From: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Date: Fri, 30 Oct 2020 09:13:27 +0000 (+0100)
Subject: string-util: simplify logic in strjoin_real()
X-Git-Tag: v247-rc2~31^2~3
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=020003f235ca2e5e7897b4bd1d4a0dba7c463b08;p=thirdparty%2Fsystemd.git

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 ab725d0dab4..c8993000b04 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;
-
-                        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;
 }