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65 lines
3.0 KiB
C
65 lines
3.0 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#pragma once
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#include <sys/sysmacros.h>
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#include "forward.h"
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int parse_devnum(const char *s, dev_t *ret);
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#define DEVNUM_MAJOR_MAX ((UINT32_C(1) << 12) - 1U)
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#define DEVNUM_MINOR_MAX ((UINT32_C(1) << 20) - 1U)
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/* glibc and the Linux kernel have different ideas about the major/minor size. These calls will check whether the
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* specified major is valid by the Linux kernel's standards, not by glibc's. Linux has 20bits of minor, and 12 bits of
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* major space. See MINORBITS in linux/kdev_t.h in the kernel sources. (If you wonder why we define _y here, instead of
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* comparing directly >= 0: it's to trick out -Wtype-limits, which would otherwise complain if the type is unsigned, as
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* such a test would be pointless in such a case.) */
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#define DEVICE_MAJOR_VALID(x) \
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({ \
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typeof(x) _x = (x), _y = 0; \
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_x >= _y && _x <= DEVNUM_MAJOR_MAX; \
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\
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})
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#define DEVICE_MINOR_VALID(x) \
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({ \
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typeof(x) _x = (x), _y = 0; \
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_x >= _y && _x <= DEVNUM_MINOR_MAX; \
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})
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int device_path_make_major_minor(mode_t mode, dev_t devnum, char **ret);
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int device_path_make_inaccessible(mode_t mode, char **ret);
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int device_path_make_canonical(mode_t mode, dev_t devnum, char **ret);
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int device_path_parse_major_minor(const char *path, mode_t *ret_mode, dev_t *ret_devnum);
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static inline bool devnum_set_and_equal(dev_t a, dev_t b) {
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/* Returns true if a and b definitely refer to the same device. If either is zero, this means "don't
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* know" and we'll return false */
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return a == b && a != 0;
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}
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/* Maximum string length for a major:minor string. (Note that DECIMAL_STR_MAX includes space for a trailing NUL) */
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#define DEVNUM_STR_MAX (DECIMAL_STR_MAX(dev_t)-1+1+DECIMAL_STR_MAX(dev_t))
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#define DEVNUM_FORMAT_STR "%u:%u"
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#define DEVNUM_FORMAT_VAL(d) major(d), minor(d)
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char *format_devnum(dev_t d, char buf[static DEVNUM_STR_MAX]);
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#define FORMAT_DEVNUM(d) format_devnum((d), (char[DEVNUM_STR_MAX]) {})
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static inline bool devnum_is_zero(dev_t d) {
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return major(d) == 0 && minor(d) == 0;
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}
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#define DEVNUM_TO_PTR(u) ((void*) (uintptr_t) (u))
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#define PTR_TO_DEVNUM(p) ((dev_t) ((uintptr_t) (p)))
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/* Convert a userspace dev_t (as returned by stat()) to the kernel's internal dev_t encoding. stat() returns
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* new_encode_dev(s_dev), while various kernel interfaces (e.g. the BPF sb helpers, or unix_diag's
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* udiag_vfs_dev) report s_dev directly, which uses MKDEV(major, minor) = (major << 20) | minor. */
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#define STAT_DEV_TO_KERNEL(dev) \
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((uint32_t) major(dev) << 20 | (uint32_t) minor(dev))
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