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// See LICENSE for license details.
#include <string.h>
#include <errno.h>
#include "file.h"
#include "pk.h"
#include "frontend.h"
#include "pcr.h"
#include "vm.h"
#define MAX_FDS 32
static file_t* fds[MAX_FDS];
#define MAX_FILES 32
static file_t files[MAX_FILES] = {[0 ... MAX_FILES-1] = {-1,{0}}};
file_t *stdout, *stdin, *stderr;
void file_incref(file_t* f)
{
atomic_add(&f->refcnt, 1);
}
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);
}
}
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 (fds[i] == NULL && __sync_bool_compare_and_swap(&fds[i], 0, f))
{
file_incref(f);
return i;
}
}
return -1;
}
void file_init()
{
stdin = file_get_free();
stdout = file_get_free();
stderr = file_get_free();
stdin->kfd = 0;
stdout->kfd = 1;
stderr->kfd = 2;
// create user FDs 0, 1, and 2
file_dup(stdin);
file_dup(stdout);
file_dup(stderr);
}
file_t* file_get(int fd)
{
file_t* f;
if (fd < 0 || fd >= MAX_FDS || (f = 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;
}
sysret_t file_open(const char* fn, int flags, int mode)
{
file_t* f = file_get_free();
if(!f)
return (sysret_t){-1,ENOMEM};
size_t fn_size = strlen(fn)+1;
sysret_t ret = frontend_syscall(SYS_open, (long)fn, fn_size, flags, mode);
if(ret.result != -1)
{
f->kfd = ret.result;
ret.result = (long)f;
}
else
file_decref(f);
return ret;
}
int fd_close(int fd)
{
file_t* f = file_get(fd);
if (!f)
return -1;
int success = __sync_bool_compare_and_swap(&fds[fd], f, 0);
file_decref(f);
if (!success)
return -1;
file_decref(f);
return 0;
}
sysret_t file_read(file_t* f, void* buf, size_t size)
{
populate_mapping(buf, size, PROT_WRITE);
return frontend_syscall(SYS_read, f->kfd, (uintptr_t)buf, size, 0);
}
sysret_t file_pread(file_t* f, void* buf, size_t size, off_t offset)
{
populate_mapping(buf, size, PROT_WRITE);
return frontend_syscall(SYS_pread, f->kfd, (uintptr_t)buf, size, offset);
}
sysret_t file_write(file_t* f, const void* buf, size_t size)
{
populate_mapping(buf, size, PROT_READ);
return frontend_syscall(SYS_write, f->kfd, (uintptr_t)buf, size, 0);
}
sysret_t file_pwrite(file_t* f, const void* buf, size_t size, off_t offset)
{
populate_mapping(buf, size, PROT_READ);
return frontend_syscall(SYS_pwrite, f->kfd, (uintptr_t)buf, size, offset);
}
sysret_t file_stat(file_t* f, struct stat* s)
{
populate_mapping(s, sizeof(*s), PROT_WRITE);
return frontend_syscall(SYS_fstat, f->kfd, (uintptr_t)s, 0, 0);
}
sysret_t file_lseek(file_t* f, size_t ptr, int dir)
{
return frontend_syscall(SYS_lseek, f->kfd, ptr, dir, 0);
}
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