root/kernel/syscalls/truncate.c

/* */

DEFINITIONS

1. sys_truncate

   1 /*
   2  * fiwix/kernel/syscalls/truncate.c
   3  *
   4  * Copyright 2018, Jordi Sanfeliu. All rights reserved.
   5  * Distributed under the terms of the Fiwix License.
   6  */
   7 
   8 #include <fiwix/types.h>
   9 #include <fiwix/fs.h>
  10 #include <fiwix/stat.h>
  11 #include <fiwix/errno.h>
  12 #include <fiwix/string.h>
  13 
  14 #ifdef __DEBUG__
  15 #include <fiwix/stdio.h>
  16 #include <fiwix/process.h>
  17 #endif /*__DEBUG__ */
  18 
  19 int sys_truncate(const char *path, __off_t length)
  20 {
  21         struct inode *i;
  22         char *tmp_name;
  23         int errno;
  24 
  25 #ifdef __DEBUG__
  26         printk("(pid %d) sys_truncate(%s, %d)\n", current->pid, path, length);
  27 #endif /*__DEBUG__ */
  28 
  29         if((errno = malloc_name(path, &tmp_name)) < 0) {
  30                 return errno;
  31         }
  32         if((errno = namei(tmp_name, &i, NULL, FOLLOW_LINKS))) {
  33                 free_name(tmp_name);
  34                 return errno;
  35         }
  36         if(S_ISDIR(i->i_mode)) {
  37                 iput(i);
  38                 free_name(tmp_name);
  39                 return -EISDIR;
  40         }
  41         if(IS_RDONLY_FS(i)) {
  42                 iput(i);
  43                 free_name(tmp_name);
  44                 return -EROFS;
  45         }
  46         if(check_permission(TO_WRITE, i) < 0) {
  47                 iput(i);
  48                 free_name(tmp_name);
  49                 return -EACCES;
  50         }
  51         if(length == i->i_size) {
  52                 iput(i);
  53                 free_name(tmp_name);
  54                 return 0;
  55         }
  56 
  57         errno = 0;
  58         if(i->fsop && i->fsop->truncate) {
  59                 inode_lock(i);
  60                 errno = i->fsop->truncate(i, length);
  61                 inode_unlock(i);
  62         }
  63         iput(i);
  64         free_name(tmp_name);
  65         return errno;
  66 }

/* */