Avoid keeping pointers from `mrb_sym2name_len()`; fix #4342

The addresses for packed inline symbols reference `mrb->symbuf` that
could be overridden by the later call of `mrb_sym2name_len`. Since
file names in call stack information are kept as symbols, keeping the
address in the C structures could cause problems like #4342.

This changes small incompatible changes in function prototypes:
* `mrb_parser_get_filename`: return value changed to `mrb_sym`.
* `mrb_debug_get_filename`: add `mrb_state*` as a first argument.
* `mrb_debug_get_line`: ditto.

I believe above functions are almost internal, and no third-party
mrbgem use them.

7 files changed, 44 insertions, 37 deletions

diff --git a/mrbgems/mruby-bin-debugger/tools/mrdb/apibreak.c b/mrbgems/mruby-bin-debugger/tools/mrdb/apibreak.c
index d3ccf08ae..513db4ded 100644
--- a/mrbgems/mruby-bin-debugger/tools/mrdb/apibreak.c
+++ b/mrbgems/mruby-bin-debugger/tools/mrdb/apibreak.c
@@ -84,7 +84,7 @@ free_breakpoint(mrb_state *mrb, mrb_debug_breakpoint *bp)
 }
 
 static uint16_t
-check_file_lineno(struct mrb_irep *irep, const char *file, uint16_t lineno)
+check_file_lineno(mrb_state *mrb, struct mrb_irep *irep, const char *file, uint16_t lineno)
 {
   mrb_irep_debug_info_file *info_file;
   uint16_t result = 0;
@@ -93,8 +93,10 @@ check_file_lineno(struct mrb_irep *irep, const char *file, uint16_t lineno)
   uint16_t i;
 
   for (f_idx = 0; f_idx < irep->debug_info->flen; ++f_idx) {
+    const char *filename;
     info_file = irep->debug_info->files[f_idx];
-    if (!strcmp(info_file->filename, file)) {
+    filename = mrb_sym2name_len(mrb, info_file->filename_sym, NULL);
+    if (!strcmp(filename, file)) {
       result = MRB_DEBUG_BP_FILE_OK;
 
       fix_lineno = check_lineno(info_file, lineno);
@@ -103,7 +105,7 @@ check_file_lineno(struct mrb_irep *irep, const char *file, uint16_t lineno)
       }
     }
     for (i=0; i < irep->rlen; ++i) {
-      result  |= check_file_lineno(irep->reps[i], file, lineno);
+      result  |= check_file_lineno(mrb, irep->reps[i], file, lineno);
       if (result == (MRB_DEBUG_BP_FILE_OK | MRB_DEBUG_BP_LINENO_OK)) {
         return result;
       }
@@ -185,7 +187,7 @@ mrb_debug_set_break_line(mrb_state *mrb, mrb_debug_context *dbg, const char *fil
   }
 
   /* file and lineno check (line type mrb_debug_line_ary only.) */
-  result = check_file_lineno(dbg->root_irep, file, lineno);
+  result = check_file_lineno(mrb, dbg->root_irep, file, lineno);
   if (result == 0) {
     return MRB_DEBUG_BREAK_INVALID_FILE;
   }
@@ -426,10 +428,10 @@ mrb_debug_disable_break_all(mrb_state *mrb, mrb_debug_context *dbg)
 }
 
 static mrb_bool
-check_start_pc_for_line(mrb_irep *irep, mrb_code *pc, uint16_t line)
+check_start_pc_for_line(mrb_state *mrb, mrb_irep *irep, mrb_code *pc, uint16_t line)
 {
   if (pc > irep->iseq) {
-    if (line == mrb_debug_get_line(irep, pc - irep->iseq - 1)) {
+    if (line == mrb_debug_get_line(mrb, irep, pc - irep->iseq - 1)) {
       return FALSE;
     }
   }
@@ -447,7 +449,7 @@ mrb_debug_check_breakpoint_line(mrb_state *mrb, mrb_debug_context *dbg, const ch
     return MRB_DEBUG_INVALID_ARGUMENT;
   }
 
