.

wcfs/internal/wcfs_misc.cpp

@@ -138,19 +138,27 @@ error map_into(void *addr, size_t size, int prot, int flags, const os::File &f,
 namespace fmt {
 
 static
-string _vsprintf(const string &format, va_list argp) {
+string _vsprintf(const char *format, va_list argp) {
     // based on https://stackoverflow.com/a/26221725/9456786
     va_list argp2;
     va_copy(argp2, argp);
-    size_t size = vsnprintf(NULL, 0, format.c_str(), argp2);
+    size_t size = vsnprintf(NULL, 0, format, argp2);
     va_end(argp2);
 
     std::unique_ptr<char[]> buf( new char[size] );
-    vsnprintf(buf.get(), size, format.c_str(), argp);
+    vsnprintf(buf.get(), size, format, argp);
     return string(buf.get(), buf.get() + size - 1 ); // without trailing '\0'
 }
 
 string sprintf(const string &format, ...) {
+    va_list argp;
+    va_start(argp, format);
+    string str = fmt::_vsprintf(format.c_str(), argp);
+    va_end(argp);
+    return str;
+}
+
+string sprintf(const char *format, ...) {
     va_list argp;
     va_start(argp, format);
     string str = fmt::_vsprintf(format, argp);
@@ -159,6 +167,15 @@ string sprintf(const string &format, ...) {
 }
 
 error errorf(const string &format, ...) {
+    error err;
+    va_list argp;
+    va_start(argp, format);
+    err.err = fmt::sprintf(format.c_str(), argp);
+    va_end(argp);
+    return err;
+}
+
+error errorf(const char *format, ...) {
     error err;
     va_list argp;
     va_start(argp, format);

wcfs/internal/wcfs_misc.h

@@ -107,6 +107,13 @@ namespace fmt {
 string sprintf(const string &format, ...);
 error  errorf (const string &format, ...);
 
+// `const char *` overload just to catch format mistakes as
+// __attribute__(format) does not work with std::string.
+string sprintf(const char *format, ...)
+    __attribute__ ((format (printf, 1, 2)));
+error  errorf (const char *format, ...)
+    __attribute__ ((format (printf, 1, 2)));
+
 }   // fmt::
 
 #endif

wcfs/internal/wcfs_virtmem.cpp

@@ -355,11 +355,13 @@ error _Mapping::_remmapblk(int64_t blk, Tid at) {
     err = fsfile.stat(&st);
     if (err != nil)
         return err;
-    ASSERT(st.st_blksize == f->blksize);  // FIXME assert -> return err ?
+    if ((size_t)st.st_blksize != f->blksize)
+        return fmt::errorf("wcfs bug: blksize changed: expected %lu; got %ld",
+                f->blksize, st.st_blksize);
 
     // block is beyond file size - mmap with zeros - else access to memory
     // after file.size will raise SIGBUS. (assumes head/f size ↑=)
-    if ((blk+1)*f->blksize > st.st_size) {
+    if ((blk+1)*f->blksize > (size_t)st.st_size) {
         err = mmap_zero_into_ro(blkmem, 1*f->blksize);
         if (err != nil)
             return err;
@@ -422,7 +424,7 @@ error WatchLink::_send(StreamID stream, const string &msg) {
     pkt.rawdata = // XXX copy msg   XXX + "%d <stream> ...\n" ?
     return wlink->_write(&pkt)
 #endif
-    string pkt = fmt::sprintf("%ul %s\n", stream, msg.c_str());
+    string pkt = fmt::sprintf("%lu %s\n", stream, msg.c_str());
     return wlink->_write(pkt);
 }
 
@@ -522,7 +524,7 @@ tuple<os::File, error> WCFS::_open(const string &path, int flags) {
 // ---- misc ----
 
 static string h(uint64_t v) {
-    return fmt::sprintf("%016x", v);
+    return fmt::sprintf("%016lx", v);
 }
 
 // map_zero_ro mmaps read-only zeros into [addr +size) so that region as all zeros.