Clean up messy API for src/port/thread.c.

The point of this patch is to reduce inclusion spam by not needing
to #include <netdb.h> or <pwd.h> in port.h (which is read by every
compile in our tree).  To do that, we must remove port.h's
declarations of pqGetpwuid and pqGethostbyname.

pqGethostbyname is only used, and is only ever likely to be used,
in src/port/getaddrinfo.c --- which isn't even built on most
platforms, making pqGethostbyname dead code for most people.
Hence, deal with that by just moving it into getaddrinfo.c.

To clean up pqGetpwuid, invent a couple of simple wrapper
functions with less-messy APIs.  This allows removing some
duplicate error-handling code, too.

In passing, remove thread.c from the MSVC build, since it
contains nothing we use on Windows.

Noted while working on 376ce3e.

Discussion: https://postgr.es/m/1634252654444.90107@mit.edu

Author: tglsfdc

src/backend/libpq/auth.c

@@ -18,6 +18,7 @@
 #include <sys/param.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
+#include <pwd.h>
 #include <unistd.h>
 #ifdef HAVE_SYS_SELECT_H
 #include <sys/select.h>

src/bin/psql/common.c

@@ -10,6 +10,7 @@
 #include <ctype.h>
 #include <limits.h>
 #include <math.h>
+#include <pwd.h>
 #include <signal.h>
 #ifndef WIN32
 #include <unistd.h>				/* for write() */

src/include/port.h

@@ -14,8 +14,6 @@
 #define PG_PORT_H
 
 #include <ctype.h>
-#include <netdb.h>
-#include <pwd.h>
 
 /*
  * Windows has enough specialized port stuff that we push most of it off
@@ -484,18 +482,12 @@ extern char *dlerror(void);
 #define RTLD_GLOBAL 0
 #endif
 
-/* thread.h */
+/* thread.c */
 #ifndef WIN32
-extern int	pqGetpwuid(uid_t uid, struct passwd *resultbuf, char *buffer,
-					   size_t buflen, struct passwd **result);
+extern bool pg_get_user_name(uid_t user_id, char *buffer, size_t buflen);
+extern bool pg_get_user_home_dir(uid_t user_id, char *buffer, size_t buflen);
 #endif
 
-extern int	pqGethostbyname(const char *name,
-							struct hostent *resultbuf,
-							char *buffer, size_t buflen,
-							struct hostent **result,
-							int *herrno);
-
 extern void pg_qsort(void *base, size_t nel, size_t elsize,
 					 int (*cmp) (const void *, const void *));
 extern int	pg_qsort_strcmp(const void *a, const void *b);

src/interfaces/libpq/fe-auth.c

@@ -35,7 +35,6 @@
 #ifndef  MAXHOSTNAMELEN
 #include <netdb.h>				/* for MAXHOSTNAMELEN on some */
 #endif
-#include <pwd.h>
 #endif
 
 #include "common/md5.h"
@@ -1099,14 +1098,17 @@ pg_fe_sendauth(AuthRequest areq, int payloadlen, PGconn *conn)
 
 
 /*
- * pg_fe_getauthname
+ * pg_fe_getusername
  *
- * Returns a pointer to malloc'd space containing whatever name the user
- * has authenticated to the system.  If there is an error, return NULL,
- * and append a suitable error message to *errorMessage if that's not NULL.
+ * Returns a pointer to malloc'd space containing the name of the
+ * specified user_id.  If there is an error, return NULL, and append
+ * a suitable error message to *errorMessage if that's not NULL.
+ *
+ * Caution: on Windows, the user_id argument is ignored, and we always
+ * fetch the current user's name.
  */
 char *
-pg_fe_getauthname(PQExpBuffer errorMessage)
+pg_fe_getusername(uid_t user_id, PQExpBuffer errorMessage)
 {
 	char	   *result = NULL;
 	const char *name = NULL;
@@ -1116,17 +1118,13 @@ pg_fe_getauthname(PQExpBuffer errorMessage)
 	char		username[256 + 1];
 	DWORD		namesize = sizeof(username);
 #else
-	uid_t		user_id = geteuid();
 	char		pwdbuf[BUFSIZ];
-	struct passwd pwdstr;
-	struct passwd *pw = NULL;
-	int			pwerr;
 #endif
 
