about summary refs log tree commit diff
path: root/src/store.cc
blob: 977cd2594f0b3a719dfdc8073cda767d95a3e8b0 (plain) (blame)
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
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
#include <iostream>

#include <sys/types.h>
#include <sys/wait.h>

#include "store.hh"
#include "globals.hh"
#include "db.hh"
#include "archive.hh"


struct CopySink : DumpSink
{
    int fd;
    virtual void operator () (const unsigned char * data, unsigned int len)
    {
        if (write(fd, (char *) data, len) != (ssize_t) len)
            throw SysError("writing to child");
    }
};


struct CopySource : RestoreSource
{
    int fd;
    virtual void operator () (const unsigned char * data, unsigned int len)
    {
        ssize_t res = read(fd, (char *) data, len);
        if (res == -1)
            throw SysError("reading from parent");
        if (res != (ssize_t) len)
            throw Error("not enough data available on parent");
    }
};


void copyPath(string src, string dst)
{
    /* Unfortunately C++ doesn't support coprocedures, so we have no
       nice way to chain CopySink and CopySource together.  Instead we
       fork off a child to run the sink.  (Fork-less platforms should
       use a thread). */

    /* Create a pipe. */
    int fds[2];
    if (pipe(fds) == -1) throw SysError("creating pipe");

    /* Fork. */
    pid_t pid;
    switch (pid = fork()) {

    case -1:
        throw SysError("unable to fork");

    case 0: /* child */
        try {
            close(fds[1]);
            CopySource source;
            source.fd = fds[0];
            restorePath(dst, source);
            _exit(0);
        }  catch (exception & e) {
            cerr << "error: " << e.what() << endl;
        }
        _exit(1);        
    }

    close(fds[0]);
    
    /* Parent. */

    CopySink sink;
    sink.fd = fds[1];
    dumpPath(src, sink);

    /* Wait for the child to finish. */
    int status;
    if (waitpid(pid, &status, 0) != pid)
        throw SysError("waiting for child");

    if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
        throw Error("cannot copy file: child died");
}


Hash registerPath(const string & _path, Hash hash)
{
    string path(canonPath(_path));

    if (hash == Hash()) hash = hashPath(path);

    Strings paths;
    queryListDB(nixDB, dbRefs, hash, paths); /* non-existence = ok */

    for (Strings::iterator it = paths.begin();
         it != paths.end(); it++)
        if (*it == path) goto exists;
    
    paths.push_back(path);
    
    setListDB(nixDB, dbRefs, hash, paths);
    
 exists:
    return hash;
}


bool isInPrefix(const string & path, const string & _prefix)
{
    string prefix = canonPath(_prefix + "/");
    return string(path, 0, prefix.size()) == prefix;
}


static string queryPathByHashPrefix(Hash hash, const string & prefix)
{
    Strings paths;

    if (!queryListDB(nixDB, dbRefs, hash, paths))
        throw Error(format("no paths known with hash `%1%'") % (string) hash);

    /* Arbitrarily pick the first one that exists and still hash the
       right hash. */

    for (Strings::iterator it = paths.begin();
         it != paths.end(); it++)
    {
        string path = *it;
        try {
            if (isInPrefix(path, prefix) && hashPath(path) == hash)
                return path;
        } catch (Error & e) {
            debug(format("checking hash: %1%") % e.msg());
            /* try next one */
        }
    }
    
    throw Error(format("all paths with hash `%1%' are stale") % (string) hash);
}


string queryPathByHash(Hash hash)
{
    return queryPathByHashPrefix(hash, "/");
}


void addToStore(string srcPath, string & dstPath, Hash & hash)
{
    srcPath = absPath(srcPath);

    hash = hashPath(srcPath);

    try {
        dstPath = queryPathByHashPrefix(hash, nixStore);
        return;
    } catch (...) {
    }
    
    string baseName = baseNameOf(srcPath);
    dstPath = nixStore + "/" + (string) hash + "-" + baseName;

    copyPath(srcPath, dstPath);

    registerPath(dstPath, hash);
}


void deleteFromStore(const string & path)
{
    string prefix = nixStore + "/";
    if (string(path, 0, prefix.size()) != prefix)
        throw Error(format("path %1% is not in the store") % path);
    deletePath(path);
//     delDB(nixDB, dbRefs, hash);
}