Ensure write failure reports no-disk-space

alvherre · alvherre · commit 5b52008a6441 · 2020-06-19T16:46:07.000-04:00
A few places calling fwrite and gzwrite were not setting errno to ENOSPC when reporting errors, as is customary; this led to some failures being reported as "could not write file: Success" which makes us look silly. Make a few of these places in pg_dump and pg_basebackup use our customary pattern. Backpatch-to: 9.5 Author: Justin Pryzby <pryzby@telsasoft.com> Author: Tom Lane <tgl@sss.pgh.pa.us> Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Discussion: https://postgr.es/m/20200611153753.GU14879@telsasoft.com
diff --git a/src/bin/pg_basebackup/pg_basebackup.c b/src/bin/pg_basebackup/pg_basebackup.c
@@ -892,8 +892,12 @@ writeTarData(
 #ifdef HAVE_LIBZ
 	if (ztarfile != NULL)
 	{
+		errno = 0;
 		if (gzwrite(ztarfile, buf, r) != r)
 		{
+			/* if write didn't set errno, assume problem is no disk space */
+			if (errno == 0)
+				errno = ENOSPC;
 			pg_log_error("could not write to compressed file \"%s\": %s",
 						 current_file, get_gz_error(ztarfile));
 			exit(1);
@@ -902,8 +906,12 @@ writeTarData(
 	else
 #endif
 	{
+		errno = 0;
 		if (fwrite(buf, r, 1, tarfile) != 1)
 		{
+			/* if write didn't set errno, assume problem is no disk space */
+			if (errno == 0)
+				errno = ENOSPC;
 			pg_log_error("could not write to file \"%s\": %m", current_file);
 			exit(1);
 		}
@@ -1596,8 +1604,12 @@ ReceiveAndUnpackTarFile(PGconn *conn, PGresult *res, int rownum)
 				continue;
 			}
 
+			errno = 0;
 			if (fwrite(copybuf, r, 1, file) != 1)
 			{
+				/* if write didn't set errno, assume problem is no disk space */
+				if (errno == 0)
+					errno = ENOSPC;
 				pg_log_error("could not write to file \"%s\": %m", filename);
 				exit(1);
 			}
diff --git a/src/bin/pg_dump/pg_backup_directory.c b/src/bin/pg_dump/pg_backup_directory.c
@@ -346,10 +346,15 @@ _WriteData(ArchiveHandle *AH, const void *data, size_t dLen)
 {
 	lclContext *ctx = (lclContext *) AH->formatData;
 
+	errno = 0;
 	if (dLen > 0 && cfwrite(data, dLen, ctx->dataFH) != dLen)
+	{
+		/* if write didn't set errno, assume problem is no disk space */
+		if (errno == 0)
+			errno = ENOSPC;
 		fatal("could not write to output file: %s",
 			  get_cfp_error(ctx->dataFH));
-
+	}
 
 	return;
 }
@@ -484,9 +489,15 @@ _WriteByte(ArchiveHandle *AH, const int i)
 	unsigned char c = (unsigned char) i;
 	lclContext *ctx = (lclContext *) AH->formatData;
 
+	errno = 0;
 	if (cfwrite(&c, 1, ctx->dataFH) != 1)
+	{
+		/* if write didn't set errno, assume problem is no disk space */
+		if (errno == 0)
+			errno = ENOSPC;
 		fatal("could not write to output file: %s",
 			  get_cfp_error(ctx->dataFH));
+	}
 
 	return 1;
 }
@@ -514,9 +525,15 @@ _WriteBuf(ArchiveHandle *AH, const void *buf, size_t len)
 {
 	lclContext *ctx = (lclContext *) AH->formatData;
 
+	errno = 0;
 	if (cfwrite(buf, len, ctx->dataFH) != len)
+	{
+		/* if write didn't set errno, assume problem is no disk space */
+		if (errno == 0)
+			errno = ENOSPC;
 		fatal("could not write to output file: %s",
 			  get_cfp_error(ctx->dataFH));
+	}
 
 	return;
 }

Original file line number	Diff line number	Diff line change
`@@ -892,8 +892,12 @@ writeTarData(`
`892`	`892`	`#ifdef HAVE_LIBZ`
`893`	`893`	`if (ztarfile != NULL)`
`894`	`894`	`{`
	`895`	`+ errno = 0;`
`895`	`896`	`if (gzwrite(ztarfile, buf, r) != r)`
`896`	`897`	`{`
	`898`	`+ /* if write didn't set errno, assume problem is no disk space */`
	`899`	`+ if (errno == 0)`
	`900`	`+ errno = ENOSPC;`
`897`	`901`	`pg_log_error("could not write to compressed file \"%s\": %s",`
`898`	`902`	`current_file, get_gz_error(ztarfile));`
`899`	`903`	`exit(1);`
`@@ -902,8 +906,12 @@ writeTarData(`
`902`	`906`	`else`
`903`	`907`	`#endif`
`904`	`908`	`{`
	`909`	`+ errno = 0;`
`905`	`910`	`if (fwrite(buf, r, 1, tarfile) != 1)`
`906`	`911`	`{`
	`912`	`+ /* if write didn't set errno, assume problem is no disk space */`
	`913`	`+ if (errno == 0)`
	`914`	`+ errno = ENOSPC;`
`907`	`915`	`pg_log_error("could not write to file \"%s\": %m", current_file);`
`908`	`916`	`exit(1);`
`909`	`917`	`}`
`@@ -1596,8 +1604,12 @@ ReceiveAndUnpackTarFile(PGconn conn, PGresult res, int rownum)`
`1596`	`1604`	`continue;`
`1597`	`1605`	`}`
`1598`	`1606`
	`1607`	`+ errno = 0;`
`1599`	`1608`	`if (fwrite(copybuf, r, 1, file) != 1)`
`1600`	`1609`	`{`
	`1610`	`+ /* if write didn't set errno, assume problem is no disk space */`
	`1611`	`+ if (errno == 0)`
	`1612`	`+ errno = ENOSPC;`
`1601`	`1613`	`pg_log_error("could not write to file \"%s\": %m", filename);`
`1602`	`1614`	`exit(1);`
`1603`	`1615`	`}`