core/fs/chdir.c

   1 #include <stdio.h>
   2 #include <stdbool.h>
   3 #include <string.h>
   4 #include "fs.h"
   5 #include "cache.h"
   6
   7 /*
   8  * Convert a relative pathname to an absolute pathname
   9  * In the future this might also resolve symlinks...
  10  */
  11 void pm_realpath(com32sys_t *regs)
  12 {
  13     const char *src = MK_PTR(regs->ds, regs->esi.w[0]);
  14     char       *dst = MK_PTR(regs->es, regs->edi.w[0]);
  15
  16     realpath(dst, src, FILENAME_MAX);
  17 }
  18
  19 #define EMIT(x)                         \
  20 do {                                    \
  21     if (++n < bufsize)                  \
  22         *q++ = (x);                     \
  23 } while (0)
  24
  25 static size_t join_paths(char *dst, size_t bufsize,
  26                          const char *s1, const char *s2)
  27 {
  28     const char *list[2];
  29     int i;
  30     char c;
  31     const char *p;
  32     char *q  = dst;
  33     size_t n = 0;
  34     bool slash = false;
  35
  36     list[0] = s1;
  37     list[1] = s2;
  38
  39     for (i = 0; i < 2; i++) {
  40         p = list[i];
  41
  42         while ((c = *p++)) {
  43             if (c == '/') {
  44                 if (!slash)
  45                     EMIT(c);
  46                 slash = true;
  47             } else {
  48                 EMIT(c);
  49                 slash = false;
  50             }
  51         }
  52     }
  53
  54     if (bufsize)
  55         *q = '\0';
  56
  57     return n;
  58 }
  59
  60 size_t realpath(char *dst, const char *src, size_t bufsize)
  61 {
  62     if (this_fs->fs_ops->realpath) {
  63         return this_fs->fs_ops->realpath(this_fs, dst, src, bufsize);
  64     } else {
  65         /* Filesystems with "common" pathname resolution */
  66         return join_paths(dst, bufsize,
  67                           src[0] == '/' ? "" : this_fs->cwd_name,
  68                           src);
  69     }
  70 }
  71
  72 int chdir(const char *src)
  73 {
  74     int rv;
  75     struct file *file;
  76     char cwd_buf[CURRENTDIR_MAX];
  77
  78     if (this_fs->fs_ops->chdir)
  79         return this_fs->fs_ops->chdir(this_fs, src);
  80
  81     /* Otherwise it is a "conventional filesystem" */
  82     rv = searchdir(src);
  83     if (rv < 0)
  84         return rv;
  85
  86     file = handle_to_file(rv);
  87     if (file->inode->mode != DT_DIR) {
  88         _close_file(file);
  89         return -1;
  90     }
  91
  92     put_inode(this_fs->cwd);
  93     this_fs->cwd = get_inode(file->inode);
  94     _close_file(file);
  95
  96     /* Save the current working directory */
  97     realpath(cwd_buf, src, CURRENTDIR_MAX);
  98
  99     /* Make sure the cwd_name ends in a slash, it's supposed to be a prefix */
 100     join_paths(this_fs->cwd_name, CURRENTDIR_MAX, cwd_buf, "/");
 101
 102     return 0;
 103 }