guix/src/fix.cc
Eelco Dolstra f8d91f20e6 * Nix can now fetch prebuilts (and other files) from the network, iff
a mapping from the hash to a url has been registered through `nix
  regurl'.

* Bug fix in nix: don't pollute stdout when running tar, it made
  nix-switch barf.

* Bug fix in nix-push-prebuilts: don't create a subdirectory on the
  target when rsync'ing.
2003-05-26 09:44:18 +00:00

363 lines
9.7 KiB
C++

#include <iostream>
#include <map>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
extern "C" {
#include <aterm2.h>
}
#include "util.hh"
static string nixDescriptorDir;
static bool verbose = false;
/* Mapping of Fix file names to the hashes of the resulting Nix
descriptors. */
typedef map<string, string> DescriptorMap;
void registerFile(string filename)
{
int res = system(("nix regfile " + filename).c_str());
/* !!! escape */
if (WEXITSTATUS(res) != 0)
throw Error("cannot register " + filename + " with Nix");
}
void registerURL(string hash, string url)
{
int res = system(("nix regurl " + hash + " " + url).c_str());
/* !!! escape */
if (WEXITSTATUS(res) != 0)
throw Error("cannot register " + hash + " -> " + url + " with Nix");
}
Error badTerm(const string & msg, ATerm e)
{
char * s = ATwriteToString(e);
return Error(msg + ", in `" + s + "'");
}
/* Term evaluation. */
typedef map<string, ATerm> BindingsMap;
struct EvalContext
{
string dir;
DescriptorMap * done;
BindingsMap * vars;
};
ATerm evaluate(ATerm e, EvalContext ctx);
string instantiateDescriptor(string filename, EvalContext ctx);
string evaluateStr(ATerm e, EvalContext ctx)
{
e = evaluate(e, ctx);
char * s;
if (ATmatch(e, "Str(<str>)", &s))
return s;
else throw badTerm("string value expected", e);
}
bool evaluateBool(ATerm e, EvalContext ctx)
{
e = evaluate(e, ctx);
if (ATmatch(e, "Bool(True)"))
return true;
else if (ATmatch(e, "Bool(False)"))
return false;
else throw badTerm("boolean value expected", e);
}
ATerm evaluate(ATerm e, EvalContext ctx)
{
char * s;
ATerm e2, e3;
ATerm eCond, eTrue, eFalse;
/* Check for normal forms first. */
if (ATmatch(e, "Str(<str>)", &s) ||
ATmatch(e, "Bool(True)") || ATmatch(e, "Bool(False)"))
return e;
else if (
ATmatch(e, "Pkg(<str>)", &s) ||
ATmatch(e, "File(<str>)", &s))
{
checkHash(s);
return e;
}
/* Short-hands. */
else if (ATmatch(e, "<str>", &s))
return ATmake("Str(<str>)", s);
else if (ATmatch(e, "True", &s))
return ATmake("Bool(True)", s);
else if (ATmatch(e, "False", &s))
return ATmake("Bool(False)", s);
/* Functions. */
/* `Var' looks up a variable. */
else if (ATmatch(e, "Var(<str>)", &s)) {
string name(s);
ATerm e2 = (*ctx.vars)[name];
if (!e2) throw Error("undefined variable " + name);
return evaluate(e2, ctx); /* !!! update binding */
}
/* `Fix' recursively instantiates a Fix descriptor, returning the
hash of the generated Nix descriptor. */
else if (ATmatch(e, "Fix(<term>)", &e2)) {
string filename = absPath(evaluateStr(e2, ctx), ctx.dir); /* !!! */
return ATmake("Pkg(<str>)",
instantiateDescriptor(filename, ctx).c_str());
}
#if 0
/* `Source' copies the specified file to nixSourcesDir, registers
it with Nix, and returns the hash of the file. */
else if (ATmatch(e, "Source(<term>)", &e2)) {
string source = absPath(evaluateStr(e2, ctx), ctx.dir); /* !!! */
string target = nixSourcesDir + "/" + baseNameOf(source);
// Don't copy if filename is already in nixSourcesDir.
if (source != target) {
if (verbose)
cerr << "copying source " << source << endl;
string cmd = "cp -p " + source + " " + target;
int res = system(cmd.c_str());
if (WEXITSTATUS(res) != 0)
throw Error("cannot copy " + source + " to " + target);
}
registerFile(target);
return ATmake("File(<str>)", hashFile(target).c_str());
}
#endif
/* `Local' registers a file with Nix, and returns the file's
hash. */
else if (ATmatch(e, "Local(<term>)", &e2)) {
string filename = absPath(evaluateStr(e2, ctx), ctx.dir); /* !!! */
string hash = hashFile(filename);
registerFile(filename); /* !!! */
return ATmake("File(<str>)", hash.c_str());
}
/* `Url' registers a mapping from a hash to an url with Nix, and
returns the hash. */
else if (ATmatch(e, "Url(<term>, <term>)", &e2, &e3)) {
string hash = evaluateStr(e2, ctx);
checkHash(hash);
string url = evaluateStr(e3, ctx);
registerURL(hash, url);
return ATmake("File(<str>)", hash.c_str());
}
/* `If' provides conditional evaluation. */
else if (ATmatch(e, "If(<term>, <term>, <term>)",
&eCond, &eTrue, &eFalse))
return evaluate(evaluateBool(eCond, ctx) ? eTrue : eFalse, ctx);
