fix: Verify generated session id (#1821)

src/mido.sh

@@ -83,9 +83,18 @@ download_windows() {
   local url="https://www.microsoft.com/en-us/software-download/windows$windows_version"
 
   # uuidgen: For MacOS (installed by default) and other systems (e.g. with no /proc) that don't have a kernel interface for generating random UUIDs
-  session_id=$(cat /proc/sys/kernel/random/uuid 2> /dev/null || uuidgen --random)
+  if ! session_id=$(cat /proc/sys/kernel/random/uuid 2> /dev/null || uuidgen --random); then
+    error "Failed to generate session ID!"
+    return 1
+  fi
+
   session_id="${session_id//[![:print:]]/}"
 
+  if [ -z "$session_id" ]; then
+    error "Failed to generate session ID!"
+    return 1
+  fi
+
   # Get product edition ID for latest release of given Windows version
   # Product edition ID: This specifies both the Windows release (e.g. 22H2) and edition ("multi-edition" is default, either Home/Pro/Edu/etc., we select "Pro" in the answer files) in one number
   # This is the *only* request we make that Fido doesn't. Fido manually maintains a list of all the Windows release/edition product edition IDs in its script (see: $WindowsVersions array). This is helpful for downloading older releases (e.g. Windows 10 1909, 21H1, etc.) but we always want to get the newest release which is why we get this value dynamically
@@ -651,9 +660,15 @@ verifyFile() {
   info "$msg" && html "$msg"
 
   if [[ "${algo,,}" != "sha256" ]]; then
-    hash=$(sha1sum "$iso" | cut -f1 -d' ')
+    if ! hash=$(sha1sum "$iso" | cut -f1 -d' '); then
+      error "Failed to calculate SHA1 checksum for $iso!"
+      return 1
+    fi
   else
-    hash=$(sha256sum "$iso" | cut -f1 -d' ')
+    if ! hash=$(sha256sum "$iso" | cut -f1 -d' '); then
+      error "Failed to calculate SHA256 checksum for $iso!"
+      return 1
+    fi
   fi
 
   if [[ "$hash" == "$check" ]]; then
@@ -678,8 +693,14 @@ downloadFile() {
   agent=$(get_agent)
 
   if [ -n "$size" ] && [[ "$size" != "0" ]]; then
+
     folder=$(dirname -- "$iso")
-    space=$(df --output=avail -B 1 "$folder" | tail -n 1)
+  
+    if ! space=$(df --output=avail -B 1 "$folder" | tail -n 1); then
+      error "Failed to check free space in $folder!"
+      return 1
+    fi
+  
     total_gb=$(formatBytes "$space")
     (( size > space )) && error "Not enough free space to download file, only $total_gb left!" && return 1
   fi
@@ -710,13 +731,22 @@ downloadFile() {
   fKill "progress.sh"
 
   if (( rc == 0 )) && [ -f "$iso" ]; then
-    total=$(stat -c%s "$iso")
+
+    if ! total=$(stat -c%s "$iso"); then
+      error "Failed to determine downloaded file size: $iso"
+      return 1
+    fi
+
     total_gb=$(formatBytes "$total")
+  
     if [ "$total" -lt 100000000 ]; then
       error "Invalid download link: $url (is only $total_gb ?). Please report this at $SUPPORT/issues" && return 1
     fi
+  
     verifyFile "$iso" "$size" "$total" "$sum" || return 1
+  
     isCompressed "$url" && UNPACK="Y"
+  
     html "Download finished successfully..." && return 0
   fi