[Patch, libgfortran] PR 40330 Fix use of saved format strings

[Janne Blomqvist <blomqvist dot janne at gmail dot com>]

Hi,

the attached patch fixes PR 40330. The problem was that for the saved
format strings we were just keeping pointer to the strings that reside
in the st_parameter_dt structure. However, this lives on the stack so
once it goes out of scope the cached entries became invalid. Fixed by
using heap storage.

Regtested on x86_64-unknown-linux-gnu, Ok for trunk and 4.4?

-- 
Janne Blomqvist

Attachment: ChangeLog
Description: Binary data

diff --git a/libgfortran/io/format.c b/libgfortran/io/format.c
index a1ec43c..bd40419 100644
--- a/libgfortran/io/format.c
+++ b/libgfortran/io/format.c
@@ -87,7 +87,12 @@ free_format_hash_table (gfc_unit *u)
   for (i = 0; i < FORMAT_HASH_SIZE; i++)
     {
       if (u->format_hash_table[i].hashed_fmt != NULL)
-	free_format_data (u->format_hash_table[i].hashed_fmt);
+	{
+	  free_format_data (u->format_hash_table[i].hashed_fmt);
+	  free_mem (u->format_hash_table[i].key);
+	}
+      u->format_hash_table[i].key = NULL;
+      u->format_hash_table[i].key_len = 0;      
       u->format_hash_table[i].hashed_fmt = NULL;
     }
 }
@@ -164,7 +169,10 @@ save_parsed_format (st_parameter_dt *dtp)
     free_format_data (u->format_hash_table[hash].hashed_fmt);
   u->format_hash_table[hash].hashed_fmt = NULL;
 
-  u->format_hash_table[hash].key = dtp->format;
+  u->format_hash_table[hash].key 
+    = gfc_realloc (u->format_hash_table[hash].key, dtp->format_len);
+  memcpy (u->format_hash_table[hash].key, dtp->format, dtp->format_len);
+
   u->format_hash_table[hash].key_len = dtp->format_len;
   u->format_hash_table[hash].hashed_fmt = dtp->u.p.fmt;
 }
diff --git a/libgfortran/libgfortran.h b/libgfortran/libgfortran.h
index 3591fa9..b075ac0 100644
--- a/libgfortran/libgfortran.h
+++ b/libgfortran/libgfortran.h
@@ -681,6 +681,9 @@ internal_proto(set_fpu);
 extern void *get_mem (size_t) __attribute__ ((malloc));
 internal_proto(get_mem);
 
+extern void *gfc_realloc (void *, size_t);
+internal_proto(gfc_realloc);
+
 extern void free_mem (void *);
 internal_proto(free_mem);
 
diff --git a/libgfortran/runtime/memory.c b/libgfortran/runtime/memory.c
index d1b57f6..c7e49d3 100644
--- a/libgfortran/runtime/memory.c
+++ b/libgfortran/runtime/memory.c
@@ -48,6 +48,17 @@ get_mem (size_t n)
   return p;
 }
 
+/* Safe realloc that aborts the program on failure. */
+
+void *
+gfc_realloc (void * ptr, size_t size)
+{
+  ptr = realloc (ptr, size);
+  if (ptr == NULL)
+    os_error("Memory re-allocation failed");
+  return ptr;
+}
+
 
 void
 free_mem (void *p)