8000 Add :const for safer scripting by rhysd · Pull Request #4541 · vim/vim · GitHub
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Add :const for safer scripting #4541

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80b8e44
Add :const for safer scripting
rhysd Mar 22, 2019
cfe5ca7
Regenerate ex_cmdidxs.h
rhysd Jun 15, 2019
91b8d6b
Add tests for :const
rhysd Jun 14, 2019
09f6500
Add documentation for :const
rhysd Jun 15, 2019
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30 changes: 29 additions & 1 deletion runtime/doc/eval.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -11573,7 +11573,6 @@ text...
# Number
* Funcref


:unl[et][!] {name} ... *:unlet* *:unl* *E108* *E795*
Remove the internal variable {name}. Several variable
names can be given, they are all removed. The name
Expand All @@ -11600,6 +11599,35 @@ text...
If the system does not support deleting an environment
variable, it is made emtpy.

*:const*
:const {var-name} = {expr1}
:const [{name1}, {name2}, ...] = {expr1}
:const [{name1}, {name2}, ...] .= {expr1}
:const [{name}, ..., ; {lastname}] = {expr1}
:const {var-name} =<< [trim] {marker}
text...
text...
{marker}
Similar to |:let|, but |:const| locks the variable
after setting the result.
This is the same as locking variable with |:lockvar|
just after |:let|: >
:const x = 1
< is equivalent to: >
:let x = 1
:lockvar 1 x
< This is useful if you intend not to modify the
defined variable. And |:const| is more efficient than
using |:let| and |:lockvar| since it does both storing
the result to variable and locking the variable at the
same command.
*E995*
|:const| does not allow to redefine existing variable.
It raises an error when given variable name is already
existing: >
:let x = 1
:const x = 2 " Error!
<
:lockv[ar][!] [depth] {name} ... *:lockvar* *:lockv*
Lock the internal variable {name}. Locking means that
it can no longer be changed (until it is unlocked).
Expand Down
2 changes: 1 addition & 1 deletion src/buffer.c
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Expand Up @@ -3913,7 +3913,7 @@ build_stl_str_hl(

tv.v_type = VAR_NUMBER;
tv.vval.v_number = wp->w_id;
set_var((char_u *)"g:statusline_winid", &tv, FALSE);
set_var((char_u *)"g:statusline_winid", &tv, TRUE, FALSE);

usefmt = eval_to_string_safe(fmt + 2, NULL, use_sandbox);
if (usefmt == NULL)
Expand Down
112 changes: 90 additions & 22 deletions src/eval.c
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4F55
Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@ static char *e_missbrac = N_("E111: Missing ']'");
static char *e_dictrange = N_("E719: Cannot use [:] with a Dictionary");
static char *e_letwrong = N_("E734: Wrong variable type for %s=");
static char *e_illvar = N_("E461: Illegal variable name: %s");
static char *e_cannot_mod = N_("E995: Cannot modify existing variable");
#ifdef FEAT_FLOAT
static char *e_float_as_string = N_("E806: using Float as a String");
#endif
Expand Down Expand Up @@ -212,7 +213,8 @@ static struct vimvar
static dictitem_T vimvars_var; /* variable used for v: */
#define vimvarht vimvardict.dv_hashtab

