The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/fs/read_write.c

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    1 /*
    2  *  linux/fs/read_write.c
    3  *
    4  *  Copyright (C) 1991, 1992  Linus Torvalds
    5  */
    6 
    7 #include <linux/slab.h> 
    8 #include <linux/stat.h>
    9 #include <linux/fcntl.h>
   10 #include <linux/file.h>
   11 #include <linux/uio.h>
   12 #include <linux/fsnotify.h>
   13 #include <linux/security.h>
   14 #include <linux/export.h>
   15 #include <linux/syscalls.h>
   16 #include <linux/pagemap.h>
   17 #include <linux/splice.h>
   18 #include "read_write.h"
   19 
   20 #include <asm/uaccess.h>
   21 #include <asm/unistd.h>
   22 
   23 const struct file_operations generic_ro_fops = {
   24         .llseek         = generic_file_llseek,
   25         .read           = do_sync_read,
   26         .aio_read       = generic_file_aio_read,
   27         .mmap           = generic_file_readonly_mmap,
   28         .splice_read    = generic_file_splice_read,
   29 };
   30 
   31 EXPORT_SYMBOL(generic_ro_fops);
   32 
   33 static inline int unsigned_offsets(struct file *file)
   34 {
   35         return file->f_mode & FMODE_UNSIGNED_OFFSET;
   36 }
   37 
   38 static loff_t lseek_execute(struct file *file, struct inode *inode,
   39                 loff_t offset, loff_t maxsize)
   40 {
   41         if (offset < 0 && !unsigned_offsets(file))
   42                 return -EINVAL;
   43         if (offset > maxsize)
   44                 return -EINVAL;
   45 
   46         if (offset != file->f_pos) {
   47                 file->f_pos = offset;
   48                 file->f_version = 0;
   49         }
   50         return offset;
   51 }
   52 
   53 /**
   54  * generic_file_llseek_size - generic llseek implementation for regular files
   55  * @file:       file structure to seek on
   56  * @offset:     file offset to seek to
   57  * @whence:     type of seek
   58  * @size:       max size of this file in file system
   59  * @eof:        offset used for SEEK_END position
   60  *
   61  * This is a variant of generic_file_llseek that allows passing in a custom
   62  * maximum file size and a custom EOF position, for e.g. hashed directories
   63  *
   64  * Synchronization:
   65  * SEEK_SET and SEEK_END are unsynchronized (but atomic on 64bit platforms)
   66  * SEEK_CUR is synchronized against other SEEK_CURs, but not read/writes.
   67  * read/writes behave like SEEK_SET against seeks.
   68  */
   69 loff_t
   70 generic_file_llseek_size(struct file *file, loff_t offset, int whence,
   71                 loff_t maxsize, loff_t eof)
   72 {
   73         struct inode *inode = file->f_mapping->host;
   74 
   75         switch (whence) {
   76         case SEEK_END:
   77                 offset += eof;
   78                 break;
   79         case SEEK_CUR:
   80                 /*
   81                  * Here we special-case the lseek(fd, 0, SEEK_CUR)
   82                  * position-querying operation.  Avoid rewriting the "same"
   83                  * f_pos value back to the file because a concurrent read(),
   84                  * write() or lseek() might have altered it
   85                  */
   86                 if (offset == 0)
   87                         return file->f_pos;
   88                 /*
   89                  * f_lock protects against read/modify/write race with other
   90                  * SEEK_CURs. Note that parallel writes and reads behave
   91                  * like SEEK_SET.
   92                  */
   93                 spin_lock(&file->f_lock);
   94                 offset = lseek_execute(file, inode, file->f_pos + offset,
   95                                        maxsize);
   96                 spin_unlock(&file->f_lock);
   97                 return offset;
   98         case SEEK_DATA:
   99                 /*
  100                  * In the generic case the entire file is data, so as long as
  101                  * offset isn't at the end of the file then the offset is data.
  102                  */
  103                 if (offset >= eof)
  104                         return -ENXIO;
  105                 break;
  106         case SEEK_HOLE:
  107                 /*
  108                  * There is a virtual hole at the end of the file, so as long as
  109                  * offset isn't i_size or larger, return i_size.
