1050 lines
24 KiB
C++
1050 lines
24 KiB
C++
#include "config.h"
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#ifdef __CYGWIN__
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#include <windows.h>
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#endif
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#include <iostream>
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#include <cerrno>
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#include <cstdio>
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#include <sstream>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include <fcntl.h>
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#include <sys/types.h>
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#include <pwd.h>
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#include <grp.h>
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#include "util.hh"
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namespace nix {
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Error::Error(const format & f)
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{
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err = f.str();
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}
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Error & Error::addPrefix(const format & f)
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{
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err = f.str() + err;
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return *this;
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}
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SysError::SysError(const format & f)
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: Error(format("%1%: %2%") % f.str() % strerror(errno))
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{
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}
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string getEnv(const string & key, const string & def)
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{
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char * value = getenv(key.c_str());
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return value ? string(value) : def;
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}
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Path absPath(Path path, Path dir)
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{
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if (path[0] != '/') {
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if (dir == "") {
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char buf[PATH_MAX];
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if (!getcwd(buf, sizeof(buf)))
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throw SysError("cannot get cwd");
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dir = buf;
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}
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path = dir + "/" + path;
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}
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return canonPath(path);
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}
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Path canonPath(const Path & path, bool resolveSymlinks)
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{
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string s;
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if (path[0] != '/')
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throw Error(format("not an absolute path: `%1%'") % path);
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string::const_iterator i = path.begin(), end = path.end();
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string temp;
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/* Count the number of times we follow a symlink and stop at some
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arbitrary (but high) limit to prevent infinite loops. */
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unsigned int followCount = 0, maxFollow = 1024;
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while (1) {
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/* Skip slashes. */
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while (i != end && *i == '/') i++;
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if (i == end) break;
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/* Ignore `.'. */
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if (*i == '.' && (i + 1 == end || i[1] == '/'))
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i++;
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/* If `..', delete the last component. */
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else if (*i == '.' && i + 1 < end && i[1] == '.' &&
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(i + 2 == end || i[2] == '/'))
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{
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if (!s.empty()) s.erase(s.rfind('/'));
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i += 2;
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}
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/* Normal component; copy it. */
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else {
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s += '/';
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while (i != end && *i != '/') s += *i++;
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/* If s points to a symlink, resolve it and restart (since
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the symlink target might contain new symlinks). */
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if (resolveSymlinks && isLink(s)) {
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followCount++;
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if (followCount >= maxFollow)
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throw Error(format("infinite symlink recursion in path `%1%'") % path);
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temp = absPath(readLink(s), dirOf(s))
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+ string(i, end);
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i = temp.begin(); /* restart */
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end = temp.end();
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s = "";
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/* !!! potential for infinite loop */
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}
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}
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}
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return s.empty() ? "/" : s;
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}
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Path dirOf(const Path & path)
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{
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Path::size_type pos = path.rfind('/');
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if (pos == string::npos)
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throw Error(format("invalid file name: %1%") % path);
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return pos == 0 ? "/" : Path(path, 0, pos);
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}
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string baseNameOf(const Path & path)
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{
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Path::size_type pos = path.rfind('/');
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if (pos == string::npos)
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throw Error(format("invalid file name %1% ") % path);
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return string(path, pos + 1);
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}
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bool pathExists(const Path & path)
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{
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int res;
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struct stat st;
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res = lstat(path.c_str(), &st);
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if (!res) return true;
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if (errno != ENOENT && errno != ENOTDIR)
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throw SysError(format("getting status of %1%") % path);
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return false;
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}
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Path readLink(const Path & path)
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{
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struct stat st;
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if (lstat(path.c_str(), &st))
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throw SysError(format("getting status of `%1%'") % path);
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if (!S_ISLNK(st.st_mode))
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throw Error(format("`%1%' is not a symlink") % path);
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char buf[st.st_size];
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if (readlink(path.c_str(), buf, st.st_size) != st.st_size)
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throw SysError(format("reading symbolic link `%1%'") % path);
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return string(buf, st.st_size);
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}
