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env-util: rework env_append()

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Let's make sure the strv we are putting together always remains valid
(i.e. is NULL terminated). Also document the parameters to pass in
correctly.
This commit is contained in:
Lennart Poettering 2018-10-17 20:08:42 +02:00
parent 68ac147e8d
commit 2a13184a43
1 changed files with 17 additions and 12 deletions
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29
src/basic/env-util.c
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@ -155,20 +155,23 @@ bool strv_env_name_or_assignment_is_valid(char **l) {
static int env_append(char **r, char ***k, char **a) {
assert(r);
assert(k);
assert(*k >= r);
if (!a)
return 0;
/* Add the entries of a to *k unless they already exist in *r
* in which case they are overridden instead. This assumes
* there is enough space in the r array. */
/* Expects the following arguments: 'r' shall point to the beginning of an strv we are going to append to, 'k'
* to a pointer pointing to the NULL entry at the end of the same array. 'a' shall point to another strv.
*
* This call adds every entry of 'a' to 'r', either overriding an existing matching entry, or appending to it.
*
* This call assumes 'r' has enough pre-allocated space to grow by all of 'a''s items. */
for (; *a; a++) {
char **j;
char **j, *c;
size_t n;
n = strcspn(*a, "=");
if ((*a)[n] == '=')
n++;
@ -176,14 +179,16 @@ static int env_append(char **r, char ***k, char **a) {
if (strneq(*j, *a, n))
break;
if (j >= *k)
(*k)++;
else
free(*j);
*j = strdup(*a);
if (!*j)
c = strdup(*a);
if (!c)
return -ENOMEM;
if (j >= *k) { /* Append to the end? */
(*k)[0] = c;
(*k)[1] = NULL;
(*k)++;
} else
free_and_replace(*j, c); /* Override existing item */
}
return 0;