Purpose of this function is to open a path that is potentially pointing to a
block device or file without races, and checking ensuring block device is
not busy when path points to such.
Signed-off-by: Sami Kerola <kerolasa@xxxxxx>
---
include/blkdev.h | 3 +++
lib/blkdev.c | 27 +++++++++++++++++++++++++++
2 files changed, 30 insertions(+)
diff --git a/include/blkdev.h b/include/blkdev.h
index c994795..fde2dbf 100644
--- a/include/blkdev.h
+++ b/include/blkdev.h
@@ -97,6 +97,9 @@ struct hd_geometry {
/* are we working with block device? */
int is_blkdev(int fd);
+/* open block device or file */
+int open_blkdev_or_file(const char *name, const int oflag);
+
/* Determine size in bytes */
off_t blkdev_find_size (int fd);
diff --git a/lib/blkdev.c b/lib/blkdev.c
index 5f49582..da8d835 100644
--- a/lib/blkdev.c
+++ b/lib/blkdev.c
@@ -25,9 +25,15 @@
# include <sys/disk.h>
#endif
+#ifndef EBADFD
+# define EBADFD 77 /* File descriptor in bad state */
+#endif
+
#include "blkdev.h"
#include "c.h"
#include "linux_version.h"
+#include "fileutils.h"
+#include "nls.h"
static long
blkdev_valid_offset (int fd, off_t offset) {
@@ -254,6 +260,27 @@ int blkdev_is_misaligned(int fd)
#endif
}
+int open_blkdev_or_file(const char *name, const int oflag)
+{
+ int fd;
+ struct stat ftype;
+
+ if (stat(name, &ftype) < 0)
+ return -1;
+ if (S_ISBLK(ftype.st_mode)) {
+ fd = open(name, oflag | O_EXCL);
+ } else
+ fd = open(name, oflag);
+ if (-1 < fd && !is_same_inode(fd, name)) {
+ close(fd);
+ errno = EBADFD;
+ return -1;
+ }
+ if (-1 < fd && S_ISBLK(ftype.st_mode) && blkdev_is_misaligned(fd))
+ warnx(_("warning: %s is misaligned"), name);
+ return fd;
+}
+
int blkdev_is_cdrom(int fd)
{
#ifdef CDROM_GET_CAPABILITY
--
2.6.2
--
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