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include: fix ngx_queue_foreach() macro

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Guard against the possibility that the queue is emptied while we're iterating
over it. Simple test case:

  #include "ngx-queue.h"
  #include <assert.h>

  int main(void) {
    ngx_queue_t h;
    ngx_queue_t v[2];
    ngx_queue_t* q;
    unsigned n = 0;
    ngx_queue_init(&h);
    ngx_queue_insert_tail(&h, v + 0);
    ngx_queue_insert_tail(&h, v + 1);
    ngx_queue_foreach(q, &h) {
      ngx_queue_remove(v + 0);
      ngx_queue_remove(v + 1);
      n++;
    }
    assert(n == 1); // *not* 2
    return 0;
  }

Fixes #605.
This commit is contained in:
Ben Noordhuis 2012-10-25 04:26:56 +02:00
parent c2478b2669
commit f43ad85edd
1 changed files with 1 additions and 1 deletions
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2
include/uv-private/ngx-queue.h
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@ -101,7 +101,7 @@ struct ngx_queue_s {
#define ngx_queue_foreach(q, h) \
for ((q) = ngx_queue_head(h); \
(q) != ngx_queue_sentinel(h); \
(q) != ngx_queue_sentinel(h) && !ngx_queue_empty(h); \
(q) = ngx_queue_next(q))