string-util: simplify logic in strjoin_real()

The loops over (x, then all varargs, until a NULL is found) can be written much
simpler with an ordinary for loop. Just initialize the loop variable to x, test
that, and in the increment part, fetch the next va_arg(). That removes a level
of indentation, and avoids doing a separate strlen()/stpcpy() call for x.

While touching this code anyway, change (size_t)-1 to the more readable
SIZE_MAX.

diff --git a/src/basic/string-util.c b/src/basic/string-util.c
index ab725d0dab42d655b85da5b1b735e5f8ab9d1c07..c8993000b04c3c9f3feae7e4c5b6401000f247ca 100644 (file)
--- a/src/basic/string-util.c
+++ b/src/basic/string-util.c
@@ -145,57 +145,32 @@ char *strnappend(const char *s, const char *suffix, size_t b) {
 
 char *strjoin_real(const char *x, ...) {
         va_list ap;
-        size_t l;
+        size_t l = 0;
         char *r, *p;
 
         va_start(ap, x);
+        for (const char *t = x; t; t = va_arg(ap, const char *)) {
+                size_t n;
 
-        if (x) {
-                l = strlen(x);
-
-                for (;;) {
-                        const char *t;
-                        size_t n;
-
-                        t = va_arg(ap, const char *);
-                        if (!t)
-                                break;
-
-                        n = strlen(t);
-                        if (n > ((size_t) -1) - l) {
-                                va_end(ap);
-                                return NULL;
-                        }
-
-                        l += n;
+                n = strlen(t);
+                if (n > SIZE_MAX - l) {
+                        va_end(ap);
+                        return NULL;
                 }
-        } else
-                l = 0;
-
+                l += n;
+        }
         va_end(ap);
 
-        r = new(char, l+1);
+        p = r = new(char, l+1);
         if (!r)
                 return NULL;
 
-        if (x) {
-                p = stpcpy(r, x);
-
-                va_start(ap, x);
-
-                for (;;) {
-                        const char *t;
-
-                        t = va_arg(ap, const char *);
-                        if (!t)
-                                break;
-
-                        p = stpcpy(p, t);
-                }
+        va_start(ap, x);
+        for (const char *t = x; t; t = va_arg(ap, const char *))
+                p = stpcpy(p, t);
+        va_end(ap);
 
-                va_end(ap);
-        } else
-                r[0] = 0;
+        *p = 0;
 
         return r;
 }