Change TRUE/FALSE to true/false

The lower case spellings are C and C++ standard and are used in most
parts of the PostgreSQL sources.  The upper case spellings are only used
in some files/modules.  So standardize on the standard spellings.

The APIs for ICU, Perl, and Windows define their own TRUE and FALSE, so
those are left as is when using those APIs.

In code comments, we use the lower-case spelling for the C concepts and
keep the upper-case spelling for the SQL concepts.

Reviewed-by: Michael Paquier <michael.paquier@gmail.com>

src/backend/access/transam/clog.c

@@ -727,7 +727,7 @@ BootStrapCLOG(void)
 
 /*
  * Initialize (or reinitialize) a page of CLOG to zeroes.
- * If writeXlog is TRUE, also emit an XLOG record saying we did this.
+ * If writeXlog is true, also emit an XLOG record saying we did this.
  *
  * The page is not actually written, just set up in shared memory.
  * The slot number of the new page is returned.

src/backend/access/transam/commit_ts.c

@@ -531,7 +531,7 @@ BootStrapCommitTs(void)
 
 /*
  * Initialize (or reinitialize) a page of CommitTs to zeroes.
- * If writeXlog is TRUE, also emit an XLOG record saying we did this.
+ * If writeXlog is true, also emit an XLOG record saying we did this.
  *
  * The page is not actually written, just set up in shared memory.
  * The slot number of the new page is returned.

src/backend/access/transam/multixact.c

@@ -1892,7 +1892,7 @@ BootStrapMultiXact(void)
 
 /*
  * Initialize (or reinitialize) a page of MultiXactOffset to zeroes.
- * If writeXlog is TRUE, also emit an XLOG record saying we did this.
+ * If writeXlog is true, also emit an XLOG record saying we did this.
  *
  * The page is not actually written, just set up in shared memory.
  * The slot number of the new page is returned.

src/backend/access/transam/slru.c

@@ -629,7 +629,7 @@ SimpleLruDoesPhysicalPageExist(SlruCtl ctl, int pageno)
  * Physical read of a (previously existing) page into a buffer slot
  *
  * On failure, we cannot just ereport(ERROR) since caller has put state in
- * shared memory that must be undone.  So, we return FALSE and save enough
+ * shared memory that must be undone.  So, we return false and save enough
  * info in static variables to let SlruReportIOError make the report.
  *
  * For now, assume it's not worth keeping a file pointer open across
@@ -705,7 +705,7 @@ SlruPhysicalReadPage(SlruCtl ctl, int pageno, int slotno)
  * Physical write of a page from a buffer slot
  *
  * On failure, we cannot just ereport(ERROR) since caller has put state in
- * shared memory that must be undone.  So, we return FALSE and save enough
+ * shared memory that must be undone.  So, we return false and save enough
  * info in static variables to let SlruReportIOError make the report.
  *
  * For now, assume it's not worth keeping a file pointer open across

src/backend/access/transam/twophase.c

@@ -170,9 +170,9 @@ typedef struct GlobalTransactionData
 
 	Oid			owner;			/* ID of user that executed the xact */
 	BackendId	locking_backend;	/* backend currently working on the xact */
-	bool		valid;			/* TRUE if PGPROC entry is in proc array */
-	bool		ondisk;			/* TRUE if prepare state file is on disk */
-	bool		inredo;			/* TRUE if entry was added via xlog_redo */
+	bool		valid;			/* true if PGPROC entry is in proc array */
+	bool		ondisk;			/* true if prepare state file is on disk */
+	bool		inredo;			/* true if entry was added via xlog_redo */
 	char		gid[GIDSIZE];	/* The GID assigned to the prepared xact */
 }			GlobalTransactionData;
 

src/backend/access/transam/xact.c

@@ -671,8 +671,8 @@ SubTransactionIsActive(SubTransactionId subxid)
 /*
  *	GetCurrentCommandId
  *
- * "used" must be TRUE if the caller intends to use the command ID to mark
- * inserted/updated/deleted tuples.  FALSE means the ID is being fetched
+ * "used" must be true if the caller intends to use the command ID to mark
+ * inserted/updated/deleted tuples.  false means the ID is being fetched
  * for read-only purposes (ie, as a snapshot validity cutoff).  See
  * CommandCounterIncrement() for discussion.
  */
@@ -3470,7 +3470,7 @@ BeginTransactionBlock(void)
  *		This executes a PREPARE command.
  *
  * Since PREPARE may actually do a ROLLBACK, the result indicates what
- * happened: TRUE for PREPARE, FALSE for ROLLBACK.
+ * happened: true for PREPARE, false for ROLLBACK.
  *
  * Note that we don't actually do anything here except change blockState.
  * The real work will be done in the upcoming PrepareTransaction().
@@ -3522,7 +3522,7 @@ PrepareTransactionBlock(char *gid)
  *		This executes a COMMIT command.
  *
  * Since COMMIT may actually do a ROLLBACK, the result indicates what
- * happened: TRUE for COMMIT, FALSE for ROLLBACK.
+ * happened: true for COMMIT, false for ROLLBACK.
  *
  * Note that we don't actually do anything here except change blockState.
  * The real work will be done in the upcoming CommitTransactionCommand().

