Convert UtilStringConcat() into a varargs function.

This allows us to concatenate an arbitrary amount of strings without
having to maintain a bunch of pointers or leak memory when nesting calls.

TODO.txt

@@ -17,7 +17,8 @@ Milestone: v0.2.0
 [ ] Document UserInteractiveAuth (move docs from Matrix)
 [ ] Document MemoryHexDump
 [ ] Move String functions to a new String.h?
-[ ] Make UtilStringConcat use varargs
+[~] Make UtilStringConcat use varargs
+    [ ] Update documentation
 [x] Look into seeding random strings (possibly create Random.h?)
 [~] User registration
     [x] Username validation

src/Db.c

@@ -200,7 +200,7 @@ DbHashKey(Array * args)
 
     for (i = 0; i < ArraySize(args); i++)
     {
-        char *tmp = UtilStringConcat(str, ArrayGet(args, i));
+        char *tmp = UtilStringConcat(2, str, ArrayGet(args, i));
 
         Free(str);
         str = tmp;
@@ -213,19 +213,17 @@ static char *
 DbDirName(Db * db, Array * args)
 {
     size_t i;
-    char *str = UtilStringConcat(db->dir, "/");
+    char *str = UtilStringConcat(2, db->dir, "/");
 
     for (i = 0; i < ArraySize(args) - 1; i++)
     {
-        char *tmp, *tmp2;
+        char *tmp;
 
-        tmp = UtilStringConcat(str, ArrayGet(args, i));
-        tmp2 = UtilStringConcat(tmp, "/");
+        tmp = UtilStringConcat(3, str, ArrayGet(args, i), "/");
 
         Free(str);
-        Free(tmp);
 
-        str = tmp2;
+        str = tmp;
     }
 
     return str;
@@ -235,11 +233,11 @@ static char *
 DbFileName(Db * db, Array * args)
 {
     size_t i;
-    char *str = UtilStringConcat(db->dir, "/");
+    char *str = UtilStringConcat(2, db->dir, "/");
 
     for (i = 0; i < ArraySize(args); i++)
     {
-        char *tmp, *tmp2;
+        char *tmp;
         char *arg = UtilStringDuplicate(ArrayGet(args, i));
         size_t j = 0;
 
@@ -260,15 +258,13 @@ DbFileName(Db * db, Array * args)
             j++;
         }
 
-        tmp = UtilStringConcat(str, arg);
-        tmp2 = UtilStringConcat(tmp,
+        tmp = UtilStringConcat(3, str, arg,
                            (i < ArraySize(args) - 1) ? "/" : ".json");
 
         Free(arg);
         Free(str);
-        Free(tmp);
 
-        str = tmp2;
+        str = tmp;
     }
 
     return str;

src/Util.c

@@ -27,6 +27,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdarg.h>
 #include <string.h>
 #include <ctype.h>
 #include <math.h>
@@ -211,43 +212,53 @@ UtilStringDuplicate(char *inStr)
 }
 
 char *
-UtilStringConcat(char *str1, char *str2)
+UtilStringConcat(size_t nStr,...)
 {
-    char *ret;
-    size_t str1Len, str2Len;
+    va_list argp;
+    char *str;
+    char *strp;
+    size_t strLen = 0;
+    size_t i;
 
-    str1Len = str1 ? strlen(str1) : 0;
-    str2Len = str2 ? strlen(str2) : 0;
-
-    ret = Malloc(str1Len + str2Len + 1);
-
-    if (!ret)
+    va_start(argp, nStr);
+    for (i = 0; i < nStr; i++)
     {
-        return NULL;
-    }
+        char *argStr = va_arg(argp, char *);
 
-    if (str1 && str2)
-    {
-        strcpy(ret, str1);
-        strcpy(ret + str1Len, str2);
-    }
-    else
-    {
-        if (str1)
+        if (argStr)
         {
-            strcpy(ret, str1);
+            strLen += strlen(argStr);
         }
-        else if (str2)
+    }
+    va_end(argp);
+
+    str = Malloc(strLen + 1);
+    strp = str;
+
+    va_start(argp, nStr);
+
+    for (i = 0; i < nStr; i++)
+    {
+        /* Manually copy chars instead of using strcopy() so we don't
+         * have to call strlen() on the strings again, and we aren't
+         * writing useless null chars. */
+
+        char *argStr = va_arg(argp, char *);
+
+        if (argStr)
         {
-            strcpy(ret, str2);
-        }
-        else
-        {
-            strcpy(ret, "");
+            while (*argStr)
+            {
+                *strp = *argStr;
+                strp++;
+                argStr++;
+            }
         }
     }
 
-    return ret;
+    va_end(argp);
+    str[strLen] = '\0';
+    return str;
 }
 
 int

src/include/Util.h

@@ -45,7 +45,7 @@ extern char *
  UtilStringDuplicate(char *);
 
 extern char *
- UtilStringConcat(char *, char *);
+ UtilStringConcat(size_t,...);
 
 extern int
  UtilSleepMillis(long);