static int ex_let_vars(char_u *arg, typval_T *tv, int copy, int semicolon, int var_count, char_u *nextchars);
static void ex_let_const(exarg_T *eap, int lock);
static int ex_let_vars(char_u *arg, typval_T *tv, int copy, int semicolon, int var_count, int lock, char_u *nextchars);
static char_u *skip_var_list(char_u *arg, int *var_count, int *semicolon);
static char_u *skip_var_one(char_u *arg);
static void list_glob_vars(int *first);
Expand All @@ -222,8 +224,8 @@ static void list_tab_vars(int *first);
static void list_vim_vars(int *first);
static void list_script_vars(int *first);
static char_u *list_arg_vars(exarg_T *eap, char_u *arg, int *first);
static char_u *ex_let_one(char_u *arg, typval_T *tv, int copy, char_u *endchars, char_u *op);
static void set_var_lval(lval_T *lp, char_u *endp, typval_T *rettv, int copy, char_u *op);
static char_u *ex_let_one(char_u *arg, typval_T *tv, int copy, int lock, char_u *endchars, char_u *op);
static void set_var_lval(lval_T *lp, char_u *endp, typval_T *rettv, int copy, int lock, char_u *op);
static int tv_op(typval_T *tv1, typval_T *tv2, char_u *op);
static void ex_unletlock(exarg_T *eap, char_u *argstart, int deep);
static int do_unlet_var(lval_T *lp, char_u *name_end, int forceit);
Expand Down Expand Up @@ -457,7 +459,7 @@ set_internal_string_var(char_u *name, char_u *value)
tvp = alloc_string_tv(val);
if (tvp != NULL)
{
set_var(name, tvp, FALSE);
set_var(name, tvp, FALSE, FALSE);
free_tv(tvp);
}
}
Expand Down Expand Up @@ -526,9 +528,9 @@ var_redir_start(char_u *name, int append)
tv.v_type = VAR_STRING;
tv.vval.v_string = (char_u *)"";
if (append)
set_var_lval(redir_lval, redir_endp, &tv, TRUE, (char_u *)".");
set_var_lval(redir_lval, redir_endp, &tv, TRUE, FALSE, (char_u *)".");
else
set_var_lval(redir_lval, redir_endp, &tv, TRUE, (char_u *)"=");
set_var_lval(redir_lval, redir_endp, &tv, TRUE, FALSE, (char_u *)"=");
clear_lval(redir_lval);
err = did_emsg;
did_emsg |= save_emsg;
Expand Down Expand Up @@ -601,7 +603,7 @@ var_redir_stop(void)
redir_endp = get_lval(redir_varname, NULL, redir_lval,
FALSE, FALSE, 0, FNE_CHECK_START);
if (redir_endp != NULL && redir_lval->ll_name != NULL)
set_var_lval(redir_lval, redir_endp, &tv, FALSE, (char_u *)".");
set_var_lval(redir_lval, redir_endp, &tv, FALSE, FALSE, (char_u *)".");
clear_lval(redir_lval);
}

Expand Down Expand Up @@ -1337,6 +1339,24 @@ heredoc_get(exarg_T *eap, char_u *cmd)
*/
void
ex_let(exarg_T *eap)
{
ex_let_const(eap, 0);
}

/*
* ":const" list all variable values
* ":const var1 var2" list variable values
* ":const var = expr" assignment command.
* ":const [var1, var2] = expr" unpack list.
*/
void
ex_const(exarg_T *eap)
{
ex_let_const(eap, 1);
}

static void
ex_let_const(exarg_T *eap, int lock)
{
char_u *arg = eap->arg;
char_u *expr = NULL;
Expand Down Expand Up @@ -1396,7 +1416,7 @@ ex_let(exarg_T *eap)
op[0] = '=';
op[1] = NUL;
(void)ex_let_vars(eap->arg, &rettv, FALSE, semicolon, var_count,
op);
lock, op);
clear_tv(&rettv);
}
}
Expand Down Expand Up @@ -1428,8 +1448,8 @@ ex_let(exarg_T *eap)
}
else if (i != FAIL)
{
(void)ex_let_vars(eap->arg, &rettv, FALSE, semicolon, var_count,
op);
(void)ex_let_vars(eap->arg, &rettv, FALSE, semicolon, var_count, lock,
op);
clear_tv(&rettv);
}
}
Expand All @@ -1450,6 +1470,7 @@ ex_let_vars(
int copy, /* copy values from "tv", don't move */
int semicolon, /* from skip_var_list() */
int var_count, /* from skip_var_list() */
int lock, /* lock variables for const */
char_u *nextchars)
{
char_u *arg = arg_start;
Expand All @@ -1463,7 +1484,7 @@ ex_let_vars(
/*
* ":let var = expr" or ":for var in list"
*/
if (ex_let_one(arg, tv, copy, nextchars, nextchars) == NULL)
if (ex_let_one(arg, tv, copy, lock, nextchars, nextchars) == NULL)
return FAIL;
return OK;
}
Expand Down Expand Up @@ -1493,7 +1514,7 @@ ex_let_vars(
while (*arg != ']')
{
arg = skipwhite(arg + 1);
arg = ex_let_one(arg, &item->li_tv, TRUE, (char_u *)",;]", nextchars);
arg = ex_let_one(arg, &item->li_tv, TRUE, lock, (char_u *)",;]", nextchars);
item = item->li_next;
if (arg == NULL)
return FAIL;
Expand All @@ -1517,8 +1538,8 @@ ex_let_vars(
ltv.vval.v_list = l;
l->lv_refcount = 1;

