[groff] 17/30: [mm]: Validate `LB` macro's 5th argument.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit c243961bcecdde89d9678223d5d1ef6a76131a67
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Wed Oct 9 23:41:01 2024 -0500

    [mm]: Validate `LB` macro's 5th argument.
    
    * contrib/mm/m.tmac (LB): Validate fifth (mark-or-format) argument.
      Getting it wrong leads to surprising formatter diagnostics.  Since
      we're (ultimately) passing it to the `af` request, ensure that it's a
      nonnegative integer or in the set {a,A,i,I}.
    
    The extra indentation is to make the next commit less noisy.
---
 contrib/mm/ChangeLog |  7 +++++++
 contrib/mm/m.tmac    | 15 ++++++++++++++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/contrib/mm/ChangeLog b/contrib/mm/ChangeLog
index 9109e80b3..b39568d01 100644
--- a/contrib/mm/ChangeLog
+++ b/contrib/mm/ChangeLog
@@ -1,3 +1,10 @@
+2024-10-09  G. Branden Robinson <g.branden.robinson@gmail.com>
+
+       * m.tmac (LB): Validate fifth (mark-or-format) argument.
+       Getting it wrong leads to surprising formatter diagnostics.
+       Since we're (ultimately) passing it to the `af` request, ensure
+       that it's a nonnegative integer or in the set {a,A,i,I}.
+
 2024-10-09  G. Branden Robinson <g.branden.robinson@gmail.com>
 
        * m.tmac: Refactor reference list formatting.
diff --git a/contrib/mm/m.tmac b/contrib/mm/m.tmac
index 24a581623..896444b73 100644
--- a/contrib/mm/m.tmac
+++ b/contrib/mm/m.tmac
@@ -2352,7 +2352,20 @@ breaking page
 .nr li*cnt!\\n[li*lvl] 0 1
 .\" assign format
 .af li*cnt!\\n[li*lvl] 1
-.if \\n[li*type] .if !'\\*[li*mf]'' .af li*cnt!\\n[li*lvl] \\*[li*mf]
+.if \\n[li*type] \{\
+.              nr li*is-format-valid 0
+.              if \B'\\*[li*mf]'&\\*[li*mf]>-1 .nr li*is-format-valid 1
+.              if '\?\\*[li*mf]\?'\?a\?'       .nr li*is-format-valid 1
+.              if '\?\\*[li*mf]\?'\?A\?'       .nr li*is-format-valid 1
+.              if '\?\\*[li*mf]\?'\?i\?'       .nr li*is-format-valid 1
+.              if '\?\\*[li*mf]\?'\?i\?'       .nr li*is-format-valid 1
+.              if !\\n[li*is-format-valid] \{\
+.                      @warning \\$0: type argument is \\n[li*type] \
+but mark argument '\\*[li*mf]' is not a valid register format; \
+assuming '0'
+.                      ds li*mf 0\"
+.              \}
+.\}
 .\"
 .if \\n[li*lb-spc] .SP (u;\\n[li*lb-spc]*\\n[Lsp])
 .in +\\n[li*tind]u