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Rewrite some manual char-buffer-handling code.

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In the course of recent refactorings I noticed a couple of cases where
we were doing old-fashioned preallocation of a char array with some
conservative maximum size, then writing into it via *p++ or similar
and hoping we got the calculation right.

Now we have strbuf and dupcat, so we shouldn't ever have to do that.
Fixed as many cases as I could find by searching for allocations of
the form 'snewn(foo, char)'.

Particularly worth a mention was the Windows GSSAPI setup code, which
was directly using the Win32 Registry API, and looks much more legible
using the windows/utils/registry.c wrappers. (But that was why I had
to enhance them in the previous commit so as to be able to open
registry keys read-only: without that, the open operation would
actually fail on this key, which is not user-writable.)

Also unix/askpass.c, which was doing a careful reallocation of its
buffer to avoid secrets being left behind in the vacated memory -
which is now just a matter of ensuring we called strbuf_new_nm().
This commit is contained in:
Simon Tatham
2022-09-13 15:00:26 +01:00
parent 7339e00f4a
commit 6cf6682c54
13 changed files with 174 additions and 291 deletions
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60
settings.c
View File

@ -267,19 +267,10 @@ static bool gppmap(settings_r *sesskey, const char *name,
static void wmap(settings_w *sesskey, char const *outkey, Conf *conf,
int primary, bool include_values)
{
char *buf, *p, *key, *realkey;
char *key, *realkey;
const char *val, *q;
int len;
len = 1; /* allow for NUL */
for (val = conf_get_str_strs(conf, primary, NULL, &key);
val != NULL;
val = conf_get_str_strs(conf, primary, key, &key))
len += 2 + 2 * (strlen(key) + strlen(val)); /* allow for escaping */
buf = snewn(len, char);
p = buf;
strbuf *sb = strbuf_new();
for (val = conf_get_str_strs(conf, primary, NULL, &key);
val != NULL;
@ -304,19 +295,19 @@ static void wmap(settings_w *sesskey, char const *outkey, Conf *conf,
realkey = NULL;
}
if (p != buf)
*p++ = ',';
if (sb->len)
put_byte(sb, ',');
for (q = key; *q; q++) {
if (*q == '=' || *q == ',' || *q == '\\')
*p++ = '\\';
*p++ = *q;
put_byte(sb, '\\');
put_byte(sb, *q);
}
if (include_values) {
*p++ = '=';
put_byte(sb, '=');
for (q = val; *q; q++) {
if (*q == '=' || *q == ',' || *q == '\\')
*p++ = '\\';
*p++ = *q;
put_byte(sb, '\\');
put_byte(sb, *q);
}
}
@ -325,9 +316,8 @@ static void wmap(settings_w *sesskey, char const *outkey, Conf *conf,
key = realkey;
}
}
*p = '\0';
write_setting_s(sesskey, outkey, buf);
sfree(buf);
write_setting_s(sesskey, outkey, sb->s);
strbuf_free(sb);
}
static int key2val(const struct keyvalwhere *mapping,
@ -456,34 +446,18 @@ static void wprefs(settings_w *sesskey, const char *name,
const struct keyvalwhere *mapping, int nvals,
Conf *conf, int primary)
{
char *buf, *p;
int i, maxlen;
strbuf *sb = strbuf_new();
for (maxlen = i = 0; i < nvals; i++) {
for (int i = 0; i < nvals; i++) {
const char *s = val2key(mapping, nvals,
conf_get_int_int(conf, primary, i));
if (s) {
maxlen += (maxlen > 0 ? 1 : 0) + strlen(s);
}
if (s)
put_fmt(sb, "%s%s", (sb->len ? "," : ""), s);
}
buf = snewn(maxlen + 1, char);
p = buf;
write_setting_s(sesskey, name, sb->s);
for (i = 0; i < nvals; i++) {
const char *s = val2key(mapping, nvals,
conf_get_int_int(conf, primary, i));
if (s) {
p += sprintf(p, "%s%s", (p > buf ? "," : ""), s);
}
}
assert(p - buf == maxlen);
*p = '\0';
write_setting_s(sesskey, name, buf);
sfree(buf);
strbuf_free(sb);
}
static void write_setting_b(settings_w *handle, const char *key, bool value)