Replace remaining StrNCpy() by strlcpy()

They are equivalent, except that StrNCpy() zero-fills the entire
destination buffer instead of providing just one trailing zero.  For
all but a tiny number of callers, that's just overhead rather than
being desirable.

Remove StrNCpy() as it is now unused.

In some cases, namestrcpy() is the more appropriate function to use.
While we're here, simplify the API of namestrcpy(): Remove the return
value, don't check for NULL input.  Nothing was using that anyway.
Also, remove a few unused name-related functions.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/44f5e198-36f6-6cdb-7fa9-60e34784daae%402ndquadrant.com

contrib/pgcrypto/crypt-des.c

@@ -720,7 +720,7 @@ px_crypt_des(const char *key, const char *setting)
 			if (des_setkey((char *) keybuf))
 				return NULL;
 		}
-		StrNCpy(output, setting, 10);
+		strlcpy(output, setting, 10);
 
 		/*
 		 * Double check that we weren't given a short setting. If we were, the

src/backend/access/transam/slru.c

@@ -252,7 +252,7 @@ SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns,
 	 */
 	ctl->shared = shared;
 	ctl->do_fsync = true;		/* default behavior */
-	StrNCpy(ctl->Dir, subdir, sizeof(ctl->Dir));
+	strlcpy(ctl->Dir, subdir, sizeof(ctl->Dir));
 }
 
 /*

src/backend/access/transam/xlogarchive.c

@@ -323,7 +323,7 @@ ExecuteRecoveryCommand(const char *command, const char *commandName, bool failOn
 				case 'r':
 					/* %r: filename of last restartpoint */
 					sp++;
-					StrNCpy(dp, lastRestartPointFname, endp - dp);
+					strlcpy(dp, lastRestartPointFname, endp - dp);
 					dp += strlen(dp);
 					break;
 				case '%':

src/backend/catalog/pg_constraint.c

@@ -484,7 +484,7 @@ ChooseConstraintName(const char *name1, const char *name2,
 	conDesc = table_open(ConstraintRelationId, AccessShareLock);
 
 	/* try the unmodified label first */
-	StrNCpy(modlabel, label, sizeof(modlabel));
+	strlcpy(modlabel, label, sizeof(modlabel));
 
 	for (;;)
 	{

src/backend/commands/indexcmds.c

@@ -2246,7 +2246,7 @@ ChooseRelationName(const char *name1, const char *name2,
 	char		modlabel[NAMEDATALEN];
 
 	/* try the unmodified label first */
-	StrNCpy(modlabel, label, sizeof(modlabel));
+	strlcpy(modlabel, label, sizeof(modlabel));
 
 	for (;;)
 	{

src/backend/commands/statscmds.c

@@ -681,7 +681,7 @@ ChooseExtendedStatisticName(const char *name1, const char *name2,
 	char		modlabel[NAMEDATALEN];
 
 	/* try the unmodified label first */
-	StrNCpy(modlabel, label, sizeof(modlabel));
+	strlcpy(modlabel, label, sizeof(modlabel));
 
 	for (;;)
 	{

src/backend/commands/tablecmds.c

@@ -606,7 +606,7 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 	 * Truncate relname to appropriate length (probably a waste of time, as
 	 * parser should have done this already).
 	 */
-	StrNCpy(relname, stmt->relation->relname, NAMEDATALEN);
+	strlcpy(relname, stmt->relation->relname, NAMEDATALEN);
 
 	/*
 	 * Check consistency of arguments

src/backend/postmaster/pgstat.c

@@ -4367,7 +4367,7 @@ pgstat_send_archiver(const char *xlog, bool failed)
 	 */
 	pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_ARCHIVER);
 	msg.m_failed = failed;
-	StrNCpy(msg.m_xlog, xlog, sizeof(msg.m_xlog));
+	strlcpy(msg.m_xlog, xlog, sizeof(msg.m_xlog));
 	msg.m_timestamp = GetCurrentTimestamp();
 	pgstat_send(&msg, sizeof(msg));
 }

src/backend/replication/logical/logical.c

@@ -39,6 +39,7 @@
 #include "replication/snapbuild.h"
 #include "storage/proc.h"
 #include "storage/procarray.h"
+#include "utils/builtins.h"
 #include "utils/memutils.h"
 
