fix: Simplify error propagation boundaries (#2104)

src/image.sh

@@ -369,7 +369,7 @@ detectVersion() {
   local -a selection_order=()
   local result="" index=""
 
-  getVersions "$xml" versions bases groups image_indexes || return 1
+  getVersions "$xml" versions bases groups image_indexes || return
 
   if [ "${#versions[@]}" -eq 0 ]; then
     printf '%s\n%s\n' "$result" "$index"
@@ -924,7 +924,6 @@ detectReactOS() {
 findIsoImage() {
 
   local iso="$1"
-
   local path
 
   # Prefer install.wim when both payload forms are present.
@@ -1060,15 +1059,7 @@ readIsoImageInfo() {
 
   result=$(udfread range --ignore-case "$iso" "$image" "$xml_offset" "$xml_size" \
            2>/dev/null | iconv -f UTF-16LE -t UTF-8 2>/dev/null
-  ) || {
+  ) || return
-    local rc=$?
-
-    if (( rc >= 129 )); then
-      exit "$rc"
-    fi
-
-    return 1
-  }
 
   [ -n "$result" ] || return 1
 
@@ -1209,15 +1200,9 @@ readImageInfo() {
   local wim="$1"
   local result=""
 
-  result=$(wimlib-imagex info --xml "$wim" | iconv -f UTF-16LE -t UTF-8) || {
+  if ! result=$(wimlib-imagex info --xml "$wim" | iconv -f UTF-16LE -t UTF-8); then
-    local rc=$?
-
-    if (( rc >= 129 )); then
-      exit "$rc"
-    fi
-
     result=""
-  }
+  fi
 
   if [ -z "$result" ]; then
     error "Failed to read Windows image information!"
@@ -1349,10 +1334,10 @@ detectImageInfo() {
 
   checkPlatform "$image_info" || exit 67
 
-  suggested=$(getSuggestion) || return 1
+  suggested=$(getSuggestion) || return
 
   local output
-  output=$(detectVersion "$image_info" "$suggested") || return 1
+  output=$(detectVersion "$image_info" "$suggested") || return
 
   local -a detected=()
   mapfile -t detected <<< "$output"
@@ -1360,19 +1345,19 @@ detectImageInfo() {
   DETECTED="${detected[0]:-}"
   index="${detected[1]:-}"
 
-  validateEdition || return 1
+  validateEdition || return
 
   if [ -z "$DETECTED" ]; then
-    unknownImage || return 1
+    unknownImage || return
     return 0
   fi
 
-  detectLanguage "$image_info" "$index" || return 1
+  detectLanguage "$image_info" "$index" || return
 
-  desc=$(describeImage) || return 1
+  desc=$(describeImage) || return
   info "Detected: $desc"
 
-  configureImage "$index" "$desc" || return 1
+  configureImage "$index" "$desc" || return
 
   return 0
 }
@@ -1381,18 +1366,14 @@ detectIsoImage() {
 
   local iso="$1"
 
-  local image header image_info rc
+  local image header image_info
 
   # Return 1 only when no directly inspectable WIM/ESD payload is available so
   # the caller may extract the media. Metadata parsing/configuration errors use 2.
   image=$(findIsoImage "$iso") || return 1
   header=$(readWimHeader "$iso" "$image") || return 2
 
-  image_info=$(readIsoImageInfo "$iso" "$image" "$header") || {
+  image_info=$(readIsoImageInfo "$iso" "$image" "$header") || return 2
-    rc=$?
-    (( rc >= 129 )) && return "$rc"
-    return 2
-  }
 
   info "Detecting version from ISO image..."
   detectImageInfo "$image_info" || return 2
@@ -1471,11 +1452,12 @@ extractESD() {
     return 1
   fi
 
-  if ! xml=$(wimlib-imagex info "$iso" --xml 2>/dev/null |
+  xml=$(wimlib-imagex info "$iso" --xml 2>/dev/null |
-      iconv -f UTF-16LE -t UTF-8 2>/dev/null); then
+    iconv -f UTF-16LE -t UTF-8 2>/dev/null) || {
+    ret=$?
     error "Cannot read ESD file information!"
-    return 1
+    return "$ret"
-  fi
+  }
 
