lib: [loopdev.c] add module for work loop devices

Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 154 insertions, 0 deletions

diff --git a/include/loopdev.h b/include/loopdev.h
new file mode 100644
index 000000000..74b9e02ec
--- /dev/null
+++ b/include/loopdev.h
@@ -0,0 +1,154 @@
+#ifndef UTIL_LINUX_LOOPDEV_H
+#define UTIL_LINUX_LOOPDEV_H
+
+/*
+ * loop_info.lo_encrypt_type
+ */
+#define LO_CRYPT_NONE	0
+#define LO_CRYPT_XOR	1
+#define LO_CRYPT_DES	2
+#define LO_CRYPT_CRYPTOAPI 18
+
+#define LOOP_SET_FD		0x4C00
+#define LOOP_CLR_FD		0x4C01
+/*
+ * Obsolete (kernel < 2.6)
+ *
+ * #define LOOP_SET_STATUS	0x4C02
+ * #define LOOP_GET_STATUS	0x4C03
+ */
+#define LOOP_SET_STATUS64	0x4C04
+#define LOOP_GET_STATUS64	0x4C05
+/* #define LOOP_CHANGE_FD	0x4C06 */
+#define LOOP_SET_CAPACITY	0x4C07
+
+/*
+ * loop_info.lo_flags
+ */
+enum {
+	LO_FLAGS_READ_ONLY  = 1,
+	LO_FLAGS_USE_AOPS   = 2,
+	LO_FLAGS_AUTOCLEAR  = 4, /* New in 2.6.25 */
+};
+
+#define LO_NAME_SIZE	64
+#define LO_KEY_SIZE	32
+
+/*
+ * Linux LOOP_{SET,GET}_STATUS64 ioclt struct
+ */
+struct loop_info64 {
+	uint64_t	lo_device;
+	uint64_t	lo_inode;
+	uint64_t	lo_rdevice;
+	uint64_t	lo_offset;
+	uint64_t	lo_sizelimit; /* bytes, 0 == max available */
+	uint32_t	lo_number;
+	uint32_t	lo_encrypt_type;
+	uint32_t	lo_encrypt_key_size;
+	uint32_t	lo_flags;
+	uint8_t		lo_file_name[LO_NAME_SIZE];
+	uint8_t		lo_crypt_name[LO_NAME_SIZE];
+	uint8_t		lo_encrypt_key[LO_KEY_SIZE];
+	uint64_t	lo_init[2];
+};
+
+#define LOOPDEV_MAJOR		7	/* loop major number */
+#define LOOPDEV_DEFAULT_NNODES	8	/* default number of loop devices */
+
+struct loopdev_iter {
+	FILE		*proc;		/* /proc/partitions */
+	int		ncur;		/* current position */
+	int		*minors;	/* ary of minor numbers (when scan whole /dev) */
+	int		nminors;	/* number of items in *minors */
+	int		ct_perm;	/* count permission problems */
+	int		ct_succ;	/* count number of detected devices */
+
+	int		done:1;		/* scanning done */
+	int		default_check:1;/* check first LOOPDEV_NLOOPS */
+	int		flags;		/* LOOPITER_FL_* flags */
+};
+
+enum {
+	LOOPITER_FL_FREE	= (1 << 0),
+	LOOPITER_FL_USED	= (1 << 1)
+};
+
+/*
+ * handler for work with loop devices
+ */
+struct loopdev_cxt {
+	char		device[128];	/* device path (e.g. /dev/loop<N>) */
+	char		*filename;	/* backing file for loopcxt_set_... */
+	int		fd;		/* open(/dev/looo<N>) */
+
+	int		flags;		/* LOOPDEV_FL_* flags */
+	int		has_info:1;	/* .info contains data */
+	int		extra_check:1;	/* unusual stuff for iterator */
+
+	struct sysfs_cxt	sysfs;	/* pointer to /sys/dev/block/<maj:min>/ */
+	struct loop_info64	info;	/* for GET/SET ioctl */
+	struct loopdev_iter	iter;	/* scans /sys or /dev for used/free devices */
+};
+
+/*
+ * loopdev_cxt.flags
+ */
+enum {
+	LOOPDEV_FL_RDONLY	= (1 << 0),	/* default */
+	LOOPDEV_FL_RDWR		= (1 << 1),	/* necessary for loop setup only */
+	LOOPDEV_FL_OFFSET	= (1 << 4),
+	LOOPDEV_FL_NOSYSFS	= (1 << 5),
+	LOOPDEV_FL_NOIOCTL	= (1 << 6),
+	LOOPDEV_FL_DEVSUBDIR	= (1 << 7)
+};
+
+/*
+ * High-level
+ */
+extern int is_loopdev(const char *device);
+extern int loopdev_is_autoclear(const char *device);
+extern char *loopdev_get_backing_file(const char *device);
+extern int loopdev_is_used(const char *device, const char *filename,
+			   uint64_t offset, int flags);
+extern char *loopdev_find_by_backing_file(const char *filename,
+					  uint64_t offset, int flags);
+extern int loopcxt_find_unused(struct loopdev_cxt *lc);
+extern int loopdev_delete(const char *device);
+
+/*
+ * Low-level
+ */
+extern int loopcxt_init(struct loopdev_cxt *lc, int flags);
+extern void loopcxt_deinit(struct loopdev_cxt *lc);
+
+extern int loopcxt_set_device(struct loopdev_cxt *lc, const char *device);
+extern char *loopcxt_strdup_device(struct loopdev_cxt *lc);
+extern const char *loopcxt_get_device(struct loopdev_cxt *lc);
+extern struct sysfs_cxt *loopcxt_get_sysfs(struct loopdev_cxt *lc);
+extern int loopcxt_get_fd(struct loopdev_cxt *lc);
+
+extern int loopcxt_init_iterator(struct loopdev_cxt *lc, int flags);
+extern int loopcxt_deinit_iterator(struct loopdev_cxt *lc);
+extern int loopcxt_next(struct loopdev_cxt *lc);
+
+extern int loopcxt_setup_device(struct loopdev_cxt *lc);
+extern int loopcxt_delete_device(struct loopdev_cxt *lc);
+
+int loopcxt_set_offset(struct loopdev_cxt *lc, uint64_t offset);
+int loopcxt_set_sizelimit(struct loopdev_cxt *lc, uint64_t sizelimit);
+int loopcxt_set_flags(struct loopdev_cxt *lc, uint32_t flags);
+int loopcxt_set_backing_file(struct loopdev_cxt *lc, const char *filename);
+int loopcxt_set_encryption(struct loopdev_cxt *lc,
+                           const char *encryption,
+                           const char *password);
+
+extern char *loopcxt_get_backing_file(struct loopdev_cxt *lc);
+extern int loopcxt_get_offset(struct loopdev_cxt *lc, uint64_t *offset);
+extern int loopcxt_get_sizelimit(struct loopdev_cxt *lc, uint64_t *size);
+extern int loopcxt_is_autoclear(struct loopdev_cxt *lc);
+extern int loopcxt_find_by_backing_file(struct loopdev_cxt *lc,
+				const char *filename,
+                                uint64_t offset, int flags);
+
+#endif /* UTIL_LINUX_LOOPDEV_H */