-  if (!check_start_pc_for_line(dbg->irep, dbg->pc, line)) {
+  if (!check_start_pc_for_line(mrb, dbg->irep, dbg->pc, line)) {
     return MRB_DEBUG_OK;
   }
 
diff --git a/mrbgems/mruby-bin-debugger/tools/mrdb/apilist.c b/mrbgems/mruby-bin-debugger/tools/mrdb/apilist.c
index 21fe64127..66ddfa783 100644
--- a/mrbgems/mruby-bin-debugger/tools/mrdb/apilist.c
+++ b/mrbgems/mruby-bin-debugger/tools/mrdb/apilist.c
@@ -181,7 +181,7 @@ mrb_debug_get_source(mrb_state *mrb, mrdb_state *mrdb, const char *srcpath, cons
   else srcname = filename;
 
   search_path[0] = srcpath;
-  search_path[1] = dirname(mrb, mrb_debug_get_filename(mrdb->dbg->irep, 0));
+  search_path[1] = dirname(mrb, mrb_debug_get_filename(mrb, mrdb->dbg->irep, 0));
   search_path[2] = ".";
 
   for (i = 0; i < 3; i++) {
diff --git a/mrbgems/mruby-bin-debugger/tools/mrdb/cmdbreak.c b/mrbgems/mruby-bin-debugger/tools/mrdb/cmdbreak.c
index 8e5901754..bc9937e94 100644
--- a/mrbgems/mruby-bin-debugger/tools/mrdb/cmdbreak.c
+++ b/mrbgems/mruby-bin-debugger/tools/mrdb/cmdbreak.c
@@ -242,7 +242,7 @@ info_break_select(mrb_state *mrb, mrdb_state *mrdb)
 }
 
 mrb_debug_bptype
-parse_breakcommand(mrdb_state *mrdb, const char **file, uint32_t *line, char **cname, char **method)
+parse_breakcommand(mrb_state *mrb, mrdb_state *mrdb, const char **file, uint32_t *line, char **cname, char **method)
 {
   mrb_debug_context *dbg = mrdb->dbg;
   char *args;
@@ -274,7 +274,7 @@ parse_breakcommand(mrdb_state *mrdb, const char **file, uint32_t *line, char **c
       STRTOUL(l, body);
       if (l <= 65535) {
         *line = l;
-        *file = (body == args)? mrb_debug_get_filename(dbg->irep, dbg->pc - dbg->irep->iseq): args;
+        *file = (body == args)? mrb_debug_get_filename(mrb, dbg->irep, dbg->pc - dbg->irep->iseq): args;
       }
       else {
         puts(BREAK_ERR_MSG_RANGEOVER);
@@ -332,7 +332,7 @@ dbgcmd_break(mrb_state *mrb, mrdb_state *mrdb)
   char *method = NULL;
   int32_t ret;
 
-  type = parse_breakcommand(mrdb, &file, &line, &cname, &method);
+  type = parse_breakcommand(mrb, mrdb, &file, &line, &cname, &method);
   switch (type) {
     case MRB_DEBUG_BPTYPE_LINE:
       ret = mrb_debug_set_break_line(mrb, dbg, file, line);
diff --git a/mrbgems/mruby-bin-debugger/tools/mrdb/mrdb.c b/mrbgems/mruby-bin-debugger/tools/mrdb/mrdb.c
index 5256ac5e3..003406172 100644
--- a/mrbgems/mruby-bin-debugger/tools/mrdb/mrdb.c
+++ b/mrbgems/mruby-bin-debugger/tools/mrdb/mrdb.c
@@ -569,8 +569,8 @@ mrb_code_fetch_hook(mrb_state *mrb, mrb_irep *irep, mrb_code *pc, mrb_value *reg
     dbg->xphase = DBG_PHASE_RUNNING;
   }
 
-  file = mrb_debug_get_filename(irep, pc - irep->iseq);
-  line = mrb_debug_get_line(irep, pc - irep->iseq);
+  file = mrb_debug_get_filename(mrb, irep, pc - irep->iseq);
+  line = mrb_debug_get_line(mrb, irep, pc - irep->iseq);
 
   switch (dbg->xm) {
   case DBG_STEP:
diff --git a/mrbgems/mruby-compiler/core/codegen.c b/mrbgems/mruby-compiler/core/codegen.c
index a2d790e32..927cc3a0f 100644
--- a/mrbgems/mruby-compiler/core/codegen.c
+++ b/mrbgems/mruby-compiler/core/codegen.c
@@ -62,7 +62,7 @@ typedef struct scope {
 
