From ec885e883c99825e7d737752b1b0aebbbafbd670 Mon Sep 17 00:00:00 2001 From: Lukas Larsson Date: Mon, 5 Dec 2011 18:45:44 +0100 Subject: Clarify some code comments Thanks Tuncer Ayaz --- erts/emulator/drivers/unix/unix_efile.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) (limited to 'erts/emulator/drivers/unix') diff --git a/erts/emulator/drivers/unix/unix_efile.c b/erts/emulator/drivers/unix/unix_efile.c index 2b68334ad7..92314fce36 100644 --- a/erts/emulator/drivers/unix/unix_efile.c +++ b/erts/emulator/drivers/unix/unix_efile.c @@ -1469,6 +1469,9 @@ efile_fadvise(Efile_error* errInfo, int fd, Sint64 offset, } #ifdef HAVE_SENDFILE + +// For some reason the maximum size_t cannot be used as the max size +// 3GB seems to work on all platforms #define SENDFILE_CHUNK_SIZE ((1 << 30) -1) /* @@ -1477,7 +1480,13 @@ efile_fadvise(Efile_error* errInfo, int fd, Sint64 offset, * we have to emulate some things in linux and play with variables on * bsd/darwin. * - * It could be possible to implement header/trailer in sendfile, though + * All of the calls will split a command which tries to send more than + * SENDFILE_CHUNK_SIZE of data at once. + * + * On platforms where *nbytes of 0 does not mean the entire file, this is + * simulated. + * + * It could be possible to implement header/trailer in sendfile. Though * you would have to emulate it in linux and on BSD/Darwin some complex * calculations have to be made when using a non blocking socket to figure * out how much of the header/file/trailer was sent in each command. @@ -1491,7 +1500,7 @@ efile_sendfile(Efile_error* errInfo, int in_fd, int out_fd, #if defined(__linux__) ssize_t retval; do { - // check if *nbytes is 0 or greater than the largest size_t + // check if *nbytes is 0 or greater than chunk size if (*nbytes == 0 || *nbytes > SENDFILE_CHUNK_SIZE) retval = sendfile(out_fd, in_fd, offset, SENDFILE_CHUNK_SIZE); else @@ -1512,6 +1521,7 @@ efile_sendfile(Efile_error* errInfo, int in_fd, int out_fd, do { fdrec.sfv_off = *offset; len = 0; + // check if *nbytes is 0 or greater than chunk size if (*nbytes == 0 || *nbytes > SENDFILE_CHUNK_SIZE) fdrec.sfv_len = SENDFILE_CHUNK_SIZE; else @@ -1529,7 +1539,7 @@ efile_sendfile(Efile_error* errInfo, int in_fd, int out_fd, int retval; off_t len; do { - // check if *nbytes is 0 or greater than the largest off_t + // check if *nbytes is 0 or greater than chunk size if(*nbytes > SENDFILE_CHUNK_SIZE) len = SENDFILE_CHUNK_SIZE; else -- cgit v1.2.3