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cc73685d | 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
72d0e1cb | 2 | |
f1a4a029 ÇO |
3 | #ifndef __LXC_LXCLOCK_H |
4 | #define __LXC_LXCLOCK_H | |
953e611c | 5 | |
b19aabf5 | 6 | #include <fcntl.h> |
72d0e1cb SG |
7 | #include <semaphore.h> |
8 | #include <string.h> | |
b19aabf5 | 9 | #include <sys/file.h> |
d38dd64a | 10 | #include <sys/stat.h> |
72d0e1cb | 11 | #include <time.h> |
b19aabf5 CB |
12 | #include <unistd.h> |
13 | ||
a7692df5 CB |
14 | #include "compiler.h" |
15 | ||
b19aabf5 CB |
16 | #ifndef F_OFD_GETLK |
17 | #define F_OFD_GETLK 36 | |
18 | #endif | |
19 | ||
20 | #ifndef F_OFD_SETLK | |
21 | #define F_OFD_SETLK 37 | |
22 | #endif | |
23 | ||
24 | #ifndef F_OFD_SETLKW | |
25 | #define F_OFD_SETLKW 38 | |
26 | #endif | |
72d0e1cb | 27 | |
953e611c JH |
28 | #define LXC_LOCK_ANON_SEM 1 /*!< Anonymous semaphore lock */ |
29 | #define LXC_LOCK_FLOCK 2 /*!< flock(2) lock */ | |
30 | ||
1a0e70ac | 31 | /* private */ |
953e611c JH |
32 | /*! |
33 | * LXC Lock | |
34 | */ | |
df271a59 | 35 | struct lxc_lock { |
1a0e70ac | 36 | short type; /*!< Lock type */ |
953e611c | 37 | |
df271a59 | 38 | union { |
1a0e70ac | 39 | sem_t *sem; /*!< Anonymous semaphore (LXC_LOCK_ANON_SEM) */ |
953e611c | 40 | /*! LXC_LOCK_FLOCK details */ |
df271a59 | 41 | struct { |
1a0e70ac CB |
42 | int fd; /*!< fd on which a lock is held (if not -1) */ |
43 | char *fname; /*!< Name of lock */ | |
df271a59 | 44 | } f; |
1a0e70ac | 45 | } u; /*!< Container for lock type elements */ |
df271a59 SH |
46 | }; |
47 | ||
953e611c JH |
48 | /*! |
49 | * \brief Create a new (unlocked) lock. | |
50 | * | |
51 | * \param lxcpath lxcpath lock should relate to. | |
52 | * \param name Name for lock. | |
53 | * | |
54 | * \return Newly-allocated lxclock on success, \c NULL on failure. | |
55 | ||
56 | * \note If \p name is not given, create an unnamed semaphore | |
57 | * (used to protect against racing threads). | |
58 | * | |
59 | * \note Note that an unnamed sem was malloced by us and needs to be freed. | |
df271a59 | 60 | * |
953e611c JH |
61 | * \internal \ref sem is initialized to a value of \c 1. |
62 | * A 'sem_t *' which can be passed to \ref lxclock() and \ref lxcunlock() | |
63 | * will be placed in \c l->u.sem. | |
72d0e1cb | 64 | * |
953e611c | 65 | * If \ref lxcpath and \ref name are given (both must be given if either is |
ccfc84ca LW |
66 | * given) then a lockfile is created as \c /run/lxc/lock/$lxcpath/.$name if root, |
67 | * or \c $XDG_RUNTIME_DIR/lxc/lock/$lxcpath/.$name if non-root. | |
953e611c | 68 | * The lock is used to protect the containers on-disk representation. |
72d0e1cb | 69 | * |
953e611c JH |
70 | * \internal This function allocates the pathname for the given lock in memory |
71 | * such that it can be can quickly opened and locked by \ref lxclock(). | |
72 | * \c l->u.f.fname will contain the malloc'ed name (which must be | |
73 | * freed when the container is freed), and \c u.f.fd = -1. | |
df271a59 | 74 | * |
72d0e1cb | 75 | */ |
a7692df5 | 76 | __hidden extern struct lxc_lock *lxc_newlock(const char *lxcpath, const char *name); |
