The segmentation fault occurs everytime when calling g_fprintf() in update-mime-database.c, first on line 3849. See the gdb output below (on a build with debugging symbols). Could this be related to libglib2 somehow not being fully configured yet when first installing shared-mime-info? I don't understand, but I effectively worked around the problem by replacing g_fprintf() with standard printf().
(gdb) break update-mime-database.c:3624 Breakpoint 1 at 0x40a6d2: file update-mime-database.c, line 3624. (gdb) run /usr/share/mime Starting program: /usr/bin/update-mime-database.real /usr/share/mime [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". Breakpoint 1, main (argc=2, argv=0x7fffffffe3a8) at update-mime-database.c:3624 3624 g_fprintf(globs, (gdb) bt #0 main (argc=2, argv=0x7fffffffe3a8) at update-mime-database.c:3624 (gdb) print globs $1 = (FILE *) 0x64c600 (gdb) print globs_path $2 = 0x21a7ac0 "/usr/share/mime/globs.new" (gdb) continue Continuing. Program received signal SIGSEGV, Segmentation fault. 0x00007ffff77f5191 in g_fprintf () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 (gdb) bt #0 0x00007ffff77f5191 in g_fprintf () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #1 0x000000000064c600 in ?? () #2 0x000000000040a6eb in main (argc=2, argv=0x7fffffffe3a8) at update-mime-database.c:3624