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bool isLink(const Path & path)
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{
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struct stat st;
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if (lstat(path.c_str(), &st))
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throw SysError(format("getting status of `%1%'") % path);
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return S_ISLNK(st.st_mode);
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}
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Strings readDirectory(const Path & path)
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{
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Strings names;
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AutoCloseDir dir = opendir(path.c_str());
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if (!dir) throw SysError(format("opening directory `%1%'") % path);
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struct dirent * dirent;
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while (errno = 0, dirent = readdir(dir)) { /* sic */
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checkInterrupt();
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string name = dirent->d_name;
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if (name == "." || name == "..") continue;
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names.push_back(name);
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}
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if (errno) throw SysError(format("reading directory `%1%'") % path);
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return names;
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}
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template <class T>
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struct AutoDeleteArray
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{
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T * p;
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AutoDeleteArray(T * p) : p(p) { }
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~AutoDeleteArray()
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{
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delete [] p;
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}
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};
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string readFile(int fd)
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{
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struct stat st;
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if (fstat(fd, &st) == -1)
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throw SysError("statting file");
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unsigned char * buf = new unsigned char[st.st_size];
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AutoDeleteArray<unsigned char> d(buf);
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readFull(fd, buf, st.st_size);
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return string((char *) buf, st.st_size);
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}
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string readFile(const Path & path)
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{
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AutoCloseFD fd = open(path.c_str(), O_RDONLY);
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if (fd == -1)
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throw SysError(format("opening file `%1%'") % path);
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return readFile(fd);
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}
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void writeFile(const Path & path, const string & s)
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{
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AutoCloseFD fd = open(path.c_str(), O_WRONLY | O_TRUNC | O_CREAT, 0666);
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if (fd == -1)
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throw SysError(format("opening file `%1%'") % path);
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writeFull(fd, (unsigned char *) s.c_str(), s.size());
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}
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unsigned long long computePathSize(const Path & path)
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{
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unsigned long long size = 0;
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checkInterrupt();
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struct stat st;
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if (lstat(path.c_str(), &st))
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throw SysError(format("getting attributes of path `%1%'") % path);
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size += st.st_size;
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if (S_ISDIR(st.st_mode)) {
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Strings names = readDirectory(path);
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for (Strings::iterator i = names.begin(); i != names.end(); ++i)
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size += computePathSize(path + "/" + *i);
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}
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return size;
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}
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static void _deletePath(const Path & path, unsigned long long & bytesFreed)
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{
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checkInterrupt();
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printMsg(lvlVomit, format("%1%") % path);
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struct stat st;
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if (lstat(path.c_str(), &st))
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throw SysError(format("getting attributes of path `%1%'") % path);
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bytesFreed += st.st_size;
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if (S_ISDIR(st.st_mode)) {
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Strings names = readDirectory(path);
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/* Make the directory writable. */
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if (!(st.st_mode & S_IWUSR)) {
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if (chmod(path.c_str(), st.st_mode | S_IWUSR) == -1)
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throw SysError(format("making `%1%' writable") % path);
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}
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for (Strings::iterator i = names.begin(); i != names.end(); ++i)
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_deletePath(path + "/" + *i, bytesFreed);
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}
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if (remove(path.c_str()) == -1)
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throw SysError(format("cannot unlink `%1%'") % path);
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}
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void deletePath(const Path & path)
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{
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unsigned long long dummy;
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deletePath(path, dummy);
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}
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void deletePath(const Path & path, unsigned long long & bytesFreed)
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{
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startNest(nest, lvlDebug,
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format("recursively deleting path `%1%'") % path);
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bytesFreed = 0;
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_deletePath(path, bytesFreed);
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}
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void makePathReadOnly(const Path & path)
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{
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checkInterrupt();
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struct stat st;
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if (lstat(path.c_str(), &st))
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throw SysError(format("getting attributes of path `%1%'") % path);
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if (!S_ISLNK(st.st_mode) && (st.st_mode & S_IWUSR)) {
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if (chmod(path.c_str(), st.st_mode & ~S_IWUSR) == -1)
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throw SysError(format("making `%1%' read-only") % path);
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}
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if (S_ISDIR(st.st_mode)) {
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Strings names = readDirectory(path);
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for (Strings::iterator i = names.begin(); i != names.end(); ++i)
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makePathReadOnly(path + "/" + *i);
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}
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}
