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udev: split udev_event_apply_format() into small pieces

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Also, this makes the function refuse invalid formatting and
propagate error in substituing variable.
This commit is contained in:
Yu Watanabe
2019-06-03 08:35:08 +09:00
parent 3c209d6070
commit 13cd553f91
1 changed files with 103 additions and 101 deletions
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src/udev/udev-event.c
+103 -101
View File
@@ -134,6 +134,76 @@ static const struct subst_map_entry map[] = {
{ .name = "sys", .fmt = 'S', .type = FORMAT_SUBST_SYS },
};
static const char *format_type_to_string(FormatSubstitutionType t) {
for (size_t i = 0; i < ELEMENTSOF(map); i++)
if (map[i].type == t)
return map[i].name;
return NULL;
}
static char format_type_to_char(FormatSubstitutionType t) {
for (size_t i = 0; i < ELEMENTSOF(map); i++)
if (map[i].type == t)
return map[i].fmt;
return '\0';
}
static int get_subst_type(const char **str, FormatSubstitutionType *ret_type, char ret_attr[static UTIL_PATH_SIZE]) {
const char *p = *str, *q = NULL;
size_t i;
assert(str);
assert(*str);
assert(ret_type);
if (p[0] == '$') {
p++;
if (p[0] == '$') {
*str = p;
return 0;
}
for (i = 0; i < ELEMENTSOF(map); i++)
if ((q = startswith(p, map[i].name)))
break;
} else if (p[0] == '%') {
p++;
if (p[0] == '%') {
*str = p;
return 0;
}
for (i = 0; i < ELEMENTSOF(map); i++)
if (p[0] == map[i].fmt) {
q = p + 1;
break;
}
}
if (!q)
return 0;
if (q[0] == '{') {
const char *start, *end;
size_t len;
start = q + 1;
end = strchr(start, '}');
if (!end)
return -EINVAL;
len = end - start;
if (len == 0 || len >= UTIL_PATH_SIZE)
return -EINVAL;
strnscpy(ret_attr, UTIL_PATH_SIZE, start, len);
q = end + 1;
} else
ret_attr[0] = '\0';
*str = q;
*ret_type = map[i].type;
return 1;
}
static ssize_t udev_event_subst_format(
UdevEvent *event,
FormatSubstitutionType type,
@@ -205,7 +275,7 @@ static ssize_t udev_event_subst_format(
/* get part of the result string */
i = 0;
if (attr)
if (!isempty(attr))
i = strtoul(attr, &rest, 10);
if (i > 0) {
char result[UTIL_PATH_SIZE], tmp[UTIL_PATH_SIZE], *cpos;
@@ -241,7 +311,7 @@ static ssize_t udev_event_subst_format(
size_t len;
int count;
if (!attr)
if (isempty(attr))
return -EINVAL;
/* try to read the value specified by "[dmi/id]product_name" */
@@ -320,8 +390,8 @@ static ssize_t udev_event_subst_format(
l = strpcpy(&s, l, "/sys");
break;
case FORMAT_SUBST_ENV:
if (!attr)
goto null_terminate;
if (isempty(attr))
return -EINVAL;
r = sd_device_get_property_value(dev, attr, &val);
if (r == -ENOENT)
goto null_terminate;
@@ -343,9 +413,8 @@ null_terminate:
ssize_t udev_event_apply_format(UdevEvent *event,
const char *src, char *dest, size_t size,
bool replace_whitespace) {
const char *from;
char *s;
size_t l;
const char *s = src;
int r;
assert(event);
assert(event->dev);
@@ -353,108 +422,41 @@ ssize_t udev_event_apply_format(UdevEvent *event,
assert(dest);
assert(size > 0);
from = src;
s = dest;
l = size;
for (;;) {
const struct subst_map_entry *entry = NULL;
char attrbuf[UTIL_PATH_SIZE], *attr;
bool format_dollar = false;
while (s[0] != '\0') {
FormatSubstitutionType type;
char attr[UTIL_PATH_SIZE];
ssize_t subst_len;
while (from[0] != '\0') {
if (from[0] == '$') {
/* substitute named variable */
unsigned i;
if (from[1] == '$') {
from++;
goto copy;
}
for (i = 0; i < ELEMENTSOF(map); i++) {
if (startswith(&from[1], map[i].name)) {
entry = &map[i];
from += strlen(map[i].name)+1;
format_dollar = true;
goto subst;
}
}
} else if (from[0] == '%') {
/* substitute format char */
unsigned i;
if (from[1] == '%') {
from++;
goto copy;
}
for (i = 0; i < ELEMENTSOF(map); i++) {
if (from[1] == map[i].fmt) {
entry = &map[i];
from += 2;
goto subst;
}
}
}
copy:
/* copy char */
if (l < 2) /* need space for this char and the terminating NUL */
goto out;
s[0] = from[0];
from++;
s++;
l--;
}
goto out;
subst:
/* extract possible $format{attr} */
if (from[0] == '{') {
unsigned i;
from++;
for (i = 0; from[i] != '}'; i++)
if (from[i] == '\0') {
log_error("missing closing brace for format '%s'", src);
goto out;
}
if (i >= sizeof(attrbuf))
goto out;
memcpy(attrbuf, from, i);
attrbuf[i] = '\0';
from += i+1;
attr = attrbuf;
} else
attr = NULL;
subst_len = udev_event_subst_format(event, entry->type, attr, s, l);
if (subst_len < 0) {
if (format_dollar)
log_device_warning_errno(event->dev, subst_len, "Failed to substitute variable '$%s', ignoring: %m", entry->name);
else
log_device_warning_errno(event->dev, subst_len, "Failed to apply format '%%%c', ignoring: %m", entry->fmt);
r = get_subst_type(&s, &type, attr);
if (r < 0)
return log_device_warning_errno(event->dev, r, "Invalid format string, ignoring: %s", src);
if (r == 0) {
if (size < 2) /* need space for this char and the terminating NUL */
break;
*dest++ = *s++;
size--;
continue;
}
/* FORMAT_SUBST_RESULT handles spaces itself */
if (replace_whitespace && entry->type != FORMAT_SUBST_RESULT)
/* util_replace_whitespace can replace in-place,
* and does nothing if subst_len == 0
*/
subst_len = util_replace_whitespace(s, s, subst_len);
subst_len = udev_event_subst_format(event, type, attr, dest, size);
if (subst_len < 0)
return log_device_warning_errno(event->dev, subst_len,
"Failed to substitute variable '$%s' or apply format '%%%c', ignoring: %m",
format_type_to_string(type), format_type_to_char(type));
s += subst_len;
l -= subst_len;
/* FORMAT_SUBST_RESULT handles spaces itself */
if (replace_whitespace && type != FORMAT_SUBST_RESULT)
/* util_replace_whitespace can replace in-place,
* and does nothing if subst_len == 0 */
subst_len = util_replace_whitespace(dest, dest, subst_len);
dest += subst_len;
size -= subst_len;
}
out:
assert(l >= 1);
s[0] = '\0';
return l;
assert(size >= 1);
dest[0] = '\0';
return size;
}
static int on_spawn_io(sd_event_source *s, int fd, uint32_t revents, void *userdata) {