 	/*
 	 * Some users are using configure --enable-thread-safety-force, so we
 	 * might as well do the locking within our library to protect
-	 * pqGetpwuid(). In fact, application developers can use getpwuid() in
+	 * getpwuid(). In fact, application developers can use getpwuid() in
 	 * their application if they use the locking call we provide, or install
 	 * their own locking function using PQregisterThreadLock().
 	 */
@@ -1140,21 +1138,10 @@ pg_fe_getauthname(PQExpBuffer errorMessage)
 						  libpq_gettext("user name lookup failure: error code %lu\n"),
 						  GetLastError());
 #else
-	pwerr = pqGetpwuid(user_id, &pwdstr, pwdbuf, sizeof(pwdbuf), &pw);
-	if (pw != NULL)
-		name = pw->pw_name;
+	if (pg_get_user_name(user_id, pwdbuf, sizeof(pwdbuf)))
+		name = pwdbuf;
 	else if (errorMessage)
-	{
-		if (pwerr != 0)
-			appendPQExpBuffer(errorMessage,
-							  libpq_gettext("could not look up local user ID %d: %s\n"),
-							  (int) user_id,
-							  strerror_r(pwerr, pwdbuf, sizeof(pwdbuf)));
-		else
-			appendPQExpBuffer(errorMessage,
-							  libpq_gettext("local user with ID %d does not exist\n"),
-							  (int) user_id);
-	}
+		appendPQExpBuffer(errorMessage, "%s\n", pwdbuf);
 #endif
 
 	if (name)
@@ -1170,6 +1157,23 @@ pg_fe_getauthname(PQExpBuffer errorMessage)
 	return result;
 }
 
+/*
+ * pg_fe_getauthname
+ *
+ * Returns a pointer to malloc'd space containing whatever name the user
+ * has authenticated to the system.  If there is an error, return NULL,
+ * and append a suitable error message to *errorMessage if that's not NULL.
+ */
+char *
+pg_fe_getauthname(PQExpBuffer errorMessage)
+{
+#ifdef WIN32
+	return pg_fe_getusername(0, errorMessage);
+#else
+	return pg_fe_getusername(geteuid(), errorMessage);
+#endif
+}
+
 
 /*
  * PQencryptPassword -- exported routine to encrypt a password with MD5

src/interfaces/libpq/fe-auth.h

@@ -20,6 +20,7 @@
 
 /* Prototypes for functions in fe-auth.c */
 extern int	pg_fe_sendauth(AuthRequest areq, int payloadlen, PGconn *conn);
+extern char *pg_fe_getusername(uid_t user_id, PQExpBuffer errorMessage);
 extern char *pg_fe_getauthname(PQExpBuffer errorMessage);
 
 /* Mechanisms in fe-auth-scram.c */

src/interfaces/libpq/fe-connect.c

@@ -2813,10 +2813,7 @@ PQconnectPoll(PGconn *conn)
 					IS_AF_UNIX(conn->raddr.addr.ss_family))
 				{
 #ifndef WIN32
-					char		pwdbuf[BUFSIZ];
-					struct passwd pass_buf;
-					struct passwd *pass;
-					int			passerr;
+					char	   *remote_username;
 #endif
 					uid_t		uid;
 					gid_t		gid;
@@ -2839,28 +2836,20 @@ PQconnectPoll(PGconn *conn)
 					}
 
 #ifndef WIN32
-					passerr = pqGetpwuid(uid, &pass_buf, pwdbuf, sizeof(pwdbuf), &pass);
-					if (pass == NULL)
-					{
-						if (passerr != 0)
-							appendPQExpBuffer(&conn->errorMessage,
-											  libpq_gettext("could not look up local user ID %d: %s\n"),
-											  (int) uid,
-											  strerror_r(passerr, sebuf, sizeof(sebuf)));
-						else
-							appendPQExpBuffer(&conn->errorMessage,
-											  libpq_gettext("local user with ID %d does not exist\n"),
-											  (int) uid);
-						goto error_return;
-					}
+					remote_username = pg_fe_getusername(uid,
+														&conn->errorMessage);
+					if (remote_username == NULL)
+						goto error_return;	/* message already logged */
 