   struct loopinfo *loop;
   int ensure_level;
-  char const *filename;
+  mrb_sym filename_sym;
   uint16_t lineno;
 
   mrb_code *iseq;
@@ -106,8 +106,9 @@ codegen_error(codegen_scope *s, const char *message)
     s = tmp;
   }
 #ifndef MRB_DISABLE_STDIO
-  if (s->filename && s->lineno) {
-    fprintf(stderr, "codegen error:%s:%d: %s\n", s->filename, s->lineno, message);
+  if (s->filename_sym && s->lineno) {
+    const char *filename = mrb_sym2name_len(s->mrb, s->filename_sym, NULL);
+    fprintf(stderr, "codegen error:%s:%d: %s\n", filename, s->lineno, message);
   }
   else {
     fprintf(stderr, "codegen error: %s\n", message);
@@ -1399,13 +1400,14 @@ codegen(codegen_scope *s, node *tree, int val)
     codegen_error(s, "too complex expression");
   }
   if (s->irep && s->filename_index != tree->filename_index) {
-    const char *filename = mrb_parser_get_filename(s->parser, s->filename_index);
+    mrb_sym fname = mrb_parser_get_filename(s->parser, s->filename_index);
+    const char *filename = mrb_sym2name_len(s->mrb, fname, NULL);
 
     mrb_debug_info_append_file(s->mrb, s->irep->debug_info,
                                filename, s->lines, s->debug_start_pos, s->pc);
     s->debug_start_pos = s->pc;
     s->filename_index = tree->filename_index;
-    s->filename = mrb_parser_get_filename(s->parser, tree->filename_index);
+    s->filename_sym = mrb_parser_get_filename(s->parser, tree->filename_index);
   }
 
   nt = nint(tree->car);
@@ -2990,15 +2992,15 @@ scope_new(mrb_state *mrb, codegen_scope *prev, node *lv)
   }
   p->ai = mrb_gc_arena_save(mrb);
 
-  p->filename = prev->filename;
-  if (p->filename) {
+  p->filename_sym = prev->filename_sym;
+  if (p->filename_sym) {
     p->lines = (uint16_t*)mrb_malloc(mrb, sizeof(short)*p->icapa);
   }
   p->lineno = prev->lineno;
 
   /* debug setting */
   p->debug_start_pos = 0;
-  if (p->filename) {
+  if (p->filename_sym) {
     mrb_debug_info_alloc(mrb, p->irep);
   }
   else {
@@ -3026,8 +3028,9 @@ scope_finish(codegen_scope *s)
   irep->pool = (mrb_value*)codegen_realloc(s, irep->pool, sizeof(mrb_value)*irep->plen);
   irep->syms = (mrb_sym*)codegen_realloc(s, irep->syms, sizeof(mrb_sym)*irep->slen);
   irep->reps = (mrb_irep**)codegen_realloc(s, irep->reps, sizeof(mrb_irep*)*irep->rlen);
-  if (s->filename) {
-    const char *filename = mrb_parser_get_filename(s->parser, s->filename_index);
+  if (s->filename_sym) {
+    mrb_sym fname = mrb_parser_get_filename(s->parser, s->filename_index);
+    const char *filename = mrb_sym2name_len(s->mrb, fname, NULL);
 
     mrb_debug_info_append_file(s->mrb, s->irep->debug_info,
                                filename, s->lines, s->debug_start_pos, s->pc);
@@ -3136,7 +3139,7 @@ generate_code(mrb_state *mrb, parser_state *p, int val)
   }
   scope->mrb = mrb;
   scope->parser = p;
-  scope->filename = p->filename;
+  scope->filename_sym = p->filename_sym;
   scope->filename_index = p->current_filename_index;
 