  110                  */
  111                 if (offset >= eof)
  112                         return -ENXIO;
  113                 offset = eof;
  114                 break;
  115         }
  116 
  117         return lseek_execute(file, inode, offset, maxsize);
  118 }
  119 EXPORT_SYMBOL(generic_file_llseek_size);
  120 
  121 /**
  122  * generic_file_llseek - generic llseek implementation for regular files
  123  * @file:       file structure to seek on
  124  * @offset:     file offset to seek to
  125  * @whence:     type of seek
  126  *
  127  * This is a generic implemenation of ->llseek useable for all normal local
  128  * filesystems.  It just updates the file offset to the value specified by
  129  * @offset and @whence under i_mutex.
  130  */
  131 loff_t generic_file_llseek(struct file *file, loff_t offset, int whence)
  132 {
  133         struct inode *inode = file->f_mapping->host;
  134 
  135         return generic_file_llseek_size(file, offset, whence,
  136                                         inode->i_sb->s_maxbytes,
  137                                         i_size_read(inode));
  138 }
  139 EXPORT_SYMBOL(generic_file_llseek);
  140 
  141 /**
  142  * noop_llseek - No Operation Performed llseek implementation
  143  * @file:       file structure to seek on
  144  * @offset:     file offset to seek to
  145  * @whence:     type of seek
  146  *
  147  * This is an implementation of ->llseek useable for the rare special case when
  148  * userspace expects the seek to succeed but the (device) file is actually not
  149  * able to perform the seek. In this case you use noop_llseek() instead of
  150  * falling back to the default implementation of ->llseek.
  151  */
  152 loff_t noop_llseek(struct file *file, loff_t offset, int whence)
  153 {
  154         return file->f_pos;
  155 }
  156 EXPORT_SYMBOL(noop_llseek);
  157 
  158 loff_t no_llseek(struct file *file, loff_t offset, int whence)
  159 {
  160         return -ESPIPE;
  161 }
  162 EXPORT_SYMBOL(no_llseek);
  163 
  164 loff_t default_llseek(struct file *file, loff_t offset, int whence)
  165 {
  166         struct inode *inode = file->f_path.dentry->d_inode;
  167         loff_t retval;
  168 
  169         mutex_lock(&inode->i_mutex);
  170         switch (whence) {
  171                 case SEEK_END:
  172                         offset += i_size_read(inode);
  173                         break;
  174                 case SEEK_CUR:
  175                         if (offset == 0) {
  176                                 retval = file->f_pos;
  177                                 goto out;
  178                         }
  179                         offset += file->f_pos;
  180                         break;
  181                 case SEEK_DATA:
  182                         /*
  183                          * In the generic case the entire file is data, so as
  184                          * long as offset isn't at the end of the file then the
  185                          * offset is data.
  186                          */
  187                         if (offset >= inode->i_size) {
  188                                 retval = -ENXIO;
  189                                 goto out;
  190                         }
  191                         break;
  192                 case SEEK_HOLE:
  193                         /*
  194                          * There is a virtual hole at the end of the file, so
  195                          * as long as offset isn't i_size or larger, return
  196                          * i_size.
