lix/src/libstore/exec.cc
Eelco Dolstra 447089a5f6 * Catch SIGINT to terminate cleanly when the user tries to interrupt
Nix.  This is to prevent Berkeley DB from becoming wedged.

  Unfortunately it is not possible to throw C++ exceptions from a
  signal handler.  In fact, you can't do much of anything except
  change variables of type `volatile sig_atomic_t'.  So we set an
  interrupt flag in the signal handler and check it at various
  strategic locations in the code (by calling checkInterrupt()).
  Since this is unlikely to cover all cases (e.g., (semi-)infinite
  loops), sometimes SIGTERM may now be required to kill Nix.
2004-01-15 20:23:55 +00:00

131 lines
3.9 KiB
C++

#include <iostream>
#include <cstdio>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>
#include <fcntl.h>
#include "exec.hh"
#include "util.hh"
#include "globals.hh"
static string pathNullDevice = "/dev/null";
/* Run a program. */
void runProgram(const string & program,
const Strings & args, const Environment & env,
const string & logFileName)
{
/* Create a log file. */
string logCommand =
verbosity >= buildVerbosity
? "tee " + logFileName + " >&2"
: "cat > " + logFileName;
/* !!! auto-pclose on exit */
FILE * logFile = popen(logCommand.c_str(), "w"); /* !!! escaping */
if (!logFile)
throw SysError(format("creating log file `%1%'") % logFileName);
/* Create a temporary directory where the build will take
place. */
string tmpDir = createTempDir();
AutoDelete delTmpDir(tmpDir);
/* 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 (chdir(tmpDir.c_str()) == -1)
throw SysError(format("changing into to `%1%'") % tmpDir);
/* Fill in the arguments. */
const char * argArr[args.size() + 2];
const char * * p = argArr;
string progName = baseNameOf(program);
*p++ = progName.c_str();
for (Strings::const_iterator i = args.begin();
i != args.end(); i++)
*p++ = i->c_str();
*p = 0;
/* Fill in the environment. */
Strings envStrs;
const char * envArr[env.size() + 1];
p = envArr;
for (Environment::const_iterator i = env.begin();
i != env.end(); i++)
*p++ = envStrs.insert(envStrs.end(),
i->first + "=" + i->second)->c_str();
*p = 0;
/* Dup the log handle into stderr. */
if (dup2(fileno(logFile), STDERR_FILENO) == -1)
throw SysError("cannot pipe standard error into log file");
/* Dup stderr to stdin. */
if (dup2(STDERR_FILENO, STDOUT_FILENO) == -1)
throw SysError("cannot dup stderr into stdout");
/* Reroute stdin to /dev/null. */
int fdDevNull = open(pathNullDevice.c_str(), O_RDWR);
if (fdDevNull == -1)
throw SysError(format("cannot open `%1%'") % pathNullDevice);
if (dup2(fdDevNull, STDIN_FILENO) == -1)
throw SysError("cannot dup null device into stdin");
/* Execute the program. This should not return. */
execve(program.c_str(), (char * *) argArr, (char * *) envArr);
throw SysError(format("unable to execute %1%") % program);
} catch (exception & e) {
cerr << format("build error: %1%\n") % e.what();
}
_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");
checkInterrupt();
if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
if (keepFailed) {
printMsg(lvlTalkative,
format("program `%1%' failed; keeping build directory `%2%'")
% program % tmpDir);
delTmpDir.cancel();
}
if (WIFEXITED(status))
throw Error(format("program `%1%' failed with exit code %2%")
% program % WEXITSTATUS(status));
else if (WIFSIGNALED(status))
throw Error(format("program `%1%' failed due to signal %2%")
% program % WTERMSIG(status));
else
throw Error(format("program `%1%' died abnormally") % program);
}
}