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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 | ||
14 | #ifndef F_OFD_GETLK | |
15 | #define F_OFD_GETLK 36 | |
16 | #endif | |
17 | ||
18 | #ifndef F_OFD_SETLK | |
19 | #define F_OFD_SETLK 37 | |
20 | #endif | |
21 | ||
22 | #ifndef F_OFD_SETLKW | |
23 | #define F_OFD_SETLKW 38 | |
24 | #endif | |
72d0e1cb | 25 | |
953e611c JH |
26 | #define LXC_LOCK_ANON_SEM 1 /*!< Anonymous semaphore lock */ |
27 | #define LXC_LOCK_FLOCK 2 /*!< flock(2) lock */ | |
28 | ||
1a0e70ac | 29 | /* private */ |
953e611c JH |
30 | /*! |
31 | * LXC Lock | |
32 | */ | |
df271a59 | 33 | struct lxc_lock { |
1a0e70ac | 34 | short type; /*!< Lock type */ |
953e611c | 35 | |
df271a59 | 36 | union { |
1a0e70ac | 37 | sem_t *sem; /*!< Anonymous semaphore (LXC_LOCK_ANON_SEM) */ |
953e611c | 38 | /*! LXC_LOCK_FLOCK details */ |
df271a59 | 39 | struct { |
1a0e70ac CB |
40 | int fd; /*!< fd on which a lock is held (if not -1) */ |
41 | char *fname; /*!< Name of lock */ | |
df271a59 | 42 | } f; |
1a0e70ac | 43 | } u; /*!< Container for lock type elements */ |
df271a59 SH |
44 | }; |
45 | ||
953e611c JH |
46 | /*! |
47 | * \brief Create a new (unlocked) lock. | |
48 | * | |
49 | * \param lxcpath lxcpath lock should relate to. | |
50 | * \param name Name for lock. | |
51 | * | |
52 | * \return Newly-allocated lxclock on success, \c NULL on failure. | |
53 | ||
54 | * \note If \p name is not given, create an unnamed semaphore | |
55 | * (used to protect against racing threads). | |
56 | * | |
57 | * \note Note that an unnamed sem was malloced by us and needs to be freed. | |
df271a59 | 58 | * |
953e611c JH |
59 | * \internal \ref sem is initialized to a value of \c 1. |
60 | * A 'sem_t *' which can be passed to \ref lxclock() and \ref lxcunlock() | |
61 | * will be placed in \c l->u.sem. | |
72d0e1cb | 62 | * |
953e611c | 63 | * If \ref lxcpath and \ref name are given (both must be given if either is |
ccfc84ca LW |
64 | * given) then a lockfile is created as \c /run/lxc/lock/$lxcpath/.$name if root, |
65 | * or \c $XDG_RUNTIME_DIR/lxc/lock/$lxcpath/.$name if non-root. | |
953e611c | 66 | * The lock is used to protect the containers on-disk representation. |
72d0e1cb | 67 | * |
953e611c JH |
68 | * \internal This function allocates the pathname for the given lock in memory |
69 | * such that it can be can quickly opened and locked by \ref lxclock(). | |
70 | * \c l->u.f.fname will contain the malloc'ed name (which must be | |
71 | * freed when the container is freed), and \c u.f.fd = -1. | |
df271a59 | 72 | * |
72d0e1cb | 73 | */ |
df271a59 | 74 | extern struct lxc_lock *lxc_newlock(const char *lxcpath, const char *name); |
72d0e1cb | 75 | |
953e611c JH |
76 | /*! |
77 | * \brief Take an existing lock. | |
78 | * | |
79 | * \param lock Lock to operate on. | |
80 | * \param timeout Seconds to wait to take lock (\c 0 signifies an | |
81 | * indefinite wait). | |
df271a59 | 82 | * |
953e611c | 83 | * \return \c 0 if lock obtained, \c -2 on failure to set timeout, |
ccfc84ca LW |
84 | * or \c -1 on any other error (\c errno will be set by \c sem_wait(3) |
85 | * or \c fcntl(2)). | |
953e611c JH |
86 | * |
87 | * \note \p timeout is (currently?) only supported for privlock, not | |
df271a59 SH |
88 | * for slock. Since currently there is not a single use of the timeout |
89 | * (except in the test case) I may remove the support for it in sem as | |
90 | * well. | |
72d0e1cb | 91 | */ |
df271a59 | 92 | extern int lxclock(struct lxc_lock *lock, int timeout); |
72d0e1cb | 93 | |
953e611c JH |
94 | /*! |
95 | * \brief Unlock specified lock previously locked using \ref lxclock(). | |
96 | * | |
97 | * \param lock \ref lxc_lock. | |
98 | * | |
99 | * \return \c 0 on success, \c -2 if provided lock was not already held, | |
ccfc84ca | 100 | * otherwise \c -1 with \c errno saved from \c fcntl(2) or sem_post function. |
72d0e1cb | 101 | */ |
df271a59 SH |
102 | extern int lxcunlock(struct lxc_lock *lock); |
103 | ||
953e611c JH |
104 | /*! |
105 | * \brief Free a lock created by \ref lxc_newlock(). | |
106 | * | |
107 | * \param lock Lock. | |
108 | */ | |
109 | extern void lxc_putlock(struct lxc_lock *lock); | |
5cee8c50 | 110 | |
953e611c JH |
111 | /*! |
112 | * \brief Lock the current process. | |
113 | */ | |
025ed0f3 | 114 | extern void process_lock(void); |
953e611c JH |
115 | |
116 | /*! | |
117 | * \brief Unlock the current process. | |
118 | */ | |
5cee8c50 | 119 | extern void process_unlock(void); |
953e611c | 120 | |
5cee8c50 | 121 | struct lxc_container; |
953e611c JH |
122 | |
123 | /*! | |
124 | * \brief Lock the containers memory. | |
125 | * | |
126 | * \param c Container. | |
127 | * | |
128 | * \return As for \ref lxclock(). | |
129 | */ | |
5cee8c50 | 130 | extern int container_mem_lock(struct lxc_container *c); |
953e611c JH |
131 | |
132 | /*! | |
133 | * \brief Unlock the containers memory. | |
134 | * | |
135 | * \param c Container. | |
136 | */ | |
5cee8c50 | 137 | extern void container_mem_unlock(struct lxc_container *c); |
953e611c JH |
138 | |
139 | /*! | |
140 | * \brief Lock the containers disk data. | |
141 | * | |
142 | * \param c Container. | |
143 | * | |
144 | * \return \c 0 on success, or an \ref lxclock() error return | |
145 | * values on error. | |
146 | */ | |
5cee8c50 | 147 | extern int container_disk_lock(struct lxc_container *c); |
953e611c JH |
148 | |
149 | /*! | |
150 | * \brief Unlock the containers disk data. | |
ccfc84ca LW |
151 | * |
152 | * \param c Container. | |
153 | * | |
953e611c | 154 | */ |
5cee8c50 | 155 | extern void container_disk_unlock(struct lxc_container *c); |
953e611c | 156 | |
5cee8c50 | 157 | #endif |