* Call find-runtime-roots.pl from the garbage collector to prevent

running applications etc. from being garbage collected.
This commit is contained in:
Eelco Dolstra 2006-07-20 12:17:25 +00:00
parent ebcccbd358
commit c15f544356
6 changed files with 138 additions and 16 deletions

View file

@ -66,6 +66,9 @@ irreversible.</para></warning>
<listitem><para>TODO: nix-pack-closure and
nix-unpack-closure.</para></listitem>
<listitem><para>TODO: open files etc. are now used as roots of the
garbage collector.</para></listitem>
</itemizedlist>
</section>

View file

@ -12,10 +12,6 @@
#include <unistd.h>
#include <errno.h>
#ifdef __CYGWIN__
#include <windows.h>
#endif
#include <pwd.h>
#include <grp.h>
@ -321,13 +317,6 @@ const char * * strings2CharPtrs(const Strings & ss)
}
/* Hack for Cygwin: _exit() doesn't seem to work quite right, since
some Berkeley DB code appears to be called when a child exits
through _exit() (e.g., because execve() failed). So call the
Windows API directly. */
#ifdef __CYGWIN__
#define _exit(n) ExitProcess(n)
#endif
//////////////////////////////////////////////////////////////////////
@ -460,9 +449,9 @@ static void killUser(uid_t uid)
} catch (exception & e) {
cerr << format("build error: %1%\n") % e.what();
_exit(1);
quickExit(1);
}
_exit(0);
quickExit(0);
}
/* parent */
@ -944,7 +933,7 @@ DerivationGoal::HookReply DerivationGoal::tryBuildHook()
} catch (exception & e) {
cerr << format("build error: %1%\n") % e.what();
}
_exit(1);
quickExit(1);
}
/* parent */
@ -1340,7 +1329,7 @@ void DerivationGoal::startBuilder()
} catch (exception & e) {
cerr << format("build error: %1%\n") % e.what();
}
_exit(1);
quickExit(1);
}
@ -1779,7 +1768,7 @@ void SubstitutionGoal::tryToRun()
} catch (exception & e) {
cerr << format("substitute error: %1%\n") % e.what();
}
_exit(1);
quickExit(1);
}
/* parent */

View file

@ -316,6 +316,31 @@ static void findRoots(const Path & path, bool recurseSymlinks,
}
static void addAdditionalRoots(PathSet & roots)
{
Path rootFinder = getEnv("NIX_ROOT_FINDER",
"/nix/libexec/nix/find-runtime-roots.pl"); /* !!! */
if (rootFinder.empty()) return;
printMsg(lvlDebug, format("executing `%1%' to find additional roots") % rootFinder);
string result = runProgram(rootFinder);
Strings paths = tokenizeString(result, "\n");
for (Strings::iterator i = paths.begin(); i != paths.end(); ++i) {
if (isInStore(*i)) {
Path path = toStorePath(*i);
if (roots.find(path) == roots.end()) {
debug(format("found additional root `%1%'") % path);
roots.insert(path);
}
}
}
}
static void dfsVisit(const PathSet & paths, const Path & path,
PathSet & visited, Paths & sorted)
{
@ -370,6 +395,12 @@ void collectGarbage(GCAction action, const PathSet & pathsToDelete,
if (!ignoreLiveness)
findRoots(rootsDir, true, roots);
/* Add additional roots returned by the program specified by the
NIX_ROOT_FINDER environment variable. This is typically used
to add running programs to the set of roots (to prevent them
from being garbage collected). */
addAdditionalRoots(roots);
if (action == gcReturnRoots) {
result = roots;
return;

View file

@ -13,6 +13,10 @@
#include <fcntl.h>
#include <signal.h>
#ifdef __CYGWIN__
#include <windows.h>
#endif
#include "util.hh"
@ -434,6 +438,23 @@ void writeFull(int fd, const unsigned char * buf, size_t count)
}
string drainFD(int fd)
{
string result;
unsigned char buffer[4096];
while (1) {
ssize_t rd = read(fd, buffer, sizeof buffer);
if (rd == -1) {
if (errno != EINTR)
throw SysError("reading from file");
}
else if (rd == 0) break;
else result.append((char *) buffer, rd);
}
return result;
}
//////////////////////////////////////////////////////////////////////
@ -643,6 +664,69 @@ void Pid::setSeparatePG(bool separatePG)
//////////////////////////////////////////////////////////////////////
string runProgram(Path program)
{
/* Create a pipe. */
Pipe pipe;
pipe.create();
/* Fork. */
Pid pid;
pid = fork();
switch (pid) {
case -1:
throw SysError("unable to fork");
case 0: /* child */
try {
pipe.readSide.close();
if (dup2(pipe.writeSide, STDOUT_FILENO) == -1)
throw SysError("dupping from-hook write side");
execl(program.c_str(), program.c_str(), (char *) 0);
throw SysError(format("executing `%1%'") % program);
} catch (exception & e) {
cerr << "error: " << e.what() << endl;
}
quickExit(1);
}
/* Parent. */
pipe.writeSide.close();
string result = drainFD(pipe.readSide);
/* Wait for the child to finish. */
int status = pid.wait(true);
if (!statusOk(status))
throw Error(format("program `%1% %2%")
% program % statusToString(status));
return result;
}
void quickExit(int status)
{
#ifdef __CYGWIN__
/* Hack for Cygwin: _exit() doesn't seem to work quite right,
since some Berkeley DB code appears to be called when a child
exits through _exit() (e.g., because execve() failed). So call
the Windows API directly. */
ExitProcess(status);
#else
_exit(status);
#endif
}
//////////////////////////////////////////////////////////////////////

View file

@ -185,6 +185,11 @@ void readFull(int fd, unsigned char * buf, size_t count);
void writeFull(int fd, const unsigned char * buf, size_t count);
/* Read a file descriptor until EOF occurs. */
string drainFD(int fd);
/* Automatic cleanup of resources. */
class AutoDelete
@ -249,6 +254,15 @@ public:
};
/* Run a program and return its stdout in a string (i.e., like the
shell backtick operator). */
string runProgram(Path program);
/* Wrapper around _exit() on Unix and ExitProcess() on Windows. (On
Cygwin, _exit() doesn't seem to do the right thing.) */
void quickExit(int status);
/* User interruption. */
extern volatile sig_atomic_t _isInterrupted;

View file

@ -13,6 +13,7 @@ export NIX_DB_DIR=$TEST_ROOT/db
export NIX_CONF_DIR=$TEST_ROOT/etc
export NIX_BIN_DIR=$TEST_ROOT/bin
export NIX_LIBEXEC_DIR=$TEST_ROOT/bin
export NIX_ROOT_FINDER=
export SHARED=$TEST_ROOT/shared
export REAL_BIN_DIR=@bindir@