zend_shared_alloc.c

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/*
   +----------------------------------------------------------------------+
   | Zend OPcache                                                         |
   +----------------------------------------------------------------------+
   | Copyright (c) The PHP Group                                          |
   +----------------------------------------------------------------------+
   | This source file is subject to version 3.01 of the PHP license,      |
   | that is bundled with this package in the file LICENSE, and is        |
   | available through the world-wide-web at the following url:           |
   | https://www.php.net/license/3_01.txt                                 |
   | If you did not receive a copy of the PHP license and are unable to   |
   | obtain it through the world-wide-web, please send a note to          |
   | license@php.net so we can mail you a copy immediately.               |
   +----------------------------------------------------------------------+
   | Authors: Andi Gutmans <andi@php.net>                                 |
   |          Zeev Suraski <zeev@php.net>                                 |
   |          Stanislav Malyshev <stas@zend.com>                          |
   |          Dmitry Stogov <dmitry@php.net>                              |
   +----------------------------------------------------------------------+
*/
 
#if defined(__linux__) && defined(HAVE_MEMFD_CREATE)
# ifndef _GNU_SOURCE
#  define _GNU_SOURCE
# endif
# include <sys/mman.h>
#endif
 
#include <errno.h>
#include "ZendAccelerator.h"
#include "zend_shared_alloc.h"
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#include <fcntl.h>
#ifndef ZEND_WIN32
# include <sys/types.h>
# include <signal.h>
# include <sys/stat.h>
# include <stdio.h>
#endif
 
#ifdef HAVE_MPROTECT
# include "sys/mman.h"
#endif
 
#define SEM_FILENAME_PREFIX ".ZendSem."
#define S_H(s) g_shared_alloc_handler->s
 
/* True globals */
/* old/new mapping. We can use true global even for ZTS because its usage
   is wrapped with exclusive lock anyway */
static const zend_shared_memory_handlers *g_shared_alloc_handler = NULL;
static const char *g_shared_model;
/* pointer to globals allocated in SHM and shared across processes */
ZEND_EXT_API zend_smm_shared_globals *smm_shared_globals;
 
#ifndef ZEND_WIN32
#ifdef ZTS
static MUTEX_T zts_lock;
#endif
int lock_file = -1;
static char lockfile_name[MAXPATHLEN];
#endif
 
static const zend_shared_memory_handler_entry handler_table[] = {
#ifdef USE_MMAP
    { "mmap", &zend_alloc_mmap_handlers },
#endif
#ifdef USE_SHM
    { "shm", &zend_alloc_shm_handlers },
#endif
#ifdef USE_SHM_OPEN
    { "posix", &zend_alloc_posix_handlers },
#endif
#ifdef ZEND_WIN32
    { "win32", &zend_alloc_win32_handlers },
#endif
    { NULL, NULL}
};
 
#ifndef ZEND_WIN32
void zend_shared_alloc_create_lock(char *lockfile_path)
{
    int val;
 
#ifdef ZTS
    zts_lock = tsrm_mutex_alloc();
#endif
 
#if defined(__linux__) && defined(HAVE_MEMFD_CREATE)
    /* on Linux, we can use a memfd instead of a "real" file, so
     * we can do this without a writable filesystem and without
     * needing to clean up */
    /* note: FreeBSD has memfd_create(), too, but fcntl(F_SETLKW)
     * on it fails with EBADF, therefore we use this only on
     * Linux */
    lock_file = memfd_create("opcache_lock", MFD_CLOEXEC);
    if (lock_file >= 0)
        return;
#endif
 