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static Path tempName()
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{
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static int counter = 0;
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Path tmpRoot = canonPath(getEnv("TMPDIR", "/tmp"), true);
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return (format("%1%/nix-%2%-%3%") % tmpRoot % getpid() % counter++).str();
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}
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Path createTempDir()
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{
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while (1) {
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checkInterrupt();
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Path tmpDir = tempName();
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if (mkdir(tmpDir.c_str(), 0777) == 0) {
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/* Explicitly set the group of the directory. This is to
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work around around problems caused by BSD's group
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ownership semantics (directories inherit the group of
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the parent). For instance, the group of /tmp on
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FreeBSD is "wheel", so all directories created in /tmp
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will be owned by "wheel"; but if the user is not in
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"wheel", then "tar" will fail to unpack archives that
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have the setgid bit set on directories. */
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if (chown(tmpDir.c_str(), (uid_t) -1, getegid()) != 0)
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throw SysError(format("setting group of directory `%1%'") % tmpDir);
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return tmpDir;
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}
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if (errno != EEXIST)
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throw SysError(format("creating directory `%1%'") % tmpDir);
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}
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}
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void createDirs(const Path & path)
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{
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if (path == "/") return;
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createDirs(dirOf(path));
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if (!pathExists(path))
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if (mkdir(path.c_str(), 0777) == -1)
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throw SysError(format("creating directory `%1%'") % path);
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}
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void writeStringToFile(const Path & path, const string & s)
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{
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AutoCloseFD fd(open(path.c_str(),
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O_CREAT | O_EXCL | O_WRONLY, 0666));
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if (fd == -1)
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throw SysError(format("creating file `%1%'") % path);
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writeFull(fd, (unsigned char *) s.c_str(), s.size());
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}
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LogType logType = ltPretty;
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Verbosity verbosity = lvlInfo;
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static int nestingLevel = 0;
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Nest::Nest()
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{
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nest = false;
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}
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Nest::~Nest()
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{
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close();
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}
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static string escVerbosity(Verbosity level)
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{
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return int2String((int) level);
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}
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void Nest::open(Verbosity level, const format & f)
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{
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if (level <= verbosity) {
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if (logType == ltEscapes)
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std::cerr << "\033[" << escVerbosity(level) << "p"
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<< f.str() << "\n";
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else
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printMsg_(level, f);
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nest = true;
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nestingLevel++;
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}
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}
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void Nest::close()
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{
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if (nest) {
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nestingLevel--;
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if (logType == ltEscapes)
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std::cerr << "\033[q";
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nest = false;
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}
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}
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void printMsg_(Verbosity level, const format & f)
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{
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checkInterrupt();
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if (level > verbosity) return;
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string prefix;
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if (logType == ltPretty)
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for (int i = 0; i < nestingLevel; i++)
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prefix += "| ";
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else if (logType == ltEscapes && level != lvlInfo)
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prefix = "\033[" + escVerbosity(level) + "s";
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string s = (format("%1%%2%\n") % prefix % f.str()).str();
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writeFull(STDERR_FILENO, (const unsigned char *) s.c_str(), s.size());
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}
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void warnOnce(bool & haveWarned, const format & f)
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{
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if (!haveWarned) {
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printMsg(lvlError, format("warning: %1%") % f.str());
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haveWarned = true;
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}
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}
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void readFull(int fd, unsigned char * buf, size_t count)
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{
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while (count) {
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checkInterrupt();
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ssize_t res = read(fd, (char *) buf, count);
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if (res == -1) {
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if (errno == EINTR) continue;
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throw SysError("reading from file");
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}
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if (res == 0) throw Error("unexpected end-of-file");
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count -= res;
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buf += res;
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}
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}
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void writeFull(int fd, const unsigned char * buf, size_t count)
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{
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while (count) {
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checkInterrupt();
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ssize_t res = write(fd, (char *) buf, count);
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if (res == -1) {
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if (errno == EINTR) continue;
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throw SysError("writing to file");
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}
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count -= res;
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buf += res;
