Unbreak OTA on crappy shells (#5850)

* Unbreak OTA on crappy shells

  Very, very old ash versions abort on set -o failures (as mandated by
POSIX, granted). This makes it impossible to reliably catch failures in
a single step.

So do it from the Lua side instead.

Should fix #5844

* Launch the zsync wrapper through bash on Cervantes

Makefile

@@ -451,8 +451,8 @@ cervantesupdate: all
 	# remove old package if any
 	rm -f $(CERVANTES_PACKAGE)
 	# Cervantes launching scripts
+	cp $(COMMON_DIR)/spinning_zsync $(INSTALL_DIR)/koreader/spinning_zsync.sh
 	cp $(CERVANTES_DIR)/*.sh $(INSTALL_DIR)/koreader
-	cp $(COMMON_DIR)/spinning_zsync $(INSTALL_DIR)/koreader
 	# create new package
 	cd $(INSTALL_DIR) && \
 		zip -9 -r \

frontend/ui/otamanager.lua

@@ -399,14 +399,22 @@ end
 function OTAManager:zsync(full_dl)
     if full_dl or self:_buildLocalPackage() == 0 then
         local zsync_wrapper = "zsync2"
+        local use_pipefail = true
         -- With visual feedback if supported...
         if self.can_pretty_print then
             zsync_wrapper = "spinning_zsync"
+            -- And because everything is terrible, we can't check for pipefail's usability in spinning_zsync,
+            -- because older ash versions abort on set -o failures...
+            -- c.f., ko/#5844
+            -- So, instead, check from this side of the fence...
+            -- (remember, os.execute is essentially system(), it goes through sh)
+            use_pipefail = (os.execute("set -o pipefail 2>/dev/null") == 0)
         end
         -- If that's a full-download fallback, drop the input tarball
         if full_dl then
             return os.execute(
-            ("./%s -o '%s' -u '%s' '%s%s'"):format(
+            ("env WITH_PIPEFAIL='%s' ./%s -o '%s' -u '%s' '%s%s'"):format(
+                use_pipefail,
                 zsync_wrapper,
                 self.updated_package,
                 self:getOTAServer(),
@@ -415,7 +423,8 @@ function OTAManager:zsync(full_dl)
             )
         else
             return os.execute(
-            ("./%s -i '%s' -o '%s' -u '%s' '%s%s'"):format(
+            ("env WITH_PIPEFAIL='%s' ./%s -i '%s' -o '%s' -u '%s' '%s%s'"):format(
+                use_pipefail,
                 zsync_wrapper,
                 self.installed_package,
                 self.updated_package,

platform/cervantes/spinning_zsync

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+# NOTE: We can use pipefail via bash on Cervantes
+#       c.f., #5844 & #5850
+
+export WITH_PIPEFAIL="true"
+exec /bin/bash ./spinning_zsync.sh "$@"

platform/common/spinning_zsync

@@ -1,14 +1,15 @@
 #!/bin/sh
 
 # We're going to need to remember failures from the *left* side of a pipeline...
-# shellcheck disable=SC2039
+# But because we can't have nice things, some devices (hi, Kindle) may use an extremely old busybox build,
-if set -o pipefail 2>/dev/null; then
+# one in which pipefail was not yet implemented,
-    WITH_PIPEFAIL="true"
+# (it appeared in busybox 1.16.0, and is contingent on bash compatibility being enabled in ash).
-else
+
-    # But because we can't have nice things, some devices (hi, Kindle) may use an extremely old busybox build,
+# NOTE: We inherit WITH_PIPEFAIL from the env via OTAManager, because of course old busybox ash versions abort on set -o failures...
-    # one in which pipefail was not yet implemented,
+#       c.f., https://github.com/koreader/koreader/pull/5844
-    # (it appeared in busybox 1.16.0, and is contingent on bash compatibility being enabled in ash).
+if [ "${WITH_PIPEFAIL}" = "true" ]; then
-    WITH_PIPEFAIL="true"
+    # shellcheck disable=SC2039
+    set -o pipefail
 fi
 
 # Figure out whether that's a delta or a full download given the number of arguments passed...