#ifdef O_TMPFILE
    lock_file = open(lockfile_path, O_RDWR | O_TMPFILE | O_EXCL | O_CLOEXEC, 0666);
    /* lack of O_TMPFILE support results in many possible errors
     * use it only when open returns a non-negative integer */
    if (lock_file >= 0) {
        return;
    }
#endif
 
    snprintf(lockfile_name, sizeof(lockfile_name), "%s/%sXXXXXX", lockfile_path, SEM_FILENAME_PREFIX);
    lock_file = mkstemp(lockfile_name);
    if (lock_file == -1) {
        zend_accel_error_noreturn(ACCEL_LOG_FATAL, "Unable to create opcache lock file in %s: %s (%d)", lockfile_path, strerror(errno), errno);
    }
 
    fchmod(lock_file, 0666);
 
    val = fcntl(lock_file, F_GETFD, 0);
    val |= FD_CLOEXEC;
    fcntl(lock_file, F_SETFD, val);
 
    unlink(lockfile_name);
}
#endif
 
static void no_memory_bailout(size_t allocate_size, const char *error)
{
    zend_accel_error_noreturn(ACCEL_LOG_FATAL, "Unable to allocate shared memory segment of %zu bytes: %s: %s (%d)", allocate_size, error?error:"unknown", strerror(errno), errno );
}
 
static void copy_shared_segments(void *to, void *from, int count, int size)
{
    zend_shared_segment **shared_segments_v = (zend_shared_segment **)to;
    void *shared_segments_to_p = ((char *)to + count*(sizeof(void *)));
    void *shared_segments_from_p = from;
    int i;
 
    for (i = 0; i < count; i++) {
        shared_segments_v[i] =  shared_segments_to_p;
        memcpy(shared_segments_to_p, shared_segments_from_p, size);
        shared_segments_to_p = ((char *)shared_segments_to_p + size);
        shared_segments_from_p = ((char *)shared_segments_from_p + size);
    }
}
 
static int zend_shared_alloc_try(const zend_shared_memory_handler_entry *he, size_t requested_size, zend_shared_segment ***shared_segments_p, int *shared_segments_count, const char **error_in)
{
    int res;
    g_shared_alloc_handler = he->handler;
    g_shared_model = he->name;
    ZSMMG(shared_segments) = NULL;
    ZSMMG(shared_segments_count) = 0;
 
    res = S_H(create_segments)(requested_size, shared_segments_p, shared_segments_count, error_in);
 
    if (res) {
        /* this model works! */
        return res;
    }
    if (*shared_segments_p) {
        int i;
        /* cleanup */
        for (i = 0; i < *shared_segments_count; i++) {
            if ((*shared_segments_p)[i]->p && (*shared_segments_p)[i]->p != (void *)-1) {
                S_H(detach_segment)((*shared_segments_p)[i]);
            }
        }
        free(*shared_segments_p);
        *shared_segments_p = NULL;
    }
    g_shared_alloc_handler = NULL;
    return ALLOC_FAILURE;
}
 
int zend_shared_alloc_startup(size_t requested_size, size_t reserved_size)
{
    zend_shared_segment **tmp_shared_segments;
    size_t shared_segments_array_size;
    zend_smm_shared_globals tmp_shared_globals, *p_tmp_shared_globals;
    const char *error_in = NULL;
    const zend_shared_memory_handler_entry *he;
    int res = ALLOC_FAILURE;
    int i;
 
    /* shared_free must be valid before we call zend_shared_alloc()
     * - make it temporarily point to a local variable
     */
    smm_shared_globals = &tmp_shared_globals;
    ZSMMG(shared_free) = requested_size - reserved_size; /* goes to tmp_shared_globals.shared_free */
 
#ifndef ZEND_WIN32
    zend_shared_alloc_create_lock(ZCG(accel_directives).lockfile_path);
#else
    zend_shared_alloc_create_lock();
#endif
 
    if (ZCG(accel_directives).memory_model && ZCG(accel_directives).memory_model[0]) {
        const char *model = ZCG(accel_directives).memory_model;
        /* "cgi" is really "shm"... */
        if (strncmp(ZCG(accel_directives).memory_model, "cgi", sizeof("cgi")) == 0) {
            model = "shm";
        }
 
        for (he = handler_table; he->name; he++) {
            if (strcmp(model, he->name) == 0) {
                res = zend_shared_alloc_try(he, requested_size, &ZSMMG(shared_segments), &ZSMMG(shared_segments_count), &error_in);
                if (res) {
                    /* this model works! */
                    break;
                }
            }
        }
    }
 
