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poll.c
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poll.c
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#include <string.h>
#include "debug.h"
#include "kernel/fs.h"
#include "fs/fd.h"
#include "fs/poll.h"
#include "kernel/calls.h"
static int user_read_or_zero(addr_t addr, void *data, size_t size) {
if (addr == 0)
memset(data, 0, size);
else if (user_read(addr, data, size))
return _EFAULT;
return 0;
}
#define SELECT_READ (POLL_READ | POLL_HUP | POLL_ERR)
#define SELECT_WRITE (POLL_WRITE | POLL_ERR)
#define SELECT_EX (POLL_PRI)
struct select_context {
char *readfds;
char *writefds;
char *exceptfds;
};
static int select_event_callback(void *context, int types, union poll_fd_info info) {
struct select_context *c = context;
if (types & SELECT_READ)
bit_set(info.fd, c->readfds);
if (types & SELECT_WRITE)
bit_set(info.fd, c->writefds);
if (types & SELECT_EX)
bit_set(info.fd, c->exceptfds);
if (!(types & (SELECT_READ | SELECT_WRITE | SELECT_EX)))
return 0;
return 1;
}
dword_t sys_select(fd_t nfds, addr_t readfds_addr, addr_t writefds_addr, addr_t exceptfds_addr, addr_t timeout_addr) {
size_t fdset_size = BITS_SIZE(nfds);
char readfds[fdset_size];
if (user_read_or_zero(readfds_addr, readfds, fdset_size))
return _EFAULT;
char writefds[fdset_size];
if (user_read_or_zero(writefds_addr, writefds, fdset_size))
return _EFAULT;
char exceptfds[fdset_size];
if (user_read_or_zero(exceptfds_addr, exceptfds, fdset_size))
return _EFAULT;
struct timespec timeout_ts = {};
if (timeout_addr != 0) {
struct timeval_ timeout_timeval;
if (user_get(timeout_addr, timeout_timeval))
return _EFAULT;
timeout_ts.tv_sec = timeout_timeval.sec;
timeout_ts.tv_nsec = timeout_timeval.usec * 1000;
}
// Emacs likes to pass invalid timeout values
timeout_ts = timespec_normalize(timeout_ts);
STRACE("select(%d, 0x%x, 0x%x, 0x%x, 0x%x {%lds %ldns}) ",
nfds, readfds_addr, writefds_addr, exceptfds_addr,
timeout_addr, timeout_ts.tv_sec, timeout_ts.tv_nsec);
struct poll *poll = poll_create();
if (IS_ERR(poll))
return PTR_ERR(poll);
for (fd_t i = 0; i < nfds; i++) {
int events = 0;
if (bit_test(i, readfds))
events |= SELECT_READ;
if (bit_test(i, writefds))
events |= SELECT_WRITE;
if (bit_test(i, exceptfds))
events |= SELECT_EX;
if (events != 0) {
STRACE("%d{%s%s%s} ", i,
bit_test(i, readfds) ? "r" : "",
bit_test(i, writefds) ? "w" : "",
bit_test(i, exceptfds) ? "x" : "");
struct fd *fd = f_get(i);
if (fd == NULL) {
poll_destroy(poll);
return _EBADF;
}
poll_add_fd(poll, fd, events, (union poll_fd_info) i);
}
}
STRACE("...\n");
memset(readfds, 0, fdset_size);
memset(writefds, 0, fdset_size);
memset(exceptfds, 0, fdset_size);
struct select_context context = {readfds, writefds, exceptfds};
int err = poll_wait(poll, select_event_callback, &context, timeout_addr == 0 ? NULL : &timeout_ts);
STRACE("%d end select ", current->pid);
for (fd_t i = 0; i < nfds; i++) {
if (bit_test(i, readfds) || bit_test(i, writefds) || bit_test(i, exceptfds)) {
STRACE("%d{%s%s%s} ", i,
bit_test(i, readfds) ? "r" : "",
bit_test(i, writefds) ? "w" : "",
bit_test(i, exceptfds) ? "x" : "");
}
}
poll_destroy(poll);
if (err < 0)
return err;
if (readfds_addr && user_write(readfds_addr, readfds, fdset_size))
return _EFAULT;
if (writefds_addr && user_write(writefds_addr, writefds, fdset_size))
return _EFAULT;
if (exceptfds_addr && user_write(exceptfds_addr, exceptfds, fdset_size))
return _EFAULT;
return err;
}
struct poll_context {
struct pollfd_ *polls;
struct fd **files;
int nfds;
};
