Valgrind: supressed complaints about uninitialized bytes. Valgrind complains if we pass uninitialized memory to a syscall: ==36492== Syscall param sendmsg(msg.msg_iov[0]) points to uninitialised byte(s) ==36492== at 0x6B5E6A: sendmsg (in /usr/lib/system/libsystem_kernel.dylib) ==36492== by 0x10004288E: ngx_signal_worker_processes (ngx_process_cycle.c:527) ==36492== by 0x1000417A7: ngx_master_process_cycle (ngx_process_cycle.c:203) ==36492== by 0x100001F10: main (nginx.c:410) ==36492== Address 0x7fff5fbff71c is on thread 1's stack Even initialization of all members of the structure passed isn't enough, as there is padding which still remains uninitialized and results in Valgrind complaint. Note there is no real problem here as data from uninitialized memory isn't used.

/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#ifndef _NGX_SHMEM_H_INCLUDED_
#define _NGX_SHMEM_H_INCLUDED_


#include <ngx_config.h>
#include <ngx_core.h>


typedef struct {
    u_char      *addr;
    size_t       size;
    ngx_str_t    name;
    ngx_log_t   *log;
    ngx_uint_t   exists;   /* unsigned  exists:1;  */
} ngx_shm_t;


ngx_int_t ngx_shm_alloc(ngx_shm_t *shm);
void ngx_shm_free(ngx_shm_t *shm);


#endif /* _NGX_SHMEM_H_INCLUDED_ */