[Tarantool-patches] [PATCH v6] vinyl: fix check vinyl_dir existence at bootstrap

["Alexander V. Tikhonov" <avtikhon@tarantool.org>]

During implementation of openSUSE build with testing got failed test
box-tap/cfg.test.lua. Found that when memtx_dir didn't exist and
vinyl_dir existed and also errno was set to ENOENT, box configuration
succeeded, but it shouldn't. Reason of this wrong behaviour was that
not all of the failure paths in xdir_scan() set errno, but the caller
assumed it.

Debugging the issue found that after xdir_scan() there was incorrect
check for errno when it returned negative values. xdir_scan() is not
system call and negative return value from it doesn't mean that errno
whould be set too. Found that in situations when errno was left from
previous commands before xdir_scan() and xdir_scan() returned negative
value by itself than the check was wrong. The previous logic of the
check was to catch the error ENOENT from inside the xdir_scan()
function to handle the situation when vinyl_dir was not exist. In this
way errno should be reseted before xdir_scan() call to give the ability
for xdir_scan() to use return value without errno set and correctly
handle errno from inside the xdir_scan().

After discussions found that there was alternative better solution to
fix it. As mentioned above xdir_scan() function is not system call and
can be changed inside it in any possible way. So check outside of this
function on errno could be broken, because of the xdir_scan() changes.
To avoid of it we must avoid of errno checks outside of the function.
Better solution was to use the flag in xdir_scan(), to check if the
directory should exist. So errno check was removed and instead of it
the check for vinyl_dir existence using flag added.

Closes #4594
Needed for #4562

Co-authored-by: Alexander Turenko <alexander.turenko@tarantool.org>
---

Github: https://github.com/tarantool/tarantool/tree/avtikhon/gh-4562-suse-pack-full-ci
Issue: https://github.com/tarantool/tarantool/issues/4594
Issue: https://github.com/tarantool/tarantool/issues/4562

 src/box/memtx_engine.c                        |  2 +-
 src/box/recovery.cc                           |  4 +-
 src/box/vy_log.c                              |  4 +-
 src/box/wal.c                                 |  2 +-
 src/box/xlog.c                                |  4 +-
 src/box/xlog.h                                |  6 +--
 .../gh-4562-errno-at-xdir_scan.test.lua       | 54 +++++++++++++++++++
 7 files changed, 66 insertions(+), 10 deletions(-)
 create mode 100755 test/box-tap/gh-4562-errno-at-xdir_scan.test.lua

diff --git a/src/box/memtx_engine.c b/src/box/memtx_engine.c
index dfd6fce6e..9f079a6b5 100644
--- a/src/box/memtx_engine.c
+++ b/src/box/memtx_engine.c
@@ -992,7 +992,7 @@ memtx_engine_new(const char *snap_dirname, bool force_recovery,
 		    &xlog_opts_default);
 	memtx->snap_dir.force_recovery = force_recovery;
 
-	if (xdir_scan(&memtx->snap_dir) != 0)
+	if (xdir_scan(&memtx->snap_dir, true) != 0)
 		goto fail;
 
 	/*
diff --git a/src/box/recovery.cc b/src/box/recovery.cc
index d1a503cfc..cd33e7635 100644
--- a/src/box/recovery.cc
+++ b/src/box/recovery.cc
@@ -121,7 +121,7 @@ void
 recovery_scan(struct recovery *r, struct vclock *end_vclock,
 	      struct vclock *gc_vclock)
 {
-	xdir_scan_xc(&r->wal_dir);
+	xdir_scan_xc(&r->wal_dir, true);
 
 	if (xdir_last_vclock(&r->wal_dir, end_vclock) < 0 ||
 	    vclock_compare(end_vclock, &r->vclock) < 0) {
@@ -307,7 +307,7 @@ recover_remaining_wals(struct recovery *r, struct xstream *stream,
 	struct vclock *clock;
 
 	if (scan_dir)
-		xdir_scan_xc(&r->wal_dir);
+		xdir_scan_xc(&r->wal_dir, true);
 
 	if (xlog_cursor_is_open(&r->cursor)) {
 		/* If there's a WAL open, recover from it first. */
diff --git a/src/box/vy_log.c b/src/box/vy_log.c
index 311985c72..da3c50e87 100644
--- a/src/box/vy_log.c
+++ b/src/box/vy_log.c
@@ -1014,7 +1014,7 @@ vy_log_rebootstrap(void)
 int
 vy_log_bootstrap(void)
 {
-	if (xdir_scan(&vy_log.dir) < 0 && errno != ENOENT)
+	if (xdir_scan(&vy_log.dir, false) < 0)
 		return -1;
 	if (xdir_last_vclock(&vy_log.dir, &vy_log.last_checkpoint) >= 0)
 		return vy_log_rebootstrap();
@@ -1036,7 +1036,7 @@ vy_log_begin_recovery(const struct vclock *vclock)
 	 * because vinyl might not be even in use. Complain only
 	 * on an attempt to write a vylog.
 	 */
-	if (xdir_scan(&vy_log.dir) < 0 && errno != ENOENT)
+	if (xdir_scan(&vy_log.dir, false) < 0)
 		return NULL;
 