  197                          */
  198                         if (offset >= inode->i_size) {
  199                                 retval = -ENXIO;
  200                                 goto out;
  201                         }
  202                         offset = inode->i_size;
  203                         break;
  204         }
  205         retval = -EINVAL;
  206         if (offset >= 0 || unsigned_offsets(file)) {
  207                 if (offset != file->f_pos) {
  208                         file->f_pos = offset;
  209                         file->f_version = 0;
  210                 }
  211                 retval = offset;
  212         }
  213 out:
  214         mutex_unlock(&inode->i_mutex);
  215         return retval;
  216 }
  217 EXPORT_SYMBOL(default_llseek);
  218 
  219 loff_t vfs_llseek(struct file *file, loff_t offset, int whence)
  220 {
  221         loff_t (*fn)(struct file *, loff_t, int);
  222 
  223         fn = no_llseek;
  224         if (file->f_mode & FMODE_LSEEK) {
  225                 if (file->f_op && file->f_op->llseek)
  226                         fn = file->f_op->llseek;
  227         }
  228         return fn(file, offset, whence);
  229 }
  230 EXPORT_SYMBOL(vfs_llseek);
  231 
  232 SYSCALL_DEFINE3(lseek, unsigned int, fd, off_t, offset, unsigned int, whence)
  233 {
  234         off_t retval;
  235         struct fd f = fdget(fd);
  236         if (!f.file)
  237                 return -EBADF;
  238 
  239         retval = -EINVAL;
  240         if (whence <= SEEK_MAX) {
  241                 loff_t res = vfs_llseek(f.file, offset, whence);
  242                 retval = res;
  243                 if (res != (loff_t)retval)
  244                         retval = -EOVERFLOW;    /* LFS: should only happen on 32 bit platforms */
  245         }
  246         fdput(f);
  247         return retval;
  248 }
  249 
  250 #ifdef __ARCH_WANT_SYS_LLSEEK
  251 SYSCALL_DEFINE5(llseek, unsigned int, fd, unsigned long, offset_high,
  252                 unsigned long, offset_low, loff_t __user *, result,
  253                 unsigned int, whence)
  254 {
  255         int retval;
  256         struct fd f = fdget(fd);
  257         loff_t offset;
  258 
  259         if (!f.file)
  260                 return -EBADF;
  261 
  262         retval = -EINVAL;
  263         if (whence > SEEK_MAX)
  264                 goto out_putf;
  265 
  266         offset = vfs_llseek(f.file, ((loff_t) offset_high << 32) | offset_low,
  267                         whence);
  268 
  269         retval = (int)offset;
  270         if (offset >= 0) {
  271                 retval = -EFAULT;
  272                 if (!copy_to_user(result, &offset, sizeof(offset)))
  273                         retval = 0;
  274         }
  275 out_putf:
  276         fdput(f);
  277         return retval;
  278 }
  279 #endif
  280 
  281 
  282 /*
  283  * rw_verify_area doesn't like huge counts. We limit
  284  * them to something that fits in "int" so that others
  285  * won't have to do range checks all the time.
  286  */
  287 int rw_verify_area(int read_write, struct file *file, loff_t *ppos, size_t count)
  288 {
  289         struct inode *inode;
  290         loff_t pos;
  291         int retval = -EINVAL;
  292 
  293         inode = file->f_path.dentry->d_inode;
  294         if (unlikely((ssize_t) count < 0))
  295                 return retval;
  296         pos = *ppos;
  297         if (unlikely(pos < 0)) {
  298                 if (!unsigned_offsets(file))
  299                         return retval;
  300                 if (count >= -pos) /* both values are in 0..LLONG_MAX */
  301                         return -EOVERFLOW;
  302         } else if (unlikely((loff_t) (pos + count) < 0)) {
  303                 if (!unsigned_offsets(file))
  304                         return retval;
  305         }
  306 
  307         if (unlikely(inode->i_flock && mandatory_lock(inode))) {
  308                 retval = locks_mandatory_area(
  309                         read_write == READ ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE,
  310                         inode, file, pos, count);
  311                 if (retval < 0)
  312                         return retval;
  313         }
  314         retval = security_file_permission(file,
  315                                 read_write == READ ? MAY_READ : MAY_WRITE);
  316         if (retval)
  317                 return retval;
  318         return count > MAX_RW_COUNT ? MAX_RW_COUNT : count;
  319 }
  320 
  321 static void wait_on_retry_sync_kiocb(struct kiocb *iocb)
  322 {
  323         set_current_state(TASK_UNINTERRUPTIBLE);
  324         if (!kiocbIsKicked(iocb))
  325                 schedule();
  326         else
  327                 kiocbClearKicked(iocb);
  328         __set_current_state(TASK_RUNNING);
  329 }
  330 
  331 ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
  332 {
  333         struct iovec iov = { .iov_base = buf, .iov_len = len };
