lix/src/libutil/util.cc
Eelco Dolstra 630ae0c9d7 * 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.
2005-02-01 13:48:46 +00:00

653 lines
13 KiB
C++

#include "config.h"
#include <iostream>
#include <cerrno>
#include <cstdio>
#include <sstream>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>
#include <dirent.h>
#include <fcntl.h>
#include <signal.h>
#include "util.hh"
string thisSystem = SYSTEM;
Error::Error(const format & f)
{
err = f.str();
}
SysError::SysError(const format & f)
: Error(format("%1%: %2%") % f.str() % strerror(errno))
{
}
string getEnv(const string & key, const string & def)
{
char * value = getenv(key.c_str());
return value ? string(value) : def;
}
Path absPath(Path path, Path dir)
{
if (path[0] != '/') {
if (dir == "") {
char buf[PATH_MAX];
if (!getcwd(buf, sizeof(buf)))
throw SysError("cannot get cwd");
dir = buf;
}
path = dir + "/" + path;
}
return canonPath(path);
}
Path canonPath(const Path & path)
{
string s;
if (path[0] != '/')
throw Error(format("not an absolute path: `%1%'") % path);
string::const_iterator i = path.begin(), end = path.end();
while (1) {
/* Skip slashes. */
while (i != end && *i == '/') i++;
if (i == end) break;
/* Ignore `.'. */
if (*i == '.' && (i + 1 == end || i[1] == '/'))
i++;
/* If `..', delete the last component. */
else if (*i == '.' && i + 1 < end && i[1] == '.' &&
(i + 2 == end || i[2] == '/'))
{
if (!s.empty()) s.erase(s.rfind('/'));
i += 2;
}
/* Normal component; copy it. */
else {
s += '/';
while (i != end && *i != '/') s += *i++;
}
}
return s.empty() ? "/" : s;
}
Path dirOf(const Path & path)
{
unsigned int pos = path.rfind('/');
if (pos == string::npos)
throw Error(format("invalid file name: %1%") % path);
return Path(path, 0, pos);
}
string baseNameOf(const Path & path)
{
unsigned int pos = path.rfind('/');
if (pos == string::npos)
throw Error(format("invalid file name %1% ") % path);
return string(path, pos + 1);
}
bool pathExists(const Path & path)
{
int res;
struct stat st;
res = lstat(path.c_str(), &st);
if (!res) return true;
if (errno != ENOENT && errno != ENOTDIR)
throw SysError(format("getting status of %1%") % path);
return false;
}
Path readLink(const Path & path)
{
struct stat st;
if (lstat(path.c_str(), &st))
throw SysError(format("getting status of `%1%'") % path);
if (!S_ISLNK(st.st_mode))
throw Error(format("`%1%' is not a symlink") % path);
char buf[st.st_size];
if (readlink(path.c_str(), buf, st.st_size) != st.st_size)
throw SysError(format("reading symbolic link `%1%'") % path);
return string(buf, st.st_size);
}
bool isLink(const Path & path)
{
struct stat st;
if (lstat(path.c_str(), &st))
throw SysError(format("getting status of `%1%'") % path);
return S_ISLNK(st.st_mode);
}
Strings readDirectory(const Path & path)
{
Strings names;
AutoCloseDir dir = opendir(path.c_str());
if (!dir) throw SysError(format("opening directory `%1%'") % path);
struct dirent * dirent;
while (errno = 0, dirent = readdir(dir)) { /* sic */
checkInterrupt();
string name = dirent->d_name;
if (name == "." || name == "..") continue;
names.push_back(name);
}
if (errno) throw SysError(format("reading directory `%1%'") % path);
return names;
}
static void _deletePath(const Path & path)
{
checkInterrupt();
printMsg(lvlVomit, format("%1%") % path);
struct stat st;
if (lstat(path.c_str(), &st))
throw SysError(format("getting attributes of path `%1%'") % path);
if (S_ISDIR(st.st_mode)) {
Strings names = readDirectory(path);
/* Make the directory writable. */
if (!(st.st_mode & S_IWUSR)) {
if (chmod(path.c_str(), st.st_mode | S_IWUSR) == -1)
throw SysError(format("making `%1%' writable") % path);
}
for (Strings::iterator i = names.begin(); i != names.end(); ++i)
_deletePath(path + "/" + *i);
}
