summaryrefslogtreecommitdiff
path: root/lib/rpmlock.c
blob: 30a6c88524904134b4f4377deaa31d87cbceaf09 (plain)
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
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159

#include "system.h"

#include <rpmlib.h>
#include <rpmmacro.h>

#include "rpmts.h"
#include "rpmlock.h"

#include "debug.h"

/* Internal interface */

#define RPMLOCK_PATH "/var/lock/rpm/transaction"
/*@unchecked@*/ /*@observer@*/
static const char * rpmlock_path_default = "%{?_rpmlock_path}";
/*@unchecked@*/
static const char * rpmlock_path = NULL;

enum {
	RPMLOCK_READ   = 1 << 0,
	RPMLOCK_WRITE  = 1 << 1,
	RPMLOCK_WAIT   = 1 << 2,
};

typedef struct {
	int fd;
	int openmode;
} * rpmlock;

/*@null@*/
static rpmlock rpmlock_new(/*@unused@*/ const char *rootdir)
	/*@globals fileSystem @*/
	/*@modifies fileSystem @*/
{
	rpmlock lock = (rpmlock) malloc(sizeof(*lock));

	/* XXX oneshot to determine path for fcntl lock. */
	if (rpmlock_path == NULL) {
	    const char * t = rpmGenPath(rootdir, rpmlock_path_default, NULL);
	    if (t == NULL || *t == '\0' || *t == '%')
		t = strdup(RPMLOCK_PATH);
	    rpmlock_path = xstrdup(t);
	    t = _free(t);
	}
	if (lock != NULL) {
		mode_t oldmask = umask(022);
		lock->fd = open(rpmlock_path, O_RDWR|O_CREAT, 0644);
		(void) umask(oldmask);

/*@-branchstate@*/
		if (lock->fd == -1) {
			lock->fd = open(rpmlock_path, O_RDONLY);
			if (lock->fd == -1) {
				free(lock);
				lock = NULL;
			} else {
/*@-nullderef@*/	/* XXX splint on crack */
				lock->openmode = RPMLOCK_READ;
/*@=nullderef@*/
			}
		} else {
/*@-nullderef@*/	/* XXX splint on crack */
			lock->openmode = RPMLOCK_WRITE | RPMLOCK_READ;
/*@=nullderef@*/
		}
/*@=branchstate@*/
	}
/*@-compdef@*/
	return lock;
/*@=compdef@*/
}

static void rpmlock_free(/*@only@*/ /*@null@*/ rpmlock lock)
	/*@globals fileSystem, internalState @*/
	/*@modifies lock, fileSystem, internalState @*/
{
	if (lock) {
		(void) close(lock->fd);
		free(lock);
	}
}

static int rpmlock_acquire(/*@null@*/ rpmlock lock, int mode)
	/*@*/
{
	int res = 0;
	if (lock && (mode & lock->openmode)) {
		struct flock info;
		int cmd;
		if (mode & RPMLOCK_WAIT)
			cmd = F_SETLKW;
		else
			cmd = F_SETLK;
		if (mode & RPMLOCK_READ)
			info.l_type = F_RDLCK;
		else
			info.l_type = F_WRLCK;
		info.l_whence = SEEK_SET;
		info.l_start = 0;
		info.l_len = 0;
		info.l_pid = 0;
		if (fcntl(lock->fd, cmd, &info) != -1)
			res = 1;
	}
	return res;
}

static void rpmlock_release(/*@null@*/ rpmlock lock)
	/*@globals internalState @*/
	/*@modifies internalState @*/
{
	if (lock) {
		struct flock info;
		info.l_type = F_UNLCK;
		info.l_whence = SEEK_SET;
		info.l_start = 0;
		info.l_len = 0;
		info.l_pid = 0;
		(void) fcntl(lock->fd, F_SETLK, &info);
	}
}


/* External interface */

void *rpmtsAcquireLock(rpmts ts)
{
	const char *rootDir = rpmtsRootDir(ts);
	rpmlock lock;

	if (!rootDir || rpmtsChrootDone(ts))
		rootDir = "/";
	lock = rpmlock_new(rootDir);
/*@-branchstate@*/
	if (!lock) {
		rpmMessage(RPMMESS_ERROR, _("can't create transaction lock on %s\n"), rpmlock_path);
	} else if (!rpmlock_acquire(lock, RPMLOCK_WRITE)) {
		if (lock->openmode & RPMLOCK_WRITE)
			rpmMessage(RPMMESS_WARNING,
				   _("waiting for transaction lock on %s\n"), rpmlock_path);
		if (!rpmlock_acquire(lock, RPMLOCK_WRITE|RPMLOCK_WAIT)) {
			rpmMessage(RPMMESS_ERROR,
				   _("can't create transaction lock on %s\n"), rpmlock_path);
			rpmlock_free(lock);
			lock = NULL;
		}
	}
/*@=branchstate@*/
	return lock;
}

void rpmtsFreeLock(void *lock)
{
	rpmlock_release((rpmlock)lock); /* Not really needed here. */
	rpmlock_free((rpmlock)lock);
}