   # Microsoft download ESDs use images 1-3 for setup media, WinPE, and Windows
   # Setup; images 4 and higher contain installable editions. Read all metadata
@@ -1531,7 +1513,7 @@ extractESD() {
   # installation media. Peak additional usage consists of the extracted setup
   # files and boot.wim, plus the final ISO containing those files and the ESD.
   local freeSpace=$(( size + 2 * (bootSize + wimSize) + spacePad ))
-  checkFreeSpace "$dir" "$freeSpace" || return 1
+  checkFreeSpace "$dir" "$freeSpace" || return
 
   /run/progress.sh "$dir" "$bootSize" "$msg ([P])..." &
 
@@ -1540,7 +1522,7 @@ extractESD() {
     ret=$?
     fKill "progress.sh"
     error "Extracting $desc bootdisk failed ($ret)"
-    return 1
+    return "$ret"
   }
 
   fKill "progress.sh"
@@ -1559,7 +1541,7 @@ extractESD() {
     ret=$?
     fKill "progress.sh"
     error "Adding WinPE failed ($ret)"
-    return 1
+    return "$ret"
   }
 
   fKill "progress.sh"
@@ -1575,7 +1557,7 @@ extractESD() {
     ret=$?
     fKill "progress.sh"
     error "Adding Windows Setup failed ($ret)"
-    return 1
+    return "$ret"
   }
 
   fKill "progress.sh"
@@ -1602,9 +1584,9 @@ extractESD() {
       return 1
     fi
 
-    checkPlatform "$xml" || return 1
+    checkPlatform "$xml" || return
 
-    output=$(detectVersion "$installXml") || return 1
+    output=$(detectVersion "$installXml") || return
     mapfile -t detected <<< "$output"
 
     index="${detected[1]:-}"
@@ -1665,20 +1647,22 @@ extractESD() {
 
     (( image == index )) && continue
 
-    if ! wimlib-imagex delete "$installWim" "$image" --soft --quiet; then
+    wimlib-imagex delete "$installWim" "$image" --soft --quiet || {
+      ret=$?
       fKill "progress.sh"
       error "Failed to remove image $image from install.esd!"
-      return 1
+      return "$ret"
-    fi
+    }
 
   done
 
-  if ! result=$(wimlib-imagex info "$installWim" --xml 2>/dev/null |
+  result=$(wimlib-imagex info "$installWim" --xml 2>/dev/null |
-      iconv -f UTF-16LE -t UTF-8 2>/dev/null); then
+    iconv -f UTF-16LE -t UTF-8 2>/dev/null) || {
+    ret=$?
     fKill "progress.sh"
     error "Cannot verify the prepared install.esd file!"
-    return 1
+    return "$ret"
-  fi
+  }
 
   if ! metadata=$(xmlstarlet sel -t \
       -v 'count(/WIM/IMAGE)' -n \
@@ -2009,7 +1993,7 @@ buildImage() {
 
   local cat="BOOT.CAT"
   local log="/run/shm/iso.log"
-  local base size desc failed=""
+  local base size desc rc=0
 
   if [ -f "$BOOT" ]; then
     error "File $BOOT does already exist?!" && return 1
@@ -2118,15 +2102,14 @@ buildImage() {
 
   fi
 
-  if ! genisoimage "${args[@]}" -quiet "$dir" 2> "$log"; then
+  genisoimage "${args[@]}" -quiet "$dir" 2> "$log" || rc=$?
-    failed="y"
-  fi
 
   fKill "progress.sh"
 