if (remove(path.c_str()) == -1)
throw SysError(format("cannot unlink `%1%'") % path);
}
void deletePath(const Path & path)
{
startNest(nest, lvlDebug,
format("recursively deleting path `%1%'") % path);
_deletePath(path);
}
void makePathReadOnly(const Path & path)
{
checkInterrupt();
struct stat st;
if (lstat(path.c_str(), &st))
throw SysError(format("getting attributes of path `%1%'") % path);
if (!S_ISLNK(st.st_mode) && (st.st_mode & S_IWUSR)) {
if (chmod(path.c_str(), st.st_mode & ~S_IWUSR) == -1)
throw SysError(format("making `%1%' read-only") % path);
}
if (S_ISDIR(st.st_mode)) {
Strings names = readDirectory(path);
for (Strings::iterator i = names.begin(); i != names.end(); ++i)
makePathReadOnly(path + "/" + *i);
}
}
static Path tempName()
{
static int counter = 0;
Path tmpRoot = canonPath(getEnv("TMPDIR", "/tmp"));
return (format("%1%/nix-%2%-%3%") % tmpRoot % getpid() % counter++).str();
}
Path createTempDir()
{
while (1) {
checkInterrupt();
Path tmpDir = tempName();
if (mkdir(tmpDir.c_str(), 0777) == 0) return tmpDir;
if (errno != EEXIST)
throw SysError(format("creating directory `%1%'") % tmpDir);
}
}
void writeStringToFile(const Path & path, const string & s)
{
AutoCloseFD fd(open(path.c_str(),
O_CREAT | O_EXCL | O_WRONLY, 0666));
if (fd == -1)
throw SysError(format("creating file `%1%'") % path);
writeFull(fd, (unsigned char *) s.c_str(), s.size());
}
LogType logType = ltPretty;
Verbosity verbosity = lvlInfo;
static int nestingLevel = 0;
Nest::Nest()
{
nest = false;
}
Nest::~Nest()
{
close();
}
static string escVerbosity(Verbosity level)
{
int l = (int) level;
ostringstream st;
st << l;
return st.str();
}
void Nest::open(Verbosity level, const format & f)
{
if (level <= verbosity) {
if (logType == ltEscapes)
cerr << "\033[" << escVerbosity(level) << "p"
<< f.str() << "\n";
else
printMsg_(level, f);
nest = true;
nestingLevel++;
}
}
void Nest::close()
{
if (nest) {
nestingLevel--;
if (logType == ltEscapes)
cerr << "\033[q";
nest = false;
}
}
void printMsg_(Verbosity level, const format & f)
{
checkInterrupt();
if (level > verbosity) return;
string prefix;
if (logType == ltPretty)
for (int i = 0; i < nestingLevel; i++)
prefix += "| ";
else if (logType == ltEscapes && level != lvlInfo)
prefix = "\033[" + escVerbosity(level) + "s";
cerr << format("%1%%2%\n") % prefix % f.str();
}
void readFull(int fd, unsigned char * buf, size_t count)
{
while (count) {
checkInterrupt();
ssize_t res = read(fd, (char *) buf, count);
if (res == -1) {
if (errno == EINTR) continue;
throw SysError("reading from file");
}
if (res == 0) throw Error("unexpected end-of-file");
count -= res;
buf += res;
}
}
void writeFull(int fd, const unsigned char * buf, size_t count)
{
while (count) {
checkInterrupt();
ssize_t res = write(fd, (char *) buf, count);
if (res == -1) {
if (errno == EINTR) continue;
throw SysError("writing to file");
}
count -= res;
buf += res;
}
}
//////////////////////////////////////////////////////////////////////
AutoDelete::AutoDelete(const string & p) : path(p)
{
del = true;
}
AutoDelete::~AutoDelete()
{
if (del) deletePath(path);
}
void AutoDelete::cancel()
{
del = false;
}
//////////////////////////////////////////////////////////////////////
AutoCloseFD::AutoCloseFD()
{
fd = -1;
}
AutoCloseFD::AutoCloseFD(int fd)
{
this->fd = fd;
}
AutoCloseFD::AutoCloseFD(const AutoCloseFD & fd)
{
abort();
}
AutoCloseFD::~AutoCloseFD()
{
try {
close();
} catch (Error & e) {
printMsg(lvlError, format("error (ignored): %1%") % e.msg());
}
}
void AutoCloseFD::operator =(int fd)
{
if (this->fd != fd) close();
this->fd = fd;
}
AutoCloseFD::operator int() const
{
return fd;
}
void AutoCloseFD::close()
{
if (fd != -1) {
if (::close(fd) == -1)
/* This should never happen. */
