/**
* Get the raw message name present at the start of a G2 packet.
*
* @param start start of message
* @param len amount of consecutive bytes we have so far
*
* @return the message name if we can intuit it, an empty string otherwise.
*/
const char *
g2_msg_raw_name(const void *start, size_t len)
{
const char *name;
size_t namelen;
char buf[G2_FRAME_NAME_LEN_MAX + 1];
name = g2_frame_name(start, len, &namelen);
if (NULL == name)
return "";
clamp_strncpy(buf, sizeof buf, name, namelen);
return constant_str(buf);
}
/**
* Needs brief description here.
*
* Substitutes variables from string:
*
* - The leading "~" is replaced by the home directory.
* - Variables like "$PATH" or "${PATH}" are replaced by their value, as
* fetched from the environment, or the empty string if not found.
*
* If given a NULL input, we return NULL.
*
* @return string constant, which is not meant to be freed until exit time.
*/
const char *
eval_subst(const char *str)
{
char buf[MAX_STRING];
char *end = &buf[sizeof(buf)];
char *p;
size_t len;
char c;
if (str == NULL)
return NULL;
len = g_strlcpy(buf, str, sizeof buf);
if (len >= sizeof buf) {
g_warning("%s(): string too large for substitution (%zu bytes)",
G_STRFUNC, len);
return constant_str(str);
}
if (common_dbg > 3)
g_debug("%s: on entry: \"%s\"", G_STRFUNC, buf);
for (p = buf, c = *p++; c; c = *p++) {
const char *val = NULL;
char *start = p - 1;
switch (c) {
case '~':
if (start == buf && ('\0' == buf[1] || '/' == buf[1])) {
/* Leading ~ only */
val = gethomedir();
g_assert(val);
memmove(start, &start[1], len - (start - buf));
len--;
g_assert(size_is_non_negative(len));
}
break;
case '$':
{
const char *after;
val = get_variable(p, &after);
g_assert(val);
memmove(start, after, len + 1 - (after - buf));
len -= after - start; /* Also removing leading '$' */
g_assert(size_is_non_negative(len));
}
break;
}
if (val != NULL) {
char *next;
next = insert_value(val, start, start - buf, len, sizeof buf - 1);
len += next - start;
p = next;
g_assert(len < sizeof buf);
g_assert(p < end);
}
g_assert(p <= &buf[len]);
}
if (common_dbg > 3)
g_debug("%s: on exit: \"%s\"", G_STRFUNC, buf);
g_assert(len == strlen(buf));
return constant_str(buf);
}
