Mercurial > hg > nginx
view src/os/win32/ngx_shmem.c @ 9300:5be23505292b default tip
SSI: fixed incorrect or duplicate stub output.
Following 3518:eb3aaf8bd2a9 (0.8.37), r->request_output is only set
if there are data in the first buffer sent in the subrequest. As a
result, following the change mentioned this flag cannot be used to
prevent duplicate ngx_http_ssi_stub_output() calls, since it is not
set if there was already some output, but the first buffer was empty.
Still, when there are multiple subrequests, even an empty subrequest
response might be delayed by the postpone filter, leading to a second
call of ngx_http_ssi_stub_output() during finalization from
ngx_http_writer() the subreqest buffers are released by the postpone
filter. Since r->request_output is not set after the first call, this
resulted in duplicate stub output.
Additionally, checking only the first buffer might be wrong in some
unusual cases. For example, the first buffer might be empty if
$r->flush() is called before printing any data in the embedded Perl
module.
Depending on the postpone_output value and corresponding sizes, this
issue can result in either duplicate or unexpected stub output, or
"zero size buf in writer" alerts.
Following 8124:f5515e727656 (1.23.4), it became slightly easier to
reproduce the issue, as empty static files and empty cache items now
result in a response with an empty buffer. Before the change, an empty
proxied response can be used to reproduce the issue.
Fix is check all buffers and set r->request_output if any non-empty
buffers are sent. This ensures that all unusual cases of non-empty
responses are covered, and also that r->request_output will be set
after the first stub output, preventing duplicate output.
Reported by Jan Gassen.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Thu, 04 Jul 2024 17:41:28 +0300 |
parents | af7eba90645d |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> /* * Base addresses selected by system for shared memory mappings are likely * to be different on Windows Vista and later versions due to address space * layout randomization. This is however incompatible with storing absolute * addresses within the shared memory. * * To make it possible to store absolute addresses we create mappings * at the same address in all processes by starting mappings at predefined * addresses. The addresses were selected somewhat randomly in order to * minimize the probability that some other library doing something similar * conflicts with us. The addresses are from the following typically free * blocks: * * - 0x10000000 .. 0x70000000 (about 1.5 GB in total) on 32-bit platforms * - 0x000000007fff0000 .. 0x000007f68e8b0000 (about 8 TB) on 64-bit platforms * * Additionally, we allow to change the mapping address once it was detected * to be different from one originally used. This is needed to support * reconfiguration. */ #ifdef _WIN64 #define NGX_SHMEM_BASE 0x0000047047e00000 #else #define NGX_SHMEM_BASE 0x2efe0000 #endif ngx_uint_t ngx_allocation_granularity; ngx_int_t ngx_shm_alloc(ngx_shm_t *shm) { u_char *name; uint64_t size; static u_char *base = (u_char *) NGX_SHMEM_BASE; name = ngx_alloc(shm->name.len + 2 + NGX_INT32_LEN, shm->log); if (name == NULL) { return NGX_ERROR; } (void) ngx_sprintf(name, "%V_%s%Z", &shm->name, ngx_unique); ngx_set_errno(0); size = shm->size; shm->handle = CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, (u_long) (size >> 32), (u_long) (size & 0xffffffff), (char *) name); if (shm->handle == NULL) { ngx_log_error(NGX_LOG_ALERT, shm->log, ngx_errno, "CreateFileMapping(%uz, %s) failed", shm->size, name); ngx_free(name); return NGX_ERROR; } ngx_free(name); if (ngx_errno == ERROR_ALREADY_EXISTS) { shm->exists = 1; } shm->addr = MapViewOfFileEx(shm->handle, FILE_MAP_WRITE, 0, 0, 0, base); if (shm->addr != NULL) { base += ngx_align(size, ngx_allocation_granularity); return NGX_OK; } ngx_log_debug3(NGX_LOG_DEBUG_CORE, shm->log, ngx_errno, "MapViewOfFileEx(%uz, %p) of file mapping \"%V\" failed, " "retry without a base address", shm->size, base, &shm->name); /* * Order of shared memory zones may be different in the master process * and worker processes after reconfiguration. As a result, the above * may fail due to a conflict with a previously created mapping remapped * to a different address. Additionally, there may be a conflict with * some other uses of the memory. In this case we retry without a base * address to let the system assign the address itself. */ shm->addr = MapViewOfFile(shm->handle, FILE_MAP_WRITE, 0, 0, 0); if (shm->addr != NULL) { return NGX_OK; } ngx_log_error(NGX_LOG_ALERT, shm->log, ngx_errno, "MapViewOfFile(%uz) of file mapping \"%V\" failed", shm->size, &shm->name); if (CloseHandle(shm->handle) == 0) { ngx_log_error(NGX_LOG_ALERT, shm->log, ngx_errno, "CloseHandle() of file mapping \"%V\" failed", &shm->name); } return NGX_ERROR; } ngx_int_t ngx_shm_remap(ngx_shm_t *shm, u_char *addr) { if (UnmapViewOfFile(shm->addr) == 0) { ngx_log_error(NGX_LOG_ALERT, shm->log, ngx_errno, "UnmapViewOfFile(%p) of file mapping \"%V\" failed", shm->addr, &shm->name); return NGX_ERROR; } shm->addr = MapViewOfFileEx(shm->handle, FILE_MAP_WRITE, 0, 0, 0, addr); if (shm->addr != NULL) { return NGX_OK; } ngx_log_error(NGX_LOG_ALERT, shm->log, ngx_errno, "MapViewOfFileEx(%uz, %p) of file mapping \"%V\" failed", shm->size, addr, &shm->name); return NGX_ERROR; } void ngx_shm_free(ngx_shm_t *shm) { if (UnmapViewOfFile(shm->addr) == 0) { ngx_log_error(NGX_LOG_ALERT, shm->log, ngx_errno, "UnmapViewOfFile(%p) of file mapping \"%V\" failed", shm->addr, &shm->name); } if (CloseHandle(shm->handle) == 0) { ngx_log_error(NGX_LOG_ALERT, shm->log, ngx_errno, "CloseHandle() of file mapping \"%V\" failed", &shm->name); } }