Re: [PATCH 2/2] Fortran: Fix memory leak in gfc_add_include_path [PR68800]

[Harald Anlauf <anlauf@gmx.de>]

Hi Bernhard,

I cannot comment on the gcc/ parts, but

Am 05.11.21 um 22:17 schrieb Bernhard Reutner-Fischer via Gcc-patches:
> From: Bernhard Reutner-Fischer <aldot@gcc.gnu.org>
> 
> gcc/fortran/ChangeLog:
> 
> 	PR fortran/68800
> 	* cpp.h (gfc_cpp_free_cpp_dirs): New declaration.
> 	* cpp.c (gfc_cpp_free_cpp_dirs): New definition.
> 	(gfc_cpp_add_include_path, gfc_cpp_add_include_path_after): Add
> 	comment.
> 	* f95-lang.c (gfc_finish): Call gfc_cpp_free_cpp_dirs.
> 	* scanner.c (add_path_to_list): Allocate unzeroed memory.
> 	(gfc_add_include_path): Add comment and fix formatting.
> 
> ---
> Bootstrapped and regtested without regressions on x86_64-unknown-linux.
> Ok for trunk?
> 
> Note: in add_path_to_list i changed dir->path = XCNEWVEC to XNEWVEC
> since strcpy and strcat add a terminating null byte for us anyway.
> Fixes:
> 
> -== 68 bytes in 1 blocks are still reachable in loss record 228 of 371
> -==    at : malloc (vg_replace_malloc.c:380)
> -==    by : xmalloc (xmalloc.c:149)
> -==    by : xstrdup (xstrdup.c:34)
> -==    by : gfc_add_include_path(char const*, bool, bool, bool, bool) (scanner.c
> :428)
> -==    by : gfc_handle_option(unsigned long, char const*, long, int, unsigned in
> t, cl_option_handlers const*) (options.c:702)
> -==    by : handle_option(gcc_options*, gcc_options*, cl_decoded_option const*,
> unsigned int, int, unsigned int, cl_option_handlers const*, bool, diagnostic_con
> text*) (opts-common.c:1181)
> -==    by : read_cmdline_option(gcc_options*, gcc_options*, cl_decoded_option*,
> unsigned int, unsigned int, cl_option_handlers const*, diagnostic_context*) (opt
> s-common.c:1431)
> -==    by : read_cmdline_options (opts-global.c:237)
> -==    by : decode_options(gcc_options*, gcc_options*, cl_decoded_option*, unsig
> ned int, unsigned int, diagnostic_context*, void (*)()) (opts-global.c:319)
> -==    by : toplev::main(int, char**) (toplev.c:2273)
> -==    by : main (main.c:39)
> ---
>   gcc/fortran/cpp.c      | 13 +++++++++++--
>   gcc/fortran/cpp.h      |  1 +
>   gcc/fortran/f95-lang.c |  2 +-
>   gcc/fortran/scanner.c  |  7 ++++---
>   4 files changed, 17 insertions(+), 6 deletions(-)
> 
> diff --git a/gcc/fortran/cpp.c b/gcc/fortran/cpp.c
> index e86386c8b17..04fe8fe460b 100644
> --- a/gcc/fortran/cpp.c
> +++ b/gcc/fortran/cpp.c
> @@ -728,12 +728,20 @@ gfc_cpp_done (void)
>     cpp_clear_file_cache (cpp_in);
>   }

why do you introduce a wrapper for something outside of fortran
that is used only once,

> -/* PATH must be malloc-ed and NULL-terminated.  */
> +/* Free all cpp include dirs.  */
> +void
> +gfc_cpp_free_cpp_dirs (void)
> +{
> +  free_cpp_dirs ();
> +}
> +
> +/* PATH must be NULL-terminated.  */
>   void
>   gfc_cpp_add_include_path (char *path, bool user_supplied)
>   {
>     /* CHAIN sets cpp_dir->sysp which differs from 0 if PATH is a system
> -     include path. Fortran does not define any system include paths.  */
> +     include path. Fortran does not define any system include paths.
> +     incpath.c manages the incoming, xstrdup()ed path.  */
>     int cxx_aware = 0;
>   
>     add_path (path, INC_BRACKET, cxx_aware, user_supplied);
> @@ -742,6 +750,7 @@ gfc_cpp_add_include_path (char *path, bool user_supplied)
>   void
>   gfc_cpp_add_include_path_after (char *path, bool user_supplied)
>   {
> +  /* incpath.c manages the incoming, xstrdup()ed path.  */
>     int cxx_aware = 0;
>     add_path (path, INC_AFTER, cxx_aware, user_supplied);
>   }
> diff --git a/gcc/fortran/cpp.h b/gcc/fortran/cpp.h
> index 44644a2a333..963b9a9c89e 100644
> --- a/gcc/fortran/cpp.h
> +++ b/gcc/fortran/cpp.h
> @@ -46,6 +46,7 @@ void gfc_cpp_post_options (bool);
>   bool gfc_cpp_preprocess (const char *source_file);
>   
>   void gfc_cpp_done (void);
> +void gfc_cpp_free_cpp_dirs (void);
>   
>   void gfc_cpp_add_include_path (char *path, bool user_supplied);
>   void gfc_cpp_add_include_path_after (char *path, bool user_supplied);
> diff --git a/gcc/fortran/f95-lang.c b/gcc/fortran/f95-lang.c
> index 58dcaf01d75..ec4c2cf01d9 100644
> --- a/gcc/fortran/f95-lang.c
> +++ b/gcc/fortran/f95-lang.c
> @@ -275,7 +275,7 @@ gfc_finish (void)
>     gfc_cpp_done ();
>     gfc_done_1 ();
>     gfc_release_include_path ();
> -  return;

namely here?

> +  gfc_cpp_free_cpp_dirs ();
>   }

Why not call free_cpp_dirs () here directly, omit all unnecessary
stuff, and maybe only add a brief comment here?

>   /* These functions and variables deal with binding contours.  We only
> diff --git a/gcc/fortran/scanner.c b/gcc/fortran/scanner.c
> index 69b81ab97f8..268d1e3e7fb 100644
> --- a/gcc/fortran/scanner.c
> +++ b/gcc/fortran/scanner.c
> @@ -370,7 +370,7 @@ add_path_to_list (gfc_directorylist **list, const char *path,
>     char *q;
>     size_t len;
>     int i;
> -
> +
>     p = path;
>     while (*p == ' ' || *p == '\t')  /* someone might do "-I include" */
>       if (*p++ == '\0')
> @@ -409,7 +409,7 @@ add_path_to_list (gfc_directorylist **list, const char *path,
>       *list = dir;
>     dir->use_for_modules = use_for_modules;
>     dir->warn = warn; > -  dir->path = XCNEWVEC (char, strlen (p) + 2);
> +  dir->path = XNEWVEC (char, strlen (p) + 2);
>     strcpy (dir->path, p);
>     strcat (dir->path, "/");	/* make '/' last character */
>   }
> @@ -424,8 +424,9 @@ gfc_add_include_path (const char *path, bool use_for_modules, bool file_dir,
>   		    defer_warn);
>   
>     /* For '#include "..."' these directories are automatically searched.  */
> +  /* CPP manages 'path' on it's own via incpath.c so give it it's own copy.  */
>     if (!file_dir)
> -    gfc_cpp_add_include_path (xstrdup(path), true);
> +    gfc_cpp_add_include_path (xstrdup (path), true);
>   }
>   
>   
> 

Harald