ecpg: improve preprocessor's memory management.

Invent a notion of "local" storage that will automatically be
reclaimed at the end of each statement.  Use this for location
strings as well as other visibly short-lived data within the parser.

Also, make cat_str and make_str return local storage and not free
their inputs, which allows dispensing with a whole lot of retail
mm_strdup calls.  We do have to add some new ones in places where
a local-lifetime string needs to be added to a longer-lived data
structure, but on balance there are a lot less mm_strdup calls than
before.

In hopes of flushing out places where changes were necessary,
I changed YYLTYPE from "char *" to "const char *", which forced
const-ification of various function arguments that probably
should've been like that all along.

This still leaks somewhat more memory than v17, but that will be
cleaned up in future commits.

Discussion: https://postgr.es/m/2011420.1713493114@sss.pgh.pa.us

1 files changed, 17 insertions, 14 deletions

diff --git a/src/interfaces/ecpg/preproc/variable.c b/src/interfaces/ecpg/preproc/variable.c
index b23ed5edf46..6b87d5ff3d9 100644
--- a/src/interfaces/ecpg/preproc/variable.c
+++ b/src/interfaces/ecpg/preproc/variable.c
@@ -22,7 +22,7 @@ new_variable(const char *name, struct ECPGtype *type, int brace_level)
 }
 
 static struct variable *
-find_struct_member(char *name, char *str, struct ECPGstruct_member *members, int brace_level)
+find_struct_member(const char *name, char *str, struct ECPGstruct_member *members, int brace_level)
 {
 	char	   *next = strpbrk(++str, ".-["),
 			   *end,
@@ -123,7 +123,7 @@ find_struct_member(char *name, char *str, struct ECPGstruct_member *members, int
 }
 
 static struct variable *
-find_struct(char *name, char *next, char *end)
+find_struct(const char *name, char *next, char *end)
 {
 	struct variable *p;
 	char		c = *next;
@@ -174,7 +174,7 @@ find_struct(char *name, char *next, char *end)
 }
 
 static struct variable *
-find_simple(char *name)
+find_simple(const char *name)
 {
 	struct variable *p;
 
@@ -190,7 +190,7 @@ find_simple(char *name)
 /* Note that this function will end the program in case of an unknown */
 /* variable */
 struct variable *
-find_variable(char *name)
+find_variable(const char *name)
 {
 	char	   *next,
 			   *end;
@@ -513,7 +513,10 @@ get_typedef(const char *name, bool noerror)
 }
 
 void
-adjust_array(enum ECPGttype type_enum, char **dimension, char **length, char *type_dimension, char *type_index, int pointer_len, bool type_definition)
+adjust_array(enum ECPGttype type_enum,
+			 const char **dimension, const char **length,
+			 const char *type_dimension, const char *type_index,
+			 int pointer_len, bool type_definition)
 {
 	if (atoi(type_index) >= 0)
 	{
@@ -556,7 +559,7 @@ adjust_array(enum ECPGttype type_enum, char **dimension, char **length, char *ty
 			if (pointer_len)
 			{
 				*length = *dimension;
-				*dimension = mm_strdup("0");
+				*dimension = "0";
 			}
 
 			if (atoi(*length) >= 0)
@@ -567,13 +570,13 @@ adjust_array(enum ECPGttype type_enum, char **dimension, char **length, char *ty
 		case ECPGt_bytea:
 			/* pointer has to get dimension 0 */
 			if (pointer_len)
-				*dimension = mm_strdup("0");
+				*dimension = "0";
 
 			/* one index is the string length */
 			if (atoi(*length) < 0)
 			{
 				*length = *dimension;
-				*dimension = mm_strdup("-1");
+				*dimension = "-1";
 			}
 
 			break;
@@ -583,13 +586,13 @@ adjust_array(enum ECPGttype type_enum, char **dimension, char **length, char *ty
 			/* char ** */
 			if (pointer_len == 2)
 			{
-				*length = *dimension = mm_strdup("0");
+				*length = *dimension = "0";
 				break;
 			}
 
 			/* pointer has to get length 0 */
 			if (pointer_len == 1)
-				*length = mm_strdup("0");
+				*length = "0";
 
 			/* one index is the string length */
 			if (atoi(*length) < 0)
@@ -604,13 +607,13 @@ adjust_array(enum ECPGttype type_enum, char **dimension, char **length, char *ty
 					 * do not change this for typedefs since it will be
 					 * changed later on when the variable is defined
 					 */
-					*length = mm_strdup("1");
+					*length = "1";
 				else if (strcmp(*dimension, "0") == 0)
-					*length = mm_strdup("-1");
+					*length = "-1";
 				else
 					*length = *dimension;
 
-				*dimension = mm_strdup("-1");
+				*dimension = "-1";
 			}
 			break;
 		default:
@@ -618,7 +621,7 @@ adjust_array(enum ECPGttype type_enum, char **dimension, char **length, char *ty
 			if (pointer_len)
 			{
 				*length = *dimension;
-				*dimension = mm_strdup("0");
+				*dimension = "0";
 			}
 
 			if (atoi(*length) >= 0)