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Use strbuf to store results in prompts_t.

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UBsan pointed out another memcpy from NULL (again with length 0) in
the prompts_t system. When I looked at it, I realised that firstly
prompt_ensure_result_size was an early not-so-good implementation of
sgrowarray_nm that would benefit from being replaced with a call to
the real one, and secondly, the whole system for storing prompt
results should really have been replaced with strbufs with the no-move
option, because that's doing all the same jobs better.

So, now each prompt_t holds a strbuf in place of its previous manually
managed string. prompt_ensure_result_size is gone (the console
prompt-reading functions use strbuf_append, and everything else just
adds to the strbuf in the usual marshal.c way). New functions exist to
retrieve a prompt_t's result, either by reference or copied.
This commit is contained in:
Simon Tatham
2020-01-21 20:19:47 +00:00
parent 5891142aee
commit cd6bc14f04
10 changed files with 80 additions and 107 deletions
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30
windows/wincons.c
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@ -490,7 +490,6 @@ int console_get_userpass_input(prompts_t *p)
for (curr_prompt = 0; curr_prompt < p->n_prompts; curr_prompt++) {
DWORD savemode, newmode;
size_t len;
prompt_t *pr = p->prompts[curr_prompt];
GetConsoleMode(hin, &savemode);
@ -503,22 +502,23 @@ int console_get_userpass_input(prompts_t *p)
console_write(hout, ptrlen_from_asciz(pr->prompt));
len = 0;
bool failed = false;
while (1) {
DWORD toread = 65536;
size_t prev_result_len = pr->result->len;
void *ptr = strbuf_append(pr->result, toread);
DWORD ret = 0;
prompt_ensure_result_size(pr, len * 5 / 4 + 512);
if (!ReadFile(hin, pr->result + len, pr->resultsize - len - 1,
&ret, NULL) || ret == 0) {
len = (size_t)-1;
if (!ReadFile(hin, ptr, toread, &ret, NULL) || ret == 0) {
failed = true;
break;
}
len += ret;
if (pr->result[len - 1] == '\n') {
len--;
if (pr->result[len - 1] == '\r')
len--;
strbuf_shrink_to(pr->result, prev_result_len + ret);
if (pr->result->s[pr->result->len - 1] == '\n') {
strbuf_shrink_by(pr->result, 1);
if (pr->result->s[pr->result->len - 1] == '\r')
strbuf_shrink_by(pr->result, 1);
break;
}
}
@ -528,11 +528,9 @@ int console_get_userpass_input(prompts_t *p)
if (!pr->echo)
console_write(hout, PTRLEN_LITERAL("\r\n"));
if (len == (size_t)-1) {
if (failed) {
return 0; /* failure due to read error */
}
pr->result[len] = '\0';
}
return 1; /* success */