hw/9pfs/9p-util.c

   1 /*
   2  * 9p utilities
   3  *
   4  * Copyright IBM, Corp. 2017
   5  *
   6  * Authors:
   7  *  Greg Kurz <groug@kaod.org>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  */
  12
  13 #include "qemu/osdep.h"
  14 #include "qemu/xattr.h"
  15 #include "9p-util.h"
  16
  17 int relative_openat_nofollow(int dirfd, const char *path, int flags,
  18                              mode_t mode)
  19 {
  20     int fd;
  21
  22     fd = dup(dirfd);
  23     if (fd == -1) {
  24         return -1;
  25     }
  26
  27     while (*path) {
  28         const char *c;
  29         int next_fd;
  30         char *head;
  31
  32         /* Only relative paths without consecutive slashes */
  33         assert(path[0] != '/');
  34
  35         head = g_strdup(path);
  36         c = strchr(path, '/');
  37         if (c) {
  38             head[c - path] = 0;
  39             next_fd = openat_dir(fd, head);
  40         } else {
  41             next_fd = openat_file(fd, head, flags, mode);
  42         }
  43         g_free(head);
  44         if (next_fd == -1) {
  45             close_preserve_errno(fd);
  46             return -1;
  47         }
  48         close(fd);
  49         fd = next_fd;
  50
  51         if (!c) {
  52             break;
  53         }
  54         path = c + 1;
  55     }
  56
  57     return fd;
  58 }
  59
  60 ssize_t fgetxattrat_nofollow(int dirfd, const char *filename, const char *name,
  61                              void *value, size_t size)
  62 {
  63     char *proc_path = g_strdup_printf("/proc/self/fd/%d/%s", dirfd, filename);
  64     int ret;
  65
  66     ret = lgetxattr(proc_path, name, value, size);
  67     g_free(proc_path);
  68     return ret;
  69 }