Fix buffile.c error handling.

Convert buffile.c error handling to use ereport.  This fixes cases where
I/O errors were indistinguishable from EOF or not reported.  Also remove
"%m" from error messages where errno would be bogus.  While we're
modifying those strings, add block numbers and short read byte counts
where appropriate.

Back-patch to all supported releases.

Reported-by: Amit Khandekar <amitdkhan.pg@gmail.com>
Reviewed-by: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Ibrar Ahmed <ibrar.ahmad@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/CA%2BhUKGJE04G%3D8TLK0DLypT_27D9dR8F1RQgNp0jK6qR0tZGWOw%40mail.gmail.com

1 files changed, 31 insertions, 26 deletions

diff --git a/src/backend/storage/file/buffile.c b/src/backend/storage/file/buffile.c
index 9a14addfd7a..1d6b8b4d5ad 100644
--- a/src/backend/storage/file/buffile.c
+++ b/src/backend/storage/file/buffile.c
@@ -93,8 +93,7 @@ static BufFile *makeBufFile(File firstfile);
 static void extendBufFile(BufFile *file);
 static void BufFileLoadBuffer(BufFile *file);
 static void BufFileDumpBuffer(BufFile *file);
-static int	BufFileFlush(BufFile *file);
-
+static void BufFileFlush(BufFile *file);
 
 /*
  * Create a BufFile given the first underlying physical file.
@@ -247,7 +246,10 @@ BufFileLoadBuffer(BufFile *file)
 	if (file->curOffset != file->offsets[file->curFile])
 	{
 		if (FileSeek(thisfile, file->curOffset, SEEK_SET) != file->curOffset)
-			return;				/* seek failed, read nothing */
+			ereport(ERROR,
+					(errcode_for_file_access(),
+					 errmsg("could not seek in file \"%s\": %m",
+							FilePathName(thisfile))));
 		file->offsets[file->curFile] = file->curOffset;
 	}
 
@@ -256,7 +258,14 @@ BufFileLoadBuffer(BufFile *file)
 	 */
 	file->nbytes = FileRead(thisfile, file->buffer.data, sizeof(file->buffer));
 	if (file->nbytes < 0)
+	{
 		file->nbytes = 0;
+		ereport(ERROR,
+				(errcode_for_file_access(),
+				 errmsg("could not read file \"%s\": %m",
+						FilePathName(thisfile))));
+	}
+
 	file->offsets[file->curFile] += file->nbytes;
 	/* we choose not to advance curOffset here */
 
@@ -314,12 +323,19 @@ BufFileDumpBuffer(BufFile *file)
 		if (file->curOffset != file->offsets[file->curFile])
 		{
 			if (FileSeek(thisfile, file->curOffset, SEEK_SET) != file->curOffset)
-				return;			/* seek failed, give up */
+				ereport(ERROR,
+						(errcode_for_file_access(),
+						 errmsg("could not seek in file \"%s\": %m",
+								FilePathName(thisfile))));
 			file->offsets[file->curFile] = file->curOffset;
 		}
 		bytestowrite = FileWrite(thisfile, file->buffer.data + wpos, bytestowrite);
 		if (bytestowrite <= 0)
-			return;				/* failed to write */
+			ereport(ERROR,
+					(errcode_for_file_access(),
+					 errmsg("could not write to file \"%s\" : %m",
+							FilePathName(thisfile))));
+
 		file->offsets[file->curFile] += bytestowrite;
 		file->curOffset += bytestowrite;
 		wpos += bytestowrite;
@@ -352,7 +368,8 @@ BufFileDumpBuffer(BufFile *file)
 /*
  * BufFileRead
  *
- * Like fread() except we assume 1-byte element size.
+ * Like fread() except we assume 1-byte element size and report I/O errors via
+ * ereport().
  */
 size_t
 BufFileRead(BufFile *file, void *ptr, size_t size)
@@ -360,12 +377,7 @@ BufFileRead(BufFile *file, void *ptr, size_t size)
 	size_t		nread = 0;
 	size_t		nthistime;
 
-	if (file->dirty)
-	{
-		if (BufFileFlush(file) != 0)
-			return 0;			/* could not flush... */
-		Assert(!file->dirty);
-	}
+	BufFileFlush(file);
 
 	while (size > 0)
 	{
@@ -399,7 +411,8 @@ BufFileRead(BufFile *file, void *ptr, size_t size)
 /*
  * BufFileWrite
  *
- * Like fwrite() except we assume 1-byte element size.
+ * Like fwrite() except we assume 1-byte element size and report errors via
+ * ereport().
  */
 size_t
 BufFileWrite(BufFile *file, void *ptr, size_t size)
@@ -413,11 +426,7 @@ BufFileWrite(BufFile *file, void *ptr, size_t size)
 		{
 			/* Buffer full, dump it out */
 			if (file->dirty)
-			{
 				BufFileDumpBuffer(file);
-				if (file->dirty)
-					break;		/* I/O error */
-			}
 			else
 			{
 				/* Hmm, went directly from reading to writing? */
@@ -449,19 +458,15 @@ BufFileWrite(BufFile *file, void *ptr, size_t size)
 /*
  * BufFileFlush
  *
- * Like fflush()
+ * Like fflush(), except that I/O errors are reported with ereport().
  */
-static int
+static void
 BufFileFlush(BufFile *file)
 {
 	if (file->dirty)
-	{
 		BufFileDumpBuffer(file);
-		if (file->dirty)
-			return EOF;
-	}
 
-	return 0;
+	Assert(!file->dirty);
 }
 
 /*
@@ -470,6 +475,7 @@ BufFileFlush(BufFile *file)
  * Like fseek(), except that target position needs two values in order to
  * work when logical filesize exceeds maximum value representable by long.
  * We do not support relative seeks across more than LONG_MAX, however.
+ * I/O errors are reported by ereport().
  *
  * Result is 0 if OK, EOF if not.  Logical position is not moved if an
  * impossible seek is attempted.
@@ -527,8 +533,7 @@ BufFileSeek(BufFile *file, int fileno, off_t offset, int whence)
 		return 0;
 	}
 	/* Otherwise, must reposition buffer, so flush any dirty data */
-	if (BufFileFlush(file) != 0)
-		return EOF;
+	BufFileFlush(file);
 
 	/*
 	 * At this point and no sooner, check for seek past last segment. The