HPCC-33065 Improve the error message when failing to read an index he…

…ader/footer

Signed-off-by: Gavin Halliday <[email protected]>

system/jhtree/jhtree.cpp

@@ -1222,8 +1222,9 @@ CDiskKeyIndex::CDiskKeyIndex(unsigned _iD, IFileIO *_io, const char *_name, bool
     blockedIOSize = _blockedIOSize;
     io.setown(_io);
     KeyHdr hdr;
-    if (io->read(0, sizeof(hdr), &hdr) != sizeof(hdr))
-        throw MakeStringException(0, "Failed to read key header: file too small, could not read %u bytes", (unsigned) sizeof(hdr));
+    offset_t sizeRead = io->read(0, sizeof(hdr), &hdr);
+    if (sizeRead  != sizeof(hdr))
+        throw MakeStringException(0, "Failed to read key header: file too small, could not read %u bytes - read %u", (unsigned) sizeof(hdr), (unsigned)sizeRead);
 
 #ifdef _DEBUG
     //In debug mode always use the trailing header if it is available to ensure that code path is tested
@@ -1233,8 +1234,11 @@ CDiskKeyIndex::CDiskKeyIndex(unsigned _iD, IFileIO *_io, const char *_name, bool
 #endif
     {
         _WINREV(hdr.nodeSize);
-        if (!io->read(io->size() - hdr.nodeSize, sizeof(hdr), &hdr))
-            throw MakeStringException(4, "Invalid key %s: failed to read trailing key header", _name);
+        offset_t actualSize = io->size();
+        offset_t readOffset = actualSize - hdr.nodeSize;
+        sizeRead = io->read(readOffset, sizeof(hdr), &hdr);
+        if (sizeRead  != sizeof(hdr))
+            throw MakeStringException(4, "Invalid key %s: failed to read trailing key header at offset %llu, read %u", _name, readOffset, (unsigned)sizeRead);
     }
     init(hdr, isTLK);
 }

system/jlib/jio.cpp

@@ -160,7 +160,7 @@ extern jlib_decl size32_t checked_pread(const char * filename, int file, void *b
                     readNow = 0;
                     break;
                 }
-                throw makeErrnoExceptionV(errno, "checked_pread for file '%s'", filename);
+                throw makeErrnoExceptionV(errno, "checked_pread for file '%s' @%lld", filename, pos);
             }
         }
         else if (!readNow)