fs/read_write.c

/* */
This source file includes following definitions.
sys_readdir
sys_lseek
sys_read
sys_write
   1 /*
   2  *  linux/fs/read_write.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 #include <linux/types.h>
   8 #include <linux/errno.h>
   9 #include <linux/stat.h>
  10 #include <linux/kernel.h>
  11 #include <linux/sched.h>
  12 #include <linux/minix_fs.h>
  13 
  14 #include <asm/segment.h>
  15 
  16 /*
  17  * Count is not yet used: but we'll probably support reading several entries
  18  * at once in the future. Use count=1 in the library for future expansions.
  19  */
  20 int sys_readdir(unsigned int fd, struct dirent * dirent, unsigned int count)
     /*  */
  21 {
  22         struct file * file;
  23         struct inode * inode;
  24 
  25         if (fd >= NR_OPEN || !(file = current->filp[fd]) ||
  26             !(inode = file->f_inode))
  27                 return -EBADF;
  28         if (file->f_op && file->f_op->readdir) {
  29                 verify_area(dirent, sizeof (*dirent));
  30                 return file->f_op->readdir(inode,file,dirent,count);
  31         }
  32         return -ENOTDIR;
  33 }
  34 
  35 int sys_lseek(unsigned int fd, off_t offset, unsigned int origin)
     /*  */
  36 {
  37         struct file * file;
  38         int tmp = -1;
  39 
  40         if (fd >= NR_OPEN || !(file=current->filp[fd]) || !(file->f_inode))
  41                 return -EBADF;
  42         if (origin > 2)
  43                 return -EINVAL;
  44         if (file->f_op && file->f_op->lseek)
  45                 return file->f_op->lseek(file->f_inode,file,offset,origin);
  46 
  47 /* this is the default handler if no lseek handler is present */
  48         switch (origin) {
  49                 case 0:
  50                         tmp = offset;
  51                         break;
  52                 case 1:
  53                         tmp = file->f_pos + offset;
  54                         break;
  55                 case 2:
  56                         if (!file->f_inode)
  57                                 return -EINVAL;
  58                         tmp = file->f_inode->i_size + offset;
  59                         break;
  60         }
  61         if (tmp < 0)
  62                 return -EINVAL;
  63         file->f_pos = tmp;
  64         file->f_reada = 0;
  65         return file->f_pos;
  66 }
  67 
  68 int sys_read(unsigned int fd,char * buf,unsigned int count)
     /*  */
  69 {
  70         struct file * file;
  71         struct inode * inode;
  72 
  73         if (fd>=NR_OPEN || !(file=current->filp[fd]) || !(inode=file->f_inode))
  74                 return -EBADF;
  75         if (!(file->f_mode & 1))
  76                 return -EBADF;
  77         if (!count)
  78                 return 0;
  79         verify_area(buf,count);
  80         if (file->f_op && file->f_op->read)
  81                 return file->f_op->read(inode,file,buf,count);
  82         return -EINVAL;
  83 }
  84 
  85 int sys_write(unsigned int fd,char * buf,unsigned int count)
     /*  */
  86 {
  87         struct file * file;
  88         struct inode * inode;
  89         
  90         if (fd>=NR_OPEN || !(file=current->filp[fd]) || !(inode=file->f_inode))
  91                 return -EBADF;
  92         if (!(file->f_mode&2))
  93                 return -EBADF;
  94         if (!count)
  95                 return 0;
  96         if (file->f_op && file->f_op->write)
  97                 return file->f_op->write(inode,file,buf,count);
  98         return -EINVAL;
  99 }
/* */
root/fs/read_write.c

DEFINITIONS