 /* data for errcontext callback */
@@ -288,6 +289,7 @@ CreateInitDecodingContext(const char *plugin,
 {
 	TransactionId xmin_horizon = InvalidTransactionId;
 	ReplicationSlot *slot;
+	NameData	plugin_name;
 	LogicalDecodingContext *ctx;
 	MemoryContext old_context;
 
@@ -319,9 +321,14 @@ CreateInitDecodingContext(const char *plugin,
 				(errcode(ERRCODE_ACTIVE_SQL_TRANSACTION),
 				 errmsg("cannot create logical replication slot in transaction that has performed writes")));
 
-	/* register output plugin name with slot */
+	/*
+	 * Register output plugin name with slot.  We need the mutex to avoid
+	 * concurrent reading of a partially copied string.  But we don't want any
+	 * complicated code while holding a spinlock, so do namestrcpy() outside.
+	 */
+	namestrcpy(&plugin_name, plugin);
 	SpinLockAcquire(&slot->mutex);
-	StrNCpy(NameStr(slot->data.plugin), plugin, NAMEDATALEN);
+	slot->data.plugin = plugin_name;
 	SpinLockRelease(&slot->mutex);
 
 	if (XLogRecPtrIsInvalid(restart_lsn))

src/backend/replication/slot.c

@@ -275,7 +275,7 @@ ReplicationSlotCreate(const char *name, bool db_specific,
 
 	/* first initialize persistent data */
 	memset(&slot->data, 0, sizeof(ReplicationSlotPersistentData));
-	StrNCpy(NameStr(slot->data.name), name, NAMEDATALEN);
+	namestrcpy(&slot->data.name, name);
 	slot->data.database = db_specific ? MyDatabaseId : InvalidOid;
 	slot->data.persistency = persistency;
 

src/backend/utils/adt/formatting.c

@@ -3890,7 +3890,7 @@ DCH_cache_getnew(const char *str, bool std)
 		elog(DEBUG_elog_output, "OLD: '%s' AGE: %d", old->str, old->age);
 #endif
 		old->valid = false;
-		StrNCpy(old->str, str, DCH_CACHE_SIZE + 1);
+		strlcpy(old->str, str, DCH_CACHE_SIZE + 1);
 		old->age = (++DCHCounter);
 		/* caller is expected to fill format, then set valid */
 		return old;
@@ -3904,7 +3904,7 @@ DCH_cache_getnew(const char *str, bool std)
 		DCHCache[n_DCHCache] = ent = (DCHCacheEntry *)
 			MemoryContextAllocZero(TopMemoryContext, sizeof(DCHCacheEntry));
 		ent->valid = false;
-		StrNCpy(ent->str, str, DCH_CACHE_SIZE + 1);
+		strlcpy(ent->str, str, DCH_CACHE_SIZE + 1);
 		ent->std = std;
 		ent->age = (++DCHCounter);
 		/* caller is expected to fill format, then set valid */
@@ -4799,7 +4799,7 @@ NUM_cache_getnew(const char *str)
 		elog(DEBUG_elog_output, "OLD: \"%s\" AGE: %d", old->str, old->age);
 #endif
 		old->valid = false;
-		StrNCpy(old->str, str, NUM_CACHE_SIZE + 1);
+		strlcpy(old->str, str, NUM_CACHE_SIZE + 1);
 		old->age = (++NUMCounter);
 		/* caller is expected to fill format and Num, then set valid */
 		return old;
@@ -4813,7 +4813,7 @@ NUM_cache_getnew(const char *str)
 		NUMCache[n_NUMCache] = ent = (NUMCacheEntry *)
 			MemoryContextAllocZero(TopMemoryContext, sizeof(NUMCacheEntry));
 		ent->valid = false;
-		StrNCpy(ent->str, str, NUM_CACHE_SIZE + 1);
+		strlcpy(ent->str, str, NUM_CACHE_SIZE + 1);
 		ent->age = (++NUMCounter);
 		/* caller is expected to fill format and Num, then set valid */
 		++n_NUMCache;

src/backend/utils/adt/name.c

@@ -229,53 +229,13 @@ btnamesortsupport(PG_FUNCTION_ARGS)
  *	 MISCELLANEOUS PUBLIC ROUTINES											 *
  *****************************************************************************/
 
