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Kernel: Use C++ structured bindings to bind syscall parameters
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Some syscalls have to pass parameters through a struct, since we can
only fit 3 parameters with our calling convention.

This patch makes use of C++ structured binding to clean up the places
where we expand those parameters structs into local variables.
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@awesomekling
awesomekling committed Nov 10, 2019
1 parent 7e7451c commit 72fae05
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Showing 2 changed files with 44 additions and 61 deletions.
91 changes: 36 additions & 55 deletions Kernel/Process.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -196,15 +196,11 @@ void* Process::sys$mmap(const Syscall::SC_mmap_params* params)
{
if (!validate_read(params, sizeof(Syscall::SC_mmap_params)))
return (void*)-EFAULT;
if (params->name && !validate_read_str(params->name))

auto& [addr, size, prot, flags, fd, offset, name] = *params;

if (name && !validate_read_str(name))
return (void*)-EFAULT;
void* addr = (void*)params->addr;
size_t size = params->size;
int prot = params->prot;
int flags = params->flags;
int fd = params->fd;
off_t offset = params->offset;
const char* name = params->name;
if (size == 0)
return (void*)-EINVAL;
if ((u32)addr & ~PAGE_MASK)
Expand Down Expand Up @@ -1351,7 +1347,7 @@ int Process::sys$open(const Syscall::SC_open_params* params)
{
if (!validate_read_typed(params))
return -EFAULT;
auto [path, path_length, options, mode] = *params;
auto& [path, path_length, options, mode] = *params;
if (!validate_read(path, path_length))
return -EFAULT;
#ifdef DEBUG_IO
Expand All @@ -1376,7 +1372,7 @@ int Process::sys$openat(const Syscall::SC_openat_params* params)
{
if (!validate_read_typed(params))
return -EFAULT;
auto [dirfd, path, path_length, options, mode] = *params;
auto& [dirfd, path, path_length, options, mode] = *params;
if (!validate_read(path, path_length))
return -EFAULT;
#ifdef DEBUG_IO
Expand Down Expand Up @@ -2070,21 +2066,24 @@ int Process::sys$select(const Syscall::SC_select_params* params)
// FIXME: Return -EINVAL if timeout is invalid.
if (!validate_read_typed(params))
return -EFAULT;
if (params->writefds && !validate_write_typed(params->writefds))

auto& [nfds, readfds, writefds, exceptfds, timeout] = *params;

if (writefds && !validate_write_typed(writefds))
return -EFAULT;
if (params->readfds && !validate_write_typed(params->readfds))
if (readfds && !validate_write_typed(readfds))
return -EFAULT;
if (params->exceptfds && !validate_write_typed(params->exceptfds))
if (exceptfds && !validate_write_typed(exceptfds))
return -EFAULT;
if (params->timeout && !validate_read_typed(params->timeout))
if (timeout && !validate_read_typed(timeout))
return -EFAULT;
if (params->nfds < 0)
if (nfds < 0)
return -EINVAL;

timeval timeout;
timeval computed_timeout;
bool select_has_timeout = false;
if (params->timeout && (params->timeout->tv_sec || params->timeout->tv_usec)) {
timeval_add(kgettimeofday(), *params->timeout, timeout);
if (timeout && (timeout->tv_sec || timeout->tv_usec)) {
timeval_add(kgettimeofday(), *timeout, computed_timeout);
select_has_timeout = true;
}

Expand All @@ -2105,19 +2104,19 @@ int Process::sys$select(const Syscall::SC_select_params* params)
}
return 0;
};
if (int error = transfer_fds(params->writefds, wfds))
if (int error = transfer_fds(writefds, wfds))
return error;
if (int error = transfer_fds(params->readfds, rfds))
if (int error = transfer_fds(readfds, rfds))
return error;
if (int error = transfer_fds(params->exceptfds, efds))
if (int error = transfer_fds(exceptfds, efds))
return error;

#if defined(DEBUG_IO) || defined(DEBUG_POLL_SELECT)
dbgprintf("%s<%u> selecting on (read:%u, write:%u), timeout=%p\n", name().characters(), pid(), rfds.size(), wfds.size(), params->timeout);
dbgprintf("%s<%u> selecting on (read:%u, write:%u), timeout=%p\n", name().characters(), pid(), rfds.size(), wfds.size(), timeout);
#endif

if (!params->timeout || select_has_timeout) {
if (current->block<Thread::SelectBlocker>(timeout, select_has_timeout, rfds, wfds, efds) == Thread::BlockResult::InterruptedBySignal)
if (!timeout || select_has_timeout) {
if (current->block<Thread::SelectBlocker>(computed_timeout, select_has_timeout, rfds, wfds, efds) == Thread::BlockResult::InterruptedBySignal)
return -EINTR;
}

