Inherit handles only if necessary on Windows

Refs #2779 <https://github.com/Genymobile/scrcpy/issues/2779>

app/src/sys/win/process.c

@@ -1,10 +1,5 @@
-// <https://devblogs.microsoft.com/oldnewthing/20111216-00/?p=8873>
-#define _WIN32_WINNT 0x0600 // For extended process API
-
 #include "util/process.h"
 
-#include <processthreadsapi.h>
-
 #include <assert.h>
 
 #include "util/log.h"
@@ -31,8 +26,7 @@ sc_process_execute_p(const char *const argv[], HANDLE *handle,
                      HANDLE *pin, HANDLE *pout, HANDLE *perr) {
     enum sc_process_result ret = SC_PROCESS_ERROR_GENERIC;
 
-    // Add 1 per non-NULL pointer
-    unsigned handle_count = !!pin + !!pout + !!perr;
+    bool inherit_handles = pin || pout || perr;
 
     SECURITY_ATTRIBUTES sa;
     sa.nLength = sizeof(SECURITY_ATTRIBUTES);
@@ -73,94 +67,45 @@ sc_process_execute_p(const char *const argv[], HANDLE *handle,
         }
     }
 
-    STARTUPINFOEXW si;
+    STARTUPINFOW si;
     PROCESS_INFORMATION pi;
     memset(&si, 0, sizeof(si));
-    si.StartupInfo.cb = sizeof(si);
-    HANDLE handles[3];
-
-    LPPROC_THREAD_ATTRIBUTE_LIST lpAttributeList = NULL;
-    if (handle_count) {
-        si.StartupInfo.dwFlags = STARTF_USESTDHANDLES;
+    si.cb = sizeof(si);
+    if (inherit_handles) {
+        si.dwFlags = STARTF_USESTDHANDLES;
         if (pin) {
-            si.StartupInfo.hStdInput = stdin_read_handle;
+            si.hStdInput = stdin_read_handle;
         }
         if (pout) {
-            si.StartupInfo.hStdOutput = stdout_write_handle;
+            si.hStdOutput = stdout_write_handle;
         }
         if (perr) {
-            si.StartupInfo.hStdError = stderr_write_handle;
+            si.hStdError = stderr_write_handle;
         }
-
-        SIZE_T size;
-        // Call it once to know the required buffer size
-        BOOL ok =
-            InitializeProcThreadAttributeList(NULL, 1, 0, &size)
-                || GetLastError() == ERROR_INSUFFICIENT_BUFFER;
-        if (!ok) {
-            goto error_close_stderr;
-        }
-
-        lpAttributeList = malloc(size);
-        if (!lpAttributeList) {
-            goto error_close_stderr;
-        }
-
-        ok = InitializeProcThreadAttributeList(lpAttributeList, 1, 0, &size);
-        if (!ok) {
-            free(lpAttributeList);
-            goto error_close_stderr;
-        }
-
-        // Explicitly pass the HANDLEs that must be inherited
-        unsigned i = 0;
-        if (pin) {
-            handles[i++] = stdin_read_handle;
-        }
-        if (pout) {
-            handles[i++] = stdout_write_handle;
-        }
-        if (perr) {
-            handles[i++] = stderr_write_handle;
-        }
-        ok = UpdateProcThreadAttribute(lpAttributeList, 0,
-                                       PROC_THREAD_ATTRIBUTE_HANDLE_LIST,
-                                       handles, handle_count * sizeof(HANDLE),
-                                       NULL, NULL);
-        if (!ok) {
-            goto error_free_attribute_list;
-        }
-
-        si.lpAttributeList = lpAttributeList;
     }
 
     char *cmd = malloc(CMD_MAX_LEN);
     if (!cmd || !build_cmd(cmd, CMD_MAX_LEN, argv)) {
-        goto error_free_attribute_list;
+        *handle = NULL;
+        goto error_close_stderr;
     }
 
     wchar_t *wide = sc_str_to_wchars(cmd);
     free(cmd);
     if (!wide) {
         LOGC("Could not allocate wide char string");
-        goto error_free_attribute_list;
+        goto error_close_stderr;
     }
 
-    BOOL bInheritHandles = handle_count > 0;
-    DWORD dwCreationFlags = handle_count > 0 ? EXTENDED_STARTUPINFO_PRESENT : 0;
-    BOOL ok = CreateProcessW(NULL, wide, NULL, NULL, bInheritHandles,
-                             dwCreationFlags, NULL, NULL, &si.StartupInfo, &pi);
-    free(wide);
-    if (!ok) {
+    if (!CreateProcessW(NULL, wide, NULL, NULL, inherit_handles, 0, NULL, NULL,
+                        &si, &pi)) {
+        free(wide);
+        *handle = NULL;
+
         if (GetLastError() == ERROR_FILE_NOT_FOUND) {
             ret = SC_PROCESS_ERROR_MISSING_BINARY;
         }
-        goto error_free_attribute_list;
-    }
-
-    if (lpAttributeList) {
-        DeleteProcThreadAttributeList(lpAttributeList);
-        free(lpAttributeList);
+        goto error_close_stderr;
     }
 
     // These handles are used by the child process, close them for this process
@@ -174,15 +119,11 @@ sc_process_execute_p(const char *const argv[], HANDLE *handle,
         CloseHandle(stderr_write_handle);
     }
 
+    free(wide);
     *handle = pi.hProcess;
 
     return SC_PROCESS_SUCCESS;
 
-error_free_attribute_list:
-    if (lpAttributeList) {
-        DeleteProcThreadAttributeList(lpAttributeList);
-        free(lpAttributeList);
-    }
 error_close_stderr:
     if (perr) {
         CloseHandle(*perr);
@@ -229,7 +170,7 @@ sc_process_close(HANDLE handle) {
 }
 
 ssize_t
-sc_pipe_read(HANDLE pipe, char *data, size_t len) {
+sc_read_pipe(HANDLE pipe, char *data, size_t len) {
     DWORD r;
     if (!ReadFile(pipe, data, len, &r, NULL)) {
         return -1;
@@ -238,7 +179,7 @@ sc_pipe_read(HANDLE pipe, char *data, size_t len) {
 }
 
 void
-sc_pipe_close(HANDLE pipe) {
+sc_close_pipe(HANDLE pipe) {
     if (!CloseHandle(pipe)) {
         LOGW("Cannot close pipe");
     }

app/src/util/net.c

@@ -96,6 +96,27 @@ net_perror(const char *s) {
 sc_socket
 net_socket(void) {
     sc_raw_socket raw_sock = socket(AF_INET, SOCK_STREAM, 0);
+
+#ifdef _WIN32
+    /* To be able to communicate with a child process via stdin, stdout and
+     * stderr, the CreateProcess() parameter bInheritHandles must be set to
+     * TRUE. But this causes *all* handles to be inherited, including sockets.
+     *
+     * One possibility could be to use an extended API to set extra attributes
+     * on process creation:
+     *  - <https://stackoverflow.com/a/28185363/1987178>
+     *  - <https://devblogs.microsoft.com/oldnewthing/20111216-00/?p=8873>
+     * But it seems that this API is not available on MinGW (it does not
+     * compile).
+     *
+     * As an alternative, explicitly mark all sockets as non-inheritable.
+     */
+    if (!SetHandleInformation((HANDLE) raw_sock, HANDLE_FLAG_INHERIT, 0)) {
+        closesocket(raw_sock);
+        return SC_SOCKET_NONE;
+    }
+#endif
+
     sc_socket sock = wrap(raw_sock);
     if (sock == SC_SOCKET_NONE) {
         net_perror("socket");