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Unified Diff: Modules/_ctypes/libffi_ios/closures.c

Issue 23670: Modifications to support iOS as a development platform
Patch Set: Created 3 years, 9 months ago
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/Modules/_ctypes/libffi_ios/closures.c Wed Mar 02 00:01:35 2016 +0000
@@ -0,0 +1,925 @@
+/* -----------------------------------------------------------------------
+ closures.c - Copyright (c) 2007, 2009, 2010 Red Hat, Inc.
+ Copyright (C) 2007, 2009, 2010 Free Software Foundation, Inc
+ Copyright (c) 2011 Plausible Labs Cooperative, Inc.
+
+ Code to allocate and deallocate memory for closures.
+
+ Permission is hereby granted, free of charge, to any person obtaining
+ a copy of this software and associated documentation files (the
+ ``Software''), to deal in the Software without restriction, including
+ without limitation the rights to use, copy, modify, merge, publish,
+ distribute, sublicense, and/or sell copies of the Software, and to
+ permit persons to whom the Software is furnished to do so, subject to
+ the following conditions:
+
+ The above copyright notice and this permission notice shall be included
+ in all copies or substantial portions of the Software.
+
+ THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND,
+ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ DEALINGS IN THE SOFTWARE.
+ ----------------------------------------------------------------------- */
+
+#if defined __linux__ && !defined _GNU_SOURCE
+#define _GNU_SOURCE 1
+#endif
+
+#include <fficonfig.h>
+#include <ffi.h>
+#include <ffi_common.h>
+
+#if !FFI_MMAP_EXEC_WRIT && !FFI_EXEC_TRAMPOLINE_TABLE
+# if __gnu_linux__ && !defined(__ANDROID__)
+/* This macro indicates it may be forbidden to map anonymous memory
+ with both write and execute permission. Code compiled when this
+ option is defined will attempt to map such pages once, but if it
+ fails, it falls back to creating a temporary file in a writable and
+ executable filesystem and mapping pages from it into separate
+ locations in the virtual memory space, one location writable and
+ another executable. */
+# define FFI_MMAP_EXEC_WRIT 1
+# define HAVE_MNTENT 1
+# endif
+# if defined(X86_WIN32) || defined(X86_WIN64) || defined(__OS2__)
+/* Windows systems may have Data Execution Protection (DEP) enabled,
+ which requires the use of VirtualMalloc/VirtualFree to alloc/free
+ executable memory. */
+# define FFI_MMAP_EXEC_WRIT 1
+# endif
+#endif
+
+#if FFI_MMAP_EXEC_WRIT && !defined FFI_MMAP_EXEC_SELINUX
+# ifdef __linux__
+/* When defined to 1 check for SELinux and if SELinux is active,
+ don't attempt PROT_EXEC|PROT_WRITE mapping at all, as that
+ might cause audit messages. */
+# define FFI_MMAP_EXEC_SELINUX 1
+# endif
+#endif
+
+#if FFI_CLOSURES
+
+#if FFI_EXEC_TRAMPOLINE_TABLE
+
+#ifdef __MACH__
+
+#include <mach/mach.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+extern void *ffi_closure_trampoline_table_page;
+
+typedef struct ffi_trampoline_table ffi_trampoline_table;
+typedef struct ffi_trampoline_table_entry ffi_trampoline_table_entry;
+
+struct ffi_trampoline_table
+{
+ /* contiguous writable and executable pages */
+ vm_address_t config_page;
+ vm_address_t trampoline_page;
+
+ /* free list tracking */
+ uint16_t free_count;
+ ffi_trampoline_table_entry *free_list;
+ ffi_trampoline_table_entry *free_list_pool;
+
+ ffi_trampoline_table *prev;
+ ffi_trampoline_table *next;
+};
+
+struct ffi_trampoline_table_entry