Expand All @@ -2133,9 +2132,9 @@ int Process::sys$select(const Syscall::SC_select_params* params)
}
}
};
mark_fds(params->readfds, rfds, [](auto& description) { return description.can_read(); });
mark_fds(params->writefds, wfds, [](auto& description) { return description.can_write(); });
// FIXME: We should also mark params->exceptfds as appropriate.
mark_fds(readfds, rfds, [](auto& description) { return description.can_read(); });
mark_fds(writefds, wfds, [](auto& description) { return description.can_write(); });
// FIXME: We should also mark exceptfds as appropriate.

return marked_fd_count;
}
Expand Down Expand Up @@ -2465,12 +2464,7 @@ ssize_t Process::sys$sendto(const Syscall::SC_sendto_params* params)
if (!validate_read_typed(params))
return -EFAULT;

int sockfd = params->sockfd;
const void* data = params->data;
size_t data_length = params->data_length;
int flags = params->flags;
auto* addr = (const sockaddr*)params->addr;
auto addr_length = (socklen_t)params->addr_length;
auto& [sockfd, data, data_length, flags, addr, addr_length] = *params;

if (!validate_read(data, data_length))
return -EFAULT;
Expand All @@ -2491,12 +2485,7 @@ ssize_t Process::sys$recvfrom(const Syscall::SC_recvfrom_params* params)
if (!validate_read_typed(params))
return -EFAULT;

int sockfd = params->sockfd;
void* buffer = params->buffer;
size_t buffer_length = params->buffer_length;
int flags = params->flags;
auto* addr = (sockaddr*)params->addr;
auto* addr_length = (socklen_t*)params->addr_length;
auto& [sockfd, buffer, buffer_length, flags, addr, addr_length] = *params;

if (!validate_write(buffer, buffer_length))
return -EFAULT;
Expand Down Expand Up @@ -2627,11 +2616,8 @@ int Process::sys$getsockopt(const Syscall::SC_getsockopt_params* params)
{
if (!validate_read_typed(params))
return -EFAULT;
int sockfd = params->sockfd;
int level = params->level;
int option = params->option;
auto* value = params->value;
auto* value_size = (socklen_t*)params->value_size;

auto& [sockfd, level, option, value, value_size] = *params;

if (!validate_write_typed(value_size))
return -EFAULT;
Expand All @@ -2650,11 +2636,8 @@ int Process::sys$setsockopt(const Syscall::SC_setsockopt_params* params)
{
if (!validate_read_typed(params))
return -EFAULT;
int sockfd = params->sockfd;
int level = params->level;
int option = params->option;
auto* value = params->value;
auto value_size = (socklen_t)params->value_size;

auto& [sockfd, level, option, value, value_size] = *params;

if (!validate_read(value, value_size))
return -EFAULT;
Expand Down Expand Up @@ -3201,17 +3184,15 @@ int Process::sys$clock_nanosleep(const Syscall::SC_clock_nanosleep_params* param
if (!validate_read_typed(params))
return -EFAULT;

if (params->requested_sleep && !validate_read_typed(params->requested_sleep))
auto& [clock_id, flags, requested_sleep, remaining_sleep] = *params;

if (requested_sleep && !validate_read_typed(requested_sleep))
return -EFAULT;

if (params->remaining_sleep && !validate_write_typed(params->remaining_sleep))
if (remaining_sleep && !validate_write_typed(remaining_sleep))
return -EFAULT;

clockid_t clock_id = params->clock_id;
int flags = params->flags;
bool is_absolute = flags & TIMER_ABSTIME;
auto* requested_sleep = params->requested_sleep;
auto* remaining_sleep = params->remaining_sleep;

switch (clock_id) {
case CLOCK_MONOTONIC: {
Expand Down
14 changes: 8 additions & 6 deletions Kernel/Syscall.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,8 @@
extern "C" {
struct timeval;
struct timespec;
struct sockaddr;
typedef u32 socklen_t;
}

#define ENUMERATE_SYSCALLS \
Expand Down Expand Up @@ -208,33 +210,33 @@ struct SC_sendto_params {
const void* data;
size_t data_length;
int flags;
const void* addr; // const sockaddr*
size_t addr_length; // socklen_t
const sockaddr* addr;
socklen_t addr_length;
};

struct SC_recvfrom_params {
int sockfd;
void* buffer;
size_t buffer_length;
int flags;
void* addr; // sockaddr*
void* addr_length; // socklen_t*
sockaddr* addr;
socklen_t* addr_length;
};

struct SC_getsockopt_params {
int sockfd;
int level;
int option;
void* value;
void* value_size; // socklen_t*
socklen_t* value_size;
};

struct SC_setsockopt_params {
int sockfd;
int level;
int option;
const void* value;
size_t value_size; // socklen_t
socklen_t value_size;
};

void initialize();
Expand Down

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