From b3db46435e2d32aa4197753bc95a81648f794021 Mon Sep 17 00:00:00 2001 From: Raimo Niskanen Date: Thu, 8 Dec 2011 13:32:09 +0100 Subject: erts: rewrite efile_writev to handle partial writes correctly --- erts/emulator/drivers/common/efile_drv.c | 8 ++- erts/emulator/drivers/common/erl_efile.h | 2 +- erts/emulator/drivers/unix/unix_efile.c | 97 +++++++++++++------------------- erts/emulator/drivers/win32/win_efile.c | 3 +- 4 files changed, 46 insertions(+), 64 deletions(-) (limited to 'erts/emulator/drivers') diff --git a/erts/emulator/drivers/common/efile_drv.c b/erts/emulator/drivers/common/efile_drv.c index b132991a3b..36ed108b76 100644 --- a/erts/emulator/drivers/common/efile_drv.c +++ b/erts/emulator/drivers/common/efile_drv.c @@ -1385,7 +1385,11 @@ static void invoke_writev(void *data) { size = d->c.writev.size; } - /* Copy the io vector to avoid locking the port que while writing */ + /* Copy the io vector to avoid locking the port que while writing, + * also, both we and efile_writev might/will change the SysIOVec + * when segmenting or due to partial write and we do not want to + * tamper with the actual queue that we get from driver_peekq + */ MUTEX_LOCK(d->c.writev.q_mtx); /* Lock before accessing the port queue */ iov0 = driver_peekq(d->c.writev.port, &iovlen); @@ -1424,7 +1428,7 @@ static void invoke_writev(void *data) { } else { d->result_ok = efile_writev(&d->errInfo, d->flags, (int) d->fd, - iov, iovcnt, size); + iov, iovcnt); } } else if (iovlen == 0) { d->result_ok = 1; diff --git a/erts/emulator/drivers/common/erl_efile.h b/erts/emulator/drivers/common/erl_efile.h index 3868b38137..69ad02633c 100644 --- a/erts/emulator/drivers/common/erl_efile.h +++ b/erts/emulator/drivers/common/erl_efile.h @@ -162,7 +162,7 @@ int efile_write_info(Efile_error* errInfo, Efile_info* pInfo, char *name); int efile_write(Efile_error* errInfo, int flags, int fd, char* buf, size_t count); int efile_writev(Efile_error* errInfo, int flags, int fd, - SysIOVec* iov, int iovcnt, size_t size); + SysIOVec* iov, int iovcnt); int efile_read(Efile_error* errInfo, int flags, int fd, char* buf, size_t count, size_t* pBytesRead); int efile_seek(Efile_error* errInfo, int fd, diff --git a/erts/emulator/drivers/unix/unix_efile.c b/erts/emulator/drivers/unix/unix_efile.c index 7cf0a712ce..e7dd9d2bdb 100644 --- a/erts/emulator/drivers/unix/unix_efile.c +++ b/erts/emulator/drivers/unix/unix_efile.c @@ -1004,13 +1004,11 @@ efile_writev(Efile_error* errInfo, /* Where to return error codes */ * opened */ int fd, /* File descriptor to write to */ SysIOVec* iov, /* Vector of buffer structs. - * The structs are unchanged - * after the call */ - int iovcnt, /* Number of structs in vector */ - size_t size) /* Number of bytes to write */ + * The structs may be changed i.e. + * due to incomplete writes */ + int iovcnt) /* Number of structs in vector */ { int cnt = 0; /* Buffers so far written */ - int p = 0; /* Position in next buffer */ ASSERT(iovcnt >= 0); @@ -1021,66 +1019,47 @@ efile_writev(Efile_error* errInfo, /* Where to return error codes */ #endif while (cnt < iovcnt) { + if ((! iov[cnt].iov_base) || (iov[cnt].iov_len <= 0)) { + /* Empty buffer - skip */ + cnt++; + } else { /* Non-empty buffer */ + ssize_t w; /* Bytes written in this call */ #ifdef HAVE_WRITEV - int w; /* Bytes written in this call */ - int b = iovcnt - cnt; /* Buffers to write */ - if (b > MAXIOV) - b = MAXIOV; - if (iov[cnt].iov_base && iov[cnt].iov_len > 0) { - if (b == 1) { - /* Degenerated io vector */ - do { - w = write(fd, iov[cnt].iov_base + p, iov[cnt].iov_len - p); - } while (w < 0 && errno == EINTR); - } else { - /* Non-empty vector first. - * Adjust pos in first buffer in case of - * previous incomplete writev */ - iov[cnt].iov_base += p; - iov[cnt].iov_len -= p; + int b = iovcnt - cnt; /* Buffers to write */ + /* Use as many buffers as MAXIOV allows */ + if (b > MAXIOV) + b = MAXIOV; + if (b > 1) { do { w = writev(fd, &iov[cnt], b); } while (w < 0 && errno == EINTR); - iov[cnt].iov_base -= p; - iov[cnt].iov_len += p; - } - if (w < 0) - return check_error(-1, errInfo); - } else { - /* Empty vector first - skip */ - cnt++; - continue; - } - ASSERT(w >= 0); - /* Move forward to next vector to write */ - for (; cnt < iovcnt; cnt++) { - if (iov[cnt].iov_base && iov[cnt].iov_len > 0) { - if (w < iov[cnt].iov_len) - break; - else - w -= iov[cnt].iov_len; - } - } - ASSERT(w >= 0); - p = w > 0 ? w : 0; /* Skip p bytes next writev */ -#else /* #ifdef HAVE_WRITEV */ - if (iov[cnt].iov_base && iov[cnt].iov_len > 0) { - /* Non-empty vector */ - int w; /* Bytes written in this call */ - while (p < iov[cnt].iov_len) { - do { - w = write(fd, iov[cnt].iov_base + p, iov[cnt].iov_len - p); - } while (w < 0 && errno == EINTR); - if (w < 0) - return check_error(-1, errInfo); - p += w; + } else + /* Degenerated io vector - use regular write */ +#endif + { + do { + w = write(fd, iov[cnt].iov_base, iov[cnt].iov_len); + } while (w < 0 && errno == EINTR); + ASSERT(w <= iov[cnt].iov_len); + } + if (w < 0) return check_error(-1, errInfo); + /* Move forward to next buffer to write */ + for (; cnt < iovcnt && w > 0; cnt++) { + if (iov[cnt].iov_base && iov[cnt].iov_len > 0) { + if (w < iov[cnt].iov_len) { + /* Adjust the buffer for next write */ + iov[cnt].iov_len -= w; + iov[cnt].iov_base += w; + w = 0; + break; + } else { + w -= iov[cnt].iov_len; + } + } } - } - cnt++; - p = 0; -#endif /* #ifdef HAVE_WRITEV */ + ASSERT(w == 0); + } /* else Non-empty buffer */ } /* while (cnt< iovcnt) */ - size = 0; /* Avoid compiler warning */ return 1; } diff --git a/erts/emulator/drivers/win32/win_efile.c b/erts/emulator/drivers/win32/win_efile.c index 0d3d334154..606fa1d7de 100644 --- a/erts/emulator/drivers/win32/win_efile.c +++ b/erts/emulator/drivers/win32/win_efile.c @@ -1115,8 +1115,7 @@ efile_writev(Efile_error* errInfo, /* Where to return error codes */ SysIOVec* iov, /* Vector of buffer structs. * The structs are unchanged * after the call */ - int iovcnt, /* Number of structs in vector */ - size_t size) /* Number of bytes to write */ + int iovcnt) /* Number of structs in vector */ { int cnt; /* Buffers so far written */ OVERLAPPED overlapped; -- cgit v1.2.3