Re: emacs-28 e5a49f44ff: * src/emacs.c (load_pdump): Fix use of xpalloc.

[Stefan Kangas <stefankangas@gmail.com>]

Andreas Schwab <schwab@gnu.org> writes:

> diff --git a/src/emacs.c b/src/emacs.c
> index 602fa802e0..92779a8d0d 100644
> --- a/src/emacs.c
> +++ b/src/emacs.c
> @@ -867,9 +867,8 @@ load_pdump (int argc, char **argv)
>      }
>
>    /* Where's our executable?  */
> -  ptrdiff_t bufsize, exec_bufsize;
> -  emacs_executable = load_pdump_find_executable (argv[0], &bufsize);
> -  exec_bufsize = bufsize;
> +  ptrdiff_t exec_bufsize, needed;
> +  emacs_executable = load_pdump_find_executable (argv[0], &exec_bufsize);
>
>    /* If we couldn't find our executable, go straight to looking for
>       the dump in the hardcoded location.  */
> @@ -902,8 +901,8 @@ load_pdump (int argc, char **argv)
>                       strip_suffix_length))
>         exenamelen = prefix_length;
>      }
> -  ptrdiff_t needed = exenamelen + strlen (suffix) + 1;
> -  dump_file = xpalloc (NULL, &bufsize, max (1, needed - bufsize), -1, 1);
> +  ptrdiff_t bufsize = exenamelen + strlen (suffix) + 1;
> +  dump_file = xpalloc (NULL, &bufsize, 1, -1, 1);
>    memcpy (dump_file, emacs_executable, exenamelen);
>    strcpy (dump_file + exenamelen, suffix);
>    result = pdumper_load (dump_file, emacs_executable);

This change leads to the below on macOS 10.13, using Apple LLVM
version 10.0.0 (clang-1000.10.44.4):

emacs.c:899:7: warning: variable 'bufsize' is used uninitialized
whenever 'if' condition is true [-Wsometimes-uninitialized]
  if (!(emacs_executable && *emacs_executable))
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
emacs.c:964:7: note: uninitialized use occurs here
  if (bufsize < needed)
      ^~~~~~~
emacs.c:899:3: note: remove the 'if' if its condition is always false
  if (!(emacs_executable && *emacs_executable))
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
emacs.c:928:3: note: variable 'bufsize' is declared here
  ptrdiff_t bufsize = exenamelen + strlen (suffix) + 1;
  ^
1 warning generated.