From 020003f235ca2e5e7897b4bd1d4a0dba7c463b08 Mon Sep 17 00:00:00 2001
From: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Date: Fri, 30 Oct 2020 10:13:27 +0100
Subject: [PATCH] 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.
---
 src/basic/string-util.c | 55 +++++++++++------------------------------
 1 file changed, 15 insertions(+), 40 deletions(-)

diff --git a/src/basic/string-util.c b/src/basic/string-util.c
index ab725d0dab..c8993000b0 100644
--- 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 = x; t; t = va_arg(ap, const char *))
+                p = stpcpy(p, t);
+        va_end(ap);
 
-                va_start(ap, x);
-
-                for (;;) {
-                        const char *t;
-
-                        t = va_arg(ap, const char *);
-                        if (!t)
-                                break;
-
-                        p = stpcpy(p, t);
-                }
-
-                va_end(ap);
-        } else
-                r[0] = 0;
+        *p = 0;
 
         return r;
 }