-  if [ -n "$failed" ]; then
+  if (( rc != 0 )); then
     [ -s "$log" ] && echo "$(<"$log")"
-    error "Failed to build image!" && return 1
+    error "Failed to build image!"
+    return "$rc"
   fi
 
   local err=""
@@ -2139,7 +2122,7 @@ buildImage() {
     echo "$err"
   fi
 
-  mv -f "$out" "$BOOT" || return 1
+  mv -f "$out" "$BOOT" || return
 
   if ! setOwner "$BOOT"; then
     warn "Failed to set the owner for \"$BOOT\" !"

src/install.sh

@@ -43,8 +43,6 @@ selectWindowsImage() {
   local dir="$2"
   local boot="$3"
 
-  local detect_rc=0
-
   # Known versions already provide the required image metadata.
   if resolveImage "$VERSION"; then
 
@@ -67,20 +65,10 @@ selectWindowsImage() {
   fi
 
   # Inspect unknown media directly before falling back to extraction.
-  detectIsoImage "$iso" || detect_rc=$?
+  detectIsoImage "$iso" && return 0
 
-  if (( detect_rc == 0 )); then
+  local rc=$?
-    return 0
+  (( rc == 1 )) || return 76
-  fi
-
-  if (( detect_rc >= 129 )); then
-    return "$detect_rc"
-  fi
-
-  # Only code 1 indicates that extraction may recover detection.
-  if (( detect_rc != 1 )); then
-    return 76
-  fi
 
   if ! extractImage "$iso" "$dir" "$VERSION"; then
     removeImage "$iso" || :
@@ -88,21 +76,11 @@ selectWindowsImage() {
   fi
 
   extracted=1
-  detect_rc=0
 
-  detectImage "$dir" || detect_rc=$?
+  detectImage "$dir" && return 0
 
-  if (( detect_rc == 0 )); then
+  rc=$?
-    return 0
+  (( rc == 1 )) || return 76
-  fi
-
-  if (( detect_rc >= 129 )); then
-    return "$detect_rc"
-  fi
-
-  if (( detect_rc != 1 )); then
-    return 76
-  fi
 
   skipUnattended "$dir" "$iso" "$boot" || return 76
 
@@ -189,10 +167,10 @@ prepareWindowsImage() {
 
 bootWindows() {
 
-  restoreMachineState || return 1
+  restoreMachineState || return
-  restoreBootMode || return 1
+  restoreBootMode || return
-  restoreMachine || return 1
+  restoreMachine || return
-  reserveSambaPorts || return 1
+  reserveSambaPorts || return
 
   return 0
 }
@@ -752,9 +730,8 @@ getArchiveSize() {
 
   listing=$(7z l -slt "$file" 2>/dev/null) || {
     rc=$?
-    (( rc >= 129 )) && exit "$rc"
     error "Failed to read archive information: $file"
-    return 1
+    return "$rc"
   }
 
   while IFS= read -r line; do
@@ -797,11 +774,7 @@ extractImage() {
   fi
 
   if [[ "${iso,,}" == *".esd" ]]; then
-    extractESD "$iso" "$dir" "$version" "$desc" || {
+    extractESD "$iso" "$dir" "$version" "$desc" || return
-      rc=$?
-      (( rc >= 129 )) && exit "$rc"
-      return 1
-    }
     return 0
   fi
 
@@ -833,7 +806,7 @@ extractImage() {
   required="$size"
 
   if enabled "${UNPACK:-}"; then
-    getArchiveSize "$iso" archiveSize || return 1
+    getArchiveSize "$iso" archiveSize || return
     required="$archiveSize"
   fi
 
@@ -849,9 +822,8 @@ extractImage() {
   7z x "$iso" -o"$target" > /dev/null || {
     rc=$?
     fKill "progress.sh"
-    (( rc >= 129 )) && exit "$rc"
     error "Failed to extract ISO file: $iso"
-    return 1
+    return "$rc"
   }
 
   fKill "progress.sh"
@@ -897,9 +869,8 @@ extractImage() {
 
     7z x "$iso" -o"$dir" > /dev/null || {
       rc=$?
-      (( rc >= 129 )) && exit "$rc"
       error "Failed to extract nested ISO file: $iso"
-      return 1
+      return "$rc"
     }
 
     LABEL=$(isoinfo -d -i "$iso" | sed -n 's/Volume id: //p') || LABEL=""
@@ -915,32 +886,29 @@ detectImage() {
 
   local dir="$1"
 
-  local desc detect_rc=0
+  local desc rc
 
   info "Detecting version from ISO image..."
 
