fs/file.c

   1 #include <stdio.h>
   2 #include <stdint.h>
   3 #include <string.h>
   4 #include <malloc.h>
   5 #include <fs.h>
   6 #include <err.h>
   7
   8 #define MAX_FD  32
   9 uint8_t fds[MAX_FD] = {0,0,0};
  10 struct file *files[MAX_FD] = {NULL, };
  11
  12 static int get_unused_fd(void)
  13 {
  14         int i;
  15
  16         for (i = 0; i < MAX_FD; i++) {
  17                 if (fds[i] == 0)
  18                         break;
  19         }
  20
  21         if (i < MAX_FD)
  22                 fds[i] = 1;
  23
  24         return i;
  25 }
  26
  27 int sys_open(const char *pathname, uint32_t flags)
  28 {
  29         struct inode *inode = namei(pathname, flags);
  30         struct file *file;
  31         int fd;
  32
  33         if (IS_ERR_OR_NULL(inode))
  34                 return inode ? PTR_ERR(inode) : -ENOENT;
  35
  36         FS_DEBUG("%s: namei returned successfully!\n", __FUNCTION__);
  37
  38         file = malloc(sizeof(*file));
  39         if (!file)
  40                 return -ENOMEM;
  41         file->inode  = inode;
  42         file->fs     = inode->i_fs;
  43         file->offset = 0;
  44         file->f_op   = inode->i_fop;
  45
  46         fd = get_unused_fd();
  47         if (fd >= MAX_FD) {
  48                 printk("You opened two much files!\n");
  49                 free(file);
  50                 return -EINVAL;
  51         }
  52         files[fd] = file;
  53
  54         return fd;
  55 }
  56
  57 static inline struct file *fget(int fd)
  58 {
  59         return files[fd];
  60 }
  61
  62 int sys_read(int fd, void *buf, int size)
  63 {
  64         struct file *file;
  65         struct inode *inode;
  66         int blocks;
  67         int bytes_need;
  68         int bytes_read;
  69
  70         if (fd < 0 || fd > MAX_FD)
  71                 return -EBADF;
  72
  73         file = fget(fd);
  74         if (!file)
  75                 return -EBADF;
  76
  77         inode      = file->inode;
  78         bytes_need = MIN(size, inode->i_size - file->offset);
  79         blocks     = (bytes_need + inode->i_blksize - 1) >> file->fs->block_shift;
  80
  81         bytes_read = file->f_op->read(file, buf, blocks);
  82         bytes_read = MIN(bytes_need, bytes_read);
  83         if (bytes_read > 0) {
  84                 memmove(buf, buf + (file->offset & (inode->i_blksize - 1)), bytes_read);
  85                 file->offset += bytes_read;
  86         }
  87
  88         return bytes_read;
  89 }
  90
  91 int sys_write(int fd, void *buf, int size)
  92 {
  93         struct file *file;
  94         int blocks;
  95         int bytes_written;
  96
  97         if (fd < 0 || fd > MAX_FD)
  98                 return -EBADF;
  99         file = fget(fd);
 100         if (!file)
 101                 return -EBADF;
 102
 103         blocks = (size + file->inode->i_blksize - 1) >> file->fs->block_shift;
 104
 105         bytes_written = file->f_op->write(file, buf, blocks);
 106         bytes_written = MIN(size, bytes_written);
 107         if (bytes_written > 0)
 108                 file->offset += bytes_written;
 109
 110         return bytes_written;
 111 }
 112
 113 int sys_close(int fd)
 114 {
 115         struct file *file;
 116
 117         if (fd < 0 || fd > MAX_FD)
 118                 return -EBADF;
 119
 120         file = fget(fd);
 121         if (!file)
 122                 return -EBADF;
 123
 124         free_inode(file->inode);
 125         fds[fd] = 0;
 126         files[fd] = NULL;
 127         free(file);
 128         return 0;
 129 }
 130
 131 int sys_lseek(int fd, int off, int mode)
 132 {
 133         struct file *file;
 134
 135         if (fd < 0 || fd > MAX_FD)
 136                 return -EBADF;
 137
 138         file = fget(fd);
 139         if (!file)
 140                 return -EBADF;
 141
 142         if (mode == SEEK_CUR)
 143                 file->offset += off;
 144         else if (mode == SEEK_END)
 145                 file->offset = file->inode->i_size + off;
 146         else if (mode == SEEK_SET)
 147                 file->offset = off;
 148         else
 149                 return -EINVAL;
 150
 151         return file->offset;
 152 }