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mingw: make sure errno is set correctly when socket operations fail
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The winsock2 library provides functions that work on different data
types than file descriptors, therefore we wrap them.

But that is not the only difference: they also do not set `errno` but
expect the callers to enquire about errors via `WSAGetLastError()`.

Let's translate that into appropriate `errno` values whenever the socket
operations fail so that Git's code base does not have to change its
expectations.

This closes #2404

Helped-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
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@dscho
dscho committed Sep 18, 2024
1 parent f8b122e commit f5100a6
Showing 1 changed file with 147 additions and 10 deletions.
157 changes: 147 additions & 10 deletions compat/mingw.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2041,26 +2041,158 @@ static void ensure_socket_initialization(void)
initialized = 1;
}

static int winsock_error_to_errno(DWORD err)
{
switch (err) {
case WSAEINTR: return EINTR;
case WSAEBADF: return EBADF;
case WSAEACCES: return EACCES;
case WSAEFAULT: return EFAULT;
case WSAEINVAL: return EINVAL;
case WSAEMFILE: return EMFILE;
case WSAEWOULDBLOCK: return EWOULDBLOCK;
case WSAEINPROGRESS: return EINPROGRESS;
case WSAEALREADY: return EALREADY;
case WSAENOTSOCK: return ENOTSOCK;
case WSAEDESTADDRREQ: return EDESTADDRREQ;
case WSAEMSGSIZE: return EMSGSIZE;
case WSAEPROTOTYPE: return EPROTOTYPE;
case WSAENOPROTOOPT: return ENOPROTOOPT;
case WSAEPROTONOSUPPORT: return EPROTONOSUPPORT;
case WSAEOPNOTSUPP: return EOPNOTSUPP;
case WSAEAFNOSUPPORT: return EAFNOSUPPORT;
case WSAEADDRINUSE: return EADDRINUSE;
case WSAEADDRNOTAVAIL: return EADDRNOTAVAIL;
case WSAENETDOWN: return ENETDOWN;
case WSAENETUNREACH: return ENETUNREACH;
case WSAENETRESET: return ENETRESET;
case WSAECONNABORTED: return ECONNABORTED;
case WSAECONNRESET: return ECONNRESET;
case WSAENOBUFS: return ENOBUFS;
case WSAEISCONN: return EISCONN;
case WSAENOTCONN: return ENOTCONN;
case WSAETIMEDOUT: return ETIMEDOUT;
case WSAECONNREFUSED: return ECONNREFUSED;
case WSAELOOP: return ELOOP;
case WSAENAMETOOLONG: return ENAMETOOLONG;
case WSAEHOSTUNREACH: return EHOSTUNREACH;
case WSAENOTEMPTY: return ENOTEMPTY;
/* No errno equivalent; default to EIO */
case WSAESOCKTNOSUPPORT:
case WSAEPFNOSUPPORT:
case WSAESHUTDOWN:
case WSAETOOMANYREFS:
case WSAEHOSTDOWN:
case WSAEPROCLIM:
case WSAEUSERS:
case WSAEDQUOT:
case WSAESTALE:
case WSAEREMOTE:
case WSASYSNOTREADY:
case WSAVERNOTSUPPORTED:
case WSANOTINITIALISED:
case WSAEDISCON:
case WSAENOMORE:
case WSAECANCELLED:
case WSAEINVALIDPROCTABLE:
case WSAEINVALIDPROVIDER:
case WSAEPROVIDERFAILEDINIT:
case WSASYSCALLFAILURE:
case WSASERVICE_NOT_FOUND:
case WSATYPE_NOT_FOUND:
case WSA_E_NO_MORE:
case WSA_E_CANCELLED:
case WSAEREFUSED:
case WSAHOST_NOT_FOUND:
case WSATRY_AGAIN:
case WSANO_RECOVERY:
case WSANO_DATA:
case WSA_QOS_RECEIVERS:
case WSA_QOS_SENDERS:
case WSA_QOS_NO_SENDERS:
case WSA_QOS_NO_RECEIVERS:
case WSA_QOS_REQUEST_CONFIRMED:
case WSA_QOS_ADMISSION_FAILURE:
case WSA_QOS_POLICY_FAILURE:
case WSA_QOS_BAD_STYLE:
case WSA_QOS_BAD_OBJECT:
case WSA_QOS_TRAFFIC_CTRL_ERROR:
case WSA_QOS_GENERIC_ERROR:
case WSA_QOS_ESERVICETYPE:
case WSA_QOS_EFLOWSPEC:
case WSA_QOS_EPROVSPECBUF:
case WSA_QOS_EFILTERSTYLE:
case WSA_QOS_EFILTERTYPE:
case WSA_QOS_EFILTERCOUNT:
case WSA_QOS_EOBJLENGTH:
case WSA_QOS_EFLOWCOUNT:
#ifndef _MSC_VER
case WSA_QOS_EUNKNOWNPSOBJ:
#endif
case WSA_QOS_EPOLICYOBJ:
case WSA_QOS_EFLOWDESC:
case WSA_QOS_EPSFLOWSPEC:
case WSA_QOS_EPSFILTERSPEC:
case WSA_QOS_ESDMODEOBJ:
case WSA_QOS_ESHAPERATEOBJ:
case WSA_QOS_RESERVED_PETYPE:
default: return EIO;
}
}

