[nginx] Valgrind: supressed complaints about uninitialized bytes.

[Maxim Dounin]

details:   http://hg.nginx.org/nginx/rev/711fa02afae8
branches:  
changeset: 5245:711fa02afae8
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Wed Jun 05 19:44:22 2013 +0400
description:
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.

diffstat:

 src/http/ngx_http_file_cache.c  |  2 ++
 src/os/unix/ngx_process_cycle.c |  8 ++++++++
 2 files changed, 10 insertions(+), 0 deletions(-)

diffs (51 lines):

diff --git a/src/http/ngx_http_file_cache.c b/src/http/ngx_http_file_cache.c
--- a/src/http/ngx_http_file_cache.c
+++ b/src/http/ngx_http_file_cache.c
@@ -875,6 +875,8 @@ ngx_http_file_cache_set_header(ngx_http_
 
     c = r->cache;
 
+    ngx_memzero(h, sizeof(ngx_http_file_cache_header_t));
+
     h->valid_sec = c->valid_sec;
     h->last_modified = c->last_modified;
     h->date = c->date;
diff --git a/src/os/unix/ngx_process_cycle.c b/src/os/unix/ngx_process_cycle.c
--- a/src/os/unix/ngx_process_cycle.c
+++ b/src/os/unix/ngx_process_cycle.c
@@ -355,6 +355,8 @@ ngx_start_worker_processes(ngx_cycle_t *
 
     ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "start worker processes");
 
+    ngx_memzero(&ch, sizeof(ngx_channel_t));
+
     ch.command = NGX_CMD_OPEN_CHANNEL;
 
     for (i = 0; i < n; i++) {
@@ -401,6 +403,8 @@ ngx_start_cache_manager_processes(ngx_cy
                       &ngx_cache_manager_ctx, "cache manager process",
                       respawn ? NGX_PROCESS_JUST_RESPAWN : NGX_PROCESS_RESPAWN);
 
+    ngx_memzero(&ch, sizeof(ngx_channel_t));
+
     ch.command = NGX_CMD_OPEN_CHANNEL;
     ch.pid = ngx_processes[ngx_process_slot].pid;
     ch.slot = ngx_process_slot;
@@ -460,6 +464,8 @@ ngx_signal_worker_processes(ngx_cycle_t 
     ngx_err_t      err;
     ngx_channel_t  ch;
 
+    ngx_memzero(&ch, sizeof(ngx_channel_t));
+
 #if (NGX_BROKEN_SCM_RIGHTS)
 
     ch.command = 0;
@@ -561,6 +567,8 @@ ngx_reap_children(ngx_cycle_t *cycle)
     ngx_channel_t     ch;
     ngx_core_conf_t  *ccf;
 
+    ngx_memzero(&ch, sizeof(ngx_channel_t));
+
     ch.command = NGX_CMD_CLOSE_CHANNEL;
     ch.fd = -1;