On 23/02/20(Sun) 14:48, Lauri Tirkkonen wrote: > I was working on a make jobserver implementation that uses POSIX > semaphores as job tokens instead of a complicated socket-based approach. > Initially I used named semaphores, which work fine, except if child > processes with less privileges need to also open the named semaphore > (eg. 'make build' as root executing 'su build -c make'). For that reason > I wanted to use an unnamed semaphore (sem_init()) which is stored in shm > -- that way I could leave the shm fd open and pass it to children. > > But unfortunately, sem_t is currently just a pointer to the opaque > struct __sem, and sem_int() always calloc()s the storage for the struct.
That's by design. > This means the application cannot control where unnamed semaphores are > stored, so I can't put it in shm. Are you trying to use semaphore shared between process? Did you called sem_init() with pshared=1? Have you seen that the current implementation doesn't support them?
