[groff] 05/11: [troff]: Free heap-allocated memory more reliably.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit 8a62f58d924776a9454ef43899060c95de6acf0a
Author: G. Branden Robinson <g.branden.robin...@gmail.com>
AuthorDate: Sun Feb 23 18:05:18 2025 -0600

    [troff]: Free heap-allocated memory more reliably.
    
    * src/roff/troff/input.cpp: More reliably release heap memory allocated
      by `read_string()`.
    
      (next_file, do_source, pipe_source_request, pipe_output)
      (system_request, copy_file, transparent_file, do_macro_source): Do it.
    
    It is not necessary to make conditional the `delete[]` of a null
    pointer.  "If the _delete-expression_ calls the implementation
    deallocation function (3.7.3.2), and if the operand of the delete
    expression is not the null pointer constant, the deallocation function
    will deallocate the storage referenced by the pointer thus rendering the
    pointer invalid" (ISO/IEC 14882-1998, §5.3.5, paragraph 4).  Or as
    Stroustrup puts it, "Applying _delete_ to zero has no effect." (_The C++
    Programming Language, Special Edition_, p. 128).
---
 ChangeLog                |  8 ++++++++
 src/roff/troff/input.cpp | 18 ++++++++++++------
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index a4d0b4926..2d28782f4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2025-02-23  G. Branden Robinson <g.branden.robin...@gmail.com>
+
+       * src/roff/troff/input.cpp: More reliably release heap memory
+       allocated by `read_string()`.
+       (next_file, do_source, pipe_source_request, pipe_output)
+       (system_request, copy_file, transparent_file, do_macro_source):
+       Do it.
+
 2025-02-23  G. Branden Robinson <g.branden.robin...@gmail.com>
 
        * src/roff/troff/input.cpp (class file_iterator): Make class
diff --git a/src/roff/troff/input.cpp b/src/roff/troff/input.cpp
index 2b1f0faff..2656ff236 100644
--- a/src/roff/troff/input.cpp
+++ b/src/roff/troff/input.cpp
@@ -931,6 +931,7 @@ void next_file()
     else
       input_stack::next_file(fp, filename);
   }
+  delete[] filename;
   tok.next();
 }
 
@@ -6787,6 +6788,7 @@ void do_source(bool quietly)
     // expected problem.
     if (!(quietly && (ENOENT == errno)))
       error("cannot open '%1': %2", filename, strerror(errno));
+  delete[] filename;
   tok.next();
 }
 
@@ -6827,7 +6829,7 @@ void pipe_source_request() // .pso
     return;
   }
   char *pcmd = read_string();
-  // This shouldn't happen thanks to `has_arg()` above.
+  // `has_arg()` should have ensured that this pointer is non-null.
   assert(pcmd != 0 /* nullptr */);
   if (0 /* nullptr */ == pcmd)
     error("cannot apply piped command source request to empty"
@@ -7604,6 +7606,7 @@ static void open_file(bool appending)
        stream_dictionary.define(stream, (object *)grost);
       }
     }
+    delete[] filename;
     tok.next();
   }
 }
@@ -8614,7 +8617,7 @@ void pipe_output()
     return;
   }
   char *pc = read_string();
-  // This shouldn't happen thanks to `has_arg()` above.
+  // `has_arg()` should have ensured that this pointer is non-null.
   assert(pc != 0 /* nullptr */);
   if (0 /* nullptr */ == pc)
     error("cannot apply pipe request to empty command");
@@ -8633,6 +8636,7 @@ void pipe_output()
   }
   else
     pipe_command = pc;
+  delete[] pc;
   tok.next();
 }
 
@@ -8653,14 +8657,13 @@ void system_request()
     return;
   }
   char *command = read_string();
-  // This shouldn't happen thanks to `has_arg()` above.
+  // `has_arg()` should have ensured that this pointer is non-null.
   assert(command != 0 /* nullptr */);
   if (0 /* nullptr */ == command)
     error("cannot apply system request to empty command");
-  else {
+  else
     system_status = system(command);
-    delete[] command;
-  }
+  delete[] command;
   tok.next();
 }
 
@@ -8687,6 +8690,7 @@ void copy_file()
     curenv->do_break();
   if (filename != 0 /* nullptr */)
     curdiv->copy_file(filename);
+  delete[] filename;
   tok.next();
 }
 
@@ -8751,6 +8755,7 @@ void transparent_file()
       fclose(fp);
     }
   }
+  delete[] filename;
   tok.next();
 }
 
@@ -8902,6 +8907,7 @@ void do_macro_source(bool quietly)
     if (!quietly && (ENOENT == errno))
       warning(WARN_FILE, "cannot open macro file '%1': %2",
              macro_filename, strerror(errno));
+  delete[] macro_filename;
   tok.next();
 }
 

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