/*
* On Windows, `errno` is a global macro to a function call.
* This makes it difficult to debug and single-step our mappings.
*/
static inline void set_wsa_errno(void)
{
DWORD wsa = WSAGetLastError();
int e = winsock_error_to_errno(wsa);
errno = e;

#ifdef DEBUG_WSA_ERRNO
fprintf(stderr, "winsock error: %d -> %d\n", wsa, e);
fflush(stderr);
#endif
}

static inline int winsock_return(int ret)
{
if (ret < 0)
set_wsa_errno();

return ret;
}

#define WINSOCK_RETURN(x) do { return winsock_return(x); } while (0)

#undef gethostname
int mingw_gethostname(char *name, int namelen)
{
ensure_socket_initialization();
return gethostname(name, namelen);
ensure_socket_initialization();
WINSOCK_RETURN(gethostname(name, namelen));
}

#undef gethostbyname
struct hostent *mingw_gethostbyname(const char *host)
{
struct hostent *ret;

ensure_socket_initialization();
return gethostbyname(host);

ret = gethostbyname(host);
if (!ret)
set_wsa_errno();

return ret;
}

#undef getaddrinfo
int mingw_getaddrinfo(const char *node, const char *service,
const struct addrinfo *hints, struct addrinfo **res)
{
ensure_socket_initialization();
return getaddrinfo(node, service, hints, res);
WINSOCK_RETURN(getaddrinfo(node, service, hints, res));
}

int mingw_socket(int domain, int type, int protocol)
Expand All @@ -2080,7 +2212,7 @@ int mingw_socket(int domain, int type, int protocol)
* in errno so that _if_ someone looks up the code somewhere,
* then it is at least the number that are usually listed.
*/
errno = WSAGetLastError();
set_wsa_errno();
return -1;
}
/* convert into a file descriptor */
Expand All @@ -2096,35 +2228,35 @@ int mingw_socket(int domain, int type, int protocol)
int mingw_connect(int sockfd, struct sockaddr *sa, size_t sz)
{
SOCKET s = (SOCKET)_get_osfhandle(sockfd);
return connect(s, sa, sz);
WINSOCK_RETURN(connect(s, sa, sz));
}

#undef bind
int mingw_bind(int sockfd, struct sockaddr *sa, size_t sz)
{
SOCKET s = (SOCKET)_get_osfhandle(sockfd);
return bind(s, sa, sz);
WINSOCK_RETURN(bind(s, sa, sz));
}

#undef setsockopt
int mingw_setsockopt(int sockfd, int lvl, int optname, void *optval, int optlen)
{
SOCKET s = (SOCKET)_get_osfhandle(sockfd);
return setsockopt(s, lvl, optname, (const char*)optval, optlen);
WINSOCK_RETURN(setsockopt(s, lvl, optname, (const char*)optval, optlen));
}

#undef shutdown
int mingw_shutdown(int sockfd, int how)
{
SOCKET s = (SOCKET)_get_osfhandle(sockfd);
return shutdown(s, how);
WINSOCK_RETURN(shutdown(s, how));
}

#undef listen
int mingw_listen(int sockfd, int backlog)
{
SOCKET s = (SOCKET)_get_osfhandle(sockfd);
return listen(s, backlog);
WINSOCK_RETURN(listen(s, backlog));
}

#undef accept
Expand All @@ -2135,6 +2267,11 @@ int mingw_accept(int sockfd1, struct sockaddr *sa, socklen_t *sz)
SOCKET s1 = (SOCKET)_get_osfhandle(sockfd1);
SOCKET s2 = accept(s1, sa, sz);

if (s2 == INVALID_SOCKET) {
set_wsa_errno();
return -1;
}

/* convert into a file descriptor */
if ((sockfd2 = _open_osfhandle(s2, O_RDWR|O_BINARY)) < 0) {
int err = errno;
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