    if (res == FAILED_REATTACHED) {
        smm_shared_globals = NULL;
        return res;
    }
#if ENABLE_FILE_CACHE_FALLBACK
    if (ALLOC_FALLBACK == res) {
        smm_shared_globals = NULL;
        return ALLOC_FALLBACK;
    }
#endif
 
    if (!g_shared_alloc_handler) {
        /* try memory handlers in order */
        for (he = handler_table; he->name; he++) {
            res = zend_shared_alloc_try(he, requested_size, &ZSMMG(shared_segments), &ZSMMG(shared_segments_count), &error_in);
            if (res) {
                /* this model works! */
                break;
            }
        }
    }
 
    if (!g_shared_alloc_handler) {
        no_memory_bailout(requested_size, error_in);
        return ALLOC_FAILURE;
    }
 
    if (res == SUCCESSFULLY_REATTACHED) {
        return res;
    }
#if ENABLE_FILE_CACHE_FALLBACK
    if (ALLOC_FALLBACK == res) {
        smm_shared_globals = NULL;
        return ALLOC_FALLBACK;
    }
#endif
 
    for (i = 0; i < ZSMMG(shared_segments_count); i++) {
        ZSMMG(shared_segments)[i]->end = ZSMMG(shared_segments)[i]->size;
    }
 
    shared_segments_array_size = ZSMMG(shared_segments_count) * S_H(segment_type_size)();
 
    /* move shared_segments and shared_free to shared memory */
    ZCG(locked) = 1; /* no need to perform a real lock at this point */
 
    p_tmp_shared_globals = (zend_smm_shared_globals *) zend_shared_alloc(sizeof(zend_smm_shared_globals));
    if (!p_tmp_shared_globals) {
        zend_accel_error_noreturn(ACCEL_LOG_FATAL, "Insufficient shared memory!");
        return ALLOC_FAILURE;
    }
    memset(p_tmp_shared_globals, 0, sizeof(zend_smm_shared_globals));
 
    tmp_shared_segments = zend_shared_alloc(shared_segments_array_size + ZSMMG(shared_segments_count) * sizeof(void *));
    if (!tmp_shared_segments) {
        zend_accel_error_noreturn(ACCEL_LOG_FATAL, "Insufficient shared memory!");
        return ALLOC_FAILURE;
    }
 
    copy_shared_segments(tmp_shared_segments, ZSMMG(shared_segments)[0], ZSMMG(shared_segments_count), S_H(segment_type_size)());
 
    *p_tmp_shared_globals = tmp_shared_globals;
    smm_shared_globals = p_tmp_shared_globals;
 
    free(ZSMMG(shared_segments));
    ZSMMG(shared_segments) = tmp_shared_segments;
 
    ZSMMG(shared_memory_state).positions = (size_t *)zend_shared_alloc(sizeof(size_t) * ZSMMG(shared_segments_count));
    if (!ZSMMG(shared_memory_state).positions) {
        zend_accel_error_noreturn(ACCEL_LOG_FATAL, "Insufficient shared memory!");
        return ALLOC_FAILURE;
    }
 
    if (reserved_size) {
        i = ZSMMG(shared_segments_count) - 1;
        if (ZSMMG(shared_segments)[i]->size - ZSMMG(shared_segments)[i]->pos >= reserved_size) {
            ZSMMG(shared_segments)[i]->end = ZSMMG(shared_segments)[i]->size - reserved_size;
            ZSMMG(reserved) = (char*)ZSMMG(shared_segments)[i]->p + ZSMMG(shared_segments)[i]->end;
            ZSMMG(reserved_size) = reserved_size;
        } else {
            zend_accel_error_noreturn(ACCEL_LOG_FATAL, "Insufficient shared memory!");
            return ALLOC_FAILURE;
        }
    }
 
