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* nix-build: use an indirection scheme to make it easier for users to

get rid of GC roots.  Nix-build places a symlink `result' in the
  current directory.  Previously, removing that symlink would not
  remove the store path being linked to as a GC root.  Now, the GC
  root created by nix-build is actually a symlink in
  `/nix/var/nix/gcroots/auto' to `result'.  So if that symlink is
  removed the GC root automatically becomes invalid (since it can no
  longer be resolved).  The root itself is not automatically removed -
  the garbage collector should delete dangling roots.
This commit is contained in:
Eelco Dolstra 2005-02-01 13:48:46 +00:00
parent dcc37c236c
commit 630ae0c9d7
7 changed files with 101 additions and 50 deletions

View file

@ -1,9 +1,5 @@
#include <iostream>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include "globals.hh"
#include "build.hh"
#include "gc.hh"
@ -24,6 +20,7 @@ void printHelp()
static Path gcRoot;
static int rootNr = 0;
static bool indirectRoot = false;
static Path findOutput(const Derivation & drv, string id)
@ -37,11 +34,9 @@ static Path findOutput(const Derivation & drv, string id)
static Path followSymlinks(Path & path)
{
path = absPath(path);
while (!isStorePath(path)) {
struct stat st;
if (lstat(path.c_str(), &st))
throw SysError(format("getting status of `%1%'") % path);
if (!S_ISLNK(st.st_mode)) return path;
if (!isLink(path)) return path;
string target = readLink(path);
path = canonPath(string(target, 0, 1) == "/"
? target
@ -64,7 +59,9 @@ static Path realisePath(const Path & path)
if (gcRoot == "")
printGCWarning();
else
outPath = addPermRoot(outPath, makeRootName(gcRoot, rootNr));
outPath = addPermRoot(outPath,
makeRootName(gcRoot, rootNr),
indirectRoot);
return outPath;
} else {
@ -191,6 +188,7 @@ static void opQuery(Strings opFlags, Strings opArgs)
for (Strings::iterator i = opArgs.begin();
i != opArgs.end(); i++)
{
*i = followSymlinks(*i);
if (forceRealise) realisePath(*i);
Derivation drv = derivationFromPath(*i);
cout << format("%1%\n") % findOutput(drv, "out");
@ -206,6 +204,7 @@ static void opQuery(Strings opFlags, Strings opArgs)
for (Strings::iterator i = opArgs.begin();
i != opArgs.end(); i++)
{
*i = followSymlinks(*i);
Path path = maybeUseOutput(*i, useOutput, forceRealise);
if (query == qRequisites)
storePathRequisites(path, includeOutputs, paths);
@ -441,8 +440,10 @@ void run(Strings args)
else if (arg == "--add-root") {
if (i == args.end())
throw UsageError("`--add-root requires an argument");
gcRoot = *i++;
gcRoot = absPath(*i++);
}
else if (arg == "--indirect")
indirectRoot = true;
else if (arg[0] == '-')
opFlags.push_back(arg);
else