Runtime safety of non threadsafe devices and rework globals.

Some devices within Ghostscript (currently the x11 devices,
uniprint and opvp/oprp) use non const static variables, so cannot
be run in multiple instances at a time.

We now maintain a core "count" of how many non-threadsafe devices are
being used at any time. This value can be atomically adjusted by calls
to gs_lib_ctx_nts_adjust.

Non threadsafe devices now call gx_init_non_threadsafe_device either
as or as part of their initialise_device proc. This function attempts
to increment the non-threadsafe count and fails to init if there is
already a non-threadsafe device running.

On success, the device finalize method is modified so that it will
decrement the count at the end.

The known non-threadsafe devices are updated to call this.

In order to have somewhere safe to store this count, we introduce
a gs_globals structure, shared between instances. Setting this up
without race conditions requires some new gp_ functions that can
make use of platform specific threading primitives. We have these
implemented for both windows and pthread based platforms. On other
platforms, we drop back to the old unsafe mechanism for counting
instances.

While we do this work, we take the opportunity to push the
gs_memory_t pointer used for non-threadsafe debug printing into thread
local storage.

This enables us to remove the remaining GS_THREADSAFE guarded
compilation from the source code. What is left is broadly down to
allowing debugging collection for statistics, and these are now
controlled by specific COLLECT_STATS_XXX defines. It is assumed
that anyone wanting to collect such stats is smart enough to not
try to do so while using Ghostscript in a multi-instance environment.

1 files changed, 24 insertions, 0 deletions

diff --git a/pcl/pl/plapi.c b/pcl/pl/plapi.c
index 1dc11b51b..2f8c18a10 100644
--- a/pcl/pl/plapi.c
+++ b/pcl/pl/plapi.c
@@ -109,6 +109,7 @@ gsapi_init_with_args(void *lib, int argc, char **argv)
     if (lib == NULL)
         return gs_error_Fatal;
 
+    gp_set_debug_mem_ptr(ctx->memory);
     return pl_main_init_with_args(pl_main_get_instance(ctx->memory), argc, argv);
 }
 
@@ -124,6 +125,7 @@ gsapi_run_file(void *lib, const char *file_name, int user_errors, int *pexit_cod
     if (lib == NULL)
         return gs_error_Fatal;
 
+    gp_set_debug_mem_ptr(ctx->memory);
     code = gs_add_control_path(ctx->memory, gs_permit_file_reading, file_name);
     if (code < 0) return code;
 
@@ -142,6 +144,7 @@ gsapi_exit(void *lib)
     if (lib == NULL)
         return gs_error_Fatal;
 
+    gp_set_debug_mem_ptr(ctx->memory);
     return pl_to_exit(ctx->memory);
 }
 
@@ -152,6 +155,7 @@ gsapi_delete_instance(void *lib)
     if (lib == NULL)
         return gs_error_Fatal;
 
+    gp_set_debug_mem_ptr(ctx->memory);
     return pl_main_delete_instance(pl_main_get_instance(ctx->memory));
 }
 
@@ -161,6 +165,7 @@ GSDLLEXPORT int GSDLLAPI gsapi_set_poll(void *instance,
     gs_lib_ctx_t *ctx = (gs_lib_ctx_t *)instance;
     if (instance == NULL)
         return gs_error_Fatal;
+    gp_set_debug_mem_ptr(ctx->memory);
     return gsapi_set_poll_with_handle(instance, poll_fn,
                                       ctx->core->default_caller_handle);
 }
@@ -183,6 +188,7 @@ gsapi_set_display_callback(void *lib, display_callback *callback)
     gs_lib_ctx_t *ctx = (gs_lib_ctx_t *)lib;
     if (lib == NULL)
         return gs_error_Fatal;
+    gp_set_debug_mem_ptr(ctx->memory);
     pl_main_set_display_callback(pl_main_get_instance(ctx->memory), callback);
     return 0;
 }
@@ -193,6 +199,7 @@ gsapi_set_default_device_list(void *instance, const char *list, int listlen)
     gs_lib_ctx_t *ctx = (gs_lib_ctx_t *)instance;
     if (instance == NULL)
         return gs_error_Fatal;
+    gp_set_debug_mem_ptr(ctx->memory);
     return gs_lib_ctx_set_default_device_list(ctx->memory, list, listlen);
 }
 
@@ -202,6 +209,7 @@ gsapi_get_default_device_list(void *instance, char **list, int *listlen)
     gs_lib_ctx_t *ctx = (gs_lib_ctx_t *)instance;
     if (instance == NULL)
         return gs_error_Fatal;
+    gp_set_debug_mem_ptr(ctx->memory);
     return gs_lib_ctx_get_default_device_list(ctx->memory, list, listlen);
 }
 
@@ -290,6 +298,7 @@ gsapi_set_arg_encoding(void *instance, int encoding)
     if (instance == NULL)
         return gs_error_Fatal;
 
+    gp_set_debug_mem_ptr(ctx->memory);
     if (encoding == PL_ARG_ENCODING_LOCAL) {
 #if defined(__WIN32__) && !defined(METRO)
         /* For windows, we need to set it up so that we convert from 'local'
@@ -323,6 +332,7 @@ gsapi_run_string_begin(void *lib, int user_errors, int *pexit_code)
 
     if (lib == NULL)
         return gs_error_Fatal;
+    gp_set_debug_mem_ptr(ctx->memory);
     return pl_main_run_string_begin(pl_main_get_instance(ctx->memory));
 }
 
