installShellFiles: ensure shell completion has more than 256 bytes

I found an error in the completion script of tmuxp which were outputting
an error message instead of a proper script so a sanity check in the
installShellCompletion script is helpful to avoid this to happen in the
future.

After looking at possible ways to detect this, the only valid check I
found was based on the generated file size as any completion script I
could find had more than 256 bytes.

Signed-off-by: Otavio Salvador <[email protected]>

pkgs/build-support/setup-hooks/install-shell-files.sh

@@ -96,7 +96,7 @@ installManPage() {
 #
 # If any argument is `--` the remaining arguments will be treated as paths.
 installShellCompletion() {
-    local shell='' name='' cmdname='' retval=0 parseArgs=1 arg
+    local shell='' name='' cmdname='' size_check=256 retval=0 parseArgs=1 arg
     while { arg=$1; shift; }; do
         # Parse arguments
         if (( parseArgs )); then
@@ -122,6 +122,17 @@ installShellCompletion() {
                     return 1
                 }
                 continue;;
+            --size-check)
+                size_check=$1
+                shift || {
+                    echo 'installShellCompletion: error: --size-check flag expected an argument' >&2
+                    return 1
+                }
+                continue;;
+            --size-check=*)
+                # treat `--size-check=foo` the same as `--size-check foo`
+                size_check=${arg#--size-check=}
+                continue;;
             --cmd=*)
                 # treat `--cmd=foo` the same as `--cmd foo`
                 cmdname=${arg#--cmd=}
@@ -219,6 +230,12 @@ installShellCompletion() {
         else
             install -Dm644 -T "$arg" "$outPath"
         fi || return
+        # Sanity check file size to avoid assuming completion has succeed but it generate an invalid file.
+        local fileSize=$(stat -c%s "$outPath")
+        if (( fileSize < size_check )); then
+            echo "installShellCompletion: error: $outPath is too small ($fileSize only), use '--size-check $fileSize' to override" >&2
+            return 1
+        fi
         # Clear the per-path flags
         name=
     done

pkgs/test/install-shell-files/default.nix

@@ -55,7 +55,7 @@ recurseIntoAttrs {
     echo qux > qux.zsh
     echo quux > quux
 
-    installShellCompletion --bash foo bar --zsh baz qux.zsh --fish quux
+    installShellCompletion --size-check 4 --bash foo bar --zsh baz qux.zsh --fish quux
 
     cmp foo $out/share/bash-completion/completions/foo
     cmp bar $out/share/bash-completion/completions/bar
@@ -68,7 +68,7 @@ recurseIntoAttrs {
   } ''
     echo foo > foo
 
-    installShellCompletion --bash foo
+    installShellCompletion --size-check 4 --bash foo
 
     # assert it didn't go into $out
     [[ ! -f $out/share/bash-completion/completions/foo ]]
@@ -82,7 +82,7 @@ recurseIntoAttrs {
     echo bar > bar
     echo baz > baz
 
-    installShellCompletion --bash --name foobar.bash foo --zsh --name _foobar bar --fish baz
+    installShellCompletion --size-check 4 --bash --name foobar.bash foo --zsh --name _foobar bar --fish baz
 
     cmp foo $out/share/bash-completion/completions/foobar.bash
     cmp bar $out/share/zsh/site-functions/_foobar
@@ -93,7 +93,7 @@ recurseIntoAttrs {
     echo bar > bar.zsh
     echo baz > baz.fish
 
-    installShellCompletion foo.bash bar.zsh baz.fish
+    installShellCompletion --size-check 4 foo.bash bar.zsh baz.fish
 
     cmp foo.bash $out/share/bash-completion/completions/foo.bash
     cmp bar.zsh $out/share/zsh/site-functions/_bar
@@ -105,7 +105,7 @@ recurseIntoAttrs {
     echo baz > baz.fish
     echo qux > qux.fish
 
-    installShellCompletion --cmd foobar --bash foo.bash --zsh bar.zsh --fish baz.fish --name qux qux.fish
+    installShellCompletion --size-check 4 --cmd foobar --bash foo.bash --zsh bar.zsh --fish baz.fish --name qux qux.fish
 
     cmp foo.bash $out/share/bash-completion/completions/foobar.bash
     cmp bar.zsh $out/share/zsh/site-functions/_foobar
@@ -114,6 +114,7 @@ recurseIntoAttrs {
   '';
   install-completion-fifo = runTest "install-completion-fifo" {} ''
     installShellCompletion \
+      --size-check 4 \
       --bash --name foo.bash <(echo foo) \
       --zsh --name _foo <(echo bar) \
       --fish --name foo.fish <(echo baz)