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chattr-util: introduce fallback mode to set file attributes one by one

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This commit is contained in:
Yu Watanabe 2020-11-27 12:47:05 +09:00
parent d7d1d18fd2
commit 459631a0f9
2 changed files with 61 additions and 26 deletions
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76
src/basic/chattr-util.c
View File

@ -10,25 +10,31 @@
#include "fd-util.h"
#include "macro.h"
int chattr_fd(int fd, unsigned value, unsigned mask, unsigned *previous) {
int chattr_full(const char *path, int fd, unsigned value, unsigned mask, unsigned *ret_previous, unsigned *ret_final, bool fallback) {
_cleanup_close_ int fd_will_close = -1;
unsigned old_attr, new_attr;
struct stat st;
assert(fd >= 0);
assert(path || fd >= 0);
if (fd < 0) {
fd = fd_will_close = open(path, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
if (fd < 0)
return -errno;
}
if (fstat(fd, &st) < 0)
return -errno;
/* Explicitly check whether this is a regular file or
* directory. If it is anything else (such as a device node or
* fifo), then the ioctl will not hit the file systems but
* possibly drivers, where the ioctl might have different
* effects. Notably, DRM is using the same ioctl() number. */
/* Explicitly check whether this is a regular file or directory. If it is anything else (such
* as a device node or fifo), then the ioctl will not hit the file systems but possibly
* drivers, where the ioctl might have different effects. Notably, DRM is using the same
* ioctl() number. */
if (!S_ISDIR(st.st_mode) && !S_ISREG(st.st_mode))
return -ENOTTY;
if (mask == 0 && !previous)
if (mask == 0 && !ret_previous && !ret_final)
return 0;
if (ioctl(fd, FS_IOC_GETFLAGS, &old_attr) < 0)
@ -36,33 +42,55 @@ int chattr_fd(int fd, unsigned value, unsigned mask, unsigned *previous) {
new_attr = (old_attr & ~mask) | (value & mask);
if (new_attr == old_attr) {
if (previous)
*previous = old_attr;
if (ret_previous)
*ret_previous = old_attr;
if (ret_final)
*ret_final = old_attr;
return 0;
}
if (ioctl(fd, FS_IOC_SETFLAGS, &new_attr) < 0)
if (ioctl(fd, FS_IOC_SETFLAGS, &new_attr) >= 0) {
if (ret_previous)
*ret_previous = old_attr;
if (ret_final)
*ret_final = new_attr;
return 1;
}
if (errno != EINVAL || !fallback)
return -errno;
if (previous)
*previous = old_attr;
/* When -EINVAL is returned, we assume that incompatible attributes are simultaneously
* specified. E.g., compress(c) and nocow(C) attributes cannot be set to files on btrfs.
* As a fallback, let's try to set attributes one by one. */
return 1;
}
unsigned current_attr = old_attr;
for (unsigned i = 0; i < sizeof(unsigned) * 8; i++) {
unsigned new_one, mask_one = 1u << i;
int chattr_path(const char *p, unsigned value, unsigned mask, unsigned *previous) {
_cleanup_close_ int fd = -1;
if (!FLAGS_SET(mask, mask_one))
continue;
assert(p);
new_one = UPDATE_FLAG(current_attr, mask_one, FLAGS_SET(value, mask_one));
if (new_one == current_attr)
continue;
if (mask == 0)
return 0;
if (ioctl(fd, FS_IOC_SETFLAGS, &new_one) < 0) {
if (errno != EINVAL)
return -errno;
continue;
}
fd = open(p, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
if (fd < 0)
return -errno;
if (ioctl(fd, FS_IOC_GETFLAGS, &current_attr) < 0)
return -errno;
}
return chattr_fd(fd, value, mask, previous);
if (ret_previous)
*ret_previous = old_attr;
if (ret_final)
*ret_final = current_attr;
return current_attr == new_attr ? 1 : -ENOANO; /* -ENOANO indicates that some attributes cannot be set. */
}
int read_attr_fd(int fd, unsigned *ret) {

11
src/basic/chattr-util.h
View File

@ -2,6 +2,8 @@
#pragma once
#include <linux/fs.h>
#include <stdbool.h>
#include <stddef.h>
#include "missing_fs.h"
@ -32,8 +34,13 @@
FS_NOCOW_FL | \
FS_PROJINHERIT_FL)
int chattr_fd(int fd, unsigned value, unsigned mask, unsigned *previous);
int chattr_path(const char *p, unsigned value, unsigned mask, unsigned *previous);
int chattr_full(const char *path, int fd, unsigned value, unsigned mask, unsigned *ret_previous, unsigned *ret_final, bool fallback);
static inline int chattr_fd(int fd, unsigned value, unsigned mask, unsigned *previous) {
return chattr_full(NULL, fd, value, mask, previous, NULL, false);
}
static inline int chattr_path(const char *path, unsigned value, unsigned mask, unsigned *previous) {
return chattr_full(path, -1, value, mask, previous, NULL, false);
}
int read_attr_fd(int fd, unsigned *ret);
int read_attr_path(const char *p, unsigned *ret);