use fwrite() instead of fprintf() for output (saves parsing the format

string)

src/format.c

@@ -1464,11 +1464,10 @@ fmt_resize(size_t curlen)
 }
 
 char *
-FMT_Format(tx_t *tx)
+FMT_Format(tx_t *tx, size_t *curlen)
 {
     compiled_fmt_t fmt;
     char *p = obuf;
-    size_t curlen = 0;
 
     CHECK_OBJ_NOTNULL(tx, TX_MAGIC);
     assert(tx->state == TX_SUBMITTED);
@@ -1490,21 +1489,22 @@ FMT_Format(tx_t *tx)
     tx->state = TX_FORMATTING;
 
     *p = '\0';
+    *curlen = 0;
     for (int i = 0; i < fmt.n; i++) {
         char *s = NULL;
         size_t len = 0;
 
         if (fmt.str[i] != NULL) {
-            curlen += fmt.strlen[i];
-            fmt_resize(curlen);
+            *curlen += fmt.strlen[i];
+            fmt_resize(*curlen);
             memcpy(p, fmt.str[i], fmt.strlen[i]);
             p += fmt.strlen[i];
         }
         if (fmt.formatter[i] != NULL) {
             (fmt.formatter[i])(tx, &fmt.args[i], &s, &len);
             if (s != NULL && len != 0) {
-                curlen += len;
-                fmt_resize(curlen);
+                *curlen += len;
+                fmt_resize(*curlen);
                 memcpy(p, s, len);
                 p += len;
             }

src/test/test_format.c

@@ -1881,6 +1881,7 @@ static const char
     chunk_t c[NTAGS];
     struct tm *tm;
     time_t t = 1427743146;
+    size_t len;
 
     printf("... testing FMT_*() interface\n");
 
@@ -1945,13 +1946,14 @@ static const char
     add_record_data(&tx, SLT_RespStatus, &rec[9],  &c[9], "200");
     add_record_data(&tx, SLT_ReqAcct,    &rec[10], &c[10], REQACCT_PAYLOAD);
 
-    os = FMT_Format(&tx);
+    os = FMT_Format(&tx, &len);
 #define EXP_DEFAULT_OUTPUT "127.0.0.1 - varnish [%d/%b/%Y:%T %z] "\
         "\"GET http://bazquux.com/foo HTTP/1.1\" 200 105 "\
         "\"http://foobar.com/\" \"Mozilla\"\n"
     tm = localtime(&t);
     MAN(strftime(strftime_s, BUFSIZ, EXP_DEFAULT_OUTPUT, tm));
     VMASSERT(strcmp(os, strftime_s) == 0, "'%s' != '%s'", os, strftime_s);
+    MASSERT(len == strlen(strftime_s));
 
     /* Client format with all formatters */
     FMT_Fini();
@@ -2027,7 +2029,7 @@ static const char
         }
 
     setup_full_client_tx(&tx, node, nptr, rec, c);
-    os = FMT_Format(&tx);
+    os = FMT_Format(&tx, &len);
 #define EXP_FULL_CLIENT_OUTPUT "105 c 15963 HTTP/1.1 127.0.0.1 60 foohdr "\
         "barhdr - GET 283 bar=baz&quux=wilco GET "\
         "http://foobar.com/foo?bar=baz&quux=wilco HTTP/1.1 200 "\
@@ -2037,6 +2039,7 @@ static const char
     tm = localtime(&t);
     MAN(strftime(strftime_s, BUFSIZ, EXP_FULL_CLIENT_OUTPUT, tm));
     VMASSERT(strcmp(os, strftime_s) == 0, "'%s' != '%s'", os, strftime_s);
+    MASSERT(len == strlen(strftime_s));
 
     /* Backend format with all formatters */
     FMT_Fini();
@@ -2103,7 +2106,7 @@ static const char
         }
 
     setup_full_backend_tx(&tx, node, nptr, rec, c);
-    os = FMT_Format(&tx);
+    os = FMT_Format(&tx, &len);
 #define EXP_FULL_BACKEND_OUTPUT "105 b 15703 HTTP/1.1 default(127.0.0.1,,80) "\
         "283 foohdr barhdr - GET 60 bar=baz&quux=wilco GET "\
         "http://foobar.com/foo?bar=baz&quux=wilco HTTP/1.1 200 "\
@@ -2113,6 +2116,7 @@ static const char
     tm = localtime(&t);
     MAN(strftime(strftime_s, BUFSIZ, EXP_FULL_BACKEND_OUTPUT, tm));
     VMASSERT(strcmp(os, strftime_s) == 0, "'%s' != '%s'", os, strftime_s);
+    MASSERT(len == strlen(strftime_s));
 
