From 9cbb466ce80096c2c12c88be50e475265adb74b1 Mon Sep 17 00:00:00 2001
From: Sergey Matveev <stargrave@stargrave.org>
Date: Sat, 16 Jan 2021 21:14:15 +0300
Subject: [PATCH] REDO_INODE_NO_TRUST

---
 doc/faq.texi      | 5 +++--
 doc/features.texi | 5 +++--
 doc/news.texi     | 4 ++++
 inode.go          | 4 ++++
 main.go           | 1 +
 ood.go            | 2 +-
 usage.go          | 4 +++-
 7 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/doc/faq.texi b/doc/faq.texi
index 1c6def3..9b909a6 100644
--- a/doc/faq.texi
+++ b/doc/faq.texi
@@ -4,8 +4,9 @@
 @anchor{Stamping}
 @section Hashing and stamping
 
-All targets are checksummed if their @file{ctime} differs from the
-previous one. @command{apenwarr/redo} gives
+All targets are checksummed if no @env{REDO_INODE_NO_TRUST} environment
+variable is set and target's @file{ctime} differs from the previous one.
+@command{apenwarr/redo} gives
 @url{https://redo.readthedocs.io/en/latest/FAQImpl/#why-not-always-use-checksum-based-dependencies-instead-of-timestamps, many reasons}
 why every time checksumming is bad, but in my opinion in practice all of
 them do not apply.
diff --git a/doc/features.texi b/doc/features.texi
index 2c5141e..843222d 100644
--- a/doc/features.texi
+++ b/doc/features.texi
@@ -12,8 +12,9 @@
     @end itemize
 @item targets, dependency information and their directories are explicitly
   synced (can be disabled, should work faster)
-@item file's change is detected by comparing its size, @code{ctime}
-    and BLAKE3 hash
+@item file's change is detected by comparing its size, @code{ctime} (if
+    @env{REDO_INODE_NO_TRUST} environment variable is not set) and
+    BLAKE3 hash
 @item files creation is @code{umask}-friendly (unlike @code{mkstemp()}
     used in @command{redo-c})
 @item parallel build with jobs limit, optionally in infinite mode
diff --git a/doc/news.texi b/doc/news.texi
index bc4322e..3d5a651 100644
--- a/doc/news.texi
+++ b/doc/news.texi
@@ -7,6 +7,10 @@
 @item
     @code{Size} is stored in the state, for faster OOD detection.
     Previous @command{goredo} state files won't work.
+@item
+    Setting of @env{REDO_INODE_NO_TRUST} environment variable brings no
+    trust to file inode's information (except for its size), forcing its
+    checksum checking.
 @item
     @command{redo-whichdo} resembles @code{apenwarr/redo}'s one behaviour more.
 @end itemize
diff --git a/inode.go b/inode.go
index 81e77bb..2d929a2 100644
--- a/inode.go
+++ b/inode.go
@@ -28,6 +28,10 @@ import (
 	"golang.org/x/sys/unix"
 )
 
+const EnvInodeNoTrust = "REDO_INODE_NO_TRUST"
+
+var InodeTrust bool = false
+
 type Inode struct {
 	Size      int64
 	CtimeSec  int64
diff --git a/main.go b/main.go
index 873582a..7d1c719 100644
--- a/main.go
+++ b/main.go
@@ -101,6 +101,7 @@ func main() {
 
 	NoColor = os.Getenv(EnvNoColor) != ""
 	NoSync = os.Getenv(EnvNoSync) == "1"
+	InodeTrust = os.Getenv(EnvInodeNoTrust) == ""
 
 	TopDir = os.Getenv(EnvTopDir)
 	if TopDir == "" {
diff --git a/ood.go b/ood.go
index e75dd43..5fe1104 100644
--- a/ood.go
+++ b/ood.go
@@ -139,7 +139,7 @@ func isOOD(cwd, tgtOrig string, level int, seen map[string]struct{}) (bool, erro
 			ood = true
 			goto Done
 		}
-		if inode.Equals(theirInode) {
+		if InodeTrust && inode.Equals(theirInode) {
 			trace(CDebug, "ood: %s%s -> %s: same inode", indent, tgtOrig, dep)
 		} else {
 			trace(CDebug, "ood: %s%s -> %s: inode differs", indent, tgtOrig, dep)
diff --git a/usage.go b/usage.go
index ce838b4..beb221f 100644
--- a/usage.go
+++ b/usage.go
@@ -91,5 +91,7 @@ Additional environment variables:
   NO_COLOR -- disable messages colouring
   REDO_NO_SYNC -- disable files/directories explicit filesystem syncing
   REDO_TOP_DIR -- do not search for .do above that directory
-                  (it can contain .redo/top as an alternative)`)
+                  (it can contain .redo/top as an alternative)
+  REDO_INODE_NO_TRUST -- do not trust inode information (except for size)
+                         and always check file's hash`)
 }
-- 
2.44.0