   # Marker-based legacy and ReactOS detection must run before looking for a WIM.
-  detectLegacy "$dir" || detect_rc=$?
+  if detectLegacy "$dir"; then
-
-  if (( detect_rc == 0 )); then
     desc=$(printEdition "$DETECTED" "$DETECTED" "Y") || return 2
     info "Detected: $desc"
     return 0
+  else
+    rc=$?
+    (( rc == 1 )) || return "$rc"
   fi
 
-  (( detect_rc == 1 )) || return "$detect_rc"
+  if detectReactOS "$dir"; then
-
-  detect_rc=0
-  detectReactOS "$dir" || detect_rc=$?
-
-  if (( detect_rc == 0 )); then
     desc=$(printEdition "$DETECTED" "$DETECTED" "Y") || return 2
     info "Detected: $desc"
     return 0
+  else
+    rc=$?
+    (( rc == 1 )) || return "$rc"
   fi
 
-  (( detect_rc == 1 )) || return "$detect_rc"
-
   local wim
   wim=$(findImage "$dir") || return $?
 
@@ -1370,11 +1338,11 @@ checkMemory() {
   local id="$1"
   local required name
 
-  required=$(getRequiredMemory "$id") || return 1
+  required=$(getRequiredMemory "$id") || return
   RAM_MINIMUM="$required"
 
-  name=$(printVersion "$id" "") || return 1
+  name=$(printVersion "$id" "") || return
-  checkMemoryRequirement "$name" || return 1
+  checkMemoryRequirement "$name" || return
 
   return 0
 }

src/mido.sh

@@ -126,11 +126,7 @@ downloadWindowsLink() {
     --output /dev/null \
     --header "Accept:" \
     --max-filesize 100K \
-    -- "$vlsUrl" || {
+    -- "$vlsUrl" || return
-      local rc=$?
-      (( rc >= 129 )) && exit "$rc"
-      return 1
-    }
 
   # Complete Microsoft's ov-df challenge by retrieving a token and timing
   # value, then returning both with the current timestamp.
@@ -143,11 +139,7 @@ downloadWindowsLink() {
   ovData=$(curlRequest "Microsoft" "$agent" \
     --header "Accept:" \
     --max-filesize 1M \
-    -- "$ovUrl") || {
+    -- "$ovUrl") || return
-      local rc=$?
-      (( rc >= 129 )) && exit "$rc"
-      return 1
-    }
 
   if [[ $ovData =~ [\?\&]w=([A-Fa-f0-9]+) ]]; then
     ovToken="${BASH_REMATCH[1]}"
@@ -175,11 +167,7 @@ downloadWindowsLink() {
     --output /dev/null \
     --header "Accept:" \
     --max-filesize 100K \
-    -- "$ovUrl" || {
+    -- "$ovUrl" || return
-      local rc=$?
-      (( rc >= 129 )) && exit "$rc"
-      return 1
-    }
 
   enabled "$DEBUG" && echo -n "Getting language SKU ID: "
 
@@ -189,17 +177,13 @@ downloadWindowsLink() {
     --referer "$url" \
     --header "Accept:" \
     --max-filesize 100K \
-    -- "$skuUrl") || {
+    -- "$skuUrl") || return
-      local rc=$?
-      (( rc >= 129 )) && exit "$rc"
-      return 1
-    }
 
-  # Guard jq under errexit so malformed API data can be handled as a normal
+  # Let jq parsing failures propagate so malformed API data is not mistaken
-  # missing-result error. The same pattern is reused for the link response.
+  # for a normal missing-result response. The same applies to the link data.
-  { skuId=$(printf '%s\n' "$skuJson" | jq --arg LANG "$language" -r 'first(.Skus[]? | select(.Language == $LANG) | .Id) // empty') 2>/dev/null; local rc=$?; } || :
+  skuId=$(printf '%s\n' "$skuJson" | jq --arg LANG "$language" -r 'first(.Skus[]? | select(.Language == $LANG) | .Id) // empty') 2>/dev/null || return
 