  334         struct kiocb kiocb;
  335         ssize_t ret;
  336 
  337         init_sync_kiocb(&kiocb, filp);
  338         kiocb.ki_pos = *ppos;
  339         kiocb.ki_left = len;
  340         kiocb.ki_nbytes = len;
  341 
  342         for (;;) {
  343                 ret = filp->f_op->aio_read(&kiocb, &iov, 1, kiocb.ki_pos);
  344                 if (ret != -EIOCBRETRY)
  345                         break;
  346                 wait_on_retry_sync_kiocb(&kiocb);
  347         }
  348 
  349         if (-EIOCBQUEUED == ret)
  350                 ret = wait_on_sync_kiocb(&kiocb);
  351         *ppos = kiocb.ki_pos;
  352         return ret;
  353 }
  354 
  355 EXPORT_SYMBOL(do_sync_read);
  356 
  357 ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
  358 {
  359         ssize_t ret;
  360 
  361         if (!(file->f_mode & FMODE_READ))
  362                 return -EBADF;
  363         if (!file->f_op || (!file->f_op->read && !file->f_op->aio_read))
  364                 return -EINVAL;
  365         if (unlikely(!access_ok(VERIFY_WRITE, buf, count)))
  366                 return -EFAULT;
  367 
  368         ret = rw_verify_area(READ, file, pos, count);
  369         if (ret >= 0) {
  370                 count = ret;
  371                 if (file->f_op->read)
  372                         ret = file->f_op->read(file, buf, count, pos);
  373                 else
  374                         ret = do_sync_read(file, buf, count, pos);
  375                 if (ret > 0) {
  376                         fsnotify_access(file);
  377                         add_rchar(current, ret);
  378                 }
  379                 inc_syscr(current);
  380         }
  381 
  382         return ret;
  383 }
  384 
  385 EXPORT_SYMBOL(vfs_read);
  386 
  387 ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
  388 {
  389         struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = len };
  390         struct kiocb kiocb;
  391         ssize_t ret;
  392 
  393         init_sync_kiocb(&kiocb, filp);
  394         kiocb.ki_pos = *ppos;
  395         kiocb.ki_left = len;
  396         kiocb.ki_nbytes = len;
  397 
  398         for (;;) {
  399                 ret = filp->f_op->aio_write(&kiocb, &iov, 1, kiocb.ki_pos);
  400                 if (ret != -EIOCBRETRY)
  401                         break;
  402                 wait_on_retry_sync_kiocb(&kiocb);
  403         }
  404 
  405         if (-EIOCBQUEUED == ret)
  406                 ret = wait_on_sync_kiocb(&kiocb);
  407         *ppos = kiocb.ki_pos;
  408         return ret;
  409 }
  410 
  411 EXPORT_SYMBOL(do_sync_write);
  412 
  413 ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
  414 {
  415         ssize_t ret;
  416 
  417         if (!(file->f_mode & FMODE_WRITE))
  418                 return -EBADF;
  419         if (!file->f_op || (!file->f_op->write && !file->f_op->aio_write))
  420                 return -EINVAL;
  421         if (unlikely(!access_ok(VERIFY_READ, buf, count)))
  422                 return -EFAULT;
  423 
  424         ret = rw_verify_area(WRITE, file, pos, count);
  425         if (ret >= 0) {
  426                 count = ret;
  427                 if (file->f_op->write)
  428                         ret = file->f_op->write(file, buf, count, pos);
  429                 else
  430                         ret = do_sync_write(file, buf, count, pos);
  431                 if (ret > 0) {
  432                         fsnotify_modify(file);
  433                         add_wchar(current, ret);
  434                 }
  435                 inc_syscw(current);
  436         }
  437 
  438         return ret;
  439 }
  440 
  441 EXPORT_SYMBOL(vfs_write);
  442 
  443 static inline loff_t file_pos_read(struct file *file)
  444 {
  445         return file->f_pos;
  446 }
  447 
  448 static inline void file_pos_write(struct file *file, loff_t pos)
  449 {
  450         file->f_pos = pos;
  451 }
  452 
  453 SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count)
  454 {
  455         struct fd f = fdget(fd);
  456         ssize_t ret = -EBADF;
  457 
  458         if (f.file) {
  459                 loff_t pos = file_pos_read(f.file);
  460                 ret = vfs_read(f.file, buf, count, &pos);
  461                 file_pos_write(f.file, pos);
  462                 fdput(f);
  463         }
  464         return ret;
  465 }
  466 
  467 SYSCALL_DEFINE3(write, unsigned int, fd, const char __user *, buf,
  468                 size_t, count)
  469 {
  470         struct fd f = fdget(fd);
  471         ssize_t ret = -EBADF;
  472 
  473         if (f.file) {
  474                 loff_t pos = file_pos_read(f.file);
  475                 ret = vfs_write(f.file, buf, count, &pos);
  476                 file_pos_write(f.file, pos);
  477                 fdput(f);
  478         }
  479 
  480         return ret;
  481 }
  482 
  483 SYSCALL_DEFINE(pread64)(unsigned int fd, char __user *buf,
  484                         size_t count, loff_t pos)
