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loop-util: introduce loop_device_open_full()

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This commit is contained in:
Yu Watanabe 2022-09-05 02:48:01 +09:00
parent 9b5626d67a
commit a8d8a61980
2 changed files with 43 additions and 14 deletions
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52
src/shared/loop-util.c
View file

@ -791,41 +791,55 @@ void loop_device_unrelinquish(LoopDevice *d) {
d->relinquished = false;
}
int loop_device_open(
int loop_device_open_full(
const char *loop_path,
int loop_fd,
int open_flags,
int lock_op,
LoopDevice **ret) {
_cleanup_close_ int loop_fd = -1, lock_fd = -1;
_cleanup_close_ int fd = -1, lock_fd = -1;
_cleanup_free_ char *p = NULL;
struct loop_info64 info;
uint64_t diskseq = 0;
struct stat st;
LoopDevice *d;
int nr;
int r, nr = -1;
assert(loop_path);
assert(loop_path || loop_fd >= 0);
assert(IN_SET(open_flags, O_RDWR, O_RDONLY));
assert(ret);
loop_fd = open(loop_path, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags);
if (loop_fd < 0)
return -errno;
if (loop_fd < 0) {
fd = open(loop_path, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags);
if (fd < 0)
return -errno;
loop_fd = fd;
}
if (fstat(loop_fd, &st) < 0)
return -errno;
if (!S_ISBLK(st.st_mode))
return -ENOTBLK;
if (fd < 0) {
/* If loop_fd is provided through the argument, then we reopen the inode here, instead of
* keeping just a dup() clone of it around, since we want to ensure that the O_DIRECT
* flag of the handle we keep is off, we have our own file index, and have the right
* read/write mode in effect.*/
fd = fd_reopen(loop_fd, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags);
if (fd < 0)
return fd;
loop_fd = fd;
}
if (ioctl(loop_fd, LOOP_GET_STATUS64, &info) >= 0) {
#if HAVE_VALGRIND_MEMCHECK_H
/* Valgrind currently doesn't know LOOP_GET_STATUS64. Remove this once it does */
VALGRIND_MAKE_MEM_DEFINED(&info, sizeof(info));
#endif
nr = info.lo_number;
} else
nr = -1;
}
r = fd_get_diskseq(loop_fd, &diskseq);
if (r < 0 && r != -EOPNOTSUPP)
@ -837,16 +851,28 @@ int loop_device_open(
return lock_fd;
}
p = strdup(loop_path);
if (!p)
return -ENOMEM;
if (loop_path) {
/* If loop_path is provided, then honor it. */
p = strdup(loop_path);
if (!p)
return -ENOMEM;
} else if (nr >= 0) {
/* This is a loopback block device. Use its index. */
if (asprintf(&p, "/dev/loop%i", nr) < 0)
return -ENOMEM;
} else {
/* This is a non-loopback block device. Let's get the path to the device node. */
r = devname_from_stat_rdev(&st, &p);
if (r < 0)
return r;
}
d = new(LoopDevice, 1);
if (!d)
return -ENOMEM;
*d = (LoopDevice) {
.fd = TAKE_FD(loop_fd),
.fd = TAKE_FD(fd),
.lock_fd = TAKE_FD(lock_fd),
.nr = nr,
.node = TAKE_PTR(p),

5
src/shared/loop-util.h
View file

@ -25,7 +25,10 @@ struct LoopDevice {
int loop_device_make(int fd, int open_flags, uint64_t offset, uint64_t size, uint32_t loop_flags, int lock_op, LoopDevice **ret);
int loop_device_make_by_path(const char *path, int open_flags, uint32_t loop_flags, int lock_op, LoopDevice **ret);
int loop_device_open(const char *loop_path, int open_flags, int lock_op, LoopDevice **ret);
int loop_device_open_full(const char *loop_path, int loop_fd, int open_flags, int lock_op, LoopDevice **ret);
static inline int loop_device_open(const char *loop_path, int open_flags, int lock_op, LoopDevice **ret) {
return loop_device_open_full(loop_path, -1, open_flags, lock_op, ret);
}
LoopDevice* loop_device_unref(LoopDevice *d);
DEFINE_TRIVIAL_CLEANUP_FUNC(LoopDevice*, loop_device_unref);