From d716cdbe8c579587f1d27734c755dfa39ab66b71 Mon Sep 17 00:00:00 2001
From: Raman Gupta <rocketraman@gmail.com>
Date: Fri, 6 Aug 2021 12:49:03 -0400
Subject: [PATCH 1/2] Fix the multi-output loop

Resolves #33.

Fixes the arithmetic comparison in the while loop being
incorrect.

Also, handles the situation in which there are more output
files being specified than scans available, in addition
to the already handled reverse situation.
---
 scan | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/scan b/scan
index 836f92a..bea5fb0 100755
--- a/scan
+++ b/scan
@@ -283,10 +283,10 @@ if [[ $numscans > 0 ]]; then
     echo "Truncated $TRUNCPAGE pages"
   fi
   if [[ $numscans > 1 && $USEARRAY == 1 ]]; then
-    echo "Naming pdfs based on output list..."
     output_count=${#OUTPUT[@]}
+    echo "Naming $numscans pdfs based on output list of $output_count names..."
     index=0
-    while [[ "$index" < "$output_count" ]]; do
+    while (( $index < $output_count && $numscans > $index )); do
       let "scanno = $index + 1"
       if [[ -f "${OUTPUT[$index]}" ]]; then
         mv "${OUTPUT[$index]}" "${OUTPUT[$index]}.orig"

From 9ed52ab2faeed13e0eb95cc24bc98d219750c70d Mon Sep 17 00:00:00 2001
From: Raman Gupta <rocketraman@gmail.com>
Date: Fri, 6 Aug 2021 17:45:40 -0400
Subject: [PATCH 2/2] More arithmetic context improvements, corner cases

* Handle truncate pages greater than or equal to the number of
scans.
---
 scan | 31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/scan b/scan
index bea5fb0..f805cf5 100755
--- a/scan
+++ b/scan
@@ -271,23 +271,34 @@ else
   MODE="--mode '$MODE'"
 fi
 eval scanadf -d \'"$DEVICE"\' $MAXPAGE $PGHEIGHT $PGWIDTH -S $SCRIPT --script-wait --resolution $RESOLUTION $MODE $DESKEW $CROP $DRIVER_OPTION $SOURCE -o $TMP_DIR/scan-%04d
+# Simulate empty page scanner outputs for debugging
+#convert xc:none -page Letter $TMP_DIR/scan-0001.pdf
 
 shopt -s extglob nullglob
 pdffiles=($TMP_DIR/scan-[0-9]*.pdf)
 numscans=${#pdffiles[@]}
-if [[ $numscans > 0 ]]; then
+if (( numscans > 0 )); then
   echo "Processing $numscans pages"
-  if [[ $numscans > $TRUNCPAGE && $TRUNCPAGE > 0 ]]; then
-    for x in ${pdffiles[@]:$numscans-$TRUNCPAGE:$TRUNCPAGE}; do rm "$x"; done;
-    pdffiles=(${pdffiles[@]:0:$numscans-$TRUNCPAGE})
-    echo "Truncated $TRUNCPAGE pages"
+  if (( TRUNCPAGE > 0 )); then
+    truncpage=$TRUNCPAGE
+    if (( numscans < TRUNCPAGE )); then
+      truncpage=$numscans
+    fi
+    for x in ${pdffiles[@]:$numscans-$truncpage:$truncpage}; do rm "$x"; done;
+    pdffiles=(${pdffiles[@]:0:$numscans-$truncpage})
+    echo "Truncated $truncpage pages"
+    let "numscans = numscans - truncpage"
   fi
-  if [[ $numscans > 1 && $USEARRAY == 1 ]]; then
+  if (( numscans <= 0 )); then
+    echo "Found no scans."
+    exit 0
+  fi
+  if (( numscans > 1 && USEARRAY == 1 )); then
     output_count=${#OUTPUT[@]}
     echo "Naming $numscans pdfs based on output list of $output_count names..."
     index=0
-    while (( $index < $output_count && $numscans > $index )); do
-      let "scanno = $index + 1"
+    while (( index < output_count && numscans > index )); do
+      let "scanno = index + 1"
       if [[ -f "${OUTPUT[$index]}" ]]; then
         mv "${OUTPUT[$index]}" "${OUTPUT[$index]}.orig"
         if [[ $APPEND == 1 ]]; then
@@ -303,9 +314,9 @@ if [[ $numscans > 0 ]]; then
       else
         mv $TMP_DIR/scan-*(0)$scanno.pdf "${OUTPUT[$index]}"
       fi
-      let "index = $index + 1"
+      let "index = index + 1"
     done
-  elif [[ $numscans > 1 || $APPEND == 1 ]]; then
+  elif (( numscans > 1 || APPEND == 1 )); then
     echo "Concatenating pdfs..."
     if [[ -f "$OUTPUT" ]]; then
       mv "$OUTPUT" "${OUTPUT}.orig"