   MRB_TRY(&scope->jmp) {
diff --git a/mrbgems/mruby-compiler/core/parse.y b/mrbgems/mruby-compiler/core/parse.y
index 90f01e3a8..88d9ea4ee 100644
--- a/mrbgems/mruby-compiler/core/parse.y
+++ b/mrbgems/mruby-compiler/core/parse.y
@@ -3162,7 +3162,7 @@ var_ref         : variable
                     }
                 | keyword__FILE__
                     {
-                      const char *fn = p->filename;
+                      const char *fn = mrb_sym2name_len(p->mrb, p->filename_sym, NULL);
                       if (!fn) {
                         fn = "(null)";
                       }
@@ -3671,8 +3671,9 @@ yyerror(parser_state *p, const char *s)
 
   if (! p->capture_errors) {
 #ifndef MRB_DISABLE_STDIO
-    if (p->filename) {
-      fprintf(stderr, "%s:%d:%d: %s\n", p->filename, p->lineno, p->column, s);
+    if (p->filename_sym) {
+      const char *filename = mrb_sym2name_len(p->mrb, p->filename_sym, NULL);
+      fprintf(stderr, "%s:%d:%d: %s\n", filename, p->lineno, p->column, s);
     }
     else {
       fprintf(stderr, "line %d:%d: %s\n", p->lineno, p->column, s);
@@ -3707,8 +3708,9 @@ yywarn(parser_state *p, const char *s)
 
   if (! p->capture_errors) {
 #ifndef MRB_DISABLE_STDIO
-    if (p->filename) {
-      fprintf(stderr, "%s:%d:%d: warning: %s\n", p->filename, p->lineno, p->column, s);
+    if (p->filename_sym) {
+      const char *filename = mrb_sym2name_len(p->mrb, p->filename_sym, NULL);
+      fprintf(stderr, "%s:%d:%d: warning: %s\n", filename, p->lineno, p->column, s);
     }
     else {
       fprintf(stderr, "line %d:%d: warning: %s\n", p->lineno, p->column, s);
@@ -6012,7 +6014,7 @@ mrb_parser_set_filename(struct mrb_parser_state *p, const char *f)
   mrb_sym* new_table;
 
   sym = mrb_intern_cstr(p->mrb, f);
-  p->filename = mrb_sym2name_len(p->mrb, sym, NULL);
+  p->filename_sym = sym;
   p->lineno = (p->filename_table_length > 0)? 0 : 1;
 
   for (i = 0; i < p->filename_table_length; ++i) {
@@ -6036,11 +6038,11 @@ mrb_parser_set_filename(struct mrb_parser_state *p, const char *f)
   p->filename_table[p->filename_table_length - 1] = sym;
 }
 
-MRB_API char const*
+MRB_API mrb_sym
 mrb_parser_get_filename(struct mrb_parser_state* p, uint16_t idx) {
-  if (idx >= p->filename_table_length) return NULL;
+  if (idx >= p->filename_table_length) return 0;
   else {
-    return mrb_sym2name_len(p->mrb, p->filename_table[idx], NULL);
+    return p->filename_table[idx];
   }
 }
 
diff --git a/mrbgems/mruby-proc-ext/src/proc.c b/mrbgems/mruby-proc-ext/src/proc.c
index 4b85c245d..17884e3c6 100644
--- a/mrbgems/mruby-proc-ext/src/proc.c
+++ b/mrbgems/mruby-proc-ext/src/proc.c
@@ -25,8 +25,8 @@ mrb_proc_source_location(mrb_state *mrb, mrb_value self)
     int32_t line;
     const char *filename;
 
-    filename = mrb_debug_get_filename(irep, 0);
-    line = mrb_debug_get_line(irep, 0);
+    filename = mrb_debug_get_filename(mrb, irep, 0);
+    line = mrb_debug_get_line(mrb, irep, 0);
 
     return (!filename && line == -1)? mrb_nil_value()
         : mrb_assoc_new(mrb, mrb_str_new_cstr(mrb, filename), mrb_fixnum_value(line));
@@ -46,11 +46,11 @@ mrb_proc_inspect(mrb_state *mrb, mrb_value self)
     int32_t line;
     mrb_str_cat_lit(mrb, str, "@");
 
-    filename = mrb_debug_get_filename(irep, 0);
+    filename = mrb_debug_get_filename(mrb, irep, 0);
     mrb_str_cat_cstr(mrb, str, filename ? filename : "-");
     mrb_str_cat_lit(mrb, str, ":");
 
-    line = mrb_debug_get_line(irep, 0);
+    line = mrb_debug_get_line(mrb, irep, 0);
     if (line != -1) {
       str = mrb_format(mrb, "%S:%S", str, mrb_fixnum_value(line));
     }