  485 {
  486         struct fd f;
  487         ssize_t ret = -EBADF;
  488 
  489         if (pos < 0)
  490                 return -EINVAL;
  491 
  492         f = fdget(fd);
  493         if (f.file) {
  494                 ret = -ESPIPE;
  495                 if (f.file->f_mode & FMODE_PREAD)
  496                         ret = vfs_read(f.file, buf, count, &pos);
  497                 fdput(f);
  498         }
  499 
  500         return ret;
  501 }
  502 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
  503 asmlinkage long SyS_pread64(long fd, long buf, long count, loff_t pos)
  504 {
  505         return SYSC_pread64((unsigned int) fd, (char __user *) buf,
  506                             (size_t) count, pos);
  507 }
  508 SYSCALL_ALIAS(sys_pread64, SyS_pread64);
  509 #endif
  510 
  511 SYSCALL_DEFINE(pwrite64)(unsigned int fd, const char __user *buf,
  512                          size_t count, loff_t pos)
  513 {
  514         struct fd f;
  515         ssize_t ret = -EBADF;
  516 
  517         if (pos < 0)
  518                 return -EINVAL;
  519 
  520         f = fdget(fd);
  521         if (f.file) {
  522                 ret = -ESPIPE;
  523                 if (f.file->f_mode & FMODE_PWRITE)  
  524                         ret = vfs_write(f.file, buf, count, &pos);
  525                 fdput(f);
  526         }
  527 
  528         return ret;
  529 }
  530 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
  531 asmlinkage long SyS_pwrite64(long fd, long buf, long count, loff_t pos)
  532 {
  533         return SYSC_pwrite64((unsigned int) fd, (const char __user *) buf,
  534                              (size_t) count, pos);
  535 }
  536 SYSCALL_ALIAS(sys_pwrite64, SyS_pwrite64);
  537 #endif
  538 
  539 /*
  540  * Reduce an iovec's length in-place.  Return the resulting number of segments
  541  */
  542 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
  543 {
  544         unsigned long seg = 0;
  545         size_t len = 0;
  546 
  547         while (seg < nr_segs) {
  548                 seg++;
  549                 if (len + iov->iov_len >= to) {
  550                         iov->iov_len = to - len;
  551                         break;
  552                 }
  553                 len += iov->iov_len;
  554                 iov++;
  555         }
  556         return seg;
  557 }
  558 EXPORT_SYMBOL(iov_shorten);
  559 
  560 ssize_t do_sync_readv_writev(struct file *filp, const struct iovec *iov,
  561                 unsigned long nr_segs, size_t len, loff_t *ppos, iov_fn_t fn)
  562 {
  563         struct kiocb kiocb;
  564         ssize_t ret;
  565 
  566         init_sync_kiocb(&kiocb, filp);
  567         kiocb.ki_pos = *ppos;
  568         kiocb.ki_left = len;
  569         kiocb.ki_nbytes = len;
  570 
  571         for (;;) {
  572                 ret = fn(&kiocb, iov, nr_segs, kiocb.ki_pos);
  573                 if (ret != -EIOCBRETRY)
  574                         break;
  575                 wait_on_retry_sync_kiocb(&kiocb);
  576         }
  577 
  578         if (ret == -EIOCBQUEUED)
  579                 ret = wait_on_sync_kiocb(&kiocb);
  580         *ppos = kiocb.ki_pos;
  581         return ret;
  582 }
  583 
  584 /* Do it by hand, with file-ops */
  585 ssize_t do_loop_readv_writev(struct file *filp, struct iovec *iov,
  586                 unsigned long nr_segs, loff_t *ppos, io_fn_t fn)
  587 {
  588         struct iovec *vector = iov;
  589         ssize_t ret = 0;
  590 
  591         while (nr_segs > 0) {
  592                 void __user *base;
  593                 size_t len;
  594                 ssize_t nr;
  595 
  596                 base = vector->iov_base;
  597                 len = vector->iov_len;
  598                 vector++;
  599                 nr_segs--;
  600 
  601                 nr = fn(filp, base, len, ppos);
  602 
  603                 if (nr < 0) {
  604                         if (!ret)
  605                                 ret = nr;
  606                         break;
  607                 }
  608                 ret += nr;
  609                 if (nr != len)
  610                         break;
  611         }
  612 
  613         return ret;
  614 }
  615 
  616 /* A write operation does a read from user space and vice versa */
  617 #define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)
  618 
  619 ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
  620                               unsigned long nr_segs, unsigned long fast_segs,
  621                               struct iovec *fast_pointer,
  622                               struct iovec **ret_pointer)
  623 {
  624         unsigned long seg;
  625         ssize_t ret;
  626         struct iovec *iov = fast_pointer;
  627 
  628         /*
  629          * SuS says "The readv() function *may* fail if the iovcnt argument
  630          * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
  631          * traditionally returned zero for zero segments, so...
