pragma: define a hander for generic output (and debug) pragmas

There are cases where we may want to implement generic pragmas, while
still make them selective based on output and/or debug formats.
Initially, use this for the prefix/suffix options.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Chang Seok Bae <chang.seok.bae@intel.com>

3 files changed, 25 insertions, 14 deletions

diff --git a/asm/pragma.c b/asm/pragma.c
index 71861a94..a4e76094 100644
--- a/asm/pragma.c
+++ b/asm/pragma.c
@@ -1,6 +1,6 @@
 /* ----------------------------------------------------------------------- *
  *
- *   Copyright 1996-2017 The NASM Authors - All Rights Reserved
+ *   Copyright 1996-2018 The NASM Authors - All Rights Reserved
  *   See the file AUTHORS included with the NASM distribution for
  *   the specific copyright holders.
  *
@@ -49,7 +49,7 @@
 #include "assemble.h"
 #include "error.h"
 
-static enum directive_result asm_pragma(const struct pragma *pragma);
+static enum directive_result output_pragma(const struct pragma *pragma);
 static enum directive_result limit_pragma(const struct pragma *pragma);
 
 /*
@@ -87,14 +87,14 @@ static enum directive_result limit_pragma(const struct pragma *pragma);
  */
 static struct pragma_facility global_pragmas[] =
 {
-    { "asm",		asm_pragma },
+    { "asm",		NULL },
     { "limit",          limit_pragma },
     { "list",		NULL },
     { "file",		NULL },
     { "input",		NULL },
 
-    /* None of these should actually happen... */
-    { "preproc",	NULL }, /* This shouldn't happen... */
+    /* None of these should actually happen due to special handling */
+    { "preproc",	NULL }, /* Handled in the preprocessor by necessity */
     { "output",		NULL },
     { "debug",	        NULL },
     { "ignore",		NULL },
@@ -110,6 +110,7 @@ static struct pragma_facility global_pragmas[] =
  */
 static bool search_pragma_list(const struct pragma_facility *list,
                                const char *default_name,
+                               pragma_handler generic_handler,
 			       struct pragma *pragma)
 {
     const struct pragma_facility *pf;
@@ -137,6 +138,10 @@ found_it:
     else
         rv = DIRR_UNKNOWN;
 
+    /* Is there an additional, applicable generic handler? */
+    if (rv == DIRR_UNKNOWN && generic_handler)
+        rv = generic_handler(pragma);
+
     switch (rv) {
     case DIRR_UNKNOWN:
         switch (pragma->opcode) {
@@ -210,15 +215,16 @@ void process_pragma(char *str)
     pragma.tail = nasm_trim_spaces(p);
 
     /* Look for a global pragma namespace */
-    if (search_pragma_list(global_pragmas, NULL, &pragma))
+    if (search_pragma_list(global_pragmas, NULL, NULL, &pragma))
 	return;
 
     /* Look to see if it is an output backend pragma */
-    if (search_pragma_list(ofmt->pragmas, ofmt->shortname, &pragma))
+    if (search_pragma_list(ofmt->pragmas, ofmt->shortname,
+                           output_pragma, &pragma))
 	return;
 
     /* Look to see if it is a debug format pragma */
-    if (search_pragma_list(dfmt->pragmas, dfmt->shortname, &pragma))
+    if (search_pragma_list(dfmt->pragmas, dfmt->shortname, NULL, &pragma))
 	return;
 
     /*
@@ -234,9 +240,10 @@ void process_pragma(char *str)
 }
 
 /*
- * Pragmas for the assembler proper
+ * Generic pragmas that apply to all output backends; these are handled
+ * specially so they can be made selective based on the output format.
  */
-static enum directive_result asm_pragma(const struct pragma *pragma)
+static enum directive_result output_pragma(const struct pragma *pragma)
 {
     switch (pragma->opcode) {
     case D_PREFIX:
@@ -258,6 +265,9 @@ static enum directive_result asm_pragma(const struct pragma *pragma)
     }
 }
 
+/*
+ * %pragma limit to set resource limits
+ */
 static enum directive_result limit_pragma(const struct pragma *pragma)
 {
     return nasm_set_limit(pragma->opname, pragma->tail);
diff --git a/include/nasm.h b/include/nasm.h
index 00cea322..9eae9b8b 100644
--- a/include/nasm.h
+++ b/include/nasm.h
@@ -727,10 +727,11 @@ enum directive_result {
  * as part of the struct pragma.
  */
 struct pragma;
+typedef enum directive_result (*pragma_handler)(const struct pragma *);
 
 struct pragma_facility {
     const char *name;
-    enum directive_result (*handler)(const struct pragma *);
+    pragma_handler handler;
 };
 
 /*
diff --git a/test/subsection.asm b/test/subsection.asm
index ce8ed4aa..8ba61978 100644
--- a/test/subsection.asm
+++ b/test/subsection.asm
@@ -4,9 +4,9 @@
 ; Test of Mach-O subsection_by_symbol
 ;
 
-%pragma output subsections_via_symbols
-%pragma asm gprefix _
-%pragma asm lprefix L_
+%pragma macho subsections_via_symbols
+%pragma macho gprefix _
+%pragma macho lprefix L.
 
 	bits 32