delmail(): don't truncate the .sid file to 0-bytes before writing the contents,

instead truncate to the new length after writing the contents. This should
make mail.sid files more tolerant of "out of disk space" situations and reduce
the risk of lost data (0-byte mail.sid files) due to low/no free disk space.

src/sbbs3/mail.cpp

@@ -113,19 +113,17 @@ int sbbs_t::delmail(uint usernumber, int which)
 		l++; 
 	}
 	smb_rewind(smb.sid_fp);
-	if(smb_fsetlength(smb.sid_fp,0) != 0)
-		errormsg(WHERE, "truncating", smb.file, 0);
-	else {
-		for(i=0;i<l;i++) {
-			if(smb_fwrite(&smb,&idxbuf[i],sizeof(idxrec_t),smb.sid_fp) != sizeof(idxrec_t)) {
-				errormsg(WHERE, ERR_WRITE, smb.file, i);
-				break;
-			}
+	for(i=0;i<l;i++) {
+		if(smb_fwrite(&smb,&idxbuf[i],sizeof(idxrec_t),smb.sid_fp) != sizeof(idxrec_t)) {
+			errormsg(WHERE, ERR_WRITE, smb.file, i);
+			break;
 		}
-		smb.status.total_msgs=i;
-		smb_putstatus(&smb);
-		smb_fflush(smb.sid_fp);
 	}
+	smb_fflush(smb.sid_fp);
+	if(smb_fsetlength(smb.sid_fp, i * sizeof(idxrec_t)) != 0)
+		errormsg(WHERE, "truncating", smb.file, i * sizeof(idxrec_t));
+	smb.status.total_msgs=i;
+	smb_putstatus(&smb);
 	free(idxbuf);
 	smb_close_ha(&smb);
 	smb_close_da(&smb);