-  if [ -z "$skuId" ] || [[ "${skuId,,}" == "null" ]] || (( rc != 0 )); then
+  if [ -z "$skuId" ] || [[ "${skuId,,}" == "null" ]]; then
     language=$(getLanguage "$lang" "desc")
     error "No download in the $language language available for $desc!"
     return 1
@@ -217,11 +201,7 @@ downloadWindowsLink() {
     --referer "$url" \
     --header "Accept:" \
     --max-filesize 100K \
-    -- "$linkUrl") || {
+    -- "$linkUrl") || return
-      local rc=$?
-      (( rc >= 129 )) && exit "$rc"
-      return 1
-    }
 
   if ! [ "$linkJson" ]; then
     error "Microsoft servers gave us an empty response to our request for an automated download."
@@ -238,9 +218,9 @@ downloadWindowsLink() {
     return 1
   fi
 
-  { link=$(printf '%s\n' "$linkJson" | jq --argjson TYPE "$type" -r 'first(.ProductDownloadOptions[]? | select(.DownloadType == $TYPE) | .Uri) // empty') 2>/dev/null; rc=$?; } || :
+  link=$(printf '%s\n' "$linkJson" | jq --argjson TYPE "$type" -r 'first(.ProductDownloadOptions[]? | select(.DownloadType == $TYPE) | .Uri) // empty') 2>/dev/null || return
 
-  if [ -z "$link" ] || [[ "${link,,}" == "null" ]] || (( rc != 0 )); then
+  if [ -z "$link" ] || [[ "${link,,}" == "null" ]]; then
     error "Microsoft server gave us no download link to our request for an automated download!"
     info "Response: $linkJson"
     return 1
@@ -256,7 +236,7 @@ downloadWindows() {
   local lang="$2"
   local desc="$3"
 
-  local agent language page
+  local agent language page rc
   local productId type winVer
 
   agent=$(getAgent)
@@ -287,9 +267,12 @@ downloadWindows() {
 
   if downloadWindowsLink "$productId" "$url" "$agent" "$language" "$lang" "$desc" "$type"; then
     return 0
+  else
+    rc=$?
+    (( rc == 1 )) || return "$rc"
   fi
 
-  sleep 1
+  sleep 1 || return
 
   # Product edition IDs can change. If the configured ID fails, recover the
   # current value from Microsoft's public download page and retry once.
@@ -300,11 +283,7 @@ downloadWindows() {
   page=$(curlRequest "Microsoft" "$agent" \
     --header "Accept:" \
     --max-filesize 1M \
-    -- "$url") || {
+    -- "$url") || return
-      local rc=$?
-      (( rc >= 129 )) && exit "$rc"
-      return 1
-    }
 
   enabled "$DEBUG" && echo -n "Getting Product edition ID: "
   productId=$(printf '%s' "$page" |
@@ -312,7 +291,7 @@ downloadWindows() {
     grep -Eio "<option[^>]*value=[\"'][0-9]+[\"'][^>]*>[[:space:]]*Windows[^<]*" |
     sed -nE "s/.*value=[\"']([0-9]+)[\"'].*/\1/p" |
     sed -n '1p' |
-    cut -c 1-16 || true)
+    cut -c 1-16) || return
   enabled "$DEBUG" && echo "$productId"
 
   if [ -z "$productId" ]; then
@@ -320,9 +299,7 @@ downloadWindows() {
     return 1
   fi
 
