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-rw-r--r--src/basic/strv.c29
1 files changed, 25 insertions, 4 deletions
diff --git a/src/basic/strv.c b/src/basic/strv.c
index e0e2d1ebbe..98d6f61067 100644
--- a/src/basic/strv.c
+++ b/src/basic/strv.c
@@ -638,6 +638,17 @@ char **strv_remove(char **l, const char *s) {
}
char **strv_parse_nulstr(const char *s, size_t l) {
+ /* l is the length of the input data, which will be split at NULs into
+ * elements of the resulting strv. Hence, the number of items in the resulting strv
+ * will be equal to one plus the number of NUL bytes in the l bytes starting at s,
+ * unless s[l-1] is NUL, in which case the final empty string is not stored in
+ * the resulting strv, and length is equal to the number of NUL bytes.
+ *
+ * Note that contrary to a normal nulstr which cannot contain empty strings, because
+ * the input data is terminated by any two consequent NUL bytes, this parser accepts
+ * empty strings in s.
+ */
+
const char *p;
unsigned c = 0, i = 0;
char **v;
@@ -700,6 +711,13 @@ char **strv_split_nulstr(const char *s) {
}
int strv_make_nulstr(char **l, char **p, size_t *q) {
+ /* A valid nulstr with two NULs at the end will be created, but
+ * q will be the length without the two trailing NULs. Thus the output
+ * string is a valid nulstr and can be iterated over using NULSTR_FOREACH,
+ * and can also be parsed by strv_parse_nulstr as long as the length
+ * is provided separately.
+ */
+
size_t n_allocated = 0, n = 0;
_cleanup_free_ char *m = NULL;
char **i;
@@ -712,7 +730,7 @@ int strv_make_nulstr(char **l, char **p, size_t *q) {
z = strlen(*i);
- if (!GREEDY_REALLOC(m, n_allocated, n + z + 1))
+ if (!GREEDY_REALLOC(m, n_allocated, n + z + 2))
return -ENOMEM;
memcpy(m + n, *i, z + 1);
@@ -723,11 +741,14 @@ int strv_make_nulstr(char **l, char **p, size_t *q) {
m = new0(char, 1);
if (!m)
return -ENOMEM;
- n = 0;
- }
+ n = 1;
+ } else
+ /* make sure there is a second extra NUL at the end of resulting nulstr */
+ m[n] = '\0';
+ assert(n > 0);
*p = m;
- *q = n;
+ *q = n - 1;
m = NULL;