-int
-namecpy(Name n1, const NameData *n2)
-{
-	if (!n1 || !n2)
-		return -1;
-	StrNCpy(NameStr(*n1), NameStr(*n2), NAMEDATALEN);
-	return 0;
-}
-
-#ifdef NOT_USED
-int
-namecat(Name n1, Name n2)
-{
-	return namestrcat(n1, NameStr(*n2));	/* n2 can't be any longer than n1 */
-}
-#endif
-
-int
+void
 namestrcpy(Name name, const char *str)
 {
-	if (!name || !str)
-		return -1;
-	StrNCpy(NameStr(*name), str, NAMEDATALEN);
-	return 0;
-}
-
-#ifdef NOT_USED
-int
-namestrcat(Name name, const char *str)
-{
-	int			i;
-	char	   *p,
-			   *q;
-
-	if (!name || !str)
-		return -1;
-	for (i = 0, p = NameStr(*name); i < NAMEDATALEN && *p; ++i, ++p)
-		;
-	for (q = str; i < NAMEDATALEN; ++i, ++p, ++q)
-	{
-		*p = *q;
-		if (!*q)
-			break;
-	}
-	return 0;
+	/* NB: We need to zero-pad the destination. */
+	strncpy(NameStr(*name), str, NAMEDATALEN);
+	NameStr(*name)[NAMEDATALEN-1] = '\0';
 }
-#endif
 
 /*
  * Compare a NAME to a C string

src/backend/utils/adt/pg_locale.c

@@ -75,16 +75,7 @@
 #endif
 
 #ifdef WIN32
-/*
- * This Windows file defines StrNCpy. We don't need it here, so we undefine
- * it to keep the compiler quiet, and undefine it again after the file is
- * included, so we don't accidentally use theirs.
- */
-#undef StrNCpy
 #include <shlwapi.h>
-#ifdef StrNCpy
-#undef StrNCpy
-#endif
 #endif
 
 #define		MAX_L10N_DATA		80

src/backend/utils/adt/ruleutils.c

@@ -2489,7 +2489,7 @@ pg_get_userbyid(PG_FUNCTION_ARGS)
 	if (HeapTupleIsValid(roletup))
 	{
 		role_rec = (Form_pg_authid) GETSTRUCT(roletup);
-		StrNCpy(NameStr(*result), NameStr(role_rec->rolname), NAMEDATALEN);
+		*result = role_rec->rolname;
 		ReleaseSysCache(roletup);
 	}
 	else

src/common/exec.c

@@ -144,7 +144,7 @@ find_my_exec(const char *argv0, char *retpath)
 	if (first_dir_separator(argv0) != NULL)
 	{
 		if (is_absolute_path(argv0))
-			StrNCpy(retpath, argv0, MAXPGPATH);
+			strlcpy(retpath, argv0, MAXPGPATH);
 		else
 			join_path_components(retpath, cwd, argv0);
 		canonicalize_path(retpath);
@@ -184,7 +184,7 @@ find_my_exec(const char *argv0, char *retpath)
 			if (!endp)
 				endp = startp + strlen(startp); /* point to end */
 
-			StrNCpy(test_path, startp, Min(endp - startp + 1, MAXPGPATH));
+			strlcpy(test_path, startp, Min(endp - startp + 1, MAXPGPATH));
 
 			if (is_absolute_path(test_path))
 				join_path_components(retpath, test_path, argv0);

src/include/c.h

@@ -932,35 +932,6 @@ extern void ExceptionalCondition(const char *conditionName,
  */
 #define Abs(x)			((x) >= 0 ? (x) : -(x))
 
