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commit    23df8822601dce04d259fed0326ef28ecc6d1fa0
Author:   Robert Haas <rhaas@postgresql.org>
Date:     Fri Sep 06 12:22:32 2019 +0000
First released in: 13.0, 9.4.25, 9.5.20, 9.6.16, 10.11, 11.6, 12.0

    When performing a base backup, check for read errors.
    
    The old code didn't differentiate between a read error and a
    concurrent truncation. fread reports both of these by returning 0;
    you have to use feof() or ferror() to distinguish between them,
    which this code did not do.
    
    It might be a better idea to use read() rather than fread() here,
    so that we can display a less-generic error message, but I'm not
    sure that would qualify as a back-patchable bug fix, so just do
    this much for now.
    
    Jeevan Chalke, reviewed by Jeevan Ladhe and by me.
    
    Discussion: http://postgr.es/m/CA+TgmobG4ywMzL5oQq2a8YKp8x2p3p1LOMMcGqpS7aekT9+ETA@mail.gmail.com


 src/backend/replication/basebackup.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index 73a56cbf16e..c6032fdf107 100644
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -84,6 +84,18 @@ static char *statrelpath = NULL;
  */
 #define THROTTLING_FREQUENCY	8
 
+/*
+ * Checks whether we encountered any error in fread().  fread() doesn't give
+ * any clue what has happened, so we check with ferror().  Also, neither
+ * fread() nor ferror() set errno, so we just throw a generic error.
+ */
+#define CHECK_FREAD_ERROR(fp, filename) \
+do { \
+	if (ferror(fp)) \
+		ereport(ERROR, \
+				(errmsg("could not read from file \"%s\"", filename))); \
+} while (0)
+
 /* The actual number of bytes, transfer of which may cause sleep. */
 static uint64 throttling_sample;
 
@@ -438,6 +450,8 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
 					break;
 			}
 
+			CHECK_FREAD_ERROR(fp, pathbuf);
+
 			if (len != XLogSegSize)
 			{
 				CheckXLogRemoved(segno, tli);
@@ -1177,6 +1191,8 @@ sendFile(char *readfilename, char *tarfilename, struct stat * statbuf,
 		}
 	}
 
+	CHECK_FREAD_ERROR(fp, readfilename);
+
 	/* If the file was truncated while we were sending it, pad it with zeros */
 	if (len < statbuf->st_size)
 	{


[parent: f4b91a50e9e6]