Merge pull request #26958 from yuwata/nulstr-optionally-drop-trailing-nulstr

nulstr: make strv_parse_nulstr() optionally drop trailing NULs

src/basic/nulstr-util.c

@@ -4,7 +4,7 @@
 #include "string-util.h"
 #include "strv.h"
 
-char** strv_parse_nulstr(const char *s, size_t l) {
+char** strv_parse_nulstr_full(const char *s, size_t l, bool drop_trailing_nuls) {
         /* 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
@@ -18,6 +18,10 @@ char** strv_parse_nulstr(const char *s, size_t l) {
 
         assert(s || l <= 0);
 
+        if (drop_trailing_nuls)
+                while (l > 0 && s[l-1] == '\0')
+                        l--;
+
         if (l <= 0)
                 return new0(char*, 1);
 

src/basic/nulstr-util.h

@@ -20,7 +20,10 @@ static inline bool nulstr_contains(const char *nulstr, const char *needle) {
         return nulstr_get(nulstr, needle);
 }
 
-char** strv_parse_nulstr(const char *s, size_t l);
+char** strv_parse_nulstr_full(const char *s, size_t l, bool drop_trailing_nuls);
+static inline char** strv_parse_nulstr(const char *s, size_t l) {
+        return strv_parse_nulstr_full(s, l, false);
+}
 char** strv_split_nulstr(const char *s);
 int strv_make_nulstr(char * const *l, char **p, size_t *n);
 int set_make_nulstr(Set *s, char **ret, size_t *ret_size);

src/basic/process-util.c

@@ -222,18 +222,12 @@ int get_process_cmdline(pid_t pid, size_t max_columns, ProcessCmdlineFlags flags
 
                 _cleanup_strv_free_ char **args = NULL;
 
-                args = strv_parse_nulstr(t, k);
+                /* Drop trailing NULs, otherwise strv_parse_nulstr() adds additional empty strings at the end.
+                 * See also issue #21186. */
+                args = strv_parse_nulstr_full(t, k, /* drop_trailing_nuls = */ true);
                 if (!args)
                         return -ENOMEM;
 
-                /* Drop trailing empty strings. See issue #21186. */
-                STRV_FOREACH_BACKWARDS(p, args) {
-                        if (!isempty(*p))
-                                break;
-
-                        *p = mfree(*p);
-                }
-
                 ans = quote_command_line(args, shflags);
                 if (!ans)
                         return -ENOMEM;