build/Makefile.common: shrink pdfs before publish

Closes: SYS#6380
Change-Id: I7c01b1cb1a0e7de385359671461a0ad142dfa5ad

build/Makefile.common.inc

@@ -9,8 +9,9 @@
 SSH_COMMAND = ssh -o 'UserKnownHostsFile=$(OSMO_GSM_MANUALS_DIR)/build/known_hosts' -p 48
 UPLOAD_PATH ?= generic@sysmocom-downloads:documents
 SYMLINKS = common build
-CLEAN_FILES += $(SYMLINKS)
+CLEAN_FILES += $(SYMLINKS) $(SHRINK_MARKER)
 PDF_FILES = $(patsubst %.adoc,%.pdf,$(ASCIIDOC)) $(patsubst %.xml,%.pdf,$(VTY_REFERENCE))
+SHRINK_MARKER = generated/.pdf_shrink_marker
 PUBLISH_REF ?= master
 PUBLISH_TEMPDIR = _publish_tmpdir
 
@@ -20,12 +21,17 @@ prefix ?= /usr/local
 $(SYMLINKS):
 	ln -s $(OSMO_GSM_MANUALS_DIR)/$@ $@
 
+# Reduce pdf size by storing the embedded images with less quality (SYS#6380)
+shrink: $(SHRINK_MARKER)
+$(SHRINK_MARKER): $(UPLOAD_FILES)
+	build/shrink-pdfs.sh $(UPLOAD_FILES)
+
 # Publish to $UPLOAD_PATH
-upload: $(UPLOAD_FILES)
+upload: shrink
 	rsync -avz $(UPLOAD_FILES) $(UPLOAD_PATH)/
 
 # Publish to https://ftp.osmocom.org/docs/
-publish: $(UPLOAD_FILES)
+publish: shrink
 	[ -n "$(OSMO_REPOSITORY)" ] || exit 1
 	rm -rf "$(PUBLISH_TEMPDIR)"
 	mkdir -p "$(PUBLISH_TEMPDIR)/$(OSMO_REPOSITORY)/$(PUBLISH_REF)"

build/shrink-pdfs.sh

@@ -0,0 +1,27 @@
+#!/bin/sh -e
+# Reduce pdf size by storing the embedded images with less quality (SYS#6380)
+# usage: shrink-pdfs.sh first.pdf [second.pdf [...]]
+mkdir -p generated
+
+for i in $@; do
+	out="generated/shrink_temp.pdf"
+	ps2pdf -dPDFSETTINGS=/ebook "$i" "$out"
+
+	size_old=$(du "$i" | cut -f1)
+	size_old_h=$(du -h "$i" | cut -f1)
+	size_new=$(du "$out" | cut -f1)
+	size_new_h=$(du -h "$out" | cut -f1)
+
+	if [ "$size_new" -lt "$size_old" ]; then
+		echo "* $i: $size_new_h (shrunk from $size_old_h)"
+		mv "$out" "$i"
+	else
+		echo "* $i: $size_old_h"
+		rm "$out"
+	fi
+done
+
+# Add a marker so the Makefile knows that the shrink script ran. The generated
+# dir is already in the gitignore files of repositories using osmo-gsm-manuals,
+# so put it there.
+touch generated/.pdf_shrink_marker