about summary refs log tree commit diff
path: root/src/eval.cc
blob: 4f59bcc21c4eadefaecdf185455317b5508c0633 (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
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
#include <map>
#include <iostream>

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>
#include <fcntl.h>

#include "eval.hh"
#include "globals.hh"
#include "values.hh"
#include "db.hh"


/* A Unix environment is a mapping from strings to strings. */
typedef map<string, string> Environment;


/* Return true iff the given path exists. */
bool pathExists(string path)
{
    int res;
    struct stat st;
    res = stat(path.c_str(), &st);
    if (!res) return true;
    if (errno != ENOENT)
        throw SysError("getting status of " + path);
    return false;
}


#if 0
/* Compute a derived value by running a program. */
static Hash computeDerived(Hash sourceHash, string targetName,
    string platform, Hash prog, Environment env)
{
    string targetPath = nixValues + "/" + 
        (string) sourceHash + "-nf";

    /* Check whether the target already exists. */
    if (pathExists(targetPath)) 
        throw Error("derived value in " + targetPath + " already exists");

    /* Find the program corresponding to the hash `prog'. */
    string progPath = queryValuePath(prog);

    /* Finalize the environment. */
    env["out"] = targetPath;

    /* Create a log file. */
    string logFileName = 
        nixLogDir + "/" + baseNameOf(targetPath) + ".log";
    /* !!! auto-pclose on exit */
    FILE * logFile = popen(("tee " + logFileName + " >&2").c_str(), "w"); /* !!! escaping */
    if (!logFile)
        throw SysError("unable to create log file " + logFileName);

    try {

        /* Fork a child to build the package. */
        pid_t pid;
        switch (pid = fork()) {
            
        case -1:
            throw SysError("unable to fork");

        case 0: 

            try { /* child */

#if 0
                /* Try to use a prebuilt. */
                string prebuiltHashS, prebuiltFile;
                if (queryDB(nixDB, dbPrebuilts, hash, prebuiltHashS)) {

                    try {
                        prebuiltFile = getFile(parseHash(prebuiltHashS));
                    } catch (Error e) {
                        cerr << "cannot obtain prebuilt (ignoring): " << e.what() << endl;
                        goto build;
                    }
                
                    cerr << "substituting prebuilt " << prebuiltFile << endl;

                    int res = system(("tar xfj " + prebuiltFile + " 1>&2").c_str()); // !!! escaping
                    if (WEXITSTATUS(res) != 0)
                        /* This is a fatal error, because path may now
                           have clobbered. */
                        throw Error("cannot unpack " + prebuiltFile);

                    _exit(0);
                }
#endif

//             build:

                /* Fill in the environment.  We don't bother freeing
                   the strings, since we'll exec or die soon
                   anyway. */
                const char * env2[env.size() + 1];
                int i = 0;
                for (Environment::iterator it = env.begin();
                     it != env.end(); it++, i++)
                    env2[i] = (new string(it->first + "=" + it->second))->c_str();
                env2[i] = 0;

                /* Dup the log handle into stderr. */
                if (dup2(fileno(logFile), STDERR_FILENO) == -1)
                    throw Error("cannot pipe standard error into log file: " + string(strerror(errno)));
            
                /* Dup stderr to stdin. */
                if (dup2(STDERR_FILENO, STDOUT_FILENO) == -1)
                    throw Error("cannot dup stderr into stdout");

                /* Make the program executable.  !!! hack. */
                if (chmod(progPath.c_str(), 0755))
                    throw Error("cannot make program executable");

                /* Execute the program.  This should not return. */
                execle(progPath.c_str(), baseNameOf(progPath).c_str(), 0, env2);

                throw Error("unable to execute builder: " +
                    string(strerror(errno)));
            
            } catch (exception & e) {
                cerr << "build error: " << e.what() << endl;
            }
            _exit(1);

        }

        /* parent */

        /* Close the logging pipe.  Note that this should not cause
           the logger to exit until builder exits (because the latter
           has an open file handle to the former). */
        pclose(logFile);
    
        /* Wait for the child to finish. */
        int status;
        if (waitpid(pid, &status, 0) != pid)
            throw Error("unable to wait for child");
    
        if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
            throw Error("unable to build package");