else throw badTerm("invalid expression", e);
}
string getStringFromMap(BindingsMap & bindingsMap,
const string & name)
{
ATerm e = bindingsMap[name];
if (!e) throw Error("binding " + name + " is not set");
char * s;
if (ATmatch(e, "Str(<str>)", &s))
return s;
else
throw Error("binding " + name + " is not a string");
}
/* Instantiate a Fix descriptors into a Nix descriptor, recursively
instantiating referenced descriptors as well. */
string instantiateDescriptor(string filename, EvalContext ctx)
{
/* Already done? */
DescriptorMap::iterator isInMap = ctx.done->find(filename);
if (isInMap != ctx.done->end()) return isInMap->second;
/* No. */
ctx.dir = dirOf(filename);
/* Read the Fix descriptor as an ATerm. */
ATerm inTerm = ATreadFromNamedFile(filename.c_str());
if (!inTerm) throw Error("cannot read aterm " + filename);
ATerm bindings;
if (!ATmatch(inTerm, "Descr(<term>)", &bindings))
throw Error("invalid term in " + filename);
/* Iterate over the bindings and evaluate them to normal form. */
BindingsMap bindingsMap; /* the normal forms */
ctx.vars = &bindingsMap;
char * cname;
ATerm value;
while (ATmatch(bindings, "[Bind(<str>, <term>), <list>]",
&cname, &value, &bindings))
{
string name(cname);
ATerm e = evaluate(value, ctx);
bindingsMap[name] = e;
}
/* Construct a descriptor identifier by concatenating the package
and release ids. */
string pkgId = getStringFromMap(bindingsMap, "pkgId");
string releaseId = getStringFromMap(bindingsMap, "releaseId");
string id = pkgId + "-" + releaseId;
bindingsMap["id"] = ATmake("Str(<str>)", id.c_str());
/* Add a system name. */
bindingsMap["system"] = ATmake("Str(<str>)", thisSystem.c_str());
/* Construct the resulting ATerm. Note that iterating over the
map yields the bindings in sorted order, which is exactly the
canonical form for Nix descriptors. */
ATermList bindingsList = ATempty;
for (BindingsMap::iterator it = bindingsMap.begin();
it != bindingsMap.end(); it++)
/* !!! O(n^2) */
bindingsList = ATappend(bindingsList,
ATmake("Bind(<str>, <term>)", it->first.c_str(), it->second));
ATerm outTerm = ATmake("Descr(<term>)", bindingsList);
/* Write out the resulting ATerm. */
string tmpFilename = nixDescriptorDir + "/tmp";
if (!ATwriteToNamedTextFile(outTerm, tmpFilename.c_str()))
throw Error("cannot write aterm to " + tmpFilename);
string outHash = hashFile(tmpFilename);
string outFilename = nixDescriptorDir + "/" + id + "-" + outHash + ".nix";
if (rename(tmpFilename.c_str(), outFilename.c_str()))
throw Error("cannot rename " + tmpFilename + " to " + outFilename);
/* Register it with Nix. */
registerFile(outFilename);
if (verbose)
cerr << "instantiated " << outHash << " from " << filename << endl;
(*ctx.done)[filename] = outHash;
return outHash;
}
/* Instantiate a set of Fix descriptors into Nix descriptors. */
void instantiateDescriptors(Strings filenames)
{
DescriptorMap done;
EvalContext ctx;
ctx.done = &done;
for (Strings::iterator it = filenames.begin();
it != filenames.end(); it++)
{
string filename = absPath(*it);
cout << instantiateDescriptor(filename, ctx) << endl;
}
}
/* Print help. */
void printUsage()
{
cerr <<
"Usage: fix ...
";
}
/* Parse the command-line arguments, call the right operation. */
void run(Strings::iterator argCur, Strings::iterator argEnd)
{
Strings extraArgs;
enum { cmdUnknown, cmdInstantiate } command = cmdUnknown;
char * homeDir = getenv(nixHomeDirEnvVar.c_str());
if (homeDir) nixHomeDir = homeDir;
nixDescriptorDir = nixHomeDir + "/var/nix/descriptors";
for ( ; argCur != argEnd; argCur++) {
string arg(*argCur);
if (arg == "-h" || arg == "--help") {
printUsage();
return;
} else if (arg == "-v" || arg == "--verbose") {
verbose = true;
} else if (arg == "--instantiate" || arg == "-i") {
command = cmdInstantiate;
} else if (arg[0] == '-')
throw UsageError("invalid option `" + arg + "'");
else
extraArgs.push_back(arg);
}
switch (command) {
case cmdInstantiate:
instantiateDescriptors(extraArgs);
break;
default:
throw UsageError("no operation specified");
}
}
int main(int argc, char * * argv)
{
ATerm bottomOfStack;
ATinit(argc, argv, &bottomOfStack);
/* Put the arguments in a vector. */
Strings args;
while (argc--) args.push_back(*argv++);
Strings::iterator argCur = args.begin(), argEnd = args.end();
argCur++;
try {
run(argCur, argEnd);
} catch (UsageError & e) {
cerr << "error: " << e.what() << endl
<< "Try `fix -h' for more information.\n";
return 1;
} catch (exception & e) {
cerr << "error: " << e.what() << endl;
return 1;
}
return 0;
}