3 // I measured these limits on the size of a single ReadConsoleOutputW call.
4 // The limit seems to more-or-less disppear with Windows 8, which is the first
5 // OS to stop using ALPCs for console I/O. My guess is that the new I/O
6 // method does not use the 64KiB shared memory buffer that the ALPC method
9 // I'm guessing the remaining difference between Windows 8/8.1 and Windows 10
10 // might be related to the 32-vs-64-bitness.
14 // Windows XP 32-bit VM ==> up to 13304 characters
15 // - 13304x1 works, but 13305x1 fails instantly
16 // Windows 7 32-bit VM ==> between 16-17 thousand characters
17 // - 16000x1 works, 17000x1 fails instantly
18 // - 163x100 *crashes* conhost.exe but leaves VeryLargeRead.exe running
19 // Windows 8 32-bit VM ==> between 240-250 million characters
20 // - 10000x24000 works, but 10000x25000 does not
21 // Windows 8.1 32-bit VM ==> between 240-250 million characters
22 // - 10000x24000 works, but 10000x25000 does not
23 // Windows 10 64-bit VM ==> no limit (tested to 576 million characters)
24 // - 24000x24000 works
25 // - `ver` reports [Version 10.0.10240], conhost.exe and ConhostV1.dll are
26 // 10.0.10240.16384 for file and product version. ConhostV2.dll is
27 // 10.0.10240.16391 for file and product version.
31 // Windows Server 2008 64-bit VM ==> 14300-14400 characters
32 // - 14300x1 works, 14400x1 fails instantly
33 // - This OS does not have conhost.exe.
34 // - `ver` reports [Version 6.0.6002]
35 // Windows Server 2008 R2 64-bit VM ==> 15600-15700 characters
36 // - 15600x1 works, 15700x1 fails instantly
37 // - This OS has conhost.exe, and procexp.exe reveals console ALPC ports in
38 // use in conhost.exe.
39 // - `ver` reports [Version 6.1.7601], conhost.exe is 6.1.7601.23153 for file
40 // and product version.
41 // Windows Server 2012 64-bit VM ==> at least 100 million characters
42 // - 10000x10000 works (VM had only 1GiB of RAM, so I skipped larger tests)
43 // - This OS has Windows 8's task manager and procexp.exe reveals the same
44 // lack of ALPC ports and the same \Device\ConDrv\* files as Windows 8.
45 // - `ver` reports [Version 6.2.9200], conhost.exe is 6.2.9200.16579 for file
46 // and product version.
50 // client-OS server-OS notes
51 // ---------------------------------------------------------------------------
52 // XP Server 2008 CSRSS, small reads
53 // 7 Server 2008 R2 ALPC-to-conhost, small reads
54 // 8, 8.1 Server 2012 new I/O interface, large reads allowed
55 // 10 <no server OS yet> enhanced console w/rewrapping
57 // (Presumably, Win2K, Vista, and Win2K3 behave the same as XP. conhost.exe
58 // was announced as a Win7 feature.)
65 #include "TestUtil.cc"
67 int main(int argc, char *argv[]) {
68 long long width = 9000;
69 long long height = 9000;
73 width = atoi(argv[2]);
74 height = atoi(argv[3]);
77 width = atoi(argv[1]);
78 height = atoi(argv[2]);
81 swprintf(args, 1024, L"CHILD %lld %lld", width, height);
82 startChildProcess(args);
86 const HANDLE conout = GetStdHandle(STD_OUTPUT_HANDLE);
88 setWindowPos(0, 0, 1, 1);
89 setBufferSize(width, height);
90 setWindowPos(0, 0, std::min(80LL, width), std::min(50LL, height));
95 setCursorPos(width - 2, height - 1);
99 trace("sizeof(CHAR_INFO) = %d", (int)sizeof(CHAR_INFO));
101 trace("Allocating buffer...");
102 CHAR_INFO *buffer = new CHAR_INFO[width * height];
103 assert(buffer != NULL);
104 memset(&buffer[0], 0, sizeof(CHAR_INFO));
105 memset(&buffer[width * height - 2], 0, sizeof(CHAR_INFO));
107 COORD bufSize = { width, height };
108 COORD bufCoord = { 0, 0 };
109 SMALL_RECT readRegion = { 0, 0, width - 1, height - 1 };
110 trace("ReadConsoleOutputW: calling...");
111 BOOL success = ReadConsoleOutputW(conout, buffer, bufSize, bufCoord, &readRegion);
112 trace("ReadConsoleOutputW: success=%d", success);
114 assert(buffer[0].Char.UnicodeChar == L'A');
115 assert(buffer[width * height - 2].Char.UnicodeChar == L'B');
116 trace("Top-left and bottom-right characters read successfully!");