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bind: give same treatment as connect in #8544, dedup

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It is good to propagate the underlying error so whether or not we use a
process to deal with path length issues is not observable.

Also, as these wrapper functions got more and more complex, the code
duplication got worse and worse. The new `bindConnectProcHelper`
function deduplicates them.
This commit is contained in:
John Ericson 2024-01-16 10:35:16 -05:00
parent 1d89c7b02e
commit 3016e67c21
1 changed files with 33 additions and 51 deletions
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84
src/libutil/unix-domain-socket.cc
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@ -38,52 +38,20 @@ AutoCloseFD createUnixDomainSocket(const Path & path, mode_t mode)
return fdSocket;
}
static struct sockaddr* safeSockAddrPointerCast(struct sockaddr_un *addr) {
// Casting between types like these legacy C library interfaces require
// is forbidden in C++.
// To maintain backwards compatibility, the implementation of the
// bind function contains some hints to the compiler that allow for this
static void bindConnectProcHelper(
std::string_view operationName, auto && operation,
int fd, const std::string & path)
{
struct sockaddr_un addr;
addr.sun_family = AF_UNIX;
// Casting between types like these legacy C library interfaces
// require is forbidden in C++. To maintain backwards
// compatibility, the implementation of the bind/connect functions
// contains some hints to the compiler that allow for this
// special case.
return reinterpret_cast<struct sockaddr *>(addr);
}
void bind(int fd, const std::string & path)
{
unlink(path.c_str());
struct sockaddr_un addr;
addr.sun_family = AF_UNIX;
auto psaddr {safeSockAddrPointerCast(&addr)};
if (path.size() + 1 >= sizeof(addr.sun_path)) {
Pid pid = startProcess([&] {
Path 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);
memcpy(addr.sun_path, base.c_str(), base.size() + 1);
if (bind(fd, psaddr, 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 {
memcpy(addr.sun_path, path.c_str(), path.size() + 1);
if (bind(fd, psaddr, 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;
auto psaddr {safeSockAddrPointerCast(&addr)};
auto * psaddr = reinterpret_cast<struct sockaddr *>(&addr);
if (path.size() + 1 >= sizeof(addr.sun_path)) {
Pipe pipe;
@ -98,8 +66,8 @@ void connect(int fd, const std::string & path)
if (base.size() + 1 >= sizeof(addr.sun_path))
throw Error("socket path '%s' is too long", base);
memcpy(addr.sun_path, base.c_str(), base.size() + 1);
if (connect(fd, psaddr, sizeof(addr)) == -1)
throw SysError("cannot connect to socket at '%s'", path);
if (operation(fd, psaddr, sizeof(addr)) == -1)
throw SysError("cannot %s to socket at '%s'", operationName, path);
writeFull(pipe.writeSide.get(), "0\n");
} catch (SysError & e) {
writeFull(pipe.writeSide.get(), fmt("%d\n", e.errNo));
@ -110,16 +78,30 @@ void connect(int fd, const std::string & path)
pipe.writeSide.close();
auto errNo = string2Int<int>(chomp(drainFD(pipe.readSide.get())));
if (!errNo || *errNo == -1)
throw Error("cannot connect to socket at '%s'", path);
throw Error("cannot %s to socket at '%s'", operationName, path);
else if (*errNo > 0) {
errno = *errNo;
throw SysError("cannot connect to socket at '%s'", path);
throw SysError("cannot %s to socket at '%s'", operationName, path);
}
} else {
memcpy(addr.sun_path, path.c_str(), path.size() + 1);
if (connect(fd, psaddr, sizeof(addr)) == -1)
throw SysError("cannot connect to socket at '%s'", path);
if (operation(fd, psaddr, sizeof(addr)) == -1)
throw SysError("cannot %s to socket at '%s'", operationName, path);
}
}
void bind(int fd, const std::string & path)
{
unlink(path.c_str());
bindConnectProcHelper("bind", ::bind, fd, path);
}
void connect(int fd, const std::string & path)
{
bindConnectProcHelper("connect", ::connect, fd, path);
}
}