-  if ! downloadWindowsLink "$productId" "$url" "$agent" "$language" "$lang" "$desc" "$type"; then
+  downloadWindowsLink "$productId" "$url" "$agent" "$language" "$lang" "$desc" "$type" || return
-    return 1
-  fi
 
   return 0
 }
@@ -334,12 +311,9 @@ downloadWindowsEval() {
   local desc="$3"
 
   local compare compare_name link_name
-  local agent culture language type winVer
+  local agent culture language type winVer rc
 
   case "${id,,}" in
-    "win10${PLATFORM,,}-enterprise-eval" )
-      type="enterprise"
-      winVer="windows-10-enterprise" ;;
     "win11${PLATFORM,,}-enterprise-eval" )
       type="enterprise"
       winVer="windows-11-enterprise" ;;
@@ -385,11 +359,7 @@ downloadWindowsEval() {
   page=$(curlRequest "Microsoft" "$agent" \
     --location \
     --max-filesize 1M \
-    -- "$url") || {
+    -- "$url") || return
-      local rc=$?
-      (( rc >= 129 )) && exit "$rc"
-      return 1
-    }
 
   if ! [ "$page" ]; then
     error "Evaluation Center download page gave us an empty response"
@@ -438,8 +408,8 @@ downloadWindowsEval() {
         --write-out "%{redirect_url}" \
         --head \
         -- "$candidate") || {
-          local rc=$?
+          rc=$?
-          (( rc >= 129 )) && exit "$rc"
+          (( rc == 1 )) || return "$rc"
           continue
         }
 
@@ -531,11 +501,7 @@ downloadWindowsEval() {
     --output /dev/null \
     --write-out "%{url_effective}" \
     --head \
-    -- "$link") || {
+    -- "$link") || return
-      local rc=$?
-      (( rc >= 129 )) && exit "$rc"
-      return 1
-    }
 
   local lower="${link,,}"
   local separator='(^|[[:space:]_./-])'
@@ -640,7 +606,7 @@ downloadWindowsLtsc() {
   local lang="$2"
   local desc="$3"
 
-  local alternate alternate_desc
+  local alternate alternate_desc rc
 
   case "${id,,}" in
     "win11${PLATFORM,,}-enterprise-iot-eval" )
@@ -657,19 +623,21 @@ downloadWindowsLtsc() {
   if downloadWindowsEval "$id" "$lang" "$desc" > /dev/null 2>&1; then
     MIDO_SOURCE="$id"
     return 0
+  else
+    rc=$?
+    (( rc == 1 )) || return "$rc"
   fi
 
   alternate_desc=$(printEdition "$alternate" "$alternate" "Y")
 
   info "Primary download source failed, trying $alternate_desc instead..."
 
-  if downloadWindowsEval "$alternate" "$lang" "$alternate_desc"; then
+  downloadWindowsEval "$alternate" "$lang" "$alternate_desc" || return
+
   MIDO_SOURCE="$alternate"
   warn "the requested $desc was unavailable, using $alternate_desc instead."
-    return 0
-  fi
 
-  return 1
+  return 0
 }
 
 getWindows() {
@@ -679,7 +647,7 @@ getWindows() {
   local desc="$3"
   local web_desc="$4"
 
-  local language edition
+  local language edition rc
 
   MIDO_SOURCE=""
   MIDO_STATIC="N"
@@ -727,19 +695,29 @@ getWindows() {
       if downloadWindows "$version" "$lang" "$edition"; then
         MIDO_SOURCE="$version"
         return 0
+      else
+        rc=$?
+        (( rc == 1 )) || return "$rc"
       fi ;;
 
     "win11${PLATFORM,,}-enterprise-iot-eval" | \
     "win11${PLATFORM,,}-enterprise-ltsc-eval" )
 
-      downloadWindowsLtsc "$version" "$lang" "$edition" && return 0 ;;
+      if downloadWindowsLtsc "$version" "$lang" "$edition"; then
+        return 0
+      else
+        rc=$?
+        (( rc == 1 )) || return "$rc"
+      fi ;;
 
