Fix off_t ambiguity

Depending on the build system architecture, off_t may be a 32-bit or 64-bit value. We can just use 64-bit on 32-bit as well.

Author: TheAssassin

include/zsclient.h

@@ -55,7 +55,7 @@ namespace zsync2 {
         // set fileSize to size of remote file in bytes
         // returns true if the value is available (i.e., the update has started and the value can be read from the
         // .zsync file), false otherwise
-        bool remoteFileSize(off_t& fileSize);
+        bool remoteFileSize(long long& fileSize);
 
         // set path in which the .zsync file should be stored when downloaded first
         void storeZSyncFileInPath(const std::string& path);

src/CMakeLists.txt

@@ -47,11 +47,10 @@ function(add_libzsync2 NAME BUILD_TYPE)
 
     # largefile support à la gpgme
     # libzsync uses off_t everywhere, this allows us to support files larger than 2GiB
-    # must(!) be public definitions, otherwise integrating libzsync2 elsewhere (e.g., AppImageUpdate) may lead to
-    # compiler errors because the off_t definitions differ
+    # our public APIs do not use off_t but long long to avoid this ambiguity
     target_compile_definitions("${NAME}"
-        PUBLIC -D_FILE_OFFSET_BITS=64
-        PUBLIC -DLARGEFILE_SOURCE
+        PRIVATE -D_FILE_OFFSET_BITS=64
+        PRIVATE -DLARGEFILE_SOURCE
     )
 endfunction()
 

src/zsclient.cpp

@@ -58,7 +58,7 @@ namespace zsync2 {
 
         std::string cwd;
 
-        off_t remoteFileSizeCache;
+        long long remoteFileSizeCache;
 
         unsigned long rangesOptimizationThreshold;
 
@@ -1058,12 +1058,12 @@ namespace zsync2 {
             return true;
         }
 
-        bool remoteFileSize(off_t& fileSize) {
+        bool remoteFileSize(long long& fileSize) {
             if (remoteFileSizeCache < 0) {
                 if (zsHandle == nullptr)
                     return false;
 
-                remoteFileSizeCache = zsync_filelen(zsHandle);
+                remoteFileSizeCache = static_cast<long long>(zsync_filelen(zsHandle));
             }
 
             if (remoteFileSizeCache < 0)
@@ -1134,7 +1134,7 @@ namespace zsync2 {
         return d->setCwd(path);
     }
 
-    bool ZSyncClient::remoteFileSize(off_t& fileSize) {
+    bool ZSyncClient::remoteFileSize(long long& fileSize) {
         return d->remoteFileSize(fileSize);
     }