From d1cd2f2748ecf34831cee565b29725df548da567 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Fri, 6 Jan 2023 11:57:35 +0100
Subject: [PATCH v3 1/2] Fix some BufFileRead() error reporting

Remove "%m" from error messages where errno would be bogus.  Add short
read byte counts where appropriate.

This is equivalent to what was done in
7897e3bb902c557412645b82120f4d95f7474906, but some code was apparently
developed concurrently to that and not updated accordingly.

Discussion: https://www.postgresql.org/message-id/flat/f3501945-c591-8cc3-5ef0-b72a2e0eaa9c@enterprisedb.com
---
 src/backend/backup/backup_manifest.c     |  3 ++-
 src/backend/replication/logical/worker.c | 33 ++++++++++++++----------
 2 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/src/backend/backup/backup_manifest.c b/src/backend/backup/backup_manifest.c
index 21ca2941dc..d325ef047a 100644
--- a/src/backend/backup/backup_manifest.c
+++ b/src/backend/backup/backup_manifest.c
@@ -371,7 +371,8 @@ SendBackupManifest(backup_manifest_info *manifest, bbsink *sink)
 		if (rc != bytes_to_read)
 			ereport(ERROR,
 					(errcode_for_file_access(),
-					 errmsg("could not read from temporary file: %m")));
+					 errmsg("could not read from temporary file: read only %zu of %zu bytes",
+							rc, bytes_to_read)));
 		bbsink_manifest_contents(sink, bytes_to_read);
 		manifest_bytes_done += bytes_to_read;
 	}
diff --git a/src/backend/replication/logical/worker.c b/src/backend/replication/logical/worker.c
index 79cda39445..f3856c9843 100644
--- a/src/backend/replication/logical/worker.c
+++ b/src/backend/replication/logical/worker.c
@@ -2063,7 +2063,7 @@ apply_spooled_messages(FileSet *stream_fileset, TransactionId xid,
 	nchanges = 0;
 	while (true)
 	{
-		int			nbytes;
+		size_t		nbytes;
 		int			len;
 
 		CHECK_FOR_INTERRUPTS();
@@ -2079,8 +2079,8 @@ apply_spooled_messages(FileSet *stream_fileset, TransactionId xid,
 		if (nbytes != sizeof(len))
 			ereport(ERROR,
 					(errcode_for_file_access(),
-					 errmsg("could not read from streaming transaction's changes file \"%s\": %m",
-							path)));
+					 errmsg("could not read from streaming transaction's changes file \"%s\": read only %zu of %zu bytes",
+							path, nbytes, sizeof(len))));
 
 		if (len <= 0)
 			elog(ERROR, "incorrect length %d in streaming transaction's changes file \"%s\"",
@@ -2090,11 +2090,12 @@ apply_spooled_messages(FileSet *stream_fileset, TransactionId xid,
 		buffer = repalloc(buffer, len);
 
 		/* and finally read the data into the buffer */
-		if (BufFileRead(stream_fd, buffer, len) != len)
+		nbytes = BufFileRead(stream_fd, buffer, len);
+		if (nbytes != len)
 			ereport(ERROR,
 					(errcode_for_file_access(),
-					 errmsg("could not read from streaming transaction's changes file \"%s\": %m",
-							path)));
+					 errmsg("could not read from streaming transaction's changes file \"%s\": read only %zu of %zu bytes",
+							path, nbytes, (size_t) len)));
 
 		BufFileTell(stream_fd, &fileno, &offset);
 
@@ -3992,6 +3993,7 @@ static void
 subxact_info_read(Oid subid, TransactionId xid)
 {
 	char		path[MAXPGPATH];
+	size_t		nread;
 	Size		len;
 	BufFile    *fd;
 	MemoryContext oldctx;
@@ -4011,13 +4013,12 @@ subxact_info_read(Oid subid, TransactionId xid)
 		return;
 
 	/* read number of subxact items */
-	if (BufFileRead(fd, &subxact_data.nsubxacts,
-					sizeof(subxact_data.nsubxacts)) !=
-		sizeof(subxact_data.nsubxacts))
+	nread = BufFileRead(fd, &subxact_data.nsubxacts, sizeof(subxact_data.nsubxacts));
+	if (nread != sizeof(subxact_data.nsubxacts))
 		ereport(ERROR,
 				(errcode_for_file_access(),
-				 errmsg("could not read from streaming transaction's subxact file \"%s\": %m",
-						path)));
+				 errmsg("could not read from streaming transaction's subxact file \"%s\": read only %zu of %zu bytes",
+						path, nread, sizeof(subxact_data.nsubxacts))));
 
 	len = sizeof(SubXactInfo) * subxact_data.nsubxacts;
 
@@ -4035,11 +4036,15 @@ subxact_info_read(Oid subid, TransactionId xid)
 								   sizeof(SubXactInfo));
 	MemoryContextSwitchTo(oldctx);
 
-	if ((len > 0) && ((BufFileRead(fd, subxact_data.subxacts, len)) != len))
+	if (len > 0)
+	{
+		nread = BufFileRead(fd, subxact_data.subxacts, len);
+		if (nread != len)
 		ereport(ERROR,
 				(errcode_for_file_access(),
-				 errmsg("could not read from streaming transaction's subxact file \"%s\": %m",
-						path)));
+				 errmsg("could not read from streaming transaction's subxact file \"%s\": read only %zu of %zu bytes",
+						path, nread, len)));
+	}
 
 	BufFileClose(fd);
 }

base-commit: c8ad4d8166aabd6ed5124e7e432166637d0fe646
-- 
2.39.0