-    "win10${PLATFORM,,}-enterprise-eval" | \
     "win11${PLATFORM,,}-enterprise"* )
 
       if downloadWindowsEval "$version" "$lang" "$edition"; then
         MIDO_SOURCE="$version"
         return 0
+      else
+        rc=$?
+        (( rc == 1 )) || return "$rc"
       fi ;;
 
     "win2025-eval" | "win2022-eval" | "win2019-eval" | \
@@ -748,6 +726,9 @@ getWindows() {
       if downloadWindowsEval "$version" "$lang" "$edition"; then
         MIDO_SOURCE="$version"
         return 0
+      else
+        rc=$?
+        (( rc == 1 )) || return "$rc"
       fi ;;
 
     "win2008r2"*| "win81${PLATFORM,,}"* | "win10${PLATFORM,,}-enterprise"* ) ;;
@@ -1077,7 +1058,10 @@ getESD() {
   local msg="Downloading ESD catalog..."
   info "$msg" && html "$msg"
 
-  rm -rf "$dir"
+  if ! rm -rf "$dir"; then
+    error "Failed to remove directory \"$dir\" !"
+    return 1
+  fi
 
   if ! makeDir "$dir"; then
     error "Failed to create directory \"$dir\" !"
@@ -1118,7 +1102,7 @@ getESD() {
     rm -f "$log"
 
     if (( rc >= 129 )); then
-      exit "$rc"
+      return "$rc"
     fi
 
     return 1
@@ -1160,8 +1144,7 @@ getESD() {
     validateESDCatalog "$dir/$xmlFile" "$provider" || return 1
   fi
 
-  if ! parseESD \
+  if ! parseESD "$dir/$xmlFile" "$version" "$lang" "$desc" "$edition" "$culture"; then
-    "$dir/$xmlFile" "$version" "$lang" "$desc" "$edition" "$culture"; then
     return 1
   fi
 
@@ -1222,26 +1205,16 @@ verifyFile() {
 
     hash=$(sha1sum "$iso" | cut -f1 -d' ') || {
       local rc=$?
-
-      if (( rc >= 129 )); then
-        exit "$rc"
-      fi
-
       error "Failed to calculate SHA1 checksum for $iso!"
-      return 1
+      return "$rc"
     }
 
   else
 
     hash=$(sha256sum "$iso" | cut -f1 -d' ') || {
       local rc=$?
-
-      if (( rc >= 129 )); then
-        exit "$rc"
-      fi
-
       error "Failed to calculate SHA256 checksum for $iso!"
-      return 1
+      return "$rc"
     }
 
   fi
@@ -1315,7 +1288,7 @@ tryDownload() {
     minimum="10485760"
   fi
 
-  if downloadRetry \
+  downloadRetry \
     "$iso" \
     "${CONNECTIONS:-1}" \
     "$seconds" \
@@ -1325,17 +1298,7 @@ tryDownload() {
     "$url" \
     "$size" \
     "$desc" \
-      "$web_desc"; then
+    "$web_desc" || return
-    local rc=0
-  else
-    local rc=$?
-  fi
-
-  if (( rc >= 129 )); then
-    exit "$rc"
-  fi
-
-  (( rc == 0 )) || return "$rc"
 
   # The shared helper already inspected the file, so this should
   # only fail if the downloaded file was removed unexpectedly afterward.
@@ -1345,12 +1308,15 @@ tryDownload() {
   fi
 
   # Status 2 means the completed download failed deterministic validation.
-  if ! verifyFile "$iso" "$size" "$total" "$sum"; then
+  verifyFile "$iso" "$size" "$total" "$sum" || {
+    local rc=$?
+    (( rc == 1 )) || return "$rc"
+
     if ! rm -f -- "$iso" "$iso.aria2"; then
       warn "failed to remove invalid download \"$iso\"!"
     fi
     return 2
-  fi
+  }
 
   # Extract the .iso from the compressed archive if needed.
   isCompressed "$url" && UNPACK="Y"
@@ -1379,7 +1345,7 @@ fallbackEnglish() {
   # still locate the same image, but use English installation media.
   LANGUAGE="en"
 
