《操作系统》的实验代码。
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#include <defs.h>
#include <string.h>
#include <vfs.h>
#include <proc.h>
#include <file.h>
#include <unistd.h>
#include <iobuf.h>
#include <inode.h>
#include <stat.h>
#include <dirent.h>
#include <error.h>
#include <assert.h>
#define testfd(fd) ((fd) >= 0 && (fd) < FILES_STRUCT_NENTRY)
// get_fd_array - get current process's open files table
static struct file *
get_fd_array(void) {
struct files_struct *filesp = current->filesp;
assert(filesp != NULL && files_count(filesp) > 0);
return filesp->fd_array;
}
// fd_array_init - initialize the open files table
void
fd_array_init(struct file *fd_array) {
int fd;
struct file *file = fd_array;
for (fd = 0; fd < FILES_STRUCT_NENTRY; fd ++, file ++) {
file->open_count = 0;
file->status = FD_NONE, file->fd = fd;
}
}
// fs_array_alloc - allocate a free file item (with FD_NONE status) in open files table
static int
fd_array_alloc(int fd, struct file **file_store) {
// panic("debug");
struct file *file = get_fd_array();
if (fd == NO_FD) {
for (fd = 0; fd < FILES_STRUCT_NENTRY; fd ++, file ++) {
if (file->status == FD_NONE) {
goto found;
}
}
return -E_MAX_OPEN;
}
else {
if (testfd(fd)) {
file += fd;
if (file->status == FD_NONE) {
goto found;
}
return -E_BUSY;
}
return -E_INVAL;
}
found:
assert(fopen_count(file) == 0);
file->status = FD_INIT, file->node = NULL;
*file_store = file;
return 0;
}
// fd_array_free - free a file item in open files table
static void
fd_array_free(struct file *file) {
assert(file->status == FD_INIT || file->status == FD_CLOSED);
assert(fopen_count(file) == 0);
if (file->status == FD_CLOSED) {
vfs_close(file->node);
}
file->status = FD_NONE;
}
static void
fd_array_acquire(struct file *file) {
assert(file->status == FD_OPENED);
fopen_count_inc(file);
}
// fd_array_release - file's open_count--; if file's open_count-- == 0 , then call fd_array_free to free this file item
static void
fd_array_release(struct file *file) {
assert(file->status == FD_OPENED || file->status == FD_CLOSED);
assert(fopen_count(file) > 0);
if (fopen_count_dec(file) == 0) {
fd_array_free(file);
}
}
// fd_array_open - file's open_count++, set status to FD_OPENED
void
fd_array_open(struct file *file) {
assert(file->status == FD_INIT && file->node != NULL);
file->status = FD_OPENED;
fopen_count_inc(file);
}
// fd_array_close - file's open_count--; if file's open_count-- == 0 , then call fd_array_free to free this file item
void
fd_array_close(struct file *file) {
assert(file->status == FD_OPENED);
assert(fopen_count(file) > 0);
file->status = FD_CLOSED;
if (fopen_count_dec(file) == 0) {
fd_array_free(file);
}
}
//fs_array_dup - duplicate file 'from' to file 'to'
void
fd_array_dup(struct file *to, struct file *from) {
//cprintf("[fd_array_dup]from fd=%d, to fd=%d\n",from->fd, to->fd);
assert(to->status == FD_INIT && from->status == FD_OPENED);
to->pos = from->pos;
to->readable = from->readable;
to->writable = from->writable;
struct inode *node = from->node;
vop_ref_inc(node), vop_open_inc(node);
to->node = node;
fd_array_open(to);
}
// fd2file - use fd as index of fd_array, return the array item (file)
static inline int
fd2file(int fd, struct file **file_store) {
if (testfd(fd)) {
struct file *file = get_fd_array() + fd;
if (file->status == FD_OPENED && file->fd == fd) {
*file_store = file;
return 0;
}
}
return -E_INVAL;
}
// file_testfd - test file is readble or writable?
