/
yaws_sendfile_drv.c
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/
yaws_sendfile_drv.c
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/* Interface to sendfile system call for Yaws */
/* author: vinoski@ieee.org */
/* Created : 09 Nov 2008 by Steve Vinoski <vinoski@ieee.org> */
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#if defined(__linux__)
#include <sys/sendfile.h>
#elif (defined(__APPLE__) && defined(__MACH__)) || defined(__FreeBSD__)
#include <sys/socket.h>
#include <sys/uio.h>
#else
#error "yaws_sendfile_drv not supported on this platform"
#endif
#include "erl_driver.h"
#ifndef ERL_DRV_NIL
#include "erl_driver_compat.h"
#endif
#include "hashtable.h"
typedef struct _transfer {
off_t offset;
size_t count;
ssize_t total;
int file_fd;
} Transfer;
typedef struct hashtable* Transfers;
typedef struct _desc {
ErlDrvPort port;
Transfers xfer_table;
} Desc;
static unsigned int fdhash(void* k)
{
return *(unsigned int*)&k;
}
static int fdeq(void* k1, void* k2)
{
return *(int*)&k1 == *(int*)&k2;
}
static ErlDrvData yaws_sendfile_drv_start(ErlDrvPort port, char* buf)
{
Desc* d = (Desc*)driver_alloc(sizeof(Desc));
if (d == NULL) return (ErlDrvData) -1;
d->port = port;
d->xfer_table = create_hashtable(8192, fdhash, fdeq);
if (d->xfer_table == NULL) {
driver_free(d);
return (ErlDrvData) -1;
}
return (ErlDrvData)d;
}
static void yaws_sendfile_drv_stop(ErlDrvData handle)
{
Desc* d = (Desc*)handle;
hashtable_destroy(d->xfer_table, 1);
driver_free(d);
}
typedef union {
off_t offset;
size_t size;
ssize_t count;
u_int64_t bits;
} U64_t;
typedef union {
char* buffer;
struct {
U64_t offset;
U64_t count;
unsigned int out_fd: 32;
char filename[1];
}* args;
struct {
U64_t count;
unsigned int out_fd: 32;
unsigned char success;
char errno_string[1];
}* result;
} Buffer;
static int set_error_buffer(Buffer* b, int socket_fd, int err)
{
char* s, *t;
memset(b->result, 0, sizeof *b->result);
b->result->out_fd = socket_fd;
for (s = erl_errno_id(err), t = b->result->errno_string; *s; s++, t++) {
*t = tolower(*s);
}
*t = '\0';
return sizeof(*b->result) - 1 + t - b->result->errno_string;
}
static ssize_t yaws_sendfile_call(int out_fd, int in_fd, off_t* offset, size_t count)
{
#if defined(__linux__)
off_t cur = *offset;
ssize_t retval;
do {
retval = sendfile(out_fd, in_fd, offset, count);
} while (retval < 0 && errno == EINTR);
if (retval >= 0 && retval != count) {
if (*offset == cur) {
*offset += retval;
}
retval = -1;
errno = EAGAIN;
}
return retval;
#elif defined(__APPLE__) && defined(__MACH__)
off_t len = count;
int retval;
do {
retval = sendfile(in_fd, out_fd, *offset, &len, NULL, 0);
} while (retval < 0 && errno == EINTR);
if (retval < 0 && errno == EAGAIN) {
*offset += len;
}
return retval == 0 ? len : retval;
#elif defined(__FreeBSD__)
off_t len = 0;
int retval;
do {
retval = sendfile(in_fd, out_fd, *offset, count, NULL, &len, 0);
} while (retval < 0 && errno == EINTR);
if (retval < 0 && errno == EAGAIN) {
*offset += len;
}
return retval == 0 ? len : retval;
#else
errno = ENOSYS;
return -1;
#endif
}
static void yaws_sendfile_drv_output(ErlDrvData handle, char* buf, int buflen)
{
int fd, socket_fd;
Desc* d = (Desc*)handle;
Buffer b;
b.buffer = buf;
socket_fd = b.args->out_fd;
fd = open(b.args->filename, O_RDONLY | O_NONBLOCK);
if (fd < 0) {
int out_buflen = set_error_buffer(&b, socket_fd, errno);
driver_output(d->port, buf, out_buflen);
} else {
Transfer* xfer = (Transfer*)hashtable_search(d->xfer_table, &socket_fd);
if (xfer == NULL) {
xfer = (Transfer*)malloc(sizeof(Transfer));
if (xfer == NULL) {
int out_buflen = set_error_buffer(&b, socket_fd, ENOMEM);
driver_output(d->port, buf, out_buflen);
return;
}
if (!hashtable_insert(d->xfer_table, &socket_fd, xfer)) {
int out_buflen = set_error_buffer(&b, socket_fd, ENOMEM);
driver_output(d->port, buf, out_buflen);
free(xfer);
return;
}
}
xfer->file_fd = fd;
xfer->offset = b.args->offset.offset;
xfer->count = b.args->count.size;
xfer->total = 0;
driver_select(d->port, *(ErlDrvEvent*)&socket_fd, DO_WRITE, 1);
}
}
static void yaws_sendfile_drv_ready_output(ErlDrvData handle, ErlDrvEvent ev)
{
Desc* d = (Desc*)handle;
int socket_fd = *(int*)&ev;
ssize_t result;
off_t cur_offset;
Transfer* xfer = (Transfer*)hashtable_search(d->xfer_table, &socket_fd);
if (xfer == NULL) {
/* fatal error, something is very wrong */
driver_failure_atom(d->port, "socket_fd_not_found");
return;
}
cur_offset = xfer->offset;
result = yaws_sendfile_call(socket_fd, xfer->file_fd, &xfer->offset, xfer->count);
if (result < 0 && (errno == EAGAIN || errno == EWOULDBLOCK)) {
off_t written = xfer->offset - cur_offset;
xfer->count -= written;
xfer->total += written;
} else {
int out_buflen;
char buf[36];
Buffer b;
b.buffer = buf;
memset(buf, 0, sizeof buf);
driver_select(d->port, *(ErlDrvEvent*)&socket_fd, DO_WRITE, 0);
close(xfer->file_fd);
if (result < 0) {
out_buflen = set_error_buffer(&b, socket_fd, errno);
} else {
b.result->count.count = xfer->total + result;
b.result->out_fd = socket_fd;
b.result->success = 1;
b.result->errno_string[0] = '\0';
out_buflen = sizeof(*b.result);
}
xfer->file_fd = -1;
xfer->offset = xfer->count = xfer->total = 0;
driver_output(d->port, buf, out_buflen);
}
}
static ErlDrvEntry yaws_sendfile_driver_entry = {
NULL,
yaws_sendfile_drv_start,
yaws_sendfile_drv_stop,
yaws_sendfile_drv_output,
NULL,
yaws_sendfile_drv_ready_output,
"yaws_sendfile_drv",
NULL,
NULL,
NULL,
NULL
};
DRIVER_INIT(yaws_sendfile_drv)
{
return &yaws_sendfile_driver_entry;
}