src/backend/access/transam/xlog.c

@@ -2324,7 +2324,7 @@ XLogCheckpointNeeded(XLogSegNo new_segno)
 /*
  * Write and/or fsync the log at least as far as WriteRqst indicates.
  *
- * If flexible == TRUE, we don't have to write as far as WriteRqst, but
+ * If flexible == true, we don't have to write as far as WriteRqst, but
  * may stop at any convenient boundary (such as a cache or logfile boundary).
  * This option allows us to avoid uselessly issuing multiple writes when a
  * single one would do.
@@ -2945,7 +2945,7 @@ XLogFlush(XLogRecPtr record)
  *
  * This routine is invoked periodically by the background walwriter process.
  *
- * Returns TRUE if there was any work to do, even if we skipped flushing due
+ * Returns true if there was any work to do, even if we skipped flushing due
  * to wal_writer_delay/wal_writer_flush_after.
  */
 bool
@@ -3141,12 +3141,12 @@ XLogNeedsFlush(XLogRecPtr record)
  *
  * log, seg: identify segment to be created/opened.
  *
- * *use_existent: if TRUE, OK to use a pre-existing file (else, any
- * pre-existing file will be deleted).  On return, TRUE if a pre-existing
+ * *use_existent: if true, OK to use a pre-existing file (else, any
+ * pre-existing file will be deleted).  On return, true if a pre-existing
  * file was used.
  *
- * use_lock: if TRUE, acquire ControlFileLock while moving file into
- * place.  This should be TRUE except during bootstrap log creation.  The
+ * use_lock: if true, acquire ControlFileLock while moving file into
+ * place.  This should be true except during bootstrap log creation.  The
  * caller must *not* hold the lock at call.
  *
  * Returns FD of opened file.
@@ -3441,24 +3441,24 @@ XLogFileCopy(XLogSegNo destsegno, TimeLineID srcTLI, XLogSegNo srcsegno,
  * filename while it's being created) and to recycle an old segment.
  *
  * *segno: identify segment to install as (or first possible target).
- * When find_free is TRUE, this is modified on return to indicate the
+ * When find_free is true, this is modified on return to indicate the
  * actual installation location or last segment searched.
  *
  * tmppath: initial name of file to install.  It will be renamed into place.
  *
- * find_free: if TRUE, install the new segment at the first empty segno
- * number at or after the passed numbers.  If FALSE, install the new segment
+ * find_free: if true, install the new segment at the first empty segno
+ * number at or after the passed numbers.  If false, install the new segment
  * exactly where specified, deleting any existing segment file there.
  *
  * max_segno: maximum segment number to install the new file as.  Fail if no
  * free slot is found between *segno and max_segno. (Ignored when find_free
- * is FALSE.)
+ * is false.)
  *
- * use_lock: if TRUE, acquire ControlFileLock while moving file into
- * place.  This should be TRUE except during bootstrap log creation.  The
+ * use_lock: if true, acquire ControlFileLock while moving file into
+ * place.  This should be true except during bootstrap log creation.  The
  * caller must *not* hold the lock at call.
  *
- * Returns TRUE if the file was installed successfully.  FALSE indicates that
+ * Returns true if the file was installed successfully.  false indicates that
  * max_segno limit was exceeded, or an error occurred while renaming the
  * file into place.
  */
@@ -5680,7 +5680,7 @@ getRecordTimestamp(XLogReaderState *record, TimestampTz *recordXtime)
  * For point-in-time recovery, this function decides whether we want to
  * stop applying the XLOG before the current record.
  *
- * Returns TRUE if we are stopping, FALSE otherwise. If stopping, some
+ * Returns true if we are stopping, false otherwise. If stopping, some
  * information is saved in recoveryStopXid et al for use in annotating the
  * new timeline's history file.
  */
@@ -6659,7 +6659,7 @@ StartupXLOG(void)
 	ereport(DEBUG1,
 			(errmsg_internal("redo record is at %X/%X; shutdown %s",
 							 (uint32) (checkPoint.redo >> 32), (uint32) checkPoint.redo,
-							 wasShutdown ? "TRUE" : "FALSE")));
+							 wasShutdown ? "true" : "false")));
 	ereport(DEBUG1,
 			(errmsg_internal("next transaction ID: %u:%u; next OID: %u",
 							 checkPoint.nextXidEpoch, checkPoint.nextXid,
@@ -11192,11 +11192,11 @@ GetOldestRestartPoint(XLogRecPtr *oldrecptr, TimeLineID *oldtli)
  * later than the start of the dump, and so if we rely on it as the start
  * point, we will fail to restore a consistent database state.
  *
- * Returns TRUE if a backup_label was found (and fills the checkpoint
+ * Returns true if a backup_label was found (and fills the checkpoint
  * location and its REDO location into *checkPointLoc and RedoStartLSN,
- * respectively); returns FALSE if not. If this backup_label came from a
- * streamed backup, *backupEndRequired is set to TRUE. If this backup_label
- * was created during recovery, *backupFromStandby is set to TRUE.
+ * respectively); returns false if not. If this backup_label came from a
+ * streamed backup, *backupEndRequired is set to true. If this backup_label
+ * was created during recovery, *backupFromStandby is set to true.
  */
 static bool
 read_backup_label(XLogRecPtr *checkPointLoc, bool *backupEndRequired,
@@ -11279,8 +11279,8 @@ read_backup_label(XLogRecPtr *checkPointLoc, bool *backupEndRequired,
  * recovering from a backup dump file, and we therefore need to create symlinks
  * as per the information present in tablespace_map file.
  *
- * Returns TRUE if a tablespace_map file was found (and fills the link
- * information for all the tablespace links present in file); returns FALSE
+ * Returns true if a tablespace_map file was found (and fills the link
+ * information for all the tablespace links present in file); returns false
  * if not.
  */
 static bool
@@ -11714,7 +11714,7 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
 					 * If primary_conninfo is set, launch walreceiver to try
 					 * to stream the missing WAL.
 					 *
-					 * If fetching_ckpt is TRUE, RecPtr points to the initial
+					 * If fetching_ckpt is true, RecPtr points to the initial
 					 * checkpoint location. In that case, we use RedoStartLSN
 					 * as the streaming start position instead of RecPtr, so
 					 * that when we later jump backwards to start redo at

