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1998-10-18  Zack Weinberg  <zack@rabi.phys.columbia.edu> 
 
        * sysdeps/unix/opendir.c: Check at runtime for kernel support for 
        O_DIRECTORY.
This commit is contained in:
Ulrich Drepper 1998-10-20 23:03:20 +00:00
parent 9cdc774d05
commit 413bb8ca87
2 changed files with 57 additions and 11 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
1998-10-18 Zack Weinberg <zack@rabi.phys.columbia.edu>
* sysdeps/unix/opendir.c: Check at runtime for kernel support for
O_DIRECTORY.
1998-10-20 H.J. Lu <hjl@gnu.org>
* sysdeps/unix/sysv/linux/i386/setresuid.c (__setresuid): Fix

63
sysdeps/unix/opendir.c
View File

@ -29,9 +29,40 @@
#include <dirstream.h>
/* opendir() must not accidentally open something other than a directory.
Some OS's have kernel support for that, some don't. In the worst
case we have to stat() before the open() AND fstat() after.
#ifndef O_DIRECTORY
# define O_DIRECTORY 0
We have to test at runtime for kernel support since libc may have
been compiled with different headers to the kernel it's running on.
This test can't be done reliably in the general case. We'll use
/dev/null, which if it's not a device lots of stuff will break, as
a guinea pig. It may be missing in chroot environments, so we
make sure to fail safe. */
#ifdef O_DIRECTORY
static int o_directory_works = -1;
static void
tryopen_o_directory (void)
{
int serrno = errno;
int x = __open ("/dev/null", O_RDONLY|O_NDELAY|O_DIRECTORY);
if (x >= 0)
{
__close (x);
o_directory_works = 0;
}
else if (errno != ENOTDIR)
o_directory_works = 0;
else
o_directory_works = 1;
__set_errno (serrno);
}
# define EXTRA_FLAGS O_DIRECTORY
#else
# define EXTRA_FLAGS 0
#endif
@ -53,18 +84,28 @@ __opendir (const char *name)
return NULL;
}
/* We first have to check whether the name is for a directory. We
cannot do this after the open() call since the open/close operation
performed on, say, a tape device might have undesirable effects. */
if (__stat (name, &statbuf) < 0)
return NULL;
if (! S_ISDIR (statbuf.st_mode))
#ifdef O_DIRECTORY
/* Test whether O_DIRECTORY works. */
if (o_directory_works == -1)
tryopen_o_directory ();
/* We can skip the expensive `stat' call if O_DIRECTORY works. */
if (o_directory_works == 0)
#endif
{
__set_errno (ENOTDIR);
return NULL;
/* We first have to check whether the name is for a directory. We
cannot do this after the open() call since the open/close operation
performed on, say, a tape device might have undesirable effects. */
if (__stat (name, &statbuf) < 0)
return NULL;
if (! S_ISDIR (statbuf.st_mode))
{
__set_errno (ENOTDIR);
return NULL;
}
}
fd = __open (name, O_RDONLY|O_NDELAY|O_DIRECTORY);
fd = __open (name, O_RDONLY|O_NDELAY|EXTRA_FLAGS);
if (fd < 0)
return NULL;