Check for fseeko() failure in pg_dump's _tarAddFile().

tglsfdc · tglsfdc · commit 3ed76bd3592f · 2020-08-09T12:39:08.000-04:00
Coverity pointed out, not unreasonably, that we checked fseeko's
result at every other call site but these.  Failure to seek in the
temp file (note this is NOT pg_dump's output file) seems quite
unlikely, and even if it did happen the file length cross-check
further down would probably detect the problem.  Still, that's a
poor excuse for not checking the result of a system call.
diff --git a/src/bin/pg_dump/pg_backup_tar.c b/src/bin/pg_dump/pg_backup_tar.c
@@ -1096,12 +1096,16 @@ _tarAddFile(ArchiveHandle *AH, TAR_MEMBER *th)
 	/*
 	 * Find file len & go back to start.
 	 */
-	fseeko(tmp, 0, SEEK_END);
+	if (fseeko(tmp, 0, SEEK_END) != 0)
+		exit_horribly(modulename, "error during file seek: %s\n",
+					  strerror(errno));
 	th->fileLen = ftello(tmp);
 	if (th->fileLen < 0)
 		exit_horribly(modulename, "could not determine seek position in archive file: %s\n",
 					  strerror(errno));
-	fseeko(tmp, 0, SEEK_SET);
+	if (fseeko(tmp, 0, SEEK_SET) != 0)
+		exit_horribly(modulename, "error during file seek: %s\n",
+					  strerror(errno));
 
 	_tarWriteHeader(th);
 