-/*
- * StrNCpy
- *	Like standard library function strncpy(), except that result string
- *	is guaranteed to be null-terminated --- that is, at most N-1 bytes
- *	of the source string will be kept.
- *	Also, the macro returns no result (too hard to do that without
- *	evaluating the arguments multiple times, which seems worse).
- *
- *	BTW: when you need to copy a non-null-terminated string (like a text
- *	datum) and add a null, do not do it with StrNCpy(..., len+1).  That
- *	might seem to work, but it fetches one byte more than there is in the
- *	text object.  One fine day you'll have a SIGSEGV because there isn't
- *	another byte before the end of memory.  Don't laugh, we've had real
- *	live bug reports from real live users over exactly this mistake.
- *	Do it honestly with "memcpy(dst,src,len); dst[len] = '\0';", instead.
- */
-#define StrNCpy(dst,src,len) \
-	do \
-	{ \
-		char * _dst = (dst); \
-		Size _len = (len); \
-\
-		if (_len > 0) \
-		{ \
-			strncpy(_dst, (src), _len); \
-			_dst[_len-1] = '\0'; \
-		} \
-	} while (0)
-
 
 /* Get a bit mask of the bits set in non-long aligned addresses */
 #define LONG_ALIGN_MASK (sizeof(long) - 1)

src/include/utils/builtins.h

@@ -39,8 +39,7 @@ extern uint64 hex_decode(const char *src, size_t len, char *dst);
 extern int2vector *buildint2vector(const int16 *int2s, int n);
 
 /* name.c */
-extern int	namecpy(Name n1, const NameData *n2);
-extern int	namestrcpy(Name name, const char *str);
+extern void	namestrcpy(Name name, const char *str);
 extern int	namestrcmp(Name name, const char *str);
 
 /* numutils.c */

src/interfaces/ecpg/pgtypeslib/dt_common.c

@@ -1015,7 +1015,7 @@ abstime2tm(AbsoluteTime _time, int *tzp, struct tm *tm, char **tzn)
 			 * Copy no more than MAXTZLEN bytes of timezone to tzn, in case it
 			 * contains an error message, which doesn't fit in the buffer
 			 */
-			StrNCpy(*tzn, tm->tm_zone, MAXTZLEN + 1);
+			strlcpy(*tzn, tm->tm_zone, MAXTZLEN + 1);
 			if (strlen(tm->tm_zone) > MAXTZLEN)
 				tm->tm_isdst = -1;
 		}
@@ -1033,7 +1033,7 @@ abstime2tm(AbsoluteTime _time, int *tzp, struct tm *tm, char **tzn)
 			 * Copy no more than MAXTZLEN bytes of timezone to tzn, in case it
 			 * contains an error message, which doesn't fit in the buffer
 			 */
-			StrNCpy(*tzn, TZNAME_GLOBAL[tm->tm_isdst], MAXTZLEN + 1);
+			strlcpy(*tzn, TZNAME_GLOBAL[tm->tm_isdst], MAXTZLEN + 1);
 			if (strlen(TZNAME_GLOBAL[tm->tm_isdst]) > MAXTZLEN)
 				tm->tm_isdst = -1;
 		}

src/interfaces/ecpg/test/pg_regress_ecpg.c

@@ -63,7 +63,7 @@ ecpg_filter(const char *sourcefile, const char *outfile)
 			if (plen > 1)
 			{
 				n = (char *) malloc(plen);
-				StrNCpy(n, p + 1, plen);
+				strlcpy(n, p + 1, plen);
 				replace_string(linebuf, n, "");
 			}
 		}

src/test/modules/ssl_passphrase_callback/ssl_passphrase_func.c

@@ -74,7 +74,7 @@ rot13_passphrase(char *buf, int size, int rwflag, void *userdata)
 {
 
 	Assert(ssl_passphrase != NULL);
-	StrNCpy(buf, ssl_passphrase, size);
+	strlcpy(buf, ssl_passphrase, size);
 	for (char *p = buf; *p; p++)
 	{
 		char		c = *p;