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Support for file systems that cannot handle O_EXCL.

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git-svn-id: svn://svn.code.sf.net/p/rdesktop/code/trunk/rdesktop@789 423420c4-83ab-492f-b58f-81f9feb106b5
This commit is contained in:
Peter Åstrand 2004-10-28 07:46:39 +00:00
parent 3ad942b774
commit 9af3418b70
1 changed files with 51 additions and 1 deletions
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52
disk.c
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@ -191,6 +191,56 @@ ftruncate_growable(int fd, off_t length)
return 0;
}
/* Just like open(2), but if a open with O_EXCL fails, retry with
GUARDED semantics. This might be necessary because some filesystems
(such as NFS filesystems mounted from a unfsd server) doesn't
support O_EXCL. GUARDED semantics are subject to race conditions,
but we can live with that.
*/
static int
open_weak_exclusive(const char *pathname, int flags, mode_t mode)
{
int ret;
struct stat statbuf;
ret = open(pathname, flags, mode);
if (ret != -1 || !(flags & O_EXCL))
{
/* Success, or not using O_EXCL */
return ret;
}
/* An error occured, and we are using O_EXCL. In case the FS
doesn't support O_EXCL, some kind of error will be
returned. Unfortunately, we don't know which one. Linux
2.6.8 seems to return 524, but I cannot find a documented
#define for this case. So, we'll return only on errors that
we know aren't related to O_EXCL. */
switch (errno)
{
case EACCES:
case EEXIST:
case EINTR:
case EISDIR:
case ELOOP:
case ENAMETOOLONG:
case ENOENT:
case ENOTDIR:
return ret;
}
/* Retry with GUARDED semantics */
if (stat(pathname, &statbuf) != -1)
{
/* File exists */
errno = EEXIST;
return -1;
}
else
{
return open(pathname, flags & ~O_EXCL, mode);
}
}
/* Enumeration of devices from rdesktop.c */
/* returns numer of units found and initialized. */
@ -334,7 +384,7 @@ disk_create(uint32 device_id, uint32 accessmask, uint32 sharemode, uint32 create
flags |= O_RDONLY;
}
handle = open(path, flags, mode);
handle = open_weak_exclusive(path, flags, mode);
if (handle == -1)
{
switch (errno)