-					if (strcmp(pass->pw_name, conn->requirepeer) != 0)
+					if (strcmp(remote_username, conn->requirepeer) != 0)
 					{
 						appendPQExpBuffer(&conn->errorMessage,
 										  libpq_gettext("requirepeer specifies \"%s\", but actual peer user name is \"%s\"\n"),
-										  conn->requirepeer, pass->pw_name);
+										  conn->requirepeer, remote_username);
+						free(remote_username);
 						goto error_return;
 					}
+					free(remote_username);
 #else							/* WIN32 */
 					/* should have failed with ENOSYS above */
 					Assert(false);
@@ -7271,16 +7260,7 @@ pqGetHomeDirectory(char *buf, int bufsize)
 
 	home = getenv("HOME");
 	if (home == NULL || home[0] == '\0')
-	{
-		char		pwdbuf[BUFSIZ];
-		struct passwd pwdstr;
-		struct passwd *pwd = NULL;
-
-		(void) pqGetpwuid(geteuid(), &pwdstr, pwdbuf, sizeof(pwdbuf), &pwd);
-		if (pwd == NULL)
-			return false;
-		home = pwd->pw_dir;
-	}
+		return pg_get_user_home_dir(geteuid(), buf, bufsize);
 	strlcpy(buf, home, bufsize);
 	return true;
 #else

src/port/Makefile

@@ -84,6 +84,10 @@ libpgport.a: $(OBJS)
 	rm -f $@
 	$(AR) $(AROPT) $@ $^
 
+# getaddrinfo.o and getaddrinfo_shlib.o need PTHREAD_CFLAGS (but getaddrinfo_srv.o does not)
+getaddrinfo.o: CFLAGS+=$(PTHREAD_CFLAGS)
+getaddrinfo_shlib.o: CFLAGS+=$(PTHREAD_CFLAGS)
+
 # thread.o and thread_shlib.o need PTHREAD_CFLAGS (but thread_srv.o does not)
 thread.o: CFLAGS+=$(PTHREAD_CFLAGS)
 thread_shlib.o: CFLAGS+=$(PTHREAD_CFLAGS)

src/port/getaddrinfo.c

@@ -34,6 +34,14 @@
 #include "port/pg_bswap.h"
 
 
+#ifdef FRONTEND
+static int	pqGethostbyname(const char *name,
+							struct hostent *resultbuf,
+							char *buffer, size_t buflen,
+							struct hostent **result,
+							int *herrno);
+#endif
+
 #ifdef WIN32
 /*
  * The native routines may or may not exist on the Windows platform we are on,
@@ -394,3 +402,39 @@ getnameinfo(const struct sockaddr *sa, int salen,
 
 	return 0;
 }
+
+/*
+ * Wrapper around gethostbyname() or gethostbyname_r() to mimic
+ * POSIX gethostbyname_r() behaviour, if it is not available or required.
+ */
+#ifdef FRONTEND
+static int
+pqGethostbyname(const char *name,
+				struct hostent *resultbuf,
+				char *buffer, size_t buflen,
+				struct hostent **result,
+				int *herrno)
+{
+#if defined(ENABLE_THREAD_SAFETY) && defined(HAVE_GETHOSTBYNAME_R)
+
+	/*
+	 * broken (well early POSIX draft) gethostbyname_r() which returns 'struct
+	 * hostent *'
+	 */
+	*result = gethostbyname_r(name, resultbuf, buffer, buflen, herrno);
+	return (*result == NULL) ? -1 : 0;
+#else
+
+	/* no gethostbyname_r(), just use gethostbyname() */
+	*result = gethostbyname(name);
+
+	if (*result != NULL)
+		*herrno = h_errno;
+
+	if (*result != NULL)
+		return 0;
+	else
+		return -1;
+#endif
+}
+#endif							/* FRONTEND */

src/port/path.c

@@ -815,16 +815,7 @@ get_home_path(char *ret_path)
 
 	home = getenv("HOME");
 	if (home == NULL || home[0] == '\0')
-	{
-		char		pwdbuf[BUFSIZ];
-		struct passwd pwdstr;
-		struct passwd *pwd = NULL;
-
-		(void) pqGetpwuid(geteuid(), &pwdstr, pwdbuf, sizeof(pwdbuf), &pwd);
-		if (pwd == NULL)
-			return false;
-		home = pwd->pw_dir;
-	}
+		return pg_get_user_home_dir(geteuid(), ret_path, MAXPGPATH);
 	strlcpy(ret_path, home, MAXPGPATH);
 	return true;
 #else