fs/msdos/file.c

/* */
This source file includes following definitions.
msdos_file_read
msdos_file_write
msdos_truncate
   1 /*
   2  *  linux/fs/msdos/file.c
   3  *
   4  *  Written 1992 by Werner Almesberger
   5  *
   6  *  MS-DOS regular file handling primitives
   7  */
   8 
   9 #include <asm/segment.h>
  10 #include <asm/system.h>
  11 
  12 #include <linux/sched.h>
  13 #include <linux/fs.h>
  14 #include <linux/msdos_fs.h>
  15 #include <linux/errno.h>
  16 #include <linux/fcntl.h>
  17 #include <linux/stat.h>
  18 
  19 #define MIN(a,b) (((a) < (b)) ? (a) : (b))
  20 #define MAX(a,b) (((a) > (b)) ? (a) : (b))
  21 
  22 static int msdos_file_read(struct inode *inode,struct file *filp,char *buf,
  23     int count);
  24 static int msdos_file_write(struct inode *inode,struct file *filp,char *buf,
  25     int count);
  26 
  27 
  28 static struct file_operations msdos_file_operations = {
  29         NULL,                   /* lseek - default */
  30         msdos_file_read,        /* read */
  31         msdos_file_write,       /* write */
  32         NULL,                   /* readdir - bad */
  33         NULL,                   /* select - default */
  34         NULL,                   /* ioctl - default */
  35         NULL,                   /* no special open is needed */
  36         NULL                    /* release */
  37 };
  38 
  39 struct inode_operations msdos_file_inode_operations = {
  40         &msdos_file_operations, /* default file operations */
  41         NULL,                   /* create */
  42         NULL,                   /* lookup */
  43         NULL,                   /* link */
  44         NULL,                   /* unlink */
  45         NULL,                   /* symlink */
  46         NULL,                   /* mkdir */
  47         NULL,                   /* rmdir */
  48         NULL,                   /* mknod */
  49         NULL,                   /* rename */
  50         NULL,                   /* readlink */
  51         NULL,                   /* follow_link */
  52         msdos_bmap,             /* bmap */
  53         msdos_truncate          /* truncate */
  54 };
  55 
  56 /* No bmap for MS-DOS FS' that don't align data at kByte boundaries. */
  57 
  58 struct inode_operations msdos_file_inode_operations_no_bmap = {
  59         &msdos_file_operations, /* default file operations */
  60         NULL,                   /* create */
  61         NULL,                   /* lookup */
  62         NULL,                   /* link */
  63         NULL,                   /* unlink */
  64         NULL,                   /* symlink */
  65         NULL,                   /* mkdir */
  66         NULL,                   /* rmdir */
  67         NULL,                   /* mknod */
  68         NULL,                   /* rename */
  69         NULL,                   /* readlink */
  70         NULL,                   /* follow_link */
  71         NULL,                   /* bmap */
  72         msdos_truncate          /* truncate */
  73 };
  74 
  75 
  76 static int msdos_file_read(struct inode *inode,struct file *filp,char *buf,
     /*  */
  77     int count)
  78 {
  79         char *start;
  80         int left,offset,size,sector,cnt;
  81         char ch;
  82         struct buffer_head *bh;
  83         void *data;
  84 
  85 /* printk("msdos_file_read\r\n"); */
  86         if (!inode) {
  87                 printk("msdos_file_read: inode = NULL\r\n");
  88                 return -EINVAL;
  89         }
  90         if (!S_ISREG(inode->i_mode)) {
  91                 printk("msdos_file_read: mode = %07o\n",inode->i_mode);
  92                 return -EINVAL;
  93         }
  94         if (filp->f_pos >= inode->i_size || count <= 0) return 0;
  95         start = buf;
  96         while (left = MIN(inode->i_size-filp->f_pos,count-(buf-start))) {
  97                 if (!(sector = msdos_smap(inode,filp->f_pos >> SECTOR_BITS)))
  98                         break;
  99                 offset = filp->f_pos & (SECTOR_SIZE-1);
 100                 if (!(bh = msdos_sread(inode->i_dev,sector,&data))) break;
 101                 filp->f_pos += (size = MIN(SECTOR_SIZE-offset,left));
 102                 if (inode->i_data[D_BINARY]) {
 103                         memcpy_tofs(buf,data+offset,size);
 104                         buf += size;
 105                 }
 106                 else for (cnt = size; cnt; cnt--) {