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}
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}
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string drainFD(int fd)
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{
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string result;
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unsigned char buffer[4096];
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while (1) {
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ssize_t rd = read(fd, buffer, sizeof buffer);
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if (rd == -1) {
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if (errno != EINTR)
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throw SysError("reading from file");
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}
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else if (rd == 0) break;
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else result.append((char *) buffer, rd);
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}
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return result;
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}
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//////////////////////////////////////////////////////////////////////
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AutoDelete::AutoDelete(const string & p) : path(p)
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{
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del = true;
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}
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AutoDelete::~AutoDelete()
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{
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if (del) deletePath(path);
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}
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void AutoDelete::cancel()
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{
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del = false;
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}
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//////////////////////////////////////////////////////////////////////
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AutoCloseFD::AutoCloseFD()
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{
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fd = -1;
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}
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AutoCloseFD::AutoCloseFD(int fd)
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{
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this->fd = fd;
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}
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AutoCloseFD::AutoCloseFD(const AutoCloseFD & fd)
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{
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abort();
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}
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AutoCloseFD::~AutoCloseFD()
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{
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try {
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close();
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} catch (Error & e) {
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printMsg(lvlError, format("error (ignored): %1%") % e.msg());
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}
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}
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void AutoCloseFD::operator =(int fd)
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{
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if (this->fd != fd) close();
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this->fd = fd;
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}
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AutoCloseFD::operator int() const
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{
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return fd;
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}
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void AutoCloseFD::close()
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{
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if (fd != -1) {
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if (::close(fd) == -1)
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/* This should never happen. */
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throw SysError("closing file descriptor");
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fd = -1;
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}
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}
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bool AutoCloseFD::isOpen()
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{
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return fd != -1;
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}
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/* Pass responsibility for closing this fd to the caller. */
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int AutoCloseFD::borrow()
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{
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int oldFD = fd;
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fd = -1;
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return oldFD;
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}
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void Pipe::create()
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{
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int fds[2];
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if (pipe(fds) != 0) throw SysError("creating pipe");
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readSide = fds[0];
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writeSide = fds[1];
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}
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|
|
//////////////////////////////////////////////////////////////////////
|
|
|
|
|
|
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;
|
|
}
|
|
|
|
|
|
|
|
//////////////////////////////////////////////////////////////////////
|
|
|
|
|
|
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 (std::exception & e) {
|
|
std::cerr << "error: " << e.what() << std::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
|
|
}
|
|
|
|
|
|
//////////////////////////////////////////////////////////////////////
|
|
|
|
|
|
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 (!std::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;
|
|
}
|
|
|
|
|
|
Strings tokenizeString(const string & s, const string & separators)
|
|
{
|
|
Strings result;
|
|
string::size_type pos = s.find_first_not_of(separators, 0);
|
|
while (pos != string::npos) {
|
|
string::size_type end = s.find_first_of(separators, pos + 1);
|
|
if (end == string::npos) end = s.size();
|
|
string token(s, pos, end - pos);
|
|
result.push_back(token);
|
|
pos = s.find_first_not_of(separators, end);
|
|
}
|
|
return result;
|
|
}
|
|
|
|
|
|
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;
|
|
}
|
|
|
|
|
|
string int2String(int n)
|
|
{
|
|
std::ostringstream str;
|
|
str << n;
|
|
return str.str();
|
|
}
|
|
|
|
|
|
bool string2Int(const string & s, int & n)
|
|
{
|
|
std::istringstream str(s);
|
|
str >> n;
|
|
return str && str.get() == EOF;
|
|
}
|
|
|
|
|
|
//////////////////////////////////////////////////////////////////////
|
|
|
|
|
|
static bool haveSwitched;
|
|
static uid_t savedUid, nixUid;
|
|
static gid_t savedGid, nixGid;
|
|
|
|
|
|
#if HAVE_SETRESUID
|
|
#define _setuid(uid) setresuid(uid, uid, savedUid)
|
|
#define _setgid(gid) setresgid(gid, gid, savedGid)
|
|
#else
|
|
/* Only works properly when run by root. */
|
|
#define _setuid(uid) setuid(uid)
|
|
#define _setgid(gid) setgid(gid)
|
|
#endif
|
|
|
|
|
|
SwitchToOriginalUser::SwitchToOriginalUser()
|
|
{
|
|
#if HAVE_SETRESUID
|
|
/* Temporarily switch the effective uid/gid back to the saved
|
|
uid/gid (which is the uid/gid of the user that executed the Nix
|
|
program; it's *not* the real uid/gid, since we changed that to
|
|
the Nix user in switchToNixUser()). */
|
|
if (haveSwitched) {
|
|
if (setuid(savedUid) == -1)
|
|
throw SysError(format("temporarily restoring uid to `%1%'") % savedUid);
|
|
if (setgid(savedGid) == -1)
|
|
throw SysError(format("temporarily restoring gid to `%1%'") % savedGid);
|
|
}
|
|
#endif
|
|
}
|
|
|
|
|
|
SwitchToOriginalUser::~SwitchToOriginalUser()
|
|
{
|
|
#if HAVE_SETRESUID
|
|
/* Switch the effective uid/gid back to the Nix user. */
|
|
if (haveSwitched) {
|
|
if (setuid(nixUid) == -1)
|
|
throw SysError(format("restoring uid to `%1%'") % nixUid);
|
|
if (setgid(nixGid) == -1)
|
|
throw SysError(format("restoring gid to `%1%'") % nixGid);
|
|
}
|
|
#endif
|
|
}
|
|
|
|
|
|
void switchToNixUser()
|
|
{
|
|
fprintf(stderr, "real = %d/%d, effective = %d/%d\n",
|
|
getuid(), getgid(), geteuid(), getegid());
|
|
|
|
/* Note: we require setresuid for now since I don't want to think
|
|
to deeply about whether this works on systems that don't have
|
|
setresuid. It's already hard enough. */
|
|
|
|
#if HAVE_SETRESUID
|
|
|
|
/* Setuid Nix operation works as follows:
|
|
|
|
- The Nix binaries are owned by a Nix user and group, e.g.,
|
|
nix.nix, and must setuid and setgid, e.g.,
|
|
|
|
rwsrwsr-x nix.nix
|
|
|
|
- Users (say alice.users) are only allowed to run (most) Nix
|
|
operations if they are in the Nix group. If they aren't,
|
|
some read-only operations (like nix-env -qa) may still work.
