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Kernel: Add a new fcntl() system call

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This commit is contained in:
apio 2022-10-15 10:56:06 +02:00
parent 3eb1bff2e9
commit 5c61252061
3 changed files with 55 additions and 14 deletions
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4
kernel/include/sys/Syscall.h
View File

@ -16,6 +16,7 @@
#define SYS_close 11
#define SYS_seek 12
#define SYS_exec 13
#define SYS_fcntl 14
namespace Syscall
{
@ -37,4 +38,5 @@ void sys_open(Context* context, const char* filename, int flags);
void sys_read(Context* context, int fd, size_t size, char* buffer);
void sys_close(Context* context, int fd);
void sys_seek(Context* context, int fd, long offset, int whence);
void sys_exec(Context* context, const char* pathname);
void sys_exec(Context* context, const char* pathname);
void sys_fcntl(Context* context, int fd, int command, uintptr_t arg);

3
kernel/src/sys/Syscall.cpp
View File

@ -25,12 +25,13 @@ void Syscall::entry(Context* context)
case SYS_close: sys_close(context, (int)context->rdi); break;
case SYS_seek: sys_seek(context, (int)context->rdi, (long)context->rsi, (int)context->rdx); break;
case SYS_exec: sys_exec(context, (const char*)context->rdi); break;
case SYS_fcntl: sys_fcntl(context, (int)context->rdi, (int)context->rsi, context->rdx); break;
default: context->rax = -ENOSYS; break;
}
VMM::exit_syscall_context();
}
char* Syscall::strdup_from_user(const char* user_string)
char* Syscall::strdup_from_user(const char* user_string) // FIXME: This function is a little hacky.
{
uint64_t phys = VMM::get_physical((uint64_t)user_string);
if (phys == (uint64_t)-1) { return nullptr; }

62
kernel/src/sys/stdio.cpp
View File

@ -18,6 +18,42 @@
#define SEEK_CUR 1
#define SEEK_END 2
#define FNCTL_DUPFD 0
void sys_fcntl(Context* context, int fd, int command, uintptr_t arg)
{
if (fd >= TASK_MAX_FDS || fd < 0)
{
context->rax = -EBADF;
return;
}
Task* current_task = Scheduler::current_task();
if (!current_task->files[fd].is_open())
{
context->rax = -EBADF;
return;
}
Descriptor& file = current_task->files[fd];
if (command == FNCTL_DUPFD)
{
int dupfd = current_task->alloc_fd();
if (dupfd < 0)
{
context->rax = -EMFILE;
return;
}
current_task->files[dupfd] = file;
context->rax = dupfd;
kdbgln("fcntl(F_DUPFD): duplicated fd %d, result is %d", fd, dupfd);
return;
}
else
{
context->rax = -EINVAL;
return;
}
}
void sys_seek(Context* context, int fd, long offset, int whence)
{
if (whence < SEEK_SET || whence > SEEK_END)
@ -36,12 +72,13 @@ void sys_seek(Context* context, int fd, long offset, int whence)
context->rax = -EBADF;
return;
}
Descriptor& file = current_task->files[fd];
long new_offset;
if (whence == SEEK_SET) new_offset = offset;
else if (whence == SEEK_CUR)
new_offset = offset + current_task->files[fd].offset();
new_offset = offset + file.offset();
else if (whence == SEEK_END)
new_offset = current_task->files[fd].length() + offset;
new_offset = file.length() + offset;
else
__builtin_unreachable();
if (new_offset < 0)
@ -49,7 +86,12 @@ void sys_seek(Context* context, int fd, long offset, int whence)
context->rax = -EINVAL; // FIXME: Is this the right error?
return;
}
int result = current_task->files[fd].seek(new_offset);
if (new_offset == file.offset())
{
context->rax = new_offset;
return;
}
int result = file.seek(new_offset);
if (result < 0)
{
context->rax = result;
@ -77,12 +119,13 @@ void sys_write(Context* context, int fd, size_t size, const char* addr)
context->rax = -EBADF;
return;
}
if (!current_task->files[fd].can_write())
Descriptor& file = current_task->files[fd];
if (!file.can_write())
{
context->rax = -EBADF;
return;
}
ssize_t result = current_task->files[fd].write(size, (const char*)VMM::get_physical((uint64_t)addr));
ssize_t result = file.write(size, (const char*)VMM::get_physical((uint64_t)addr));
context->rax = (size_t)result;
return;
}
@ -90,13 +133,8 @@ void sys_write(Context* context, int fd, size_t size, const char* addr)
void sys_open(Context* context, const char* filename, int flags)
{
Task* current_task = Scheduler::current_task();
int fd;
for (fd = 0; fd < TASK_MAX_FDS; fd++)
{
if (!current_task->files[fd].is_open()) break;
}
if (fd == TASK_MAX_FDS)
int fd = current_task->alloc_fd();
if (fd < 0)
{
context->rax = -EMFILE;
return;