 107                                 if ((ch = *((char *) data+offset++)) == '\r')
 108                                         size--;
 109                                 else {
 110                                         if (ch != 26) put_fs_byte(ch,buf++);
 111                                         else {
 112                                                 filp->f_pos = inode->i_size;
 113                                                 brelse(bh);
 114                                                 return buf-start;
 115                                         }
 116                                 }
 117                         }
 118                 brelse(bh);
 119         }
 120         if (start == buf) return -EIO;
 121         return buf-start;
 122 }
 123 
 124 
 125 static int msdos_file_write(struct inode *inode,struct file *filp,char *buf,
     /*  */
 126     int count)
 127 {
 128         int sector,offset,size,left,written;
 129         int error,carry;
 130         char *start,*to,ch;
 131         struct buffer_head *bh;
 132         void *data;
 133 
 134         if (!inode) {
 135                 printk("msdos_file_write: inode = NULL\n");
 136                 return -EINVAL;
 137         }
 138         if (!S_ISREG(inode->i_mode)) {
 139                 printk("msdos_file_write: mode = %07o\n",inode->i_mode);
 140                 return -EINVAL;
 141         }
 142 /*
 143  * ok, append may not work when many processes are writing at the same time
 144  * but so what. That way leads to madness anyway.
 145  */
 146         if (filp->f_flags & O_APPEND) filp->f_pos = inode->i_size;
 147         if (count <= 0) return 0;
 148         error = carry = 0;
 149         for (start = buf; count || carry; count -= size) {
 150                 while (!(sector = msdos_smap(inode,filp->f_pos >> SECTOR_BITS)))
 151                         if ((error = msdos_add_cluster(inode)) < 0) break;
 152                 if (error) break;
 153                 offset = filp->f_pos & (SECTOR_SIZE-1);
 154                 size = MIN(SECTOR_SIZE-offset,MAX(carry,count));
 155                 if (!(bh = msdos_sread(inode->i_dev,sector,&data))) {
 156                         error = -EIO;
 157                         break;
 158                 }
 159                 if (inode->i_data[D_BINARY]) {
 160                         memcpy_fromfs(data+(filp->f_pos & (SECTOR_SIZE-1)),
 161                             buf,written = size);
 162                         buf += size;
 163                 }
 164                 else {
 165                         written = left = SECTOR_SIZE-offset;
 166                         to = data+(filp->f_pos & (SECTOR_SIZE-1));
 167                         if (carry) {
 168                                 *to++ = '\n';
 169                                 left--;
 170                                 carry = 0;
 171                         }
 172                         for (size = 0; size < count && left; size++) {
 173                                 if ((ch = get_fs_byte(buf++)) == '\n') {
 174                                         *to++ = '\r';
 175                                         left--;
 176                                 }
 177                                 if (!left) carry = 1;
 178                                 else {
 179                                         *to++ = ch;
 180                                         left--;
 181                                 }
 182                         }
 183                         written -= left;
 184                 }
 185                 filp->f_pos += written;
 186                 if (filp->f_pos > inode->i_size) {
 187                         inode->i_size = filp->f_pos;
 188                         inode->i_dirt = 1;
 189                 }
 190                 bh->b_dirt = 1;
 191                 brelse(bh);
 192         }
 193         inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 194         inode->i_data[D_ATTRS] |= ATTR_ARCH;
 195         inode->i_dirt = 1;
 196         return start == buf ? error : buf-start;
 197 }
 198 
 199 
 200 void msdos_truncate(struct inode *inode)
     /*  */
 201 {
 202         int cluster;
 203 
 204         cluster = SECTOR_SIZE*MSDOS_SB(inode->i_sb)->cluster_size;
 205         (void) fat_free(inode,(inode->i_size+(cluster-1))/cluster);
 206         inode->i_data[D_ATTRS] |= ATTR_ARCH;
 207         inode->i_dirt = 1;
 208 }
/* */
root/fs/msdos/file.c

DEFINITIONS