arg = ex_let_one(skipwhite(arg + 1), &ltv, FALSE,
(char_u *)"]", nextchars);
arg = ex_let_one(skipwhite(arg + 1), &ltv, FALSE, lock,
(char_u *)"]", nextchars);
clear_tv(&ltv);
if (arg == NULL)
return FAIL;
Expand Down Expand Up @@ -1808,6 +1829,7 @@ ex_let_one(
char_u *arg, /* points to variable name */
typval_T *tv, /* value to assign to variable */
int copy, /* copy value from "tv" */
int lock, /* lock variable for const */
char_u *endchars, /* valid chars after variable name or NULL */
char_u *op) /* "+", "-", "." or NULL*/
{
Expand All @@ -1824,6 +1846,11 @@ ex_let_one(
*/
if (*arg == '$')
{
if (lock)
{
emsg(_(e_cannot_mod));
return NULL;
}
/* Find the end of the name. */
++arg;
name = arg;
Expand Down Expand Up @@ -1879,6 +1906,11 @@ ex_let_one(
*/
else if (*arg == '&')
{
if (lock)
{
emsg(_(e_cannot_mod));
return NULL;
}
/* Find the end of the name. */
p = find_option_end(&arg, &opt_flags);
if (p == NULL || (endchars != NULL
Expand Down Expand Up @@ -1943,6 +1975,11 @@ ex_let_one(
*/
else if (*arg == '@')
{
if (lock)
{
emsg(_(e_cannot_mod));
return NULL;
}
++arg;
if (op != NULL && vim_strchr((char_u *)"+-*/%", *op) != NULL)
semsg(_(e_letwrong), op);
Expand Down Expand Up @@ -1988,7 +2025,7 @@ ex_let_one(
emsg(_(e_letunexp));
else
{
set_var_lval(&lv, p, tv, copy, op);
set_var_lval(&lv, p, tv, copy, lock, op);
arg_end = p;
}
}
Expand Down Expand Up @@ -2430,6 +2467,7 @@ set_var_lval(
char_u *endp,
typval_T *rettv,
int copy,
int no_mod, /* Disallow to modify existing variable for :const */
char_u *op)
{
int cc;
Expand Down Expand Up @@ -2495,6 +2533,13 @@ set_var_lval(
{
typval_T tv;

if (no_mod)
{
emsg(_(e_cannot_mod));
*endp = cc;
return;
}

// handle +=, -=, *=, /=, %= and .=
di = NULL;
if (get_var_tv(lp->ll_name, (int)STRLEN(lp->ll_name),
Expand All @@ -2504,12 +2549,12 @@ set_var_lval(
|| (!var_check_ro(di->di_flags, lp->ll_name, FALSE)
&& !tv_check_lock(&di->di_tv, lp->ll_name, FALSE)))
&& tv_op(&tv, rettv, op) == OK)
set_var(lp->ll_name, &tv, FALSE);
set_var(lp->ll_name, &tv, FALSE, FALSE);
clear_tv(&tv);
}
}
else
set_var(lp->ll_name, rettv, copy);
set_var(lp->ll_name, rettv, copy, no_mod);
*endp = cc;
}
else if (var_check_lock(lp->ll_newkey == NULL
Expand All @@ -2521,6 +2566,12 @@ set_var_lval(
listitem_T *ll_li = lp->ll_li;
int ll_n1 = lp->ll_n1;

