log: measure the debug log with a size type that can hold it

GetFilesize() returned int while ftell() returns long, so a debug.log of
2 GiB or more came back negative. Its only caller is the -maxdebugfilesize
roll added in ae1c6a7, which skips the roll on a negative size: the
rotation written for issue #34 would have switched itself off permanently
at exactly the size it exists to prevent. Production was at 1.95 GiB
growing 51-129 MB/day, about a day short of crossing 2 GiB.

The same truncation capped the comparison at INT_MAX (2047.99 MB), so
-maxdebugfilesize=2048 or higher could never be exceeded and disabled
rotation outright. Both failures were silent.

Widen the return to int64 and seek with ftello/fseeko (_ftelli64 and
_fseeki64 on Windows). The roll in util.h is the function's only caller
in the tree, so no other behaviour changes. A 32-bit off_t would
reintroduce the same truncation, so its width is now a compile-time
assertion rather than a silent runtime surprise.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/util.h b/src/util.h
index c47b8a7..89dce2f 100644
--- a/src/util.h
+++ b/src/util.h
@@ -154,7 +154,7 @@ void ParseString(const string& str, char c, vector<string>& v);
 string FormatMoney(int64 n, bool fPlus=false);
 bool ParseMoney(const char* pszIn, int64& nRet);
 bool FileExists(const char* psz);
-int GetFilesize(FILE* file);
+int64 GetFilesize(FILE* file);
 uint64 GetRand(uint64 nMax);
 int64 GetTime();
 int64 GetAdjustedTime();
@@ -410,8 +410,8 @@ inline int OutputDebugStringF(const char* pszFormat, ...)
             // so a rename is safe here: the next line simply reopens the
             // path. One generation is kept as debug.log.old; logrotate
             // (contrib/logrotate/) handles anything longer-term.
-            int nSize = GetFilesize(fileout);
-            if (nSize >= 0 && (int64)nSize > nMaxDebugFileSize)
+            int64 nSize = GetFilesize(fileout);
+            if (nSize >= 0 && nSize > nMaxDebugFileSize)
             {
                 fclose(fileout);
                 string strOldFile = strDebugFile + ".old";