about summary refs log tree commit diff
path: root/sysdeps/unix/sysv/linux/openat.c
blob: 9bb8acec1fa6cc41aff6ebadbb8ce4ebaece5588 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
/* Copyright (C) 2005-2014 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <kernel-features.h>
#include <sysdep-cancel.h>
#include <not-cancel.h>


#ifndef OPENAT
# define OPENAT openat

# ifndef __ASSUME_ATFCTS
/* Set errno after a failed call.  If BUF is not null,
   it is a /proc/self/fd/ path name we just tried to use.  */
void
attribute_hidden
__atfct_seterrno (int errval, int fd, const char *buf)
{
  if (buf != NULL)
    {
      struct stat64 st;

      if (errval == ENOTDIR || errval == ENOENT)
	{
	  /* This can mean either the file descriptor is invalid or
	     /proc is not mounted.  */
	  if (__fxstat64 (_STAT_VER, fd, &st) != 0)
	    /* errno is already set correctly.  */
	    return;

	  /* If /proc is not mounted there is nothing we can do.  */
	  if ((errval != ENOTDIR || S_ISDIR (st.st_mode))
	      && (__xstat64 (_STAT_VER, "/proc/self/fd", &st) != 0
		  || !S_ISDIR (st.st_mode)))
	    errval = ENOSYS;
	}
    }

  __set_errno (errval);
}

int __have_atfcts;
# endif
#endif


#define OPENAT_NOT_CANCEL CONCAT (OPENAT)
#define CONCAT(name) CONCAT2 (name)
#define CONCAT2(name) __##name##_nocancel


int
OPENAT_NOT_CANCEL (fd, file, oflag, mode)
     int fd;
     const char *file;
     int oflag;
     mode_t mode;
{

  /* We have to add the O_LARGEFILE flag for openat64.  */
#ifdef MORE_OFLAGS
  oflag |= MORE_OFLAGS;
#endif

  int res;

#ifdef __NR_openat
# ifndef __ASSUME_ATFCTS
  if (__have_atfcts >= 0)
# endif
    {
      res = INLINE_SYSCALL (openat, 4, fd, file, oflag, mode);

# ifndef __ASSUME_ATFCTS
      if (res == -1 && errno == ENOSYS)
	__have_atfcts = -1;
      else
# endif
	return res;
    }
#endif

#ifndef __ASSUME_ATFCTS
  INTERNAL_SYSCALL_DECL (err);
  char *buf = NULL;

  if (fd != AT_FDCWD && file[0] != '/')
    {
      size_t filelen = strlen (file);
      if (__builtin_expect (filelen == 0, 0))
	{
	  __set_errno (ENOENT);
	  return -1;
	}

      static const char procfd[] = "/proc/self/fd/%d/%s";
      /* Buffer for the path name we are going to use.  It consists of
	 - the string /proc/self/fd/
	 - the file descriptor number
	 - the file name provided.
	 The final NUL is included in the sizeof.   A bit of overhead
	 due to the format elements compensates for possible negative
	 numbers.  */
      size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
      buf = alloca (buflen);

      /* Note: snprintf cannot be canceled.  */
      __snprintf (buf, buflen, procfd, fd, file);
      file = buf;
    }

  res = INTERNAL_SYSCALL (open, err, 3, file, oflag, mode);

  if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (res, err), 0))
    {
      __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (res, err), fd, buf);
      res = -1;
    }

  return res;
#endif
}

#define UNDERIZE(name) UNDERIZE_1 (name)
#define UNDERIZE_1(name) __##name
#define __OPENAT UNDERIZE (OPENAT)


/* Open FILE with access OFLAG.  Interpret relative paths relative to
   the directory associated with FD.  If OFLAG includes O_CREAT, a
   third argument is the file protection.  */
int
__OPENAT (fd, file, oflag)
     int fd;
     const char *file;
     int oflag;
{
  mode_t mode = 0;
  if (oflag & O_CREAT)
    {
      va_list arg;
      va_start (arg, oflag);
      mode = va_arg (arg, mode_t);
      va_end (arg);
    }

  if (SINGLE_THREAD_P)
    return OPENAT_NOT_CANCEL (fd, file, oflag, mode);

  int oldtype = LIBC_CANCEL_ASYNC ();

  int res = OPENAT_NOT_CANCEL (fd, file, oflag, mode);

  LIBC_CANCEL_RESET (oldtype);

  return res;
}
libc_hidden_def (__OPENAT)
weak_alias (__OPENAT, OPENAT)