|
|
|
|
- We run mostly under the Nix user/group, but we switch back to
|
|
the calling user/group for some work, like reading Nix
|
|
expressions.
|
|
|
|
*/
|
|
|
|
|
|
/* Don't do anything if this is not a setuid binary. */
|
|
if (getuid() == geteuid() && getgid() == getegid()) return;
|
|
|
|
/* Here we set the uid and gid to the Nix user and group,
|
|
respectively, IF the current (real) user is a member of the Nix
|
|
group. (The Nix group is the group of the current executable,
|
|
i.e., the current effective gid.) Otherwise we just drop all
|
|
privileges. */
|
|
|
|
nixGid = geteuid();
|
|
|
|
/* Get the supplementary group IDs for the current user. */
|
|
int maxGids = 512, nrGids;
|
|
gid_t gids[maxGids];
|
|
if ((nrGids = getgroups(maxGids, gids)) == -1) {
|
|
std::cerr << format("unable to query gids\n");
|
|
exit(1);
|
|
}
|
|
|
|
/* !!! Apparently it is unspecified whether getgroups() includes
|
|
the effective gid. In that case the following test is always
|
|
true *if* the program is installed setgid (which we do when we
|
|
have setresuid()). On Linux this doesn't appear to be the
|
|
case, but we should switch to the real gid before doing this
|
|
test, and then switch back to the saved gid. */
|
|
|
|
/* Check that the current user is a member of the Nix group. */
|
|
bool found = false;
|
|
for (int i = 0; i < nrGids; ++i)
|
|
if (gids[i] == nixGid) {
|
|
found = true;
|
|
break;
|
|
}
|
|
|
|
if (!found) {
|
|
/* Not in the Nix group - drop all root/Nix privileges. */
|
|
_setgid(getgid());
|
|
_setuid(getuid());
|
|
return;
|
|
}
|
|
|
|
/* Save the uid/gid of the caller so the we can switch back to
|
|
that uid/gid for temporary work, like accessing files, in
|
|
SwitchToOriginaluser. */
|
|
savedUid = getuid();
|
|
savedGid = getgid();
|
|
|
|
/* Set the real and effective gids to nixGid. Also make very sure
|
|
that this succeeded. We switch the gid first because we cannot
|
|
do it after we have dropped root uid. */
|
|
if (_setgid(nixGid) != 0 || getgid() != nixGid || getegid() != nixGid) {
|
|
std::cerr << format("unable to set gid to `%1%'\n") % nixGid;
|
|
exit(1);
|
|
}
|
|
|
|
/* The Nix uid is the effective uid of the owner of the current
|
|
executable, i.e., the current effective uid. */
|
|
nixUid = geteuid();
|
|
|
|
/* This will drop all root privileges, setting the real, effective
|
|
and saved uids to pw->pw_uid. Also make very sure that this
|
|
succeeded.*/
|
|
if (_setuid(nixUid) != 0 || getuid() != nixUid || geteuid() != nixUid) {
|
|
std::cerr << format("unable to set uid to `%1%'\n") % nixUid;
|
|
exit(1);
|
|
}
|
|
|
|
/* !!! for setuid operation, we should: 1) wipe the environment;
|
|
2) verify file descriptors 0, 1, 2; 3) etc.
|
|
See: http://www.daemon-systems.org/man/setuid.7.html
|
|
*/
|
|
|
|
haveSwitched = true;
|
|
#endif
|
|
}
|
|
|
|
|
|
}
|