fs/umsdos/symlink.c

   1 /*
   2  *  linux/fs/umsdos/file.c
   3  *
   4  *  Written 1992 by Jacques Gelinas
   5  *      inspired from linux/fs/msdos/file.c Werner Almesberger
   6  *
   7  *  Extended MS-DOS regular file handling primitives
   8  */
   9
  10 #include <linux/sched.h>
  11 #include <linux/fs.h>
  12 #include <linux/msdos_fs.h>
  13 #include <linux/errno.h>
  14 #include <linux/fcntl.h>
  15 #include <linux/stat.h>
  16 #include <linux/umsdos_fs.h>
  17 #include <linux/malloc.h>
  18
  19 #include <asm/uaccess.h>
  20 #include <asm/system.h>
  21
  22 #define PRINTK(x)
  23 #define Printk(x)       printk x
  24
  25 static struct file_operations umsdos_symlink_operations;
  26
  27
  28 /*
  29  * Read the data associate with the symlink.
  30  * Return length read in buffer or  a negative error code.
  31  *
  32  */
  33
  34 static int umsdos_readlink_x (
  35                                      struct dentry *dentry,
  36                                      char *buffer,
  37                                      int bufsiz)
  38 {
  39         int ret;
  40         loff_t loffs = 0;
  41         struct file filp;
  42
  43         ret = dentry->d_inode->i_size;
  44
  45         check_dentry (dentry);
  46         fill_new_filp (&filp, dentry);
  47
  48         filp.f_reada = 0;
  49         filp.f_flags = O_RDONLY;
  50         filp.f_op = &umsdos_symlink_operations;         /* /mn/ - we have to fill it with dummy values so we won't segfault */
  51
  52         if (ret > bufsiz)
  53                 ret = bufsiz;
  54
  55         PRINTK ((KERN_DEBUG "umsdos_readlink_x /mn/: Checkin: filp=%p, buffer=%p, size=%d, offs=%Lu\n", &filp, buffer, ret, loffs));
  56         PRINTK ((KERN_DEBUG "  f_op=%p\n", filp.f_op));
  57         PRINTK ((KERN_DEBUG "  inode=%lu, i_size=%lu\n", filp.f_dentry->d_inode->i_ino, filp.f_dentry->d_inode->i_size));
  58         PRINTK ((KERN_DEBUG "  f_pos=%Lu\n", filp.f_pos));
  59         PRINTK ((KERN_DEBUG "  name=%.*s\n", (int) filp.f_dentry->d_name.len, filp.f_dentry->d_name.name));
  60         PRINTK ((KERN_DEBUG "  i_binary(sb)=%d\n", MSDOS_I (filp.f_dentry->d_inode)->i_binary));
  61         PRINTK ((KERN_DEBUG "  f_count=%d, f_flags=%d\n", filp.f_count, filp.f_flags));
  62         PRINTK ((KERN_DEBUG "  f_owner=%d\n", filp.f_owner.uid));
  63         PRINTK ((KERN_DEBUG "  f_version=%ld\n", filp.f_version));
  64         PRINTK ((KERN_DEBUG "  f_reada=%ld, f_ramax=%ld, f_raend=%ld, f_ralen=%ld, f_rawin=%ld\n", filp.f_reada, filp.f_ramax, filp.f_raend, filp.f_ralen, filp.f_rawin));
  65
  66
  67         PRINTK ((KERN_DEBUG "umsdos_readlink_x: FIXME /mn/: running fat_file_read (%p, %p, %d, %Lu)\n", &filp, buffer, ret, loffs));
  68         if (fat_file_read (&filp, buffer, (size_t) ret, &loffs) != ret) {
  69                 ret = -EIO;
  70         }
  71 #if 0                           /* DEBUG */
  72         {
  73                 struct umsdos_dirent *mydirent = buffer;
  74
  75                 PRINTK ((KERN_DEBUG "  (DDD) uid=%d\n", mydirent->uid));
  76                 PRINTK ((KERN_DEBUG "  (DDD) gid=%d\n", mydirent->gid));
  77                 PRINTK ((KERN_DEBUG "  (DDD) name=>%.20s<\n", mydirent->name));
  78         }
  79 #endif
  80
  81         PRINTK ((KERN_DEBUG "umsdos_readlink_x: FIXME /mn/: fat_file_read returned offs=%Lu ret=%d\n", loffs, ret));
  82         return ret;
  83 }
  84
  85
  86
  87 static int UMSDOS_readlink (struct dentry *dentry, char *buffer, int buflen)
  88 {
  89         int ret;
  90
  91         PRINTK ((KERN_DEBUG "UMSDOS_readlink: calling umsdos_readlink_x for %.*s\n", (int) dentry->d_name.len, dentry->d_name.name));
  92         ret = umsdos_readlink_x (dentry, buffer, buflen);
  93         PRINTK ((KERN_DEBUG "readlink %d bufsiz %d\n", ret, buflen));
  94         /* dput(dentry); / * FIXME /mn/ */