+{
+ void *(*trampoline) ();
+ ffi_trampoline_table_entry *next;
+};
+
+/* Total number of trampolines that fit in one trampoline table */
+#define FFI_TRAMPOLINE_COUNT (PAGE_MAX_SIZE / FFI_TRAMPOLINE_SIZE)
+
+static pthread_mutex_t ffi_trampoline_lock = PTHREAD_MUTEX_INITIALIZER;
+static ffi_trampoline_table *ffi_trampoline_tables = NULL;
+
+static ffi_trampoline_table *
+ffi_trampoline_table_alloc ()
+{
+ ffi_trampoline_table *table = NULL;
+
+ /* Loop until we can allocate two contiguous pages */
+ while (table == NULL)
+ {
+ vm_address_t config_page = 0x0;
+ kern_return_t kt;
+
+ /* Try to allocate two pages */
+ kt =
+ vm_allocate (mach_task_self (), &config_page, PAGE_MAX_SIZE * 2,
+ VM_FLAGS_ANYWHERE);
+ if (kt != KERN_SUCCESS)
+ {
+ fprintf (stderr, "vm_allocate() failure: %d at %s:%d\n", kt,
+ __FILE__, __LINE__);
+ break;
+ }
+
+ /* Now drop the second half of the allocation to make room for the trampoline table */
+ vm_address_t trampoline_page = config_page + PAGE_MAX_SIZE;
+ kt = vm_deallocate (mach_task_self (), trampoline_page, PAGE_MAX_SIZE);
+ if (kt != KERN_SUCCESS)
+ {
+ fprintf (stderr, "vm_deallocate() failure: %d at %s:%d\n", kt,
+ __FILE__, __LINE__);
+ break;
+ }
+
+ /* Remap the trampoline table to directly follow the config page */
+ vm_prot_t cur_prot;
+ vm_prot_t max_prot;
+
+ vm_address_t trampoline_page_template = (vm_address_t)&ffi_closure_trampoline_table_page;
+#ifdef __arm__
+ /* ffi_closure_trampoline_table_page can be thumb-biased on some ARM archs */
+ trampoline_page_template &= ~1UL;
+#endif
+
+ kt =
+ vm_remap (mach_task_self (), &trampoline_page, PAGE_MAX_SIZE, 0x0, FALSE,
+ mach_task_self (), trampoline_page_template, FALSE,
+ &cur_prot, &max_prot, VM_INHERIT_SHARE);
+
+ /* If we lost access to the destination trampoline page, drop our config allocation mapping and retry */
+ if (kt != KERN_SUCCESS)
+ {
+ /* Log unexpected failures */
+ if (kt != KERN_NO_SPACE)
+ {
+ fprintf (stderr, "vm_remap() failure: %d at %s:%d\n", kt,
+ __FILE__, __LINE__);
+ }
+
+ vm_deallocate (mach_task_self (), config_page, PAGE_SIZE);
+ continue;
+ }
+
+ /* We have valid trampoline and config pages */
+ table = calloc (1, sizeof (ffi_trampoline_table));
+ table->free_count = FFI_TRAMPOLINE_COUNT;
+ table->config_page = config_page;
+ table->trampoline_page = trampoline_page;
+
+ /* Create and initialize the free list */
+ table->free_list_pool =
+ calloc (FFI_TRAMPOLINE_COUNT, sizeof (ffi_trampoline_table_entry));
+
+ uint16_t i;
+ for (i = 0; i < table->free_count; i++)
+ {
+ ffi_trampoline_table_entry *entry = &table->free_list_pool[i];
+ entry->trampoline =
+ (void *) (table->trampoline_page + (i * FFI_TRAMPOLINE_SIZE));
+
+ if (i < table->free_count - 1)
+ entry->next = &table->free_list_pool[i + 1];
+ }
+
+ table->free_list = table->free_list_pool;
+ }
+
+ return table;
+}
+
+void *
+ffi_closure_alloc (size_t size, void **code)
+{
+ /* Create the closure */
+ ffi_closure *closure = malloc (size);
+ if (closure == NULL)
+ return NULL;
+
+ pthread_mutex_lock (&ffi_trampoline_lock);
+
+ /* Check for an active trampoline table with available entries. */
+ ffi_trampoline_table *table = ffi_trampoline_tables;
+ if (table == NULL || table->free_list == NULL)
+ {
+ table = ffi_trampoline_table_alloc ();
+ if (table == NULL)
+ {
+ free (closure);
+ return NULL;
+ }
+
+ /* Insert the new table at the top of the list */
+ table->next = ffi_trampoline_tables;
+ if (table->next != NULL)
+ table->next->prev = table;
