_process, error_path_environment_variable_not_found, error_path_could_not_be_set, error_mark_not_found, } Error; void printWindowsError( char* message, DWORD error ) { char buffer[ 1024 ]; DWORD flags = FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS; FormatMessage( flags, 0, error, 0, buffer, 1024, 0 ); printf( "%s%s\n", message, buffer ); } int main( int argc, char* argv[ ] ) { Error error = 0; /* NOTE: Redirecting standard i/o: stdout, stdin and stderror are all required, you can't just specify one or the other will be INVALID_HANDLE_VALUE. Also you need to set inherit handles when creating the file and when creating the process. */ SECURITY_ATTRIBUTES security = { 0 }; security.nLength = sizeof( security ); security.lpSecurityDescriptor = 0; security.bInheritHandle = 1; HANDLE std_out = CreateFile( "out.txt", GENERIC_READ | GENERIC_WRITE, 0, &security, CREATE_ALWAYS, 0, 0 ); HANDLE std_in = GetStdHandle( STD_INPUT_HANDLE ); HANDLE std_error = GetStdHandle( STD_ERROR_HANDLE ); { printf( "Calling vcvarsall: " ); PROCESS_INFORMATION processInformation = { 0 }; STARTUPINFO startupInformation = { 0 }; startupInformation.cb = sizeof( startupInformation ); startupInformation.dwFlags = STARTF_USESTDHANDLES; startupInformation.hStdOutput = std_out; startupInformation.hStdInput = std_in; startupInformation.hStdError = std_error; /* NOTE: echo __env_start_mark__ because stdout will contain anything printed by vcvarsall and we want to know when the environment starts. Also if vcvarsall fails, the output will not contain the string because we used &&. */ char command[ ] = "cmd /C \"C:\\Program Files (x86)\\Microsoft Visual Studio\\2017\\Community\\VC\\Auxiliary\\Build\\vcvarsall.bat\" x64 && echo __env_start_mark__ && set"; BOOL inheritHandles = 1; if ( CreateProcessA( 0, command, 0, 0, inheritHandles, 0, 0, 0, &startupInformation, &processInformation ) ) { if ( processInformation.hProcess != 0 ) { DWORD waitStatus = WaitForSingleObject( processInformation.hProcess, INFINITE ); if ( waitStatus != WAIT_OBJECT_0 ) { error = error_wait_for_process; if ( waitStatus == WAIT_FAILED ) { printWindowsError( "FAILED.\nWait for process error: ", GetLastError( ) ); } } else { printf( "SUCCESS.\n" ); } } if ( processInformation.hProcess ) { CloseHandle( processInformation.hProcess ); } if ( processInformation.hThread ) { CloseHandle( processInformation.hThread ); } } else { error = error_create_process; printWindowsError( "FAILED.\nCreate process error: ", GetLastError( ) ); } } char* envBlockStart = 0; if ( !error ) { printf( "Creating environment block: " ); LARGE_INTEGER size; LARGE_INTEGER zero = { 0 }; GetFileSizeEx( std_out, &size ); SetFilePointerEx( std_out, zero, 0, FILE_BEGIN ); /* NOTE: +1 to make sure we have space for the block end '0'. In practice we always have space if there is at least 2 environment variables because of the '\r'.*/ char* file = malloc( size.QuadPart + 1 ); DWORD read; ReadFile( std_out, file, size.LowPart, &read, 0 ); CloseHandle( std_out ); DeleteFile( "out.txt" ); char* end = file + size.QuadPart; char* current = file; char* mark = "__env_start_mark__"; size_t markLength = sizeof( "__env_start_mark__" ) - 1; int found = 0; while ( current + markLength < end ) { if ( strncmp( mark, current, markLength ) == 0 ) { found = 1; break; } else { current++; } } if ( found ) { current += markLength; while ( current < end && *current != '\n' ) { current++; } current++; char* out = current; envBlockStart = out; /* NOTE: We need to remember the path environment variable. See below. */ char* path = 0; char* pathString1 = "PATH="; char* pathString2 = "Path="; char* pathString3 = "path="; size_t pathStringLength = sizeof( "PATH=" ) - 1; while ( current < end ) { if ( *current == '\n' ) { *out = 0; out++; if ( !path ) { char* test = current + 1; if ( test + pathStringLength < end && ( strncmp( test, pathString1, pathStringLength ) == 0 || strncmp( test, pathString2, pathStringLength ) == 0 || strncmp( test, pathString3, pathStringLength ) == 0 ) ) { path = out; } } } else if ( *current == '\r' ) { } else { *out = *current; out++; } current++; } *out = 0; out++; size_t envBlockLength = out - envBlockStart; assert( envBlockLength <= 32767 ); if ( path ) { path[ pathStringLength - 1 ] = 0; /* NOTE: We need to set the current process path so CreateProcess will search for cl.exe in Visual Studio's folders.*/ if ( !SetEnvironmentVariable( path, path + pathStringLength ) ) { error = error_path_could_not_be_set; printWindowsError( "FAILED.\nCouldn't set the path environment variable: ", GetLastError( ) ); } else { path[ pathStringLength - 1 ] = '='; printf( "SUCCESS.\nPath environment variable found and set.\n" ); } } else { error = error_path_environment_variable_not_found; printf( "FAILED.\nCould not find the path environment variable.\n" ); } } else { error = error_mark_not_found; printf( "FAILED.\nCould not find the mark.\n" ); } } if ( !error ) { printf( "Calling cl:\n" ); PROCESS_INFORMATION processInformation = { 0 }; STARTUPINFO startupInformation = { 0 }; startupInformation.cb = sizeof( startupInformation ); char command[ ] = "cl"; if ( CreateProcessA( 0, command, 0, 0, 0, 0, envBlockStart, 0, &startupInformation, &processInformation ) ) { if ( processInformation.hProcess != 0 ) { DWORD waitStatus = WaitForSingleObject( processInformation.hProcess, INFINITE ); if ( waitStatus != WAIT_OBJECT_0 ) { error = error_wait_for_process; if ( waitStatus == WAIT_FAILED ) { printWindowsError( "FAILED.\nWait for process error: ", GetLastError( ) ); } } else { printf( "SUCCESS.\n" ); } } if ( processInformation.hProcess ) { CloseHandle( processInformation.hProcess ); } if ( processInformation.hThread ) { CloseHandle( processInformation.hThread ); } } else { error = error_create_process; printWindowsError( "FAILED.\nCreate process error: ", GetLastError( ) ); } } printf( "Press any key to exit.\n" ); getchar( ); return error; } |