Commit 7ba3f4f3 authored by Thomas Haller's avatar Thomas Haller

shared: add nm_utils_dbus_path_cmp() helper

At various places we sort our D-Bus paths. For example,
server sorts them before exporting them on D-Bus.

Server knows well, that a lot of these paths are build
by attaching an incrementing number as last component.
It looks nicer to sort by this number, instead of strictly
lexical with strcmp().

Note that this handles the cases correctly where paths have
different prefixes, or where they don't end with a number.
parent 3b0d5047
......@@ -560,6 +560,95 @@ nm_utils_dbus_path_get_last_component (const char *dbus_path)
return NULL;
}
static gint64
_dbus_path_component_as_num (const char *p)
{
gint64 n;
/* no odd stuff. No leading zeros, only a non-negative, decimal integer.
*
* Otherwise, there would be multiple ways to encode the same number "10"
* and "010". That is just confusing. A number has no leading zeros,
* if it has, it's not a number (as far as we are concerned here). */
if (p[0] == '0') {
if (p[1] != '\0')
return -1;
else
return 0;
}
if (!(p[0] >= '1' && p[0] <= '9'))
return -1;
if (!NM_STRCHAR_ALL (&p[1], ch, (ch >= '0' && ch <= '9')))
return -1;
n = _nm_utils_ascii_str_to_int64 (p, 10, 0, G_MAXINT64, -1);
nm_assert (n == -1 || nm_streq0 (p, nm_sprintf_bufa (100, "%"G_GINT64_FORMAT, n)));
return n;
}
int
nm_utils_dbus_path_cmp (const char *dbus_path_a, const char *dbus_path_b)
{
const char *l_a, *l_b;
gsize plen;
gint64 n_a, n_b;
/* compare function for two D-Bus paths. It behaves like
* strcmp(), except, if both paths have the same prefix,
* and both end in a (positive) number, then the paths
* will be sorted by number. */
NM_CMP_SELF (dbus_path_a, dbus_path_b);
/* if one or both paths have no slash (and no last component)
* compare the full paths directly. */
if ( !(l_a = nm_utils_dbus_path_get_last_component (dbus_path_a))
|| !(l_b = nm_utils_dbus_path_get_last_component (dbus_path_b)))
goto comp_full;
/* check if both paths have the same prefix (up to the last-component). */
plen = l_a - dbus_path_a;
if (plen != (l_b - dbus_path_b))
goto comp_full;
NM_CMP_RETURN (strncmp (dbus_path_a, dbus_path_b, plen));
n_a = _dbus_path_component_as_num (l_a);
n_b = _dbus_path_component_as_num (l_b);
if (n_a == -1 && n_b == -1)
goto comp_l;
/* both components must be convertiable to a number. If they are not,
* (and only one of them is), then we must always strictly sort numeric parts
* after non-numeric components. If we wouldn't, we wouldn't have
* a total order.
*
* An example of a not total ordering would be:
* "8" < "010" (numeric)
* "0x" < "8" (lexical)
* "0x" > "010" (lexical)
* We avoid this, by forcing that a non-numeric entry "0x" always sorts
* before numeric entries.
*
* Additionally, _dbus_path_component_as_num() would also reject "010" as
* not a valid number.
*/
if (n_a == -1)
return -1;
if (n_b == -1)
return 1;
NM_CMP_DIRECT (n_a, n_b);
nm_assert (nm_streq (dbus_path_a, dbus_path_b));
return 0;
comp_full:
NM_CMP_DIRECT_STRCMP0 (dbus_path_a, dbus_path_b);
return 0;
comp_l:
NM_CMP_DIRECT_STRCMP0 (l_a, l_b);
nm_assert (nm_streq (dbus_path_a, dbus_path_b));
return 0;
}
/*****************************************************************************/
/**
......
......@@ -204,6 +204,8 @@ nm_utils_is_separator (const char c)
const char *nm_utils_dbus_path_get_last_component (const char *dbus_path);
int nm_utils_dbus_path_cmp (const char *dbus_path_a, const char *dbus_path_b);
/*****************************************************************************/
const char **nm_utils_strsplit_set (const char *str, const char *delimiters);
......
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