@@ -337,6 +347,7 @@ gsapi_run_string_continue(void *lib, const char *str, unsigned int length,
 
     if (lib == NULL)
         return gs_error_Fatal;
+    gp_set_debug_mem_ptr(ctx->memory);
     return pl_main_run_string_continue(pl_main_get_instance(ctx->memory), str, length);
 }
 
@@ -350,6 +361,7 @@ gsapi_run_string_end(void *lib, int user_errors, int *pexit_code)
 
     if (lib == NULL)
         return gs_error_Fatal;
+    gp_set_debug_mem_ptr(ctx->memory);
     return pl_main_run_string_end(pl_main_get_instance(ctx->memory));
 }
 
@@ -383,6 +395,7 @@ gsapi_set_param(void *lib, const char *param, const void *value, gs_set_param_ty
     gs_lib_ctx_t *ctx = (gs_lib_ctx_t *)lib;
     if (lib == NULL)
         return gs_error_Fatal;
+    gp_set_debug_mem_ptr(ctx->memory);
     return pl_main_set_typed_param(pl_main_get_instance(ctx->memory), (pl_set_param_type)type, param, value);
 }
 
@@ -392,6 +405,7 @@ gsapi_get_param(void *lib, const char *param, void *value, gs_set_param_type typ
     gs_lib_ctx_t *ctx = (gs_lib_ctx_t *)lib;
     if (lib == NULL)
         return gs_error_Fatal;
+    gp_set_debug_mem_ptr(ctx->memory);
     return pl_main_get_typed_param(pl_main_get_instance(ctx->memory), (pl_set_param_type)type, param, value);
 }
 
@@ -401,6 +415,7 @@ gsapi_enumerate_params(void *lib, void **iterator, const char **key, gs_set_para
     gs_lib_ctx_t *ctx = (gs_lib_ctx_t *)lib;
     if (lib == NULL)
         return gs_error_Fatal;
+    gp_set_debug_mem_ptr(ctx->memory);
     return pl_main_enumerate_params(pl_main_get_instance(ctx->memory),
                                     iterator, key, (pl_set_param_type*)type);
 }
@@ -411,6 +426,7 @@ gsapi_add_control_path(void *instance, int type, const char *path)
     gs_lib_ctx_t *ctx = (gs_lib_ctx_t *)instance;
     if (ctx == NULL)
         return gs_error_Fatal;
+    gp_set_debug_mem_ptr(ctx->memory);
     return gs_add_control_path(ctx->memory, type, path);
 }
 
@@ -420,6 +436,7 @@ gsapi_remove_control_path(void *instance, int type, const char *path)
     gs_lib_ctx_t *ctx = (gs_lib_ctx_t *)instance;
     if (ctx == NULL)
         return gs_error_Fatal;
+    gp_set_debug_mem_ptr(ctx->memory);
     return gs_remove_control_path(ctx->memory, type, path);
 }
 
@@ -429,6 +446,7 @@ gsapi_purge_control_paths(void *instance, int type)
     gs_lib_ctx_t *ctx = (gs_lib_ctx_t *)instance;
     if (ctx == NULL)
         return;
+    gp_set_debug_mem_ptr(ctx->memory);
     gs_purge_control_paths(ctx->memory, type);
 }
 
@@ -438,6 +456,7 @@ gsapi_activate_path_control(void *instance, int enable)
     gs_lib_ctx_t *ctx = (gs_lib_ctx_t *)instance;
     if (ctx == NULL)
         return;
+    gp_set_debug_mem_ptr(ctx->memory);
     gs_activate_path_control(ctx->memory, enable);
 }
 
@@ -447,6 +466,7 @@ gsapi_is_path_control_active(void *instance)
     gs_lib_ctx_t *ctx = (gs_lib_ctx_t *)instance;
     if (ctx == NULL)
         return 0;
+    gp_set_debug_mem_ptr(ctx->memory);
     return gs_is_path_control_active(ctx->memory);
 }
 
@@ -456,6 +476,7 @@ gsapi_add_fs(void *instance, gsapi_fs_t *fs, void *secret)
     gs_lib_ctx_t *ctx = (gs_lib_ctx_t *)instance;
     if (ctx == NULL)
         return 0;
+    gp_set_debug_mem_ptr(ctx->memory);
     return gs_add_fs(ctx->memory, (gs_fs_t *)fs, secret);
 }
 
@@ -465,6 +486,7 @@ gsapi_remove_fs(void *instance, gsapi_fs_t *fs, void *secret)
     gs_lib_ctx_t *ctx = (gs_lib_ctx_t *)instance;
     if (ctx == NULL)
         return;
+    gp_set_debug_mem_ptr(ctx->memory);
     gs_remove_fs(ctx->memory, (gs_fs_t *)fs, secret);
 }
 
@@ -474,6 +496,7 @@ GSDLLEXPORT int GSDLLAPI gsapi_register_callout(
     gs_lib_ctx_t *ctx = (gs_lib_ctx_t *)instance;
     if (instance == NULL)
         return gs_error_Fatal;
+    gp_set_debug_mem_ptr(ctx->memory);
     return gs_lib_ctx_register_callout(ctx->memory, fn, handle);
 }
 
@@ -484,5 +507,6 @@ GSDLLEXPORT void GSDLLAPI gsapi_deregister_callout(
     gs_lib_ctx_t *ctx = (gs_lib_ctx_t *)instance;
     if (instance == NULL)
         return;
+    gp_set_debug_mem_ptr(ctx->memory);
     gs_lib_ctx_deregister_callout(ctx->memory, fn, handle);
 }