altsvc: use Curl_fopen()

lib/altsvc.c

@@ -36,7 +36,7 @@
 #include "parsedate.h"
 #include "sendf.h"
 #include "warnless.h"
-#include "rand.h"
+#include "fopen.h"
 #include "rename.h"
 
 /* The last 3 #include files should be in this order */
@@ -337,8 +337,7 @@ CURLcode Curl_altsvc_save(struct Curl_easy *data,
   struct Curl_llist_element *n;
   CURLcode result = CURLE_OK;
   FILE *out;
-  char *tempstore;
-  unsigned char randsuffix[9];
+  char *tempstore = NULL;
 
   if(!altsvc)
     /* no cache activated */
@@ -352,17 +351,8 @@ CURLcode Curl_altsvc_save(struct Curl_easy *data,
     /* marked as read-only, no file or zero length file name */
     return CURLE_OK;
 
-  if(Curl_rand_hex(data, randsuffix, sizeof(randsuffix)))
-    return CURLE_FAILED_INIT;
-
-  tempstore = aprintf("%s.%s.tmp", file, randsuffix);
-  if(!tempstore)
-    return CURLE_OUT_OF_MEMORY;
-
-  out = fopen(tempstore, FOPEN_WRITETEXT);
-  if(!out)
-    result = CURLE_WRITE_ERROR;
-  else {
+  result = Curl_fopen(data, file, &out, &tempstore);
+  if(!result) {
     fputs("# Your alt-svc cache. https://curl.se/docs/alt-svc.html\n"
           "# This file was generated by libcurl! Edit at your own risk.\n",
           out);
@@ -374,10 +364,10 @@ CURLcode Curl_altsvc_save(struct Curl_easy *data,
         break;
     }
     fclose(out);
-    if(!result && Curl_rename(tempstore, file))
+    if(!result && tempstore && Curl_rename(tempstore, file))
       result = CURLE_WRITE_ERROR;
 
-    if(result)
+    if(result && tempstore)
       unlink(tempstore);
   }
   free(tempstore);