Remove peerDigestFetchStop() and peerDigestFetchAbort() wrappers (squ…

…id-cache#1869)

These wrappers were left in recent commit f036532 to reduce noise. Now
we always call finishAndDeleteFetch() directly (instead of sometimes
going through those wrappers). The new function name helps reduce the
number of use-after-free bugs in this code.

src/peer_digest.cc

@@ -42,9 +42,7 @@ static int peerDigestFetchReply(void *, char *, ssize_t);
 int peerDigestSwapInCBlock(void *, char *, ssize_t);
 int peerDigestSwapInMask(void *, char *, ssize_t);
 static int peerDigestFetchedEnough(DigestFetchState * fetch, char *buf, ssize_t size, const char *step_name);
-static void peerDigestFetchStop(DigestFetchState * fetch, char *buf, const char *reason);
-static void peerDigestFetchAbort(DigestFetchState * fetch, char *buf, const char *reason);
-static void peerDigestReqFinish(DigestFetchState *, char *buf, const char *reason, int err);
+static void finishAndDeleteFetch(DigestFetchState *, const char *reason, bool sawError);
 static void peerDigestFetchSetStats(DigestFetchState * fetch);
 static int peerDigestSetCBlock(PeerDigest * pd, const char *buf);
 static int peerDigestUseful(const PeerDigest * pd);
@@ -331,12 +329,12 @@ peerDigestHandleReply(void *data, StoreIOBuffer receivedData)
     int newsize;
 
     if (receivedData.flags.error) {
-        peerDigestFetchAbort(fetch, fetch->buf, "failure loading digest reply from Store");
+        finishAndDeleteFetch(fetch, "failure loading digest reply from Store", true);
         return;
     }
 
     if (!fetch->pd) {
-        peerDigestFetchAbort(fetch, fetch->buf, "digest disappeared while loading digest reply from Store");
+        finishAndDeleteFetch(fetch, "digest disappeared while loading digest reply from Store", true);
         return;
     }
 
@@ -411,7 +409,7 @@ peerDigestHandleReply(void *data, StoreIOBuffer receivedData)
     // that the parser does not regard EOF as a special condition (it is true now but may change
     // in the future).
     if (fetch->sc->atEof()) {
-        peerDigestFetchAbort(fetch, fetch->buf, "premature end of digest reply");
+        finishAndDeleteFetch(fetch, "premature end of digest reply", true);
         return;
     }
 
@@ -463,7 +461,7 @@ peerDigestFetchReply(void *data, char *buf, ssize_t size)
             assert(fetch->old_entry->mem_obj->request);
 
             if (!Store::Root().updateOnNotModified(fetch->old_entry, *fetch->entry)) {
-                peerDigestFetchAbort(fetch, buf, "header update failure after a 304 response");
+                finishAndDeleteFetch(fetch, "header update failure after a 304 response", true);
                 return -1;
             }
 
@@ -481,12 +479,12 @@ peerDigestFetchReply(void *data, char *buf, ssize_t size)
             /* fetch->entry->mem_obj->request = nullptr; */
 
             if (!fetch->pd->cd) {
-                peerDigestFetchAbort(fetch, buf, "304 without the old in-memory digest");
+                finishAndDeleteFetch(fetch, "304 without the old in-memory digest", true);
                 return -1;
             }
 
             // stay with the old in-memory digest
-            peerDigestFetchStop(fetch, buf, "Not modified");
+            finishAndDeleteFetch(fetch, "Not modified", false);
             return -1;
         } else if (status == Http::scOkay) {
             /* get rid of old entry if any */
@@ -502,7 +500,7 @@ peerDigestFetchReply(void *data, char *buf, ssize_t size)
             fetch->state = DIGEST_READ_CBLOCK;
         } else {
             /* some kind of a bug */
-            peerDigestFetchAbort(fetch, buf, reply.sline.reason());
+            finishAndDeleteFetch(fetch, reply.sline.reason(), true);
             return -1;      /* XXX -1 will abort stuff in ReadReply! */
         }
     }
@@ -534,14 +532,14 @@ peerDigestSwapInCBlock(void *data, char *buf, ssize_t size)
             fetch->state = DIGEST_READ_MASK;
             return StoreDigestCBlockSize;
         } else {
-            peerDigestFetchAbort(fetch, buf, "invalid digest cblock");
+            finishAndDeleteFetch(fetch, "invalid digest cblock", true);
             return -1;
         }
     }
 
     /* need more data, do we have space? */
     if (size >= SM_PAGE_SIZE) {
-        peerDigestFetchAbort(fetch, buf, "digest cblock too big");
+        finishAndDeleteFetch(fetch, "digest cblock too big", true);
         return -1;
     }
 
@@ -582,7 +580,7 @@ peerDigestSwapInMask(void *data, char *buf, ssize_t size)
 }
 
 static int
-peerDigestFetchedEnough(DigestFetchState * fetch, char *buf, ssize_t size, const char *step_name)
+peerDigestFetchedEnough(DigestFetchState * fetch, char *, ssize_t size, const char *step_name)
 {
     static const SBuf hostUnknown("<unknown>"); // peer host (if any)
     SBuf host = hostUnknown;
@@ -629,34 +627,15 @@ peerDigestFetchedEnough(DigestFetchState * fetch, char *buf, ssize_t size, const
     if (reason) {
         const int level = strstr(reason, "?!") ? 1 : 3;
         debugs(72, level, "" << step_name << ": peer " << host << ", exiting after '" << reason << "'");
-        peerDigestReqFinish(fetch, buf, reason, !no_bug);
+        finishAndDeleteFetch(fetch, reason, !no_bug);
     }
 
     return reason != nullptr;
 }
 
-/* call this when all callback data is valid and fetch must be stopped but
- * no error has occurred (e.g. we received 304 reply and reuse old digest) */
-static void
-peerDigestFetchStop(DigestFetchState * fetch, char *buf, const char *reason)
-{
-    assert(reason);
-    debugs(72, 2, "peerDigestFetchStop: peer " << fetch->pd->host << ", reason: " << reason);
-    peerDigestReqFinish(fetch, buf, reason, 0);
-}
-
-/// diff reducer: handle a peer digest fetch failure
-static void
-peerDigestFetchAbort(DigestFetchState * fetch, char *buf, const char *reason)
-{
-    assert(reason);
-    peerDigestReqFinish(fetch, buf, reason, 1);
-}
-
 /* complete the digest transfer, update stats, unlock/release everything */
 static void
-peerDigestReqFinish(DigestFetchState * fetch, char * /* buf */,
-                    const char *reason, int err)
+finishAndDeleteFetch(DigestFetchState * const fetch, const char * const reason, const bool err)
 {
     assert(reason);