    ZCG(locked) = 0;
 
    return res;
}
 
void zend_shared_alloc_shutdown(void)
{
    zend_shared_segment **tmp_shared_segments;
    zend_shared_segment *shared_segments_buf[16];
    size_t shared_segments_array_size;
    zend_smm_shared_globals tmp_shared_globals;
    int i;
 
    tmp_shared_globals = *smm_shared_globals;
    smm_shared_globals = &tmp_shared_globals;
    shared_segments_array_size = ZSMMG(shared_segments_count) * (S_H(segment_type_size)() + sizeof(void *));
    if (shared_segments_array_size > 16) {
        tmp_shared_segments = malloc(shared_segments_array_size);
    } else {
        tmp_shared_segments = shared_segments_buf;
    }
    copy_shared_segments(tmp_shared_segments, ZSMMG(shared_segments)[0], ZSMMG(shared_segments_count), S_H(segment_type_size)());
    ZSMMG(shared_segments) = tmp_shared_segments;
 
    for (i = 0; i < ZSMMG(shared_segments_count); i++) {
        S_H(detach_segment)(ZSMMG(shared_segments)[i]);
    }
    if (shared_segments_array_size > 16) {
        free(ZSMMG(shared_segments));
    }
    ZSMMG(shared_segments) = NULL;
    g_shared_alloc_handler = NULL;
#ifndef ZEND_WIN32
    close(lock_file);
 
# ifdef ZTS
    tsrm_mutex_free(zts_lock);
# endif
#endif
}
 
static size_t zend_shared_alloc_get_largest_free_block(void)
{
    int i;
    size_t largest_block_size = 0;
 
    for (i = 0; i < ZSMMG(shared_segments_count); i++) {
        size_t block_size = ZSMMG(shared_segments)[i]->end - ZSMMG(shared_segments)[i]->pos;
 
        if (block_size>largest_block_size) {
            largest_block_size = block_size;
        }
    }
    return largest_block_size;
}
 
#define MIN_FREE_MEMORY 64*1024
 
#define SHARED_ALLOC_FAILED() do {      \
        zend_accel_error(ACCEL_LOG_WARNING, "Not enough free shared space to allocate %zu bytes (%zu bytes free)", size, ZSMMG(shared_free)); \
        if (zend_shared_alloc_get_largest_free_block() < MIN_FREE_MEMORY) { \
            ZSMMG(memory_exhausted) = 1; \
        } \
    } while (0)
 
void *zend_shared_alloc(size_t size)
{
    int i;
    size_t block_size = ZEND_ALIGNED_SIZE(size);
 
#if 1
    if (!ZCG(locked)) {
        ZEND_ASSERT(0 && "Shared memory lock not obtained");
        zend_accel_error_noreturn(ACCEL_LOG_ERROR, "Shared memory lock not obtained");
    }
#endif
    if (block_size > ZSMMG(shared_free)) { /* No hope to find a big-enough block */
        SHARED_ALLOC_FAILED();
        return NULL;
    }
    for (i = 0; i < ZSMMG(shared_segments_count); i++) {
        if (ZSMMG(shared_segments)[i]->end - ZSMMG(shared_segments)[i]->pos >= block_size) { /* found a valid block */
            void *retval = (void *) (((char *) ZSMMG(shared_segments)[i]->p) + ZSMMG(shared_segments)[i]->pos);
 
            ZSMMG(shared_segments)[i]->pos += block_size;
            ZSMMG(shared_free) -= block_size;
            ZEND_ASSERT(((uintptr_t)retval & 0x7) == 0); /* should be 8 byte aligned */
            return retval;
        }
    }
    SHARED_ALLOC_FAILED();
    return NULL;
}
 
static zend_always_inline zend_ulong zend_rotr3(zend_ulong key)
{
    return (key >> 3) | (key << ((sizeof(key) * 8) - 3));
}
 
int zend_shared_memdup_size(void *source, size_t size)
{
    void *old_p;
    zend_ulong key = (zend_ulong)source;
 
    key = zend_rotr3(key);
    if ((old_p = zend_hash_index_find_ptr(&ZCG(xlat_table), key)) != NULL) {
        /* we already duplicated this pointer */
        return 0;
    }
    zend_hash_index_add_new_ptr(&ZCG(xlat_table), key, source);
    return ZEND_ALIGNED_SIZE(size);
}
 