-  removeImage "$iso" || return 1
+  removeImage "$iso" || return
 
   downloadImage "$iso" "$version" "$LANGUAGE"
 }
@@ -1410,7 +1376,7 @@ downloadImage() {
   local detected="$DETECTED"
   local requested="$version" switched=""  
   local tried="n" success="n" seconds="5"
-  local i url sum size base language desc web_desc metadata
+  local i url sum size base language desc web_desc metadata rc
 
   if [[ "${version,,}" == "http"* ]]; then
 
@@ -1418,7 +1384,7 @@ downloadImage() {
     desc=$(fromFile "$base")
     web_desc="$desc"
 
-    tryDownload "$iso" "$version" "" "" "$desc" "$seconds" "$web_desc" || return 1
+    tryDownload "$iso" "$version" "" "" "$desc" "$seconds" "$web_desc" || return
     return 0
   fi
 
@@ -1437,7 +1403,7 @@ downloadImage() {
       web_desc=$(printEdition "$version" "$web_desc")
       desc+=" in $language"
 
-      fallbackEnglish "$iso" "$version" "$lang" "$desc" || return 1
+      fallbackEnglish "$iso" "$version" "$lang" "$desc" || return
       return 0
 
     fi
@@ -1455,8 +1421,17 @@ downloadImage() {
     if getWindows "$version" "$lang" "$desc" "$web_desc"; then
       success="y"
     else
-      delay "$seconds"
+      rc=$?
-      getWindows "$version" "$lang" "$desc" "$web_desc" && success="y"
+      (( rc == 1 )) || return "$rc"
+
+      delay "$seconds" || return
+
+      if getWindows "$version" "$lang" "$desc" "$web_desc"; then
+        success="y"
+      else
+        rc=$?
+        (( rc == 1 )) || return "$rc"
+      fi
     fi
 
     if [[ "$success" == "y" ]]; then
@@ -1483,6 +1458,9 @@ downloadImage() {
         # Commit the candidate only after the image was downloaded and verified.
         DETECTED="$detected"
         return 0
+      else
+        rc=$?
+        (( rc == 1 || rc == 2 )) || return "$rc"
       fi
 
     fi
@@ -1520,7 +1498,15 @@ downloadImage() {
     if getESD "$TMP/esd" "$version" "$lang" "$desc"; then
       success="y"
     else
-      getESD "$TMP/esd" "$version" "$lang" "$desc" "wor" && success="y"
+      rc=$?
+      (( rc == 1 )) || return "$rc"
+
+      if getESD "$TMP/esd" "$version" "$lang" "$desc" "wor"; then
+        success="y"
+      else
+        rc=$?
+        (( rc == 1 )) || return "$rc"
+      fi
     fi
 
     if [[ "$success" == "y" ]]; then
@@ -1531,6 +1517,9 @@ downloadImage() {
 
       if tryDownload "$ISO" "$ESD" "$ESD_SUM" "$ESD_SIZE" "$desc" "$seconds" "$web_desc"; then
         return 0
+      else
+        rc=$?
+        (( rc == 1 || rc == 2 )) || return "$rc"
       fi
 
       ISO="$iso"
@@ -1552,14 +1541,19 @@ downloadImage() {
       size=$(getSize "$i" "$version" "$lang")
       sum=$(getHash "$i" "$version" "$lang")
 
-      tryDownload "$iso" "$url" "$sum" "$size" "$desc" "$seconds" "$web_desc" && return 0
+      if tryDownload "$iso" "$url" "$sum" "$size" "$desc" "$seconds" "$web_desc"; then
+        return 0
+      else
+        rc=$?
+        (( rc == 1 || rc == 2 )) || return "$rc"
+      fi
 
     fi
 
   done
 
   if [[ "${lang,,}" != "en" && "${lang,,}" != "en-"* ]]; then
-    fallbackEnglish "$iso" "$requested" "$lang" "$desc" || return 1
+    fallbackEnglish "$iso" "$requested" "$lang" "$desc" || return
     return 0
   fi