bool
file_testfd(int fd, bool readable, bool writable) {
int ret;
struct file *file;
if ((ret = fd2file(fd, &file)) != 0) {
return 0;
}
if (readable && !file->readable) {
return 0;
}
if (writable && !file->writable) {
return 0;
}
return 1;
}
// open file
int
file_open(char *path, uint32_t open_flags) {
bool readable = 0, writable = 0;
switch (open_flags & O_ACCMODE) {
case O_RDONLY: readable = 1; break;
case O_WRONLY: writable = 1; break;
case O_RDWR:
readable = writable = 1;
break;
default:
return -E_INVAL;
}
int ret;
struct file *file;
if ((ret = fd_array_alloc(NO_FD, &file)) != 0) {
return ret;
}
struct inode *node;
if ((ret = vfs_open(path, open_flags, &node)) != 0) {
fd_array_free(file);
return ret;
}
file->pos = 0;
if (open_flags & O_APPEND) {
struct stat __stat, *stat = &__stat;
if ((ret = vop_fstat(node, stat)) != 0) {
vfs_close(node);
fd_array_free(file);
return ret;
}
file->pos = stat->st_size;
}
file->node = node;
file->readable = readable;
file->writable = writable;
fd_array_open(file);
return file->fd;
}
// close file
int
file_close(int fd) {
int ret;
struct file *file;
if ((ret = fd2file(fd, &file)) != 0) {
return ret;
}
fd_array_close(file);
return 0;
}
// read file
int
file_read(int fd, void *base, size_t len, size_t *copied_store) {
int ret;
struct file *file;
*copied_store = 0;
if ((ret = fd2file(fd, &file)) != 0) {
return ret;
}
if (!file->readable) {
return -E_INVAL;
}
fd_array_acquire(file);
struct iobuf __iob, *iob = iobuf_init(&__iob, base, len, file->pos);
ret = vop_read(file->node, iob);
size_t copied = iobuf_used(iob);
if (file->status == FD_OPENED) {
file->pos += copied;
}
*copied_store = copied;
fd_array_release(file);
return ret;
}
// write file
int
file_write(int fd, void *base, size_t len, size_t *copied_store) {
int ret;
struct file *file;
*copied_store = 0;
if ((ret = fd2file(fd, &file)) != 0) {
return ret;
}
if (!file->writable) {
return -E_INVAL;
}
fd_array_acquire(file);
struct iobuf __iob, *iob = iobuf_init(&__iob, base, len, file->pos);
ret = vop_write(file->node, iob);
size_t copied = iobuf_used(iob);
if (file->status == FD_OPENED) {
file->pos += copied;
}
*copied_store = copied;
fd_array_release(file);
return ret;
}
// seek file
int
file_seek(int fd, off_t pos, int whence) {
struct stat __stat, *stat = &__stat;
int ret;
struct file *file;
if ((ret = fd2file(fd, &file)) != 0) {
return ret;
}
fd_array_acquire(file);
switch (whence) {
case LSEEK_SET: break;
case LSEEK_CUR: pos += file->pos; break;
case LSEEK_END:
if ((ret = vop_fstat(file->node, stat)) == 0) {
pos += stat->st_size;
}
break;
default: ret = -E_INVAL;
}
if (ret == 0) {
if ((ret = vop_tryseek(file->node, pos)) == 0) {
file->pos = pos;
}
// cprintf("file_seek, pos=%d, whence=%d, ret=%d\n", pos, whence, ret);
}
fd_array_release(file);
return ret;
}
// stat file
int
file_fstat(int fd, struct stat *stat) {
int ret;
struct file *file;
if ((ret = fd2file(fd, &file)) != 0) {
return ret;
}
fd_array_acquire(file);
ret = vop_fstat(file->node, stat);
fd_array_release(file);
return ret;
}
// sync file
int
file_fsync(int fd) {
int ret;
struct file *file;
if ((ret = fd2file(fd, &file)) != 0) {
return ret;
}
fd_array_acquire(file);
ret = vop_fsync(file->node);
fd_array_release(file);
return ret;
}
// get file entry in DIR
int
file_getdirentry(int fd, struct dirent *direntp) {
int ret;
struct file *file;
if ((ret = fd2file(fd, &file)) != 0) {
return ret;
}
fd_array_acquire(file);
struct iobuf __iob, *iob = iobuf_init(&__iob, direntp->name, sizeof(direntp->name), direntp->offset);
if ((ret = vop_getdirentry(file->node, iob)) == 0) {
direntp->offset += iobuf_used(iob);
}
fd_array_release(file);
return ret;
}
// duplicate file
int
file_dup(int fd1, int fd2) {
int ret;
struct file *file1, *file2;
if ((ret = fd2file(fd1, &file1)) != 0) {
return ret;
}
if ((ret = fd_array_alloc(fd2, &file2)) != 0) {
return ret;
}
fd_array_dup(file2, file1);
return file2->fd;
}