src/backend/access/transam/xlogarchive.c

@@ -33,11 +33,11 @@
  * Attempt to retrieve the specified file from off-line archival storage.
  * If successful, fill "path" with its complete path (note that this will be
  * a temp file name that doesn't follow the normal naming convention), and
- * return TRUE.
+ * return true.
  *
  * If not successful, fill "path" with the name of the normal on-line file
  * (which may or may not actually exist, but we'll try to use it), and return
- * FALSE.
+ * false.
  *
  * For fixed-size files, the caller may pass the expected size as an
  * additional crosscheck on successful recovery.  If the file size is not

src/backend/access/transam/xloginsert.c

@@ -797,8 +797,8 @@ XLogRecordAssemble(RmgrId rmid, uint8 info,
 /*
  * Create a compressed version of a backup block image.
  *
- * Returns FALSE if compression fails (i.e., compressed result is actually
- * bigger than original). Otherwise, returns TRUE and sets 'dlen' to
+ * Returns false if compression fails (i.e., compressed result is actually
+ * bigger than original). Otherwise, returns true and sets 'dlen' to
  * the length of compressed block image.
  */
 static bool
@@ -965,7 +965,7 @@ XLogSaveBufferForHint(Buffer buffer, bool buffer_std)
  * log_newpage_buffer instead.
  *
  * If the page follows the standard page layout, with a PageHeader and unused
- * space between pd_lower and pd_upper, set 'page_std' to TRUE. That allows
+ * space between pd_lower and pd_upper, set 'page_std' to true. That allows
  * the unused space to be left out from the WAL record, making it smaller.
  */
 XLogRecPtr
@@ -1002,7 +1002,7 @@ log_newpage(RelFileNode *rnode, ForkNumber forkNum, BlockNumber blkno,
  * function.  This function will set the page LSN.
  *
  * If the page follows the standard page layout, with a PageHeader and unused
- * space between pd_lower and pd_upper, set 'page_std' to TRUE. That allows
+ * space between pd_lower and pd_upper, set 'page_std' to true. That allows
  * the unused space to be left out from the WAL record, making it smaller.
  */
 XLogRecPtr

src/backend/access/transam/xlogreader.c

@@ -1302,8 +1302,8 @@ err:
  * Returns information about the block that a block reference refers to.
  *
  * If the WAL record contains a block reference with the given ID, *rnode,
- * *forknum, and *blknum are filled in (if not NULL), and returns TRUE.
- * Otherwise returns FALSE.
+ * *forknum, and *blknum are filled in (if not NULL), and returns true.
+ * Otherwise returns false.
  */
 bool
 XLogRecGetBlockTag(XLogReaderState *record, uint8 block_id,