Core: fixed a race resulting in extra sem_post()'s. The mtx->wait counter was not decremented if we were able to obtain the lock right after incrementing it. This resulted in unneeded sem_post() calls, eventually leading to EOVERFLOW errors being logged, "sem_post() failed while wake shmtx (75: Value too large for defined data type)". To close the race, mtx->wait is now decremented if we obtain the lock right after incrementing it in ngx_shmtx_lock(). The result can become -1 if a concurrent ngx_shmtx_unlock() decrements mtx->wait before the added code does. However, that only leads to one extra iteration in the next call of ngx_shmtx_lock().

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


#ifndef _NGX_SHA1_H_INCLUDED_
#define _NGX_SHA1_H_INCLUDED_


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


#if (NGX_HAVE_OPENSSL_SHA1_H)
#include <openssl/sha.h>
#else
#include <sha.h>
#endif


typedef SHA_CTX  ngx_sha1_t;


#define ngx_sha1_init    SHA1_Init
#define ngx_sha1_update  SHA1_Update
#define ngx_sha1_final   SHA1_Final


#endif /* _NGX_SHA1_H_INCLUDED_ */