if (no_mod)
{
emsg(_(e_cannot_mod));
return;
}

/*
* Check whether any of the list items is locked
*/
Expand Down Expand Up @@ -2574,6 +2625,11 @@ set_var_lval(
/*
* Assign to a List or Dictionary item.
*/
if (no_mod)
{
emsg(_(e_cannot_mod));
return;
}
if (lp->ll_newkey != NULL)
{
if (op != NULL && *op != '=')
Expand Down Expand Up @@ -2861,7 +2917,7 @@ next_for_item(void *fi_void, char_u *arg)
tv.vval.v_number = blob_get(fi->fi_blob, fi->fi_bi);
++fi->fi_bi;
return ex_let_vars(arg, &tv, TRUE,
fi->fi_semicolon, fi->fi_varcount, NULL) == OK;
fi->fi_semicolon, fi->fi_varcount, FALSE, NULL) == OK;
}

item = fi->fi_lw.lw_item;
Expand All @@ -2871,7 +2927,7 @@ next_for_item(void *fi_void, char_u *arg)
{
fi->fi_lw.lw_item = item->li_next;
result = (ex_let_vars(arg, &item->li_tv, TRUE,
fi->fi_semicolon, fi->fi_varcount, NULL) == OK);
fi->fi_semicolon, fi->fi_varcount, FALSE, NULL) == OK);
}
return result;
}
Expand Down Expand Up @@ -8051,7 +8107,8 @@ list_one_var_a(
set_var(
char_u *name,
typval_T *tv,
int copy) /* make copy of value in "tv" */
int copy, /* make copy of value in "tv" */
int no_mod) /* disallow to modify existing variable */
{
dictitem_T *v;
char_u *varname;
Expand All @@ -8075,6 +8132,12 @@ set_var(

if (v != NULL)
{
if (no_mod)
{
emsg(_(e_cannot_mod));
return;
}

/* existing variable, need to clear the value */
if (var_check_ro(v->di_flags, name, FALSE)
|| var_check_lock(v->di_tv.v_lock, name, FALSE))
Expand Down Expand Up @@ -8152,6 +8215,8 @@ set_var(
return;
}
v->di_flags = DI_FLAGS_ALLOC;
if (no_mod)
v->di_flags |= DI_FLAGS_LOCK;
}

if (copy || tv->v_type == VAR_NUMBER || tv->v_type == VAR_FLOAT)
Expand All @@ -8162,6 +8227,9 @@ set_var(
v->di_tv.v_lock = 0;
init_tv(tv);
}

if (no_mod)
v->di_tv.v_lock |= VAR_LOCKED;
}

/*
Expand Down Expand Up @@ -9021,7 +9089,7 @@ setwinvar(typval_T *argvars, typval_T *rettv UNUSED, int off)
{
STRCPY(winvarname, "w:");
STRCPY(winvarname + 2, varname);
set_var(winvarname, varp, TRUE);
set_var(winvarname, varp, TRUE, FALSE);
vim_free(winvarname);
}
}
Expand Down Expand Up @@ -9238,7 +9306,7 @@ read_viminfo_varlist(vir_T *virp, int writing)

/* when in a function use global variables */
save_funccal(&funccal_entry);
set_var(virp->vir_line + 1, &tv, FALSE);
set_var(virp->vir_line + 1, &tv, FALSE, FALSE);
restore_funccal();

if (tv.v_type == VAR_STRING)
Expand Down
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