+
+ ffi_trampoline_tables = table;
+ }
+
+ /* Claim the free entry */
+ ffi_trampoline_table_entry *entry = ffi_trampoline_tables->free_list;
+ ffi_trampoline_tables->free_list = entry->next;
+ ffi_trampoline_tables->free_count--;
+ entry->next = NULL;
+
+ pthread_mutex_unlock (&ffi_trampoline_lock);
+
+ /* Initialize the return values */
+ *code = entry->trampoline;
+ closure->trampoline_table = table;
+ closure->trampoline_table_entry = entry;
+
+ return closure;
+}
+
+void
+ffi_closure_free (void *ptr)
+{
+ ffi_closure *closure = ptr;
+
+ pthread_mutex_lock (&ffi_trampoline_lock);
+
+ /* Fetch the table and entry references */
+ ffi_trampoline_table *table = closure->trampoline_table;
+ ffi_trampoline_table_entry *entry = closure->trampoline_table_entry;
+
+ /* Return the entry to the free list */
+ entry->next = table->free_list;
+ table->free_list = entry;
+ table->free_count++;
+
+ /* If all trampolines within this table are free, and at least one other table exists, deallocate
+ * the table */
+ if (table->free_count == FFI_TRAMPOLINE_COUNT
+ && ffi_trampoline_tables != table)
+ {
+ /* Remove from the list */
+ if (table->prev != NULL)
+ table->prev->next = table->next;
+
+ if (table->next != NULL)
+ table->next->prev = table->prev;
+
+ /* Deallocate pages */
+ kern_return_t kt;
+ kt = vm_deallocate (mach_task_self (), table->config_page, PAGE_SIZE);
+ if (kt != KERN_SUCCESS)
+ fprintf (stderr, "vm_deallocate() failure: %d at %s:%d\n", kt,
+ __FILE__, __LINE__);
+
+ kt =
+ vm_deallocate (mach_task_self (), table->trampoline_page, PAGE_SIZE);
+ if (kt != KERN_SUCCESS)
+ fprintf (stderr, "vm_deallocate() failure: %d at %s:%d\n", kt,
+ __FILE__, __LINE__);
+
+ /* Deallocate free list */
+ free (table->free_list_pool);
+ free (table);
+ }
+ else if (ffi_trampoline_tables != table)
+ {
+ /* Otherwise, bump this table to the top of the list */
+ table->prev = NULL;
+ table->next = ffi_trampoline_tables;
+ if (ffi_trampoline_tables != NULL)
+ ffi_trampoline_tables->prev = table;
+
+ ffi_trampoline_tables = table;
+ }
+
+ pthread_mutex_unlock (&ffi_trampoline_lock);
+
+ /* Free the closure */
+ free (closure);
+}
+
+#endif
+
+// Per-target implementation; It's unclear what can reasonable be shared between two OS/architecture implementations.
+
+#elif FFI_MMAP_EXEC_WRIT /* !FFI_EXEC_TRAMPOLINE_TABLE */
+
+#define USE_LOCKS 1
+#define USE_DL_PREFIX 1
+#ifdef __GNUC__
+#ifndef USE_BUILTIN_FFS
+#define USE_BUILTIN_FFS 1
+#endif
+#endif
+
+/* We need to use mmap, not sbrk. */
+#define HAVE_MORECORE 0
+
+/* We could, in theory, support mremap, but it wouldn't buy us anything. */
+#define HAVE_MREMAP 0
+
+/* We have no use for this, so save some code and data. */
+#define NO_MALLINFO 1
+
+/* We need all allocations to be in regular segments, otherwise we
+ lose track of the corresponding code address. */
+#define DEFAULT_MMAP_THRESHOLD MAX_SIZE_T
+
+/* Don't allocate more than a page unless needed. */
+#define DEFAULT_GRANULARITY ((size_t)malloc_getpagesize)
+
+#if FFI_CLOSURE_TEST
+/* Don't release single pages, to avoid a worst-case scenario of
+ continuously allocating and releasing single pages, but release
+ pairs of pages, which should do just as well given that allocations
+ are likely to be small. */
+#define DEFAULT_TRIM_THRESHOLD ((size_t)malloc_getpagesize)
+#endif
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#ifndef _MSC_VER
+#include <unistd.h>
+#endif
+#include <string.h>
+#include <stdio.h>
