Add macros to check if a filename is a WAL segment or other such file.

We had many instances of the strlen + strspn combination to check for that.
This makes the code a bit easier to read.

src/backend/access/transam/xlog.c

@@ -3577,8 +3577,7 @@ RemoveOldXlogFiles(XLogSegNo segno, XLogRecPtr PriorRedoPtr, XLogRecPtr endptr)
 	while ((xlde = ReadDir(xldir, XLOGDIR)) != NULL)
 	{
 		/* Ignore files that are not XLOG segments */
-		if (strlen(xlde->d_name) != 24 ||
-			strspn(xlde->d_name, "0123456789ABCDEF") != 24)
+		if (!IsXLogFileName(xlde->d_name))
 			continue;
 
 		/*
@@ -3650,8 +3649,7 @@ RemoveNonParentXlogFiles(XLogRecPtr switchpoint, TimeLineID newTLI)
 	while ((xlde = ReadDir(xldir, XLOGDIR)) != NULL)
 	{
 		/* Ignore files that are not XLOG segments */
-		if (strlen(xlde->d_name) != 24 ||
-			strspn(xlde->d_name, "0123456789ABCDEF") != 24)
+		if (!IsXLogFileName(xlde->d_name))
 			continue;
 
 		/*
@@ -3839,10 +3837,7 @@ CleanupBackupHistory(void)
 
 	while ((xlde = ReadDir(xldir, XLOGDIR)) != NULL)
 	{
-		if (strlen(xlde->d_name) > 24 &&
-			strspn(xlde->d_name, "0123456789ABCDEF") == 24 &&
-			strcmp(xlde->d_name + strlen(xlde->d_name) - strlen(".backup"),
-				   ".backup") == 0)
+		if (IsBackupHistoryFileName(xlde->d_name))
 		{
 			if (XLogArchiveCheckDone(xlde->d_name))
 			{

src/backend/replication/basebackup.c

@@ -350,17 +350,14 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
 		while ((de = ReadDir(dir, "pg_xlog")) != NULL)
 		{
 			/* Does it look like a WAL segment, and is it in the range? */
-			if (strlen(de->d_name) == 24 &&
-				strspn(de->d_name, "0123456789ABCDEF") == 24 &&
+			if (IsXLogFileName(de->d_name) &&
 				strcmp(de->d_name + 8, firstoff + 8) >= 0 &&
 				strcmp(de->d_name + 8, lastoff + 8) <= 0)
 			{
 				walFileList = lappend(walFileList, pstrdup(de->d_name));
 			}
 			/* Does it look like a timeline history file? */
-			else if (strlen(de->d_name) == 8 + strlen(".history") &&
-					 strspn(de->d_name, "0123456789ABCDEF") == 8 &&
-					 strcmp(de->d_name + 8, ".history") == 0)
+			else if (IsTLHistoryFileName(de->d_name))
 			{
 				historyFileList = lappend(historyFileList, pstrdup(de->d_name));
 			}

src/bin/pg_basebackup/pg_receivexlog.c

@@ -188,23 +188,11 @@ FindStreamingStart(uint32 *tli)
 
 		/*
 		 * Check if the filename looks like an xlog file, or a .partial file.
-		 * Xlog files are always 24 characters, and .partial files are 32
-		 * characters.
 		 */
-		if (strlen(dirent->d_name) == 24)
-		{
-			if (strspn(dirent->d_name, "0123456789ABCDEF") != 24)
-				continue;
+		if (IsXLogFileName(dirent->d_name))
 			ispartial = false;
-		}
-		else if (strlen(dirent->d_name) == 32)
-		{
-			if (strspn(dirent->d_name, "0123456789ABCDEF") != 24)
-				continue;
-			if (strcmp(&dirent->d_name[24], ".partial") != 0)
-				continue;
+		else if (IsPartialXLogFileName(dirent->d_name))
 			ispartial = true;
-		}
 		else
 			continue;
 

src/bin/pg_resetxlog/pg_resetxlog.c

@@ -906,14 +906,18 @@ FindEndOfXLOG(void)
 
 	while (errno = 0, (xlde = readdir(xldir)) != NULL)
 	{
-		if (strlen(xlde->d_name) == 24 &&
-			strspn(xlde->d_name, "0123456789ABCDEF") == 24)
+		if (IsXLogFileName(xlde->d_name))
 		{
 			unsigned int tli,
 						log,
 						seg;
 			XLogSegNo	segno;
 
+			/*
+			 * Note: We don't use XLogFromFileName here, because we want
+			 * to use the segment size from the control file, not the size
+			 * the pg_resetxlog binary was compiled with
+			 */
 			sscanf(xlde->d_name, "%08X%08X%08X", &tli, &log, &seg);
 			segno = ((uint64) log) * segs_per_xlogid + seg;
 

src/include/access/xlog_internal.h

@@ -142,6 +142,14 @@ typedef XLogLongPageHeaderData *XLogLongPageHeader;
 			 (uint32) ((logSegNo) / XLogSegmentsPerXLogId), \
 			 (uint32) ((logSegNo) % XLogSegmentsPerXLogId))
 
+#define IsXLogFileName(fname) \
+	(strlen(fname) == 24 && strspn(fname, "0123456789ABCDEF") == 24)
+
+#define IsPartialXLogFileName(fname)	\
+	(strlen(fname) == 24 + strlen(".partial") &&	\
+	 strspn(fname, "0123456789ABCDEF") == 24 &&		\
+	 strcmp((fname) + 24, ".partial") == 0)
+
 #define XLogFromFileName(fname, tli, logSegNo)	\
 	do {												\
 		uint32 log;										\
@@ -158,6 +166,11 @@ typedef XLogLongPageHeaderData *XLogLongPageHeader;
 #define TLHistoryFileName(fname, tli)	\
 	snprintf(fname, MAXFNAMELEN, "%08X.history", tli)
 
+#define IsTLHistoryFileName(fname)	\
+	(strlen(fname) == 8 + strlen(".history") &&		\
+	 strspn(fname, "0123456789ABCDEF") == 8 &&		\
+	 strcmp((fname) + 8, ".history") == 0)
+
 #define TLHistoryFilePath(path, tli)	\
 	snprintf(path, MAXPGPATH, XLOGDIR "/%08X.history", tli)
 
@@ -169,6 +182,11 @@ typedef XLogLongPageHeaderData *XLogLongPageHeader;
 			 (uint32) ((logSegNo) / XLogSegmentsPerXLogId),		  \
 			 (uint32) ((logSegNo) % XLogSegmentsPerXLogId), offset)
 
+#define IsBackupHistoryFileName(fname) \
+	(strlen(fname) > 24 && \
+	 strspn(fname, "0123456789ABCDEF") == 24 && \
+	 strcmp((fname) + strlen(fname) - strlen(".backup"), ".backup") == 0)
+
 #define BackupHistoryFilePath(path, tli, logSegNo, offset)	\
 	snprintf(path, MAXPGPATH, XLOGDIR "/%08X%08X%08X.%08X.backup", tli, \
 			 (uint32) ((logSegNo) / XLogSegmentsPerXLogId), \