From 6aae43917d587be7f631673d1e1963fbb2ba15e1 Mon Sep 17 00:00:00 2001 From: Juhani Rankimies Date: Thu, 30 Sep 2010 21:08:54 +0300 Subject: Fix appending to large files (>4GB) on Windows Append mode doesn't work for files larger that 4GB on Windows. Caused by incorrect usage of SetFilePointer in win_efile.c. Fix uses OVERLAPPED structure to specify write position (EOF). http://msdn.microsoft.com/en-us/library/aa365747.aspx Opening file in append mode was also considered, but rejected, because it might cause backwards incompatibility by limiting applicable operations on the descriptor. SetFilePointerEx was not used because it would caused more system calls than using OVERLAPPED structure. --- erts/emulator/drivers/win32/win_efile.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) (limited to 'erts/emulator/drivers') diff --git a/erts/emulator/drivers/win32/win_efile.c b/erts/emulator/drivers/win32/win_efile.c index 04bd1139f5..cb186e9fab 100644 --- a/erts/emulator/drivers/win32/win_efile.c +++ b/erts/emulator/drivers/win32/win_efile.c @@ -1082,12 +1082,17 @@ char* buf; /* Buffer to write. */ size_t count; /* Number of bytes to write. */ { DWORD written; /* Bytes written in last operation. */ + OVERLAPPED overlapped; + OVERLAPPED* pOverlapped = NULL; if (flags & EFILE_MODE_APPEND) { - (void) SetFilePointer((HANDLE) fd, 0, NULL, FILE_END); + memset(&overlapped, 0, sizeof(overlapped)); + overlapped.Offset = 0xffffffff; + overlapped.OffsetHigh = 0xffffffff; + pOverlapped = &overlapped; } while (count > 0) { - if (!WriteFile((HANDLE) fd, buf, count, &written, NULL)) + if (!WriteFile((HANDLE) fd, buf, count, &written, pOverlapped)) return set_error(errInfo); buf += written; count -= written; @@ -1107,11 +1112,16 @@ efile_writev(Efile_error* errInfo, /* Where to return error codes */ size_t size) /* Number of bytes to write */ { int cnt; /* Buffers so far written */ + OVERLAPPED overlapped; + OVERLAPPED* pOverlapped = NULL; ASSERT(iovcnt >= 0); if (flags & EFILE_MODE_APPEND) { - (void) SetFilePointer((HANDLE) fd, 0, NULL, FILE_END); + memset(&overlapped, 0, sizeof(overlapped)); + overlapped.Offset = 0xffffffff; + overlapped.OffsetHigh = 0xffffffff; + pOverlapped = &overlapped; } for (cnt = 0; cnt < iovcnt; cnt++) { if (iov[cnt].iov_base && iov[cnt].iov_len > 0) { @@ -1123,7 +1133,7 @@ efile_writev(Efile_error* errInfo, /* Where to return error codes */ iov[cnt].iov_base + p, iov[cnt].iov_len - p, &w, - NULL)) + pOverlapped)) return set_error(errInfo); } } -- cgit v1.2.3