+#if !defined(X86_WIN32) && !defined(X86_WIN64)
+#ifdef HAVE_MNTENT
+#include <mntent.h>
+#endif /* HAVE_MNTENT */
+#include <sys/param.h>
+#include <pthread.h>
+
+/* We don't want sys/mman.h to be included after we redefine mmap and
+ dlmunmap. */
+#include <sys/mman.h>
+#define LACKS_SYS_MMAN_H 1
+
+#if FFI_MMAP_EXEC_SELINUX
+#include <sys/statfs.h>
+#include <stdlib.h>
+
+static int selinux_enabled = -1;
+
+static int
+selinux_enabled_check (void)
+{
+ struct statfs sfs;
+ FILE *f;
+ char *buf = NULL;
+ size_t len = 0;
+
+ if (statfs ("/selinux", &sfs) >= 0
+ && (unsigned int) sfs.f_type == 0xf97cff8cU)
+ return 1;
+ f = fopen ("/proc/mounts", "r");
+ if (f == NULL)
+ return 0;
+ while (getline (&buf, &len, f) >= 0)
+ {
+ char *p = strchr (buf, ' ');
+ if (p == NULL)
+ break;
+ p = strchr (p + 1, ' ');
+ if (p == NULL)
+ break;
+ if (strncmp (p + 1, "selinuxfs ", 10) == 0)
+ {
+ free (buf);
+ fclose (f);
+ return 1;
+ }
+ }
+ free (buf);
+ fclose (f);
+ return 0;
+}
+
+#define is_selinux_enabled() (selinux_enabled >= 0 ? selinux_enabled \
+ : (selinux_enabled = selinux_enabled_check ()))
+
+#else
+
+#define is_selinux_enabled() 0
+
+#endif /* !FFI_MMAP_EXEC_SELINUX */
+
+/* On PaX enable kernels that have MPROTECT enable we can't use PROT_EXEC. */
+#ifdef FFI_MMAP_EXEC_EMUTRAMP_PAX
+#include <stdlib.h>
+
+static int emutramp_enabled = -1;
+
+static int
+emutramp_enabled_check (void)
+{
+ char *buf = NULL;
+ size_t len = 0;
+ FILE *f;
+ int ret;
+ f = fopen ("/proc/self/status", "r");
+ if (f == NULL)
+ return 0;
+ ret = 0;
+
+ while (getline (&buf, &len, f) != -1)
+ if (!strncmp (buf, "PaX:", 4))
+ {
+ char emutramp;
+ if (sscanf (buf, "%*s %*c%c", &emutramp) == 1)
+ ret = (emutramp == 'E');
+ break;
+ }
+ free (buf);
+ fclose (f);
+ return ret;
+}
+
+#define is_emutramp_enabled() (emutramp_enabled >= 0 ? emutramp_enabled \
+ : (emutramp_enabled = emutramp_enabled_check ()))
+#endif /* FFI_MMAP_EXEC_EMUTRAMP_PAX */
+
+#elif defined (__CYGWIN__) || defined(__INTERIX)
+
+#include <sys/mman.h>
+
+/* Cygwin is Linux-like, but not quite that Linux-like. */
+#define is_selinux_enabled() 0
+
+#endif /* !defined(X86_WIN32) && !defined(X86_WIN64) */
+
+#ifndef FFI_MMAP_EXEC_EMUTRAMP_PAX
+#define is_emutramp_enabled() 0
+#endif /* FFI_MMAP_EXEC_EMUTRAMP_PAX */
+
+/* Declare all functions defined in dlmalloc.c as static. */
+static void *dlmalloc(size_t);
+static void dlfree(void*);
+static void *dlcalloc(size_t, size_t) MAYBE_UNUSED;
+static void *dlrealloc(void *, size_t) MAYBE_UNUSED;
+static void *dlmemalign(size_t, size_t) MAYBE_UNUSED;
+static void *dlvalloc(size_t) MAYBE_UNUSED;
+static int dlmallopt(int, int) MAYBE_UNUSED;
+static size_t dlmalloc_footprint(void) MAYBE_UNUSED;
+static size_t dlmalloc_max_footprint(void) MAYBE_UNUSED;
+static void** dlindependent_calloc(size_t, size_t, void**) MAYBE_UNUSED;
+static void** dlindependent_comalloc(size_t, size_t*, void**) MAYBE_UNUSED;
+static void *dlpvalloc(size_t) MAYBE_UNUSED;
+static int dlmalloc_trim(size_t) MAYBE_UNUSED;
+static size_t dlmalloc_usable_size(void*) MAYBE_UNUSED;
+static void dlmalloc_stats(void) MAYBE_UNUSED;
+
+#if !(defined(X86_WIN32) || defined(X86_WIN64) || defined(__OS2__)) || defined (__CYGWIN__) || defined(__INTERIX)
+/* Use these for mmap and munmap within dlmalloc.c. */
+static void *dlmmap(void *, size_t, int, int, int, off_t);
+static int dlmunmap(void *, size_t);
+#endif /* !(defined(X86_WIN32) || defined(X86_WIN64) || defined(__OS2__)) || defined