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// See LICENSE for license details.
#include "file.h"
#include "atomic.h"
#include "mmap.h"
#include "frontend.h"
#include "syscall.h"
#include "pk.h"
#include <string.h>
#include <errno.h>
#define MAX_FDS 128
static file_t* fds[MAX_FDS];
#define MAX_FILES 128
file_t files[MAX_FILES] = {[0 ... MAX_FILES-1] = {-1,0}};
void file_incref(file_t* f)
{
long prev = atomic_add(&f->refcnt, 1);
kassert(prev > 0);
}
void file_decref(file_t* f)
{
if (atomic_add(&f->refcnt, -1) == 2)
{
int kfd = f->kfd;
mb();
atomic_set(&f->refcnt, 0);
frontend_syscall(SYS_close, kfd, 0, 0, 0, 0, 0, 0);
}
}
static file_t* file_get_free()
{
for (file_t* f = files; f < files + MAX_FILES; f++)
if (atomic_read(&f->refcnt) == 0 && atomic_cas(&f->refcnt, 0, 2) == 0)
return f;
return NULL;
}
int file_dup(file_t* f)
{
for (int i = 0; i < MAX_FDS; i++)
{
if (atomic_cas(&fds[i], 0, f) == 0)
{
file_incref(f);
return i;
}
}
return -1;
}
int file_dup3(file_t* f, int newfd)
{
if (newfd < 0 || newfd >= MAX_FDS)
return -1;
if (atomic_cas(&fds[newfd], 0, f) == 0)
{
file_incref(f);
return newfd;
}
return -1;
}
void file_init()
{
// create stdin, stdout, stderr and FDs 0-2
for (int i = 0; i < 3; i++) {
file_t* f = file_get_free();
f->kfd = i;
file_dup(f);
}
}
file_t* file_get(int fd)
{
file_t* f;
if (fd < 0 || fd >= MAX_FDS || (f = atomic_read(&fds[fd])) == NULL)
return 0;
long old_cnt;
do {
old_cnt = atomic_read(&f->refcnt);
if (old_cnt == 0)
return 0;
} while (atomic_cas(&f->refcnt, old_cnt, old_cnt+1) != old_cnt);
return f;
}
file_t* file_open(const char* fn, int flags, int mode)
{
return file_openat(AT_FDCWD, fn, flags, mode);
}
file_t* file_openat(int dirfd, const char* fn, int flags, int mode)
{
file_t* f = file_get_free();
if (f == NULL)
return ERR_PTR(-ENOMEM);
size_t fn_size = strlen(fn)+1;
long ret = frontend_syscall(SYS_openat, dirfd, kva2pa(fn), fn_size, flags, mode, 0, 0);
if (ret >= 0)
{
f->kfd = ret;
return f;
}
else
{
file_decref(f);
return ERR_PTR(ret);
}
}
int fd_close(int fd)
{
file_t* f = file_get(fd);
if (!f)
return -1;
file_t* old = atomic_cas(&fds[fd], f, 0);
file_decref(f);
if (old != f)
return -1;
file_decref(f);
return 0;
}
ssize_t file_read(file_t* f, void* buf, size_t size)
{
return frontend_syscall(SYS_read, f->kfd, kva2pa(buf), size, 0, 0, 0, 0);
}
ssize_t file_pread(file_t* f, void* buf, size_t size, off_t offset)
{
return frontend_syscall(SYS_pread, f->kfd, kva2pa(buf), size, offset, 0, 0, 0);
}
ssize_t file_write(file_t* f, const void* buf, size_t size)
{
return frontend_syscall(SYS_write, f->kfd, kva2pa(buf), size, 0, 0, 0, 0);
}
ssize_t file_pwrite(file_t* f, const void* buf, size_t size, off_t offset)
{
return frontend_syscall(SYS_pwrite, f->kfd, kva2pa(buf), size, offset, 0, 0, 0);
}
int file_truncate(file_t* f, off_t len)
{
return frontend_syscall(SYS_ftruncate, f->kfd, len, 0, 0, 0, 0, 0);
}
ssize_t file_lseek(file_t* f, size_t ptr, int dir)
{
return frontend_syscall(SYS_lseek, f->kfd, ptr, dir, 0, 0, 0, 0);
}
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