 	if (xdir_last_vclock(&vy_log.dir, &vy_log.last_checkpoint) < 0) {
diff --git a/src/box/wal.c b/src/box/wal.c
index d8c92aa36..2b894d680 100644
--- a/src/box/wal.c
+++ b/src/box/wal.c
@@ -559,7 +559,7 @@ wal_enable(void)
 	 * existing WAL files. Required for garbage collection,
 	 * see wal_collect_garbage().
 	 */
-	if (xdir_scan(&writer->wal_dir))
+	if (xdir_scan(&writer->wal_dir, true))
 		return -1;
 
 	/* Open the most recent WAL file. */
diff --git a/src/box/xlog.c b/src/box/xlog.c
index 6ccd3d68d..74f761994 100644
--- a/src/box/xlog.c
+++ b/src/box/xlog.c
@@ -511,13 +511,15 @@ xdir_open_cursor(struct xdir *dir, int64_t signature,
  * @return nothing.
  */
 int
-xdir_scan(struct xdir *dir)
+xdir_scan(struct xdir *dir, bool is_dir_required)
 {
 	DIR *dh = opendir(dir->dirname);        /* log dir */
 	int64_t *signatures = NULL;             /* log file names */
 	size_t s_count = 0, s_capacity = 0;
 
 	if (dh == NULL) {
+		if (!is_dir_required && errno == ENOENT)
+			return 0;
 		diag_set(SystemError, "error reading directory '%s'",
 			  dir->dirname);
 		return -1;
diff --git a/src/box/xlog.h b/src/box/xlog.h
index 9ffce598b..3400eb75f 100644
--- a/src/box/xlog.h
+++ b/src/box/xlog.h
@@ -187,7 +187,7 @@ xdir_destroy(struct xdir *dir);
  * snapshot or scan through all logs.
  */
 int
-xdir_scan(struct xdir *dir);
+xdir_scan(struct xdir *dir, bool is_dir_required);
 
 /**
  * Check that a directory exists and is writable.
@@ -821,9 +821,9 @@ xdir_open_cursor(struct xdir *dir, int64_t signature,
 #include "exception.h"
 
 static inline void
-xdir_scan_xc(struct xdir *dir)
+xdir_scan_xc(struct xdir *dir, bool is_dir_required)
 {
-	if (xdir_scan(dir) == -1)
+	if (xdir_scan(dir, is_dir_required) == -1)
 		diag_raise();
 }
 
diff --git a/test/box-tap/gh-4562-errno-at-xdir_scan.test.lua b/test/box-tap/gh-4562-errno-at-xdir_scan.test.lua
new file mode 100755
index 000000000..e6dd68d54
--- /dev/null
+++ b/test/box-tap/gh-4562-errno-at-xdir_scan.test.lua
@@ -0,0 +1,54 @@
+#!/usr/bin/env tarantool
+
+local tap = require('tap')
+local test = tap.test('cfg')
+local fio = require('fio')
+test:plan(1)
+
+local tarantool_bin = arg[-1]
+local PANIC = 256
+
+local function run_script(code)
+    local dir = fio.tempdir()
+    local script_path = fio.pathjoin(dir, 'script.lua')
+    local script = fio.open(script_path, {'O_CREAT', 'O_WRONLY', 'O_APPEND'},
+        tonumber('0777', 8))
+    script:write(code)
+    script:write("\nos.exit(0)")
+    script:close()
+    local cmd = [[/bin/sh -c 'cd "%s" && "%s" ./script.lua 2> /dev/null']]
+    local res = os.execute(string.format(cmd, dir, tarantool_bin))
+    fio.rmtree(dir)
+    return res
+end
+
+--
+-- gh-4594: when memtx_dir is not exists, but vinyl_dir exists and
+-- errno is set to ENOENT, box configuration succeeds, however it
+-- should not
+--
+
+-- create vinyl_dir as temporary path
+local vinyl_dir = fio.tempdir()
+
+-- fill vinyl_dir
+run_script(string.format([[
+box.cfg{vinyl_dir = '%s'}
+s = box.schema.space.create('test', {engine = 'vinyl'})
+s:create_index('pk')
+os.exit(0)
+]], vinyl_dir))
+
+-- verify the case described above
+local code = string.format([[
+local errno = require('errno')
+errno(errno.ENOENT)
+box.cfg{vinyl_dir = '%s'}
+os.exit(0)
+]], vinyl_dir)
+test:is(run_script(code), PANIC, "bootstrap with ENOENT from non-empty vinyl_dir")
+
+-- remove vinyl_dir
+fio.rmtree(vinyl_dir)
+
+os.exit(test:check() and 0 or 1)
-- 
2.17.1