Simplify the general-purpose 64-bit integer parsing APIs

pg_strtouint64() is a wrapper around strtoull/strtoul/_strtoui64, but
it seems no longer necessary to have this indirection.
msvc/Solution.pm claims HAVE_STRTOULL, so the "MSVC only" part seems
unnecessary.  Also, we have code in c.h to substitute alternatives for
strtoull() if not found, and that would appear to cover all currently
supported platforms, so having a further fallback in pg_strtouint64()
seems unnecessary.

Therefore, we could remove pg_strtouint64(), and use strtoull()
directly in all call sites.  However, it seems useful to keep a
separate notation for parsing exactly 64-bit integers, matching the
type definition int64/uint64.  For that, add new macros strtoi64() and
strtou64() in c.h as thin wrappers around strtol()/strtoul() or
strtoll()/stroull().  This makes these functions available everywhere
instead of just in the server code, and it makes the function naming
notably different from the pg_strtointNN() functions in numutils.c,
which have a different API.

Discussion: https://www.postgresql.org/message-id/flat/a3df47c9-b1b4-29f2-7e91-427baf8b75a3%40enterprisedb.com

src/backend/nodes/readfuncs.c

@@ -80,7 +80,7 @@
 #define READ_UINT64_FIELD(fldname) \
 	token = pg_strtok(&length);		/* skip :fldname */ \
 	token = pg_strtok(&length);		/* get field value */ \
-	local_node->fldname = pg_strtouint64(token, NULL, 10)
+	local_node->fldname = strtou64(token, NULL, 10)
 
 /* Read a long integer field (anything written as ":fldname %ld") */
 #define READ_LONG_FIELD(fldname) \

src/backend/utils/adt/numutils.c

@@ -606,25 +606,3 @@ pg_ultostr(char *str, uint32 value)
 
 	return str + len;
 }
-
-/*
- * pg_strtouint64
- *		Converts 'str' into an unsigned 64-bit integer.
- *
- * This has the identical API to strtoul(3), except that it will handle
- * 64-bit ints even where "long" is narrower than that.
- *
- * For the moment it seems sufficient to assume that the platform has
- * such a function somewhere; let's not roll our own.
- */
-uint64
-pg_strtouint64(const char *str, char **endptr, int base)
-{
-#ifdef _MSC_VER					/* MSVC only */
-	return _strtoui64(str, endptr, base);
-#elif defined(HAVE_STRTOULL) && SIZEOF_LONG < 8
-	return strtoull(str, endptr, base);
-#else
-	return strtoul(str, endptr, base);
-#endif
-}

src/backend/utils/adt/xid.c

@@ -158,7 +158,7 @@ xid8in(PG_FUNCTION_ARGS)
 {
 	char	   *str = PG_GETARG_CSTRING(0);
 
-	PG_RETURN_FULLTRANSACTIONID(FullTransactionIdFromU64(pg_strtouint64(str, NULL, 0)));
+	PG_RETURN_FULLTRANSACTIONID(FullTransactionIdFromU64(strtou64(str, NULL, 0)));
 }
 
 Datum

src/backend/utils/adt/xid8funcs.c

@@ -295,12 +295,12 @@ parse_snapshot(const char *str)
 	char	   *endp;
 	StringInfo	buf;
 
-	xmin = FullTransactionIdFromU64(pg_strtouint64(str, &endp, 10));
+	xmin = FullTransactionIdFromU64(strtou64(str, &endp, 10));
 	if (*endp != ':')
 		goto bad_format;
 	str = endp + 1;
 
-	xmax = FullTransactionIdFromU64(pg_strtouint64(str, &endp, 10));
+	xmax = FullTransactionIdFromU64(strtou64(str, &endp, 10));
 	if (*endp != ':')
 		goto bad_format;
 	str = endp + 1;
@@ -318,7 +318,7 @@ parse_snapshot(const char *str)
 	while (*str != '\0')
 	{
 		/* read next value */
-		val = FullTransactionIdFromU64(pg_strtouint64(str, &endp, 10));
+		val = FullTransactionIdFromU64(strtou64(str, &endp, 10));
 		str = endp;
 
 		/* require the input to be in order */

src/backend/utils/misc/guc.c

@@ -12438,7 +12438,7 @@ check_recovery_target_xid(char **newval, void **extra, GucSource source)
 		TransactionId *myextra;
 
 		errno = 0;
-		xid = (TransactionId) pg_strtouint64(*newval, NULL, 0);
+		xid = (TransactionId) strtou64(*newval, NULL, 0);
 		if (errno == EINVAL || errno == ERANGE)
 			return false;
 

src/include/c.h

@@ -1312,6 +1312,19 @@ extern long long strtoll(const char *str, char **endptr, int base);
 extern unsigned long long strtoull(const char *str, char **endptr, int base);
 #endif
 
+/*
+ * Thin wrappers that convert strings to exactly 64-bit integers, matching our
+ * definition of int64.  (For the naming, compare that POSIX has
+ * strtoimax()/strtoumax() which return intmax_t/uintmax_t.)
+ */
+#ifdef HAVE_LONG_INT_64
+#define strtoi64(str, endptr, base) ((int64) strtol(str, endptr, base))
+#define strtou64(str, endptr, base) ((uint64) strtoul(str, endptr, base))
+#else
+#define strtoi64(str, endptr, base) ((int64) strtoll(str, endptr, base))
+#define strtou64(str, endptr, base) ((uint64) strtoull(str, endptr, base))
+#endif
+
 /*
  * Use "extern PGDLLIMPORT ..." to declare variables that are defined
  * in the core backend and need to be accessible by loadable modules.

src/include/utils/builtins.h

@@ -53,7 +53,6 @@ extern int	pg_ltoa(int32 l, char *a);
 extern int	pg_lltoa(int64 ll, char *a);
 extern char *pg_ultostr_zeropad(char *str, uint32 value, int32 minwidth);
 extern char *pg_ultostr(char *str, uint32 value);
-extern uint64 pg_strtouint64(const char *str, char **endptr, int base);
 
 /* oid.c */
 extern oidvector *buildoidvector(const Oid *oids, int n);