  95         Printk ((KERN_WARNING "UMSDOS_readlink /mn/: FIXME! skipped dput(dentry). returning %d\n", ret));
  96         return ret;
  97
  98 }
  99
 100 /* this one mostly stolen from romfs :) */
 101 static struct dentry *UMSDOS_followlink (struct dentry *dentry, struct dentry *base)
 102 {
 103         struct inode *inode = dentry->d_inode;
 104         char *symname = NULL;
 105         int len, cnt;
 106         mm_segment_t old_fs = get_fs ();
 107
 108         Printk ((KERN_DEBUG "UMSDOS_followlink /mn/: (%.*s/%.*s)\n", (int) dentry->d_parent->d_name.len, dentry->d_parent->d_name.name, (int) dentry->d_name.len, dentry->d_name.name));
 109
 110         len = inode->i_size;
 111
 112         if (!(symname = kmalloc (len + 1, GFP_KERNEL))) {
 113                 dentry = ERR_PTR (-EAGAIN);     /* correct? */
 114                 goto outnobuf;
 115         }
 116         set_fs (KERNEL_DS);     /* we read into kernel space this time */
 117         PRINTK ((KERN_DEBUG "UMSDOS_followlink /mn/: Here goes umsdos_readlink_x %p, %p, %d\n", dentry, symname, len));
 118         cnt = umsdos_readlink_x (dentry, symname, len);
 119         PRINTK ((KERN_DEBUG "UMSDOS_followlink /mn/: back from umsdos_readlink_x %p, %p, %d!\n", dentry, symname, len));
 120         set_fs (old_fs);
 121         Printk ((KERN_DEBUG "UMSDOS_followlink /mn/: link name is %.*s with len %d\n", cnt, symname, cnt));
 122
 123         if (len != cnt) {
 124                 dentry = ERR_PTR (-EIO);
 125                 goto out;
 126         } else
 127                 symname[len] = 0;
 128
 129         dentry = lookup_dentry (symname, base, 1);
 130         kfree (symname);
 131
 132         if (0) {
 133               out:
 134                 kfree (symname);
 135               outnobuf:
 136                 dput (base);
 137         }
 138         return dentry;
 139 }
 140
 141
 142 static struct file_operations umsdos_symlink_operations =
 143 {
 144         NULL,                   /* lseek - default */
 145         NULL,                   /* read */
 146         NULL,                   /* write */
 147         NULL,                   /* readdir - bad */
 148         NULL,                   /* poll - default */
 149         NULL,                   /* ioctl - default */
 150         NULL,                   /* mmap */
 151         NULL,                   /* no special open is needed */
 152         NULL,                   /* no flush code */
 153         NULL,                   /* release */
 154         NULL                    /* fsync */
 155 };
 156
 157
 158 struct inode_operations umsdos_symlink_inode_operations =
 159 {
 160         NULL,                   /* default file operations */
 161         NULL,                   /* create */
 162         NULL,                   /* lookup */
 163         NULL,                   /* link */
 164         NULL,                   /* unlink */
 165         NULL,                   /* symlink */
 166         NULL,                   /* mkdir */
 167         NULL,                   /* rmdir */
 168         NULL,                   /* mknod */
 169         NULL,                   /* rename */
 170         UMSDOS_readlink,        /* readlink */
 171         UMSDOS_followlink,      /* followlink *//* /mn/ is this REALLY needed ? I recall seeing it working w/o it... */
 172         generic_readpage,       /* readpage *//* in original NULL. changed to generic_readpage. FIXME? /mn/ */
 173         NULL,                   /* writepage */
 174         fat_bmap,               /* bmap *//* in original NULL. changed to fat_bmap. FIXME? /mn/ */
 175         NULL,                   /* truncate */
 176         NULL,                   /* permission */
 177         NULL,                   /* smap */
 178         NULL,                   /* updatepage */
 179         NULL                    /* revalidate */
 180
 181 };