     /* Both backend and client formats */
     FMT_Fini();
@@ -2216,16 +2220,18 @@ static const char
         }
 
     setup_full_client_tx(&tx, node, nptr, rec, c);
-    os = FMT_Format(&tx);
+    os = FMT_Format(&tx, &len);
     tm = localtime(&t);
     MAN(strftime(strftime_s, BUFSIZ, EXP_FULL_CLIENT_OUTPUT, tm));
     VMASSERT(strcmp(os, strftime_s) == 0, "'%s' != '%s'", os, strftime_s);
+    MASSERT(len == strlen(strftime_s));
 
     setup_full_backend_tx(&tx, node, nptr, rec, c);
-    os = FMT_Format(&tx);
+    os = FMT_Format(&tx, &len);
     tm = localtime(&t);
     MAN(strftime(strftime_s, BUFSIZ, EXP_FULL_BACKEND_OUTPUT, tm));
     VMASSERT(strcmp(os, strftime_s) == 0, "'%s' != '%s'", os, strftime_s);
+    MASSERT(len == strlen(strftime_s));
 
     /* Raw format */
     FMT_Fini();
@@ -2259,12 +2265,13 @@ static const char
 #define HEALTH_PAYLOAD "b Still healthy 4--X-RH 5 4 5 0.032728 0.035774 " \
         "HTTP/1.1 200 OK"
     add_record_data(&tx, SLT_Backend_health, &rec[0],  &c[0], HEALTH_PAYLOAD);
-    os = FMT_Format(&tx);
+    os = FMT_Format(&tx, &len);
 #define EXP_FULL_RAW_OUTPUT "[%d/%b/%Y:%T %z] %F-%T.529143 "\
         "b Still healthy 4--X-RH 5 4 5 0.032728 0.035774 HTTP/1.1 200 OK 4711\n"
     tm = localtime(&t);
     MAN(strftime(strftime_s, BUFSIZ, EXP_FULL_RAW_OUTPUT, tm));
     VMASSERT(strcmp(os, strftime_s) == 0, "'%s' != '%s'", os, strftime_s);
+    MASSERT(len == strlen(strftime_s));
 
     /* Illegal backend formats */
     FMT_Fini();

src/varnishevent.h

@@ -278,7 +278,7 @@ void MON_Output(void);
 int FMT_Init(char *err);
 int FMT_GetMaxIdx(void);
 int FMT_Estimate_RecsPerTx(void);
-char *FMT_Format(tx_t *tx);
+char *FMT_Format(tx_t *tx, size_t *len);
 void FMT_Fini(void);
 
 /* handler.c */

src/writer.c

@@ -180,6 +180,7 @@ wrt_write(tx_t *tx)
 {
     char *os;
     int ready = 1;
+    size_t len;
     
     CHECK_OBJ_NOTNULL(tx, TX_MAGIC);
     assert(tx->state == TX_SUBMITTED);
@@ -207,7 +208,7 @@ wrt_write(tx_t *tx)
     AZ(pthread_mutex_unlock(&reopen_lock));
 
     VRMB();
-    os = FMT_Format(tx);
+    os = FMT_Format(tx, &len);
     assert(tx->state == TX_WRITTEN);
 
     if (blocking) {
@@ -242,17 +243,19 @@ wrt_write(tx_t *tx)
         }
     }
     if (ready) {
+        errno = 0;
         double start = VTIM_mono();
-        int ret = fprintf(fo, "%s", os);
+        int items = fwrite(os, 1, len, fo);
         writet += VTIM_mono() - start;
-        if (ret < 0) {
+        if (ferror(fo) || items < len) {
             LOG_Log(LOG_ERR, "Output error %d (%s), DATA DISCARDED: %s",
                     errno, strerror(errno), os);
             errors++;
+            clearerr(fo);
         }
         else {
             writes++;
-            bytes += strlen(os);
+            bytes += len;
         }
     }