static zend_always_inline void *_zend_shared_memdup(void *source, size_t size, bool get_xlat, bool set_xlat, bool free_source)
{
    void *old_p, *retval;
    zend_ulong key;
 
    if (get_xlat) {
        key = (zend_ulong)source;
        key = zend_rotr3(key);
        if ((old_p = zend_hash_index_find_ptr(&ZCG(xlat_table), key)) != NULL) {
            /* we already duplicated this pointer */
            return old_p;
        }
    }
    retval = ZCG(mem);
    ZCG(mem) = (void*)(((char*)ZCG(mem)) + ZEND_ALIGNED_SIZE(size));
    memcpy(retval, source, size);
    if (set_xlat) {
        if (!get_xlat) {
            key = (zend_ulong)source;
            key = zend_rotr3(key);
        }
        zend_hash_index_add_new_ptr(&ZCG(xlat_table), key, retval);
    }
    if (free_source) {
        efree(source);
    }
    return retval;
}
 
void *zend_shared_memdup_get_put_free(void *source, size_t size)
{
    return _zend_shared_memdup(source, size, true, true, true);
}
 
void *zend_shared_memdup_put_free(void *source, size_t size)
{
    return _zend_shared_memdup(source, size, false, true, true);
}
 
void *zend_shared_memdup_free(void *source, size_t size)
{
    return _zend_shared_memdup(source, size, false, false, true);
}
 
void *zend_shared_memdup_get_put(void *source, size_t size)
{
    return _zend_shared_memdup(source, size, true, true, false);
}
 
void *zend_shared_memdup_put(void *source, size_t size)
{
    return _zend_shared_memdup(source, size, false, true, false);
}
 
void *zend_shared_memdup(void *source, size_t size)
{
    return _zend_shared_memdup(source, size, false, false, false);
}
 
void zend_shared_alloc_safe_unlock(void)
{
    if (ZCG(locked)) {
        zend_shared_alloc_unlock();
    }
}
 
void zend_shared_alloc_lock(void)
{
    ZEND_ASSERT(!ZCG(locked));
 
#ifndef ZEND_WIN32
    struct flock mem_write_lock;
 
    mem_write_lock.l_type = F_WRLCK;
    mem_write_lock.l_whence = SEEK_SET;
    mem_write_lock.l_start = 0;
    mem_write_lock.l_len = 1;
 
#ifdef ZTS
    tsrm_mutex_lock(zts_lock);
#endif
 
#if 0
    /* this will happen once per process, and will un-globalize mem_write_lock */
    if (mem_write_lock.l_pid == -1) {
        mem_write_lock.l_pid = getpid();
    }
#endif
 
    while (1) {
        if (fcntl(lock_file, F_SETLKW, &mem_write_lock) == -1) {
            if (errno == EINTR) {
                continue;
            }
            zend_accel_error_noreturn(ACCEL_LOG_ERROR, "Cannot create lock - %s (%d)", strerror(errno), errno);
        }
        break;
    }
#else
    zend_shared_alloc_lock_win32();
#endif
 
    ZCG(locked) = 1;
}
 
void zend_shared_alloc_unlock(void)
{
    ZEND_ASSERT(ZCG(locked));
 
#ifndef ZEND_WIN32
    struct flock mem_write_unlock;
 
    mem_write_unlock.l_type = F_UNLCK;
    mem_write_unlock.l_whence = SEEK_SET;
    mem_write_unlock.l_start = 0;
    mem_write_unlock.l_len = 1;
#endif
 
    ZCG(locked) = 0;
 
