X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Fbasic%2Fstrv.c;h=baaa72e674dc98b3ca3126efc1e385019ef361d0;hp=2e2dc3e4436e19d047babe1d66752767c60b156b;hb=c60d32aa37fc0b10451b0d392d90b3b96eb88ebc;hpb=479020f14217990e24e588bf26d9826b18b64d8c

diff --git a/src/basic/strv.c b/src/basic/strv.c
index 2e2dc3e44..baaa72e67 100644
--- a/src/basic/strv.c
+++ b/src/basic/strv.c
@@ -648,6 +648,17 @@ 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;
@@ -711,6 +722,13 @@ char **strv_split_nulstr(const char *s) {
 
 #if 0 /// UNNEEDED by elogind
 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;
@@ -723,7 +741,7 @@ 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);
@@ -734,11 +752,14 @@ 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;
 
@@ -888,7 +909,7 @@ int strv_extend_n(char ***l, const char *value, size_t n) {
         if (n == 0)
                 return 0;
 
-        /* Adds the value value n times to l */
+        /* Adds the value n times to l */
 
         k = strv_length(*l);