Subject: ensure libsmbclient.h is being used with LFS enabled From: Michael Tokarev Date: Sat, 02 Apr 2022 19:01:55 +0300 Bug-Debian: https://bugs.debian.org/221618 We build samba with LFS (Large File Support) even on 32bits. This means some types like off_t are 64-bit wide, again, even on a 32bit host. libsmbclient.h uses off_t in function prototypes, and thes prototypes muct match those which were used at samba compile time - if some other source includes libsmbclient.h without LFS, it'll get wrong prototypes and the resulting binary will most likely crash when using libsmbclient functions. Detect and error-out this at compile time. We can not do anything with this in the public header since it is alredy too late to redefine things, since we can't guarantee we're the first header a program #includes, and at the time this libsmbclient.h is included, off_t can already be defined so our (re)define of _FILE_OFFSET_BITS does nothing already. Patching libsmbclient.h to use off64_t means client program should change their off_t to off64_t too when storing file offsets returning from libsmbclient, so this is not an option too. With this change, we will error out even if the user source does not use any off_t-related functions. Namely, it was ok to #include and use smbc_open/smbc_read/ smbc_write/smbc_close without _F_O_B=64, - neither of these functions uses off_t. smbc_lseek and others doesn't work, but if a program does not use them anyway, whole thing will just work even without enabling LFS. Ideally we can probably check each individual function which is being affected, by replacing it with #error if sizeof(off_t) < 8. But this requires quite some hackery... diff --git a/source3/include/libsmbclient.h b/source3/include/libsmbclient.h index 84c98089251..1a6ea599cfa 100644 --- a/source3/include/libsmbclient.h +++ b/source3/include/libsmbclient.h @@ -82,4 +82,6 @@ extern "C" { #include +typedef int smbc_off_t_should_be_at_least_64bits_use_LFS_CFLAGS[sizeof(off_t)-7]; + #define SMBC_BASE_FD 10000 /* smallest file descriptor returned */