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[nginx] Gzip: compatibility with recent zlib-ng versions.

Sergey Kandaurov
March 27, 2023 03:36PM
details: https://hg.nginx.org/nginx/rev/fcb2333c9982
branches:
changeset: 8153:fcb2333c9982
user: Maxim Dounin <mdounin@mdounin.ru>
date: Mon Mar 27 21:25:05 2023 +0300
description:
Gzip: compatibility with recent zlib-ng versions.

It now uses custom alloc_aligned() wrapper for all allocations,
therefore all allocations are larger than expected by (64 + sizeof(void*)).
Further, they are seen as allocations of 1 element. Relevant calculations
were adjusted to reflect this, and state allocation is now protected
with a flag to avoid misinterpreting other allocations as the zlib
deflate_state allocation.

Further, it no longer forces window bits to 13 on compression level 1,
so the comment was adjusted to reflect this.

diffstat:

src/http/modules/ngx_http_gzip_filter_module.c | 18 ++++++++++++------
1 files changed, 12 insertions(+), 6 deletions(-)

diffs (54 lines):

diff -r d1cf09451ae8 -r fcb2333c9982 src/http/modules/ngx_http_gzip_filter_module.c
--- a/src/http/modules/ngx_http_gzip_filter_module.c Fri Mar 24 02:57:43 2023 +0300
+++ b/src/http/modules/ngx_http_gzip_filter_module.c Mon Mar 27 21:25:05 2023 +0300
@@ -57,6 +57,7 @@ typedef struct {
unsigned nomem:1;
unsigned buffering:1;
unsigned zlib_ng:1;
+ unsigned state_allocated:1;

size_t zin;
size_t zout;
@@ -514,9 +515,10 @@ ngx_http_gzip_filter_memory(ngx_http_req
} else {
/*
* Another zlib variant, https://github.com/zlib-ng/zlib-ng.
- * It forces window bits to 13 for fast compression level,
- * uses 16-byte padding in one of window-sized buffers, and
- * uses 128K hash.
+ * It used to force window bits to 13 for fast compression level,
+ * uses (64 + sizeof(void*)) additional space on all allocations
+ * for alignment, 16-byte padding in one of window-sized buffers,
+ * and 128K hash.
*/

if (conf->level == 1) {
@@ -524,7 +526,8 @@ ngx_http_gzip_filter_memory(ngx_http_req
}

ctx->allocated = 8192 + 16 + (1 << (wbits + 2))
- + 131072 + (1 << (memlevel + 8));
+ + 131072 + (1 << (memlevel + 8))
+ + 4 * (64 + sizeof(void*));
ctx->zlib_ng = 1;
}
}
@@ -926,13 +929,16 @@ ngx_http_gzip_filter_alloc(void *opaque,

alloc = items * size;

- if (items == 1 && alloc % 512 != 0 && alloc < 8192) {
-
+ if (items == 1 && alloc % 512 != 0 && alloc < 8192
+ && !ctx->state_allocated)
+ {
/*
* The zlib deflate_state allocation, it takes about 6K,
* we allocate 8K. Other allocations are divisible by 512.
*/

+ ctx->state_allocated = 1;
+
alloc = 8192;
}

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[nginx] Gzip: compatibility with recent zlib-ng versions.

Sergey Kandaurov 427 March 27, 2023 03:36PM



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