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fix building by gcc 4.x with -O2/3/s in some Linux distributions:

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dereferencing type-punned pointer will break strict-aliasing rules
This commit is contained in:
Igor Sysoev 2009-12-22 15:29:56 +00:00
parent 8c97fa9ae4
commit fb0c73b08d
1 changed files with 15 additions and 2 deletions
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17
src/os/unix/ngx_channel.c
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@ -36,7 +36,18 @@ ngx_write_channel(ngx_socket_t s, ngx_channel_t *ch, size_t size,
cmsg.cm.cmsg_len = CMSG_LEN(sizeof(int)); cmsg.cm.cmsg_len = CMSG_LEN(sizeof(int));
cmsg.cm.cmsg_level = SOL_SOCKET; cmsg.cm.cmsg_level = SOL_SOCKET;
cmsg.cm.cmsg_type = SCM_RIGHTS; cmsg.cm.cmsg_type = SCM_RIGHTS;
*(int *) CMSG_DATA(&cmsg.cm) = ch->fd;
/*
* We have to use ngx_memcpy() instead of simple
* *(int *) CMSG_DATA(&cmsg.cm) = ch->fd;
* because some gcc 4.4 with -O2/3/s optimization issues the warning:
* dereferencing type-punned pointer will break strict-aliasing rules
*
* Fortunately, gcc with -O1 compiles this ngx_memcpy()
* in the same simple assigment as in the code above
*/
ngx_memcpy(CMSG_DATA(&cmsg.cm), &ch->fd, sizeof(int));
} }
msg.msg_flags = 0; msg.msg_flags = 0;
@ -153,7 +164,9 @@ ngx_read_channel(ngx_socket_t s, ngx_channel_t *ch, size_t size, ngx_log_t *log)
return NGX_ERROR; return NGX_ERROR;
} }
ch->fd = *(int *) CMSG_DATA(&cmsg.cm); /* ch->fd = *(int *) CMSG_DATA(&cmsg.cm); */
ngx_memcpy(&ch->fd, CMSG_DATA(&cmsg.cm), sizeof(int));
} }
if (msg.msg_flags & (MSG_TRUNC|MSG_CTRUNC)) { if (msg.msg_flags & (MSG_TRUNC|MSG_CTRUNC)) {