throw SysError("closing file descriptor");
fd = -1;
}
}
bool AutoCloseFD::isOpen()
{
return fd != -1;
}
/* Pass responsibility for closing this fd to the caller. */
int AutoCloseFD::borrow()
{
int oldFD = fd;
fd = -1;
return oldFD;
}
void Pipe::create()
{
int fds[2];
if (pipe(fds) != 0) throw SysError("creating pipe");
readSide = fds[0];
writeSide = fds[1];
}
//////////////////////////////////////////////////////////////////////
AutoCloseDir::AutoCloseDir()
{
dir = 0;
}
AutoCloseDir::AutoCloseDir(DIR * dir)
{
this->dir = dir;
}
AutoCloseDir::~AutoCloseDir()
{
if (dir) closedir(dir);
}
void AutoCloseDir::operator =(DIR * dir)
{
this->dir = dir;
}
AutoCloseDir::operator DIR *()
{
return dir;
}
//////////////////////////////////////////////////////////////////////
Pid::Pid()
{
pid = -1;
separatePG = false;
}
Pid::~Pid()
{
kill();
}
void Pid::operator =(pid_t pid)
{
if (this->pid != pid) kill();
this->pid = pid;
}
Pid::operator pid_t()
{
return pid;
}
void Pid::kill()
{
if (pid == -1) return;
printMsg(lvlError, format("killing process %1%") % pid);
/* Send a KILL signal to the child. If it has its own process
group, send the signal to every process in the child process
group (which hopefully includes *all* its children). */
if (::kill(separatePG ? -pid : pid, SIGKILL) != 0)
printMsg(lvlError, (SysError(format("killing process %1%") % pid).msg()));
/* Wait until the child dies, disregarding the exit status. */
int status;
while (waitpid(pid, &status, 0) == -1)
if (errno != EINTR) printMsg(lvlError,
(SysError(format("waiting for process %1%") % pid).msg()));
pid = -1;
}
int Pid::wait(bool block)
{
while (1) {
int status;
int res = waitpid(pid, &status, block ? 0 : WNOHANG);
if (res == pid) {
pid = -1;
return status;
}
if (res == 0 && !block) return -1;
if (errno != EINTR)
throw SysError("cannot get child exit status");
}
}
void Pid::setSeparatePG(bool separatePG)
{
this->separatePG = separatePG;
}
//////////////////////////////////////////////////////////////////////
volatile sig_atomic_t _isInterrupted = 0;
void _interrupted()
{
/* Block user interrupts while an exception is being handled.
Throwing an exception while another exception is being handled
kills the program! */
if (!uncaught_exception()) {
_isInterrupted = 0;
throw Error("interrupted by the user");
}
}
//////////////////////////////////////////////////////////////////////
string packStrings(const Strings & strings)
{
string d;
for (Strings::const_iterator i = strings.begin();
i != strings.end(); ++i)
{
unsigned int len = i->size();
d += len & 0xff;
d += (len >> 8) & 0xff;
d += (len >> 16) & 0xff;
d += (len >> 24) & 0xff;
d += *i;
}
return d;
}
Strings unpackStrings(const string & s)
{
Strings strings;
string::const_iterator i = s.begin();
while (i != s.end()) {
if (i + 4 > s.end())
throw Error(format("short db entry: `%1%'") % s);
unsigned int len;
len = (unsigned char) *i++;
len |= ((unsigned char) *i++) << 8;
len |= ((unsigned char) *i++) << 16;
len |= ((unsigned char) *i++) << 24;
if (len == 0xffffffff) return strings; /* explicit end-of-list */
if (i + len > s.end())
throw Error(format("short db entry: `%1%'") % s);
strings.push_back(string(i, i + len));
i += len;
}
return strings;
}
string statusToString(int status)
{
if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
if (WIFEXITED(status))
return (format("failed with exit code %1%") % WEXITSTATUS(status)).str();
else if (WIFSIGNALED(status))
return (format("failed due to signal %1%") % WTERMSIG(status)).str();
else
return "died abnormally";
} else return "succeeded";
}
bool statusOk(int status)
{
return WIFEXITED(status) && WEXITSTATUS(status) == 0;
}
bool string2Int(const string & s, int & n)
{
istringstream str(s);
str >> n;
return str && str.eof();
}