        /* Check whether the result was created. */
        if (!pathExists(targetPath))
            throw Error("program " + progPath + 
                " failed to create a result in " + targetPath);

#if 0
        /* Remove write permission from the value. */
        int res = system(("chmod -R -w " + targetPath).c_str()); // !!! escaping
        if (WEXITSTATUS(res) != 0)
            throw Error("cannot remove write permission from " + targetPath);
#endif

    } catch (exception &) {
//         system(("rm -rf " + targetPath).c_str());
        throw;
    }

    /* Hash the result. */
    Hash targetHash = hashPath(targetPath);

    /* Register targetHash -> targetPath.  !!! this should be in
       values.cc. */
    setDB(nixDB, dbRefs, targetHash, targetName);

    /* Register that targetHash was produced by evaluating
       sourceHash; i.e., that targetHash is a normal form of
       sourceHash. !!! this shouldn't be here */
    setDB(nixDB, dbNFs, sourceHash, targetHash);

    return targetHash;
}
#endif


/* Throw an exception if the given platform string is not supported by
   the platform we are executing on. */
static void checkPlatform(string platform)
{
    if (platform != thisSystem)
        throw Error(format("a `%1%' is required, but I am a `%2%'")
            % platform % thisSystem);
}


string printTerm(ATerm t)
{
    char * s = ATwriteToString(t);
    return s;
}


/* Throw an exception with an error message containing the given
   aterm. */
static Error badTerm(const format & f, ATerm t)
{
    return Error(format("%1%, in `%2%'") % f.str() % printTerm(t));
}


Hash hashTerm(ATerm t)
{
    return hashString(printTerm(t));
}


#if 0
/* Evaluate a list of arguments into normal form. */
void evalArgs(ATermList args, ATermList & argsNF, Environment & env)
{
    argsNF = ATempty;

    while (!ATisEmpty(args)) {
        ATerm eName, eVal, arg = ATgetFirst(args);
        if (!ATmatch(arg, "Tup(<term>, <term>)", &eName, &eVal))
            throw badTerm("invalid argument", arg);

        string name = evalString(eName);
        eVal = evalValue(eVal);

        char * s;
        if (ATmatch(eVal, "Str(<str>)", &s)) {
            env[name] = s;
        } else if (ATmatch(eVal, "Hash(<str>)", &s)) {
            env[name] = queryValuePath(parseHash(s));
        } else throw badTerm("invalid argument value", eVal);

        argsNF = ATinsert(argsNF,
            ATmake("Tup(Str(<str>), <term>)", name.c_str(), eVal));

        args = ATgetNext(args);
    }

    argsNF = ATreverse(argsNF);
}
#endif


struct RStatus
{
    /* !!! the comparator of this hash should match the semantics of
       the file system */
//     map<string, Hash> paths;
};


static void realise(RStatus & status, FState fs)
{
    char * s;
    Content content;
    ATermList refs;
    
    if (ATmatch(fs, "File(<str>, <term>, [<list>])", &s, &content, &refs)) {
        string path(s);

        if (path[0] != '/') throw Error("absolute path expected: " + path);

        /* Realise referenced paths. */
        while (!ATisEmpty(refs)) {
            realise(status, ATgetFirst(refs));
            refs = ATgetNext(refs);
        }

        if (!ATmatch(content, "Hash(<str>)", &s))
            throw badTerm("hash expected", content);
        Hash hash = parseHash(s);

        /* Perhaps the path already exists and has the right hash? */
        if (pathExists(path)) {
            if (hash == hashPath(path)) {
                debug(format("path %1% already has hash %2%")
                    % path % (string) hash);
                return;
            }

            throw Error(format("path %1% exists, but does not have hash %2%")
                % path % (string) hash);
        }

        /* Do we know a path with that hash?  If so, copy it. */
        string path2 = queryFromStore(hash);
        copyFile(path2, path);
    }

    else if (ATmatch(fs, "Derive()")) {
        
        
    }

    else throw badTerm("bad file system state expression", fs);
}


void realiseFState(FState fs)
{
    RStatus status;
    realise(status, fs);
}