#define POLL_ALWAYS_LISTENING (POLL_ERR|POLL_HUP|POLL_NVAL)
static int poll_event_callback(void *context, int types, union poll_fd_info info) {
struct poll_context *c = context;
struct pollfd_ *polls = c->polls;
int nfds = c->nfds;
int res = 0;
for (int i = 0; i < nfds; i++) {
if (c->files[i] == info.ptr) {
polls[i].revents = types & (polls[i].events | POLL_ALWAYS_LISTENING);
res = 1;
}
}
return res;
}
dword_t sys_poll(addr_t fds, dword_t nfds, int_t timeout) {
STRACE("poll(0x%x, %d, %d)", fds, nfds, timeout);
struct pollfd_ polls[nfds];
if (fds != 0 || nfds != 0)
if (user_read(fds, polls, sizeof(struct pollfd_) * nfds))
return _EFAULT;
struct poll *poll = poll_create();
if (IS_ERR(poll))
return PTR_ERR(poll);
for (unsigned i = 0; i < nfds; i++)
STRACE(" {%d, %#x}", polls[i].fd, polls[i].events);
STRACE("...\n");
struct fd *files[nfds];
for (unsigned i = 0; i < nfds; i++) {
files[i] = f_get(polls[i].fd);
if (files[i] != NULL)
// FIXME it might have been closed by now by another thread
fd_retain(files[i]);
// clear revents, which is reused to mark whether a pollfd has been added or not
polls[i].revents = 0;
}
// convert polls array into poll_add_fd calls
// FIXME this is quadratic
for (unsigned i = 0; i < nfds; i++) {
if (polls[i].fd < 0 || polls[i].revents)
continue;
// if the same fd is listed more than once, merge the events bits together
int events = polls[i].events;
polls[i].revents = 1;
if (files[i] == NULL)
continue;
for (unsigned j = 0; j < nfds; j++) {
if (polls[j].revents)
continue;
if (files[i] == files[j]) {
events |= polls[j].events;
polls[j].revents = 1;
}
}
poll_add_fd(poll, files[i], events | POLL_ALWAYS_LISTENING, (union poll_fd_info) (void *) files[i]);
}
for (unsigned i = 0; i < nfds; i++) {
polls[i].revents = 0;
if (f_get(polls[i].fd) == NULL)
polls[i].revents = POLL_NVAL;
}
struct poll_context context = {polls, files, nfds};
struct timespec timeout_ts;
if (timeout >= 0) {
timeout_ts.tv_sec = timeout / 1000;
timeout_ts.tv_nsec = (timeout % 1000) * 1000000;
}
int res = poll_wait(poll, poll_event_callback, &context, timeout < 0 ? NULL : &timeout_ts);
poll_destroy(poll);
for (unsigned i = 0; i < nfds; i++) {
if (files[i] != NULL)
fd_close(files[i]);
}
STRACE("%d end poll", current->pid);
if (res < 0)
return res;
if (fds != 0 || nfds != 0)
if (user_write(fds, polls, sizeof(struct pollfd_) * nfds))
return _EFAULT;
return res;
}
dword_t sys_pselect(fd_t nfds, addr_t readfds_addr, addr_t writefds_addr, addr_t exceptfds_addr, addr_t timeout_addr, addr_t sigmask_addr) {
// a system call can only take 6 parameters, so the last two need to be passed as a pointer to a struct
struct {
addr_t mask_addr;
dword_t mask_size;
} sigmask;
if (user_get(sigmask_addr, sigmask))
return _EFAULT;
sigset_t_ mask;
if (sigmask.mask_addr != 0) {
if (sigmask.mask_size != sizeof(sigset_t_))
return _EINVAL;
if (user_get(sigmask.mask_addr, mask))
return _EFAULT;
sigmask_set_temp(mask);
}
return sys_select(nfds, readfds_addr, writefds_addr, exceptfds_addr, timeout_addr);
}
dword_t sys_ppoll(addr_t fds, dword_t nfds, addr_t timeout_addr, addr_t sigmask_addr, dword_t sigsetsize) {
int timeout = -1;
if (timeout_addr != 0) {
struct timespec_ timeout_timespec;
if (user_get(timeout_addr, timeout_timespec))
return _EFAULT;
timeout = timeout_timespec.sec * 1000 + timeout_timespec.nsec / 1000000;
}
sigset_t_ mask;
if (sigmask_addr != 0) {
if (sigsetsize != sizeof(sigset_t_))
return _EINVAL;
if (user_get(sigmask_addr, mask))
return _EFAULT;
sigmask_set_temp(mask);
}
return sys_poll(fds, nfds, timeout);
}