> From: Philipp <p.stephani2@gmail.com>
> Date: Sat, 06 Jan 2018 12:39:43 +0100
>
> (call-interactively (lambda (a b) (interactive "sa\0b\ns")))
>
> the prompt is only "a" and a `wrong-number-of-argument' signal is
> raised. This is because `call-interactively' copies the interactive
> specification to a C string, ignoring embedded nulls.
No, it copies the spec in its entirety, including embedded null bytes,
but then _processes_ the result as a C string, taking the first null
byte as the end of the string.
Does the patch below look right, and give good results?
Yes, thanks. Just some minor nits inline to make the code shorter.
diff --git a/src/callint.c b/src/callint.c
index 2253cdf..3d2ed00 100644
--- a/src/callint.c
+++ b/src/callint.c
@@ -288,7 +288,8 @@ invoke it. If KEYS is omitted or nil, the return value of
ptrdiff_t next_event;
Lisp_Object prefix_arg;
- char *string;
+ char *string, *string_end;
+ ptrdiff_t string_len;
I think these days (where we require C99) we always declare variables when we first use them.
const char *tem;
/* If varies[i] > 0, the i'th argument shouldn't just have its value
@@ -396,6 +397,8 @@ invoke it. If KEYS is omitted or nil, the return value of
/* SPECS is set to a string; use it as an interactive prompt.
Copy it so that STRING will be valid even if a GC relocates SPECS. */
SAFE_ALLOCA_STRING (string, specs);
+ string_len = SBYTES (specs);
+ string_end = string + string_len;
/* Here if function specifies a string to control parsing the defaults. */
@@ -418,7 +421,7 @@ invoke it. If KEYS is omitted or nil, the return value of
if (!NILP (record_flag))
{
char *p = string;
- while (*p)
+ while (p < string_end)
{
if (! (*p == 'r' || *p == 'p' || *p == 'P'
|| *p == '\n'))
@@ -469,7 +472,7 @@ invoke it. If KEYS is omitted or nil, the return value of
`funcall-interactively') plus the number of arguments the interactive spec
would have us give to the function. */
tem = string;
- for (nargs = 2; *tem; )
+ for (nargs = 2; tem < string_end; )
{
/* 'r' specifications ("point and mark as 2 numeric args")
produce *two* arguments. */
@@ -477,7 +480,7 @@ invoke it. If KEYS is omitted or nil, the return value of
nargs += 2;
else
nargs++;
- tem = strchr (tem, '\n');
+ tem = memchr (tem, '\n', string_len - (tem - string));
You can write the third argument as string_end - tem.
if (tem)
++tem;
else
@@ -503,9 +506,12 @@ invoke it. If KEYS is omitted or nil, the return value of
specbind (Qenable_recursive_minibuffers, Qt);
tem = string;
- for (i = 2; *tem; i++)
+ for (i = 2; tem < string_end; i++)
{
- visargs[1] = make_string (tem + 1, strcspn (tem + 1, "\n"));
+ char *pnl = memchr (tem + 1, '\n', string_len - (tem + 1 - string));
Here you can write the third argument as string_end - (tem + 1).
+ ptrdiff_t sz = pnl ? pnl - (tem + 1) : string_end - (tem + 1);
You can write the RHS as (pnl ? pnl : string_end) - (tem + 1).
+
+ visargs[1] = make_string (tem + 1, sz);
callint_message = Fformat_message (i - 1, visargs + 1);
switch (*tem)
@@ -781,7 +787,7 @@ invoke it. If KEYS is omitted or nil, the return value of
{
/* How many bytes are left unprocessed in the specs string?
(Note that this excludes the trailing null byte.) */
- ptrdiff_t bytes_left = SBYTES (specs) - (tem - string);
+ ptrdiff_t bytes_left = string_len - (tem - string);
Same (string-end - tem).
unsigned letter;
/* If we have enough bytes left to treat the sequence as a
@@ -803,9 +809,9 @@ invoke it. If KEYS is omitted or nil, the return value of
if (NILP (visargs[i]) && STRINGP (args[i]))
visargs[i] = args[i];
- tem = strchr (tem, '\n');
+ tem = memchr (tem, '\n', string_len - (tem - string));
again, string_end - tem.
if (tem) tem++;
- else tem = "";
+ else tem = string_end;
}
unbind_to (speccount, Qnil);