72d0e1cb | 77 | |
953e611c JH |
78 | /*! |
79 | * \brief Take an existing lock. | |
80 | * | |
81 | * \param lock Lock to operate on. | |
82 | * \param timeout Seconds to wait to take lock (\c 0 signifies an | |
83 | * indefinite wait). | |
df271a59 | 84 | * |
953e611c | 85 | * \return \c 0 if lock obtained, \c -2 on failure to set timeout, |
ccfc84ca LW |
86 | * or \c -1 on any other error (\c errno will be set by \c sem_wait(3) |
87 | * or \c fcntl(2)). | |
953e611c JH |
88 | * |
89 | * \note \p timeout is (currently?) only supported for privlock, not | |
df271a59 SH |
90 | * for slock. Since currently there is not a single use of the timeout |
91 | * (except in the test case) I may remove the support for it in sem as | |
92 | * well. | |
72d0e1cb | 93 | */ |
a7692df5 | 94 | __hidden extern int lxclock(struct lxc_lock *lock, int timeout); |
72d0e1cb | 95 | |
953e611c JH |
96 | /*! |
97 | * \brief Unlock specified lock previously locked using \ref lxclock(). | |
98 | * | |
99 | * \param lock \ref lxc_lock. | |
100 | * | |
101 | * \return \c 0 on success, \c -2 if provided lock was not already held, | |
ccfc84ca | 102 | * otherwise \c -1 with \c errno saved from \c fcntl(2) or sem_post function. |
72d0e1cb | 103 | */ |
a7692df5 | 104 | __hidden extern int lxcunlock(struct lxc_lock *lock); |
df271a59 | 105 | |
953e611c JH |
106 | /*! |
107 | * \brief Free a lock created by \ref lxc_newlock(). | |
108 | * | |
109 | * \param lock Lock. | |
110 | */ | |
a7692df5 | 111 | __hidden extern void lxc_putlock(struct lxc_lock *lock); |
5cee8c50 | 112 | |
953e611c JH |
113 | /*! |
114 | * \brief Lock the current process. | |
115 | */ | |
a7692df5 | 116 | __hidden extern void process_lock(void); |
953e611c JH |
117 | |
118 | /*! | |
119 | * \brief Unlock the current process. | |
120 | */ | |
a7692df5 | 121 | __hidden extern void process_unlock(void); |
953e611c | 122 | |
5cee8c50 | 123 | struct lxc_container; |
953e611c JH |
124 | |
125 | /*! | |
126 | * \brief Lock the containers memory. | |
127 | * | |
128 | * \param c Container. | |
129 | * | |
130 | * \return As for \ref lxclock(). | |
131 | */ | |
a7692df5 | 132 | __hidden extern int container_mem_lock(struct lxc_container *c); |
953e611c JH |
133 | |
134 | /*! | |
135 | * \brief Unlock the containers memory. | |
136 | * | |
137 | * \param c Container. | |
138 | */ | |
a7692df5 | 139 | __hidden extern void container_mem_unlock(struct lxc_container *c); |
953e611c JH |
140 | |
141 | /*! | |
142 | * \brief Lock the containers disk data. | |
143 | * | |
144 | * \param c Container. | |
145 | * | |
146 | * \return \c 0 on success, or an \ref lxclock() error return | |
147 | * values on error. | |
148 | */ | |
a7692df5 | 149 | __hidden extern int container_disk_lock(struct lxc_container *c); |
953e611c JH |
150 | |
151 | /*! | |
152 | * \brief Unlock the containers disk data. | |
ccfc84ca LW |
153 | * |
154 | * \param c Container. | |
155 | * | |
953e611c | 156 | */ |
a7692df5 | 157 | __hidden extern void container_disk_unlock(struct lxc_container *c); |
953e611c | 158 | |
5cee8c50 | 159 | #endif |