#ifndef ZEND_WIN32
    if (fcntl(lock_file, F_SETLK, &mem_write_unlock) == -1) {
        zend_accel_error_noreturn(ACCEL_LOG_ERROR, "Cannot remove lock - %s (%d)", strerror(errno), errno);
    }
#ifdef ZTS
    tsrm_mutex_unlock(zts_lock);
#endif
#else
    zend_shared_alloc_unlock_win32();
#endif
}
 
void zend_shared_alloc_init_xlat_table(void)
{
    /* Prepare translation table */
    zend_hash_init(&ZCG(xlat_table), 128, NULL, NULL, 0);
}
 
void zend_shared_alloc_destroy_xlat_table(void)
{
    /* Destroy translation table */
    zend_hash_destroy(&ZCG(xlat_table));
}
 
void zend_shared_alloc_clear_xlat_table(void)
{
    zend_hash_clean(&ZCG(xlat_table));
}
 
uint32_t zend_shared_alloc_checkpoint_xlat_table(void)
{
    return ZCG(xlat_table).nNumUsed;
}
 
void zend_shared_alloc_restore_xlat_table(uint32_t checkpoint)
{
    zend_hash_discard(&ZCG(xlat_table), checkpoint);
}
 
void zend_shared_alloc_register_xlat_entry(const void *key_pointer, const void *value)
{
    zend_ulong key = (zend_ulong)key_pointer;
 
    key = zend_rotr3(key);
    zend_hash_index_add_new_ptr(&ZCG(xlat_table), key, (void*)value);
}
 
void *zend_shared_alloc_get_xlat_entry(const void *key_pointer)
{
    void *retval;
    zend_ulong key = (zend_ulong)key_pointer;
 
    key = zend_rotr3(key);
    if ((retval = zend_hash_index_find_ptr(&ZCG(xlat_table), key)) == NULL) {
        return NULL;
    }
    return retval;
}
 
size_t zend_shared_alloc_get_free_memory(void)
{
    return ZSMMG(shared_free);
}
 
void zend_shared_alloc_save_state(void)
{
    int i;
 
    for (i = 0; i < ZSMMG(shared_segments_count); i++) {
        ZSMMG(shared_memory_state).positions[i] = ZSMMG(shared_segments)[i]->pos;
    }
    ZSMMG(shared_memory_state).shared_free = ZSMMG(shared_free);
}
 
void zend_shared_alloc_restore_state(void)
{
    int i;
 
    for (i = 0; i < ZSMMG(shared_segments_count); i++) {
        ZSMMG(shared_segments)[i]->pos = ZSMMG(shared_memory_state).positions[i];
    }
    ZSMMG(shared_free) = ZSMMG(shared_memory_state).shared_free;
    ZSMMG(memory_exhausted) = 0;
    ZSMMG(wasted_shared_memory) = 0;
}
 
const char *zend_accel_get_shared_model(void)
{
    return g_shared_model;
}
 
void zend_accel_shared_protect(bool protected)
{
#ifdef HAVE_MPROTECT
    int i;
 
    if (!smm_shared_globals) {
        return;
    }
 
    const int mode = protected ? PROT_READ : PROT_READ|PROT_WRITE;
 
    for (i = 0; i < ZSMMG(shared_segments_count); i++) {
        mprotect(ZSMMG(shared_segments)[i]->p, ZSMMG(shared_segments)[i]->end, mode);
    }
#elif defined(ZEND_WIN32)
    int i;
 
    if (!smm_shared_globals) {
        return;
    }
 
    const int mode = protected ? PAGE_READONLY : PAGE_READWRITE;
 
    for (i = 0; i < ZSMMG(shared_segments_count); i++) {
        DWORD oldProtect;
        if (!VirtualProtect(ZSMMG(shared_segments)[i]->p, ZSMMG(shared_segments)[i]->end, mode, &oldProtect)) {
            zend_accel_error_noreturn(ACCEL_LOG_ERROR, "Failed to protect memory");
        }
    }
#endif
}
 
bool zend_accel_in_shm(void *ptr)
{
    int i;
 
    if (!smm_shared_globals) {
        return false;
    }
 
    for (i = 0; i < ZSMMG(shared_segments_count); i++) {
        if ((char*)ptr >= (char*)ZSMMG(shared_segments)[i]->p &&
            (char*)ptr < (char*)ZSMMG(shared_segments)[i]->p + ZSMMG(shared_segments)[i]->end) {
            return true;
        }
    }
    return false;
}