  632          */
  633         if (nr_segs == 0) {
  634                 ret = 0;
  635                 goto out;
  636         }
  637 
  638         /*
  639          * First get the "struct iovec" from user memory and
  640          * verify all the pointers
  641          */
  642         if (nr_segs > UIO_MAXIOV) {
  643                 ret = -EINVAL;
  644                 goto out;
  645         }
  646         if (nr_segs > fast_segs) {
  647                 iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
  648                 if (iov == NULL) {
  649                         ret = -ENOMEM;
  650                         goto out;
  651                 }
  652         }
  653         if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector))) {
  654                 ret = -EFAULT;
  655                 goto out;
  656         }
  657 
  658         /*
  659          * According to the Single Unix Specification we should return EINVAL
  660          * if an element length is < 0 when cast to ssize_t or if the
  661          * total length would overflow the ssize_t return value of the
  662          * system call.
  663          *
  664          * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the
  665          * overflow case.
  666          */
  667         ret = 0;
  668         for (seg = 0; seg < nr_segs; seg++) {
  669                 void __user *buf = iov[seg].iov_base;
  670                 ssize_t len = (ssize_t)iov[seg].iov_len;
  671 
  672                 /* see if we we're about to use an invalid len or if
  673                  * it's about to overflow ssize_t */
  674                 if (len < 0) {
  675                         ret = -EINVAL;
  676                         goto out;
  677                 }
  678                 if (type >= 0
  679                     && unlikely(!access_ok(vrfy_dir(type), buf, len))) {
  680                         ret = -EFAULT;
  681                         goto out;
  682                 }
  683                 if (len > MAX_RW_COUNT - ret) {
  684                         len = MAX_RW_COUNT - ret;
  685                         iov[seg].iov_len = len;
  686                 }
  687                 ret += len;
  688         }
  689 out:
  690         *ret_pointer = iov;
  691         return ret;
  692 }
  693 
  694 static ssize_t do_readv_writev(int type, struct file *file,
  695                                const struct iovec __user * uvector,
  696                                unsigned long nr_segs, loff_t *pos)
  697 {
  698         size_t tot_len;
  699         struct iovec iovstack[UIO_FASTIOV];
  700         struct iovec *iov = iovstack;
  701         ssize_t ret;
  702         io_fn_t fn;
  703         iov_fn_t fnv;
  704 
  705         if (!file->f_op) {
  706                 ret = -EINVAL;
  707                 goto out;
  708         }
  709 
  710         ret = rw_copy_check_uvector(type, uvector, nr_segs,
  711                                     ARRAY_SIZE(iovstack), iovstack, &iov);
  712         if (ret <= 0)
  713                 goto out;
  714 
  715         tot_len = ret;
  716         ret = rw_verify_area(type, file, pos, tot_len);
  717         if (ret < 0)
  718                 goto out;
  719 
  720         fnv = NULL;
  721         if (type == READ) {
  722                 fn = file->f_op->read;
  723                 fnv = file->f_op->aio_read;
  724         } else {
  725                 fn = (io_fn_t)file->f_op->write;
  726                 fnv = file->f_op->aio_write;
  727         }
  728 
  729         if (fnv)
  730                 ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
  731                                                 pos, fnv);
  732         else
  733                 ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn);
  734 
  735 out:
  736         if (iov != iovstack)
  737                 kfree(iov);
  738         if ((ret + (type == READ)) > 0) {
  739                 if (type == READ)
  740                         fsnotify_access(file);
  741                 else
  742                         fsnotify_modify(file);
  743         }
  744         return ret;
  745 }
  746 
  747 ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
