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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 | #ifndef _LINUX_HIGHUID_H
#define _LINUX_HIGHUID_H
#include <linux/config.h>
#include <linux/types.h>
/*
* general notes:
*
* CONFIG_UID16 is defined if the given architecture needs to
* support backwards compatibility for old system calls.
*
* kernel code should use uid_t and gid_t at all times when dealing with
* kernel-private data.
*
* old_uid_t and old_gid_t should only be different if CONFIG_UID16 is
* defined, else the platform should provide dummy typedefs for them
* such that they are equivalent to __kernel_{u,g}id_t.
*
* uid16_t and gid16_t are used on all architectures. (when dealing
* with structures hard coded to 16 bits, such as in filesystems)
*/
/*
* This is the "overflow" UID and GID. They are used to signify uid/gid
* overflow to old programs when they request uid/gid information but are
* using the old 16 bit interfaces.
* When you run a libc5 program, it will think that all highuid files or
* processes are owned by this uid/gid.
* The idea is that it's better to do so than possibly return 0 in lieu of
* 65536, etc.
*/
extern int overflowuid;
extern int overflowgid;
#define DEFAULT_OVERFLOWUID 65534
#define DEFAULT_OVERFLOWGID 65534
#ifdef CONFIG_UID16
/* prevent uid mod 65536 effect by returning a default value for high UIDs */
#define high2lowuid(uid) ((uid) > 65535 ? (old_uid_t)overflowuid : (old_uid_t)(uid))
#define high2lowgid(gid) ((gid) > 65535 ? (old_gid_t)overflowgid : (old_gid_t)(gid))
/*
* -1 is different in 16 bits than it is in 32 bits
* these macros are used by chown(), setreuid(), ...,
*/
#define low2highuid(uid) ((uid) == (old_uid_t)-1 ? (uid_t)-1 : (uid_t)(uid))
#define low2highgid(gid) ((gid) == (old_gid_t)-1 ? (gid_t)-1 : (gid_t)(gid))
/* Avoid extra ifdefs with these macros */
#define SET_UID16(var, uid) var = high2lowuid(uid)
#define SET_GID16(var, gid) var = high2lowgid(gid)
#define NEW_TO_OLD_UID(uid) high2lowuid(uid)
#define NEW_TO_OLD_GID(gid) high2lowgid(gid)
/* specific to fs/stat.c */
#define SET_OLDSTAT_UID(stat, uid) (stat).st_uid = high2lowuid(uid)
#define SET_OLDSTAT_GID(stat, gid) (stat).st_gid = high2lowgid(gid)
#define SET_STAT_UID(stat, uid) (stat).st_uid = high2lowuid(uid)
#define SET_STAT_GID(stat, gid) (stat).st_gid = high2lowgid(gid)
#else
#define SET_UID16(var, uid) do { ; } while (0)
#define SET_GID16(var, gid) do { ; } while (0)
#define NEW_TO_OLD_UID(uid) (uid)
#define NEW_TO_OLD_GID(gid) (gid)
#define SET_OLDSTAT_UID(stat, uid) (stat).st_uid = (uid)
#define SET_OLDSTAT_GID(stat, gid) (stat).st_gid = (gid)
#define SET_STAT_UID(stat, uid) (stat).st_uid = (uid)
#define SET_STAT_GID(stat, gid) (stat).st_gid = (gid)
#endif /* CONFIG_UID16 */
/*
* Everything below this line is needed on all architectures, to deal with
* filesystems that only store 16 bits of the UID/GID, etc.
*/
/*
* This is the UID and GID that will get written to disk if a filesystem
* only supports 16-bit UIDs and the kernel has a high UID/GID to write
*/
extern int fs_overflowuid;
extern int fs_overflowgid;
#define DEFAULT_FS_OVERFLOWUID 65534
#define DEFAULT_FS_OVERFLOWGID 65534
/*
* Since these macros are used in architectures that only need limited
* 16-bit UID back compatibility, we won't use old_uid_t and old_gid_t
*/
#define fs_high2lowuid(uid) ((uid) > 65535 ? (uid16_t)fs_overflowuid : (uid16_t)(uid))
#define fs_high2lowgid(gid) ((gid) > 65535 ? (gid16_t)fs_overflowgid : (gid16_t)(gid))
#define low_16_bits(x) ((x) & 0xFFFF)
#define high_16_bits(x) (((x) & 0xFFFF0000) >> 16)
#endif /* _LINUX_HIGHUID_H */
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