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Connect/bind Unix domain sockets in a child process

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In the child process, we can do a chdir() and avoid the problem of the
path not fitting into sockaddr_un.
This commit is contained in:
Eelco Dolstra 2021-08-24 13:52:55 +02:00
parent 08cc572f89
commit 43d4d75e22
3 changed files with 69 additions and 21 deletions
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71
src/libutil/util.cc
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@ -1686,16 +1686,7 @@ AutoCloseFD createUnixDomainSocket(const Path & path, mode_t mode)
closeOnExec(fdSocket.get());
struct sockaddr_un addr;
addr.sun_family = AF_UNIX;
if (path.size() + 1 >= sizeof(addr.sun_path))
throw Error("socket path '%1%' is too long", path);
strcpy(addr.sun_path, path.c_str());
unlink(path.c_str());
if (bind(fdSocket.get(), (struct sockaddr *) &addr, sizeof(addr)) == -1)
throw SysError("cannot bind to socket '%1%'", path);
bind(fdSocket.get(), path);
if (chmod(path.c_str(), mode) == -1)
throw SysError("changing permissions on '%1%'", path);
@ -1707,6 +1698,66 @@ AutoCloseFD createUnixDomainSocket(const Path & path, mode_t mode)
}
void bind(int fd, const std::string & path)
{
unlink(path.c_str());
struct sockaddr_un addr;
addr.sun_family = AF_UNIX;
if (path.size() + 1 >= sizeof(addr.sun_path)) {
Pid pid = startProcess([&]() {
auto dir = dirOf(path);
if (chdir(dir.c_str()) == -1)
throw SysError("chdir to '%s' failed", dir);
std::string base(baseNameOf(path));
if (base.size() + 1 >= sizeof(addr.sun_path))
throw Error("socket path '%s' is too long", base);
strcpy(addr.sun_path, base.c_str());
if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1)
throw SysError("cannot bind to socket '%s'", path);
_exit(0);
});
int status = pid.wait();
if (status != 0)
throw Error("cannot bind to socket '%s'", path);
} else {
strcpy(addr.sun_path, path.c_str());
if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1)
throw SysError("cannot bind to socket '%s'", path);
}
}
void connect(int fd, const std::string & path)
{
struct sockaddr_un addr;
addr.sun_family = AF_UNIX;
if (path.size() + 1 >= sizeof(addr.sun_path)) {
Pid pid = startProcess([&]() {
auto dir = dirOf(path);
if (chdir(dir.c_str()) == -1)
throw SysError("chdir to '%s' failed", dir);
std::string base(baseNameOf(path));
if (base.size() + 1 >= sizeof(addr.sun_path))
throw Error("socket path '%s' is too long", base);
strcpy(addr.sun_path, base.c_str());
if (connect(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1)
throw SysError("cannot connect to socket at '%s'", path);
_exit(0);
});
int status = pid.wait();
if (status != 0)
throw Error("cannot connect to socket ar '%s'", path);
} else {
strcpy(addr.sun_path, path.c_str());
if (connect(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1)
throw SysError("cannot connect to socket at '%s'", path);
}
}
string showBytes(uint64_t bytes)
{
return fmt("%.2f MiB", bytes / (1024.0 * 1024.0));