  748                   unsigned long vlen, loff_t *pos)
  749 {
  750         if (!(file->f_mode & FMODE_READ))
  751                 return -EBADF;
  752         if (!file->f_op || (!file->f_op->aio_read && !file->f_op->read))
  753                 return -EINVAL;
  754 
  755         return do_readv_writev(READ, file, vec, vlen, pos);
  756 }
  757 
  758 EXPORT_SYMBOL(vfs_readv);
  759 
  760 ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
  761                    unsigned long vlen, loff_t *pos)
  762 {
  763         if (!(file->f_mode & FMODE_WRITE))
  764                 return -EBADF;
  765         if (!file->f_op || (!file->f_op->aio_write && !file->f_op->write))
  766                 return -EINVAL;
  767 
  768         return do_readv_writev(WRITE, file, vec, vlen, pos);
  769 }
  770 
  771 EXPORT_SYMBOL(vfs_writev);
  772 
  773 SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec,
  774                 unsigned long, vlen)
  775 {
  776         struct fd f = fdget(fd);
  777         ssize_t ret = -EBADF;
  778 
  779         if (f.file) {
  780                 loff_t pos = file_pos_read(f.file);
  781                 ret = vfs_readv(f.file, vec, vlen, &pos);
  782                 file_pos_write(f.file, pos);
  783                 fdput(f);
  784         }
  785 
  786         if (ret > 0)
  787                 add_rchar(current, ret);
  788         inc_syscr(current);
  789         return ret;
  790 }
  791 
  792 SYSCALL_DEFINE3(writev, unsigned long, fd, const struct iovec __user *, vec,
  793                 unsigned long, vlen)
  794 {
  795         struct fd f = fdget(fd);
  796         ssize_t ret = -EBADF;
  797 
  798         if (f.file) {
  799                 loff_t pos = file_pos_read(f.file);
  800                 ret = vfs_writev(f.file, vec, vlen, &pos);
  801                 file_pos_write(f.file, pos);
  802                 fdput(f);
  803         }
  804 
  805         if (ret > 0)
  806                 add_wchar(current, ret);
  807         inc_syscw(current);
  808         return ret;
  809 }
  810 
  811 static inline loff_t pos_from_hilo(unsigned long high, unsigned long low)
  812 {
  813 #define HALF_LONG_BITS (BITS_PER_LONG / 2)
  814         return (((loff_t)high << HALF_LONG_BITS) << HALF_LONG_BITS) | low;
  815 }
  816 
  817 SYSCALL_DEFINE5(preadv, unsigned long, fd, const struct iovec __user *, vec,
  818                 unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
  819 {
  820         loff_t pos = pos_from_hilo(pos_h, pos_l);
  821         struct fd f;
  822         ssize_t ret = -EBADF;
  823 
  824         if (pos < 0)
  825                 return -EINVAL;
  826 
  827         f = fdget(fd);
  828         if (f.file) {
  829                 ret = -ESPIPE;
  830                 if (f.file->f_mode & FMODE_PREAD)
  831                         ret = vfs_readv(f.file, vec, vlen, &pos);
  832                 fdput(f);
  833         }
  834 
  835         if (ret > 0)
  836                 add_rchar(current, ret);
  837         inc_syscr(current);
  838         return ret;
  839 }
  840 
  841 SYSCALL_DEFINE5(pwritev, unsigned long, fd, const struct iovec __user *, vec,
  842                 unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
  843 {
  844         loff_t pos = pos_from_hilo(pos_h, pos_l);
  845         struct fd f;
  846         ssize_t ret = -EBADF;
  847 
  848         if (pos < 0)
  849                 return -EINVAL;
  850 
  851         f = fdget(fd);
  852         if (f.file) {
  853                 ret = -ESPIPE;
  854                 if (f.file->f_mode & FMODE_PWRITE)
  855                         ret = vfs_writev(f.file, vec, vlen, &pos);
  856                 fdput(f);
  857         }
  858 
  859         if (ret > 0)
  860                 add_wchar(current, ret);
  861         inc_syscw(current);
  862         return ret;
  863 }
  864 
  865 ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos, size_t count,
  866                     loff_t max)
  867 {
  868         struct fd in, out;
  869         struct inode *in_inode, *out_inode;
  870         loff_t pos;
  871         ssize_t retval;
  872         int fl;
  873 
  874         /*
  875          * Get input file, and verify that it is ok..
  876          */
  877         retval = -EBADF;
  878         in = fdget(in_fd);
  879         if (!in.file)
  880                 goto out;
  881         if (!(in.file->f_mode & FMODE_READ))
  882                 goto fput_in;
  883         retval = -ESPIPE;
  884         if (!ppos)
  885                 ppos = &in.file->f_pos;
  886         else
  887                 if (!(in.file->f_mode & FMODE_PREAD))
  888                         goto fput_in;
  889         retval = rw_verify_area(READ, in.file, ppos, count);
  890         if (retval < 0)
  891                 goto fput_in;
  892         count = retval;
  893 
  894         /*
  895          * Get output file, and verify that it is ok..
  896          */
  897         retval = -EBADF;
  898         out = fdget(out_fd);
  899         if (!out.file)
  900                 goto fput_in;
  901         if (!(out.file->f_mode & FMODE_WRITE))
  902                 goto fput_out;
  903         retval = -EINVAL;
  904         in_inode = in.file->f_path.dentry->d_inode;
  905         out_inode = out.file->f_path.dentry->d_inode;
  906         retval = rw_verify_area(WRITE, out.file, &out.file->f_pos, count);
  907         if (retval < 0)
  908                 goto fput_out;
  909         count = retval;
  910 
  911         if (!max)
  912                 max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
  913 
  914         pos = *ppos;
  915         if (unlikely(pos + count > max)) {
  916                 retval = -EOVERFLOW;
  917                 if (pos >= max)
  918                         goto fput_out;
  919                 count = max - pos;
  920         }
  921 
  922         fl = 0;
  923 #if 0
  924         /*
  925          * We need to debate whether we can enable this or not. The
  926          * man page documents EAGAIN return for the output at least,
  927          * and the application is arguably buggy if it doesn't expect
  928          * EAGAIN on a non-blocking file descriptor.
  929          */
  930         if (in.file->f_flags & O_NONBLOCK)
  931                 fl = SPLICE_F_NONBLOCK;
  932 #endif
  933         retval = do_splice_direct(in.file, ppos, out.file, count, fl);
  934 
  935         if (retval > 0) {
  936                 add_rchar(current, retval);
  937                 add_wchar(current, retval);
  938                 fsnotify_access(in.file);
  939                 fsnotify_modify(out.file);
  940         }
  941 
  942         inc_syscr(current);
  943         inc_syscw(current);
  944         if (*ppos > max)
  945                 retval = -EOVERFLOW;
  946 
  947 fput_out:
  948         fdput(out);
  949 fput_in:
  950         fdput(in);
  951 out:
  952         return retval;
  953 }
  954 
  955 SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd, off_t __user *, offset, size_t, count)
  956 {
  957         loff_t pos;
  958         off_t off;
  959         ssize_t ret;
  960 
  961         if (offset) {
  962                 if (unlikely(get_user(off, offset)))
  963                         return -EFAULT;
  964                 pos = off;
  965                 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
  966                 if (unlikely(put_user(pos, offset)))
  967                         return -EFAULT;
  968                 return ret;
  969         }
  970 
  971         return do_sendfile(out_fd, in_fd, NULL, count, 0);
  972 }
  973 
  974 SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd, loff_t __user *, offset, size_t, count)
  975 {
  976         loff_t pos;
  977         ssize_t ret;
  978 
  979         if (offset) {
  980                 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
  981                         return -EFAULT;
  982                 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
  983                 if (unlikely(put_user(pos, offset)))
  984                         return -EFAULT;
  985                 return ret;
  986         }
  987 
  988         return do_sendfile(out_fd, in_fd, NULL, count, 0);
  989 }

Cache object: 1d59269f53490cbdd691132e0201b4eb


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