fd: new abstraction

src/fs/fd.c

@@ -0,0 +1,123 @@
+#include <kernel/fd.h>
+#include <arch/spinlock.h>
+#include <stdbool.h>
+#include <kernel/alloc.h>
+
+// XXX limit the max fd number
+
+int fd_release(fd_t* fd){	
+	spinlock_release(&fd->lock);
+	return 0;
+}
+
+int fd_access(fdtable_t* fdtable, fd_t** fd, int ifd){
+	spinlock_acquire(&fdtable->lock);
+	
+	if(ifd >= fdtable->fdcount || fdtable->fd[ifd] == NULL){
+		spinlock_release(&fdtable->lock);
+		return EBADF;
+	}
+
+	*fd = fdtable->fd[ifd];
+	fd_t* efd = *fd;
+	spinlock_acquire(&efd->lock);
+	spinlock_release(&fdtable->lock);
+
+	return 0;
+
+}
+
+int fd_alloc(fdtable_t* fdtable, fd_t** fd, int* ifd){
+	spinlock_acquire(&fdtable->lock);
+	
+	// find fd to use
+	
+	bool ok = false;
+
+	for(uintmax_t i = fdtable->firstfreefd; i < fdtable->fdcount; ++i){
+		if(!fdtable->fd[i]){
+			fdtable->firstfreefd = i;
+			*ifd = i;
+			ok = true;
+			break;
+		}
+	}
+
+	// resize table
+
+	if(!ok){
+		
+		fd_t** tmp = realloc(fdtable->fd, sizeof(fd_t*)*(fdtable->fdcount + 1));
+		
+		if(!tmp){
+			spinlock_release(&fdtable->lock);
+			return ENOMEM;
+		}	
+
+		fdtable->fd = tmp;
+		*ifd = fdtable->fdcount;
+		++fdtable->fdcount;
+		
+	}
+	
+	fd_t* tmp = alloc(sizeof(fd_t));
+	
+	if(!tmp){
+		spinlock_release(&fdtable->lock);
+		return ENOMEM;
+	}	
+
+	spinlock_acquire(&tmp->lock);
+	tmp->refcount = 1;
+
+
+	fdtable->fd[*ifd] = tmp;
+
+	spinlock_release(&fdtable->lock);
+
+	*fd = tmp;
+
+	return 0;
+
+}
+
+int fd_free(fdtable_t* fdtable, int ifd){
+	spinlock_acquire(&fdtable->lock);
+	
+	if(ifd >= fdtable->fdcount || fdtable->fd[ifd] == NULL){
+		spinlock_release(&fdtable->lock);
+		return EBADF;
+	}
+
+	fd_t* fd = fdtable->fd[ifd];
+	spinlock_acquire(&fd->lock);
+	
+	if(--fd->refcount > 0){
+		spinlock_release(&fd->lock);
+		spinlock_release(&fdtable->lock);
+		return 0;
+	}
+
+	fdtable->fd[ifd] = NULL;
+	
+	spinlock_release(&fdtable->lock);
+	
+	int err = vfs_close(fd->node);
+
+	free(fd);
+
+	return err;
+	
+}
+
+int fd_tableinit(fdtable_t* fdtable){
+	
+	fdtable->fd = alloc(sizeof(fd_t*)*3);
+
+	if(!fdtable->fd) return ENOMEM;
+
+	fdtable->fdcount = 3;
+	
+	return 0;
+
+}