diff options
Diffstat (limited to 'src/os/win32/ngx_shmem.c')
| -rw-r--r-- | src/os/win32/ngx_shmem.c | 82 |
1 files changed, 80 insertions, 2 deletions
diff --git a/src/os/win32/ngx_shmem.c b/src/os/win32/ngx_shmem.c index 5f3af8bc5..c3ed699f7 100644 --- a/src/os/win32/ngx_shmem.c +++ b/src/os/win32/ngx_shmem.c @@ -9,11 +9,44 @@ #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; + 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) { @@ -46,6 +79,27 @@ ngx_shm_alloc(ngx_shm_t *shm) 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) { @@ -66,6 +120,30 @@ ngx_shm_alloc(ngx_shm_t *shm) } +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) { |