Rework error messages around file handling

Some error messages related to file handling are using the code path
context to define their state.  For example, 2PC-related errors are
referring to "two-phase status files", or "relation mapping file" is
used for catalog-to-filenode mapping, however those prove to be
difficult to translate, and are not more helpful than just referring to
the path of the file being worked on.  So simplify all those error
messages by just referring to files with their path used.  In some
cases, like the manipulation of WAL segments, the context is actually
helpful so those are kept.

Calls to the system function read() have also been rather inconsistent
with their error handling sometimes not reporting the number of bytes
read, and some other code paths trying to use an errno which has not
been set.  The in-core functions are using a more consistent pattern
with this patch, which checks for both errno if set or if an
inconsistent read is happening.

So as to care about pluralization when reading an unexpected number of
byte(s), "could not read: read %d of %zu" is used as error message, with
%d field being the output result of read() and %zu the expected size.
This simplifies the work of translators with less variations of the same
message.

Author: Michael Paquier
Reviewed-by: Álvaro Herrera
Discussion: https://postgr.es/m/20180520000522.GB1603@paquier.xyz

1 files changed, 18 insertions, 10 deletions

diff --git a/src/backend/utils/cache/relmapper.c b/src/backend/utils/cache/relmapper.c
index 99d095f2df3..2d31f9f912a 100644
--- a/src/backend/utils/cache/relmapper.c
+++ b/src/backend/utils/cache/relmapper.c
@@ -629,6 +629,7 @@ load_relmap_file(bool shared)
 	char		mapfilename[MAXPGPATH];
 	pg_crc32c	crc;
 	int			fd;
+	int			r;
 
 	if (shared)
 	{
@@ -648,7 +649,7 @@ load_relmap_file(bool shared)
 	if (fd < 0)
 		ereport(FATAL,
 				(errcode_for_file_access(),
-				 errmsg("could not open relation mapping file \"%s\": %m",
+				 errmsg("could not open file \"%s\": %m",
 						mapfilename)));
 
 	/*
@@ -659,11 +660,18 @@ load_relmap_file(bool shared)
 	 * are able to access any relation that's affected by the change.
 	 */
 	pgstat_report_wait_start(WAIT_EVENT_RELATION_MAP_READ);
-	if (read(fd, map, sizeof(RelMapFile)) != sizeof(RelMapFile))
-		ereport(FATAL,
-				(errcode_for_file_access(),
-				 errmsg("could not read relation mapping file \"%s\": %m",
-						mapfilename)));
+	r = read(fd, map, sizeof(RelMapFile));
+	if (r != sizeof(RelMapFile))
+	{
+		if (r < 0)
+			ereport(FATAL,
+					(errcode_for_file_access(),
+					 errmsg("could not read file \"%s\": %m", mapfilename)));
+		else
+			ereport(FATAL,
+					(errmsg("could not read file \"%s\": read %d of %zu",
+							mapfilename, r, sizeof(RelMapFile))));
+	}
 	pgstat_report_wait_end();
 
 	CloseTransientFile(fd);
@@ -748,7 +756,7 @@ write_relmap_file(bool shared, RelMapFile *newmap,
 	if (fd < 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
-				 errmsg("could not open relation mapping file \"%s\": %m",
+				 errmsg("could not open file \"%s\": %m",
 						mapfilename)));
 
 	if (write_wal)
@@ -782,7 +790,7 @@ write_relmap_file(bool shared, RelMapFile *newmap,
 			errno = ENOSPC;
 		ereport(ERROR,
 				(errcode_for_file_access(),
-				 errmsg("could not write to relation mapping file \"%s\": %m",
+				 errmsg("could not write file \"%s\": %m",
 						mapfilename)));
 	}
 	pgstat_report_wait_end();
@@ -797,14 +805,14 @@ write_relmap_file(bool shared, RelMapFile *newmap,
 	if (pg_fsync(fd) != 0)
 		ereport(ERROR,
 				(errcode_for_file_access(),
-				 errmsg("could not fsync relation mapping file \"%s\": %m",
+				 errmsg("could not fsync file \"%s\": %m",
 						mapfilename)));
 	pgstat_report_wait_end();
 
 	if (CloseTransientFile(fd))
 		ereport(ERROR,
 				(errcode_for_file_access(),
-				 errmsg("could not close relation mapping file \"%s\": %m",
+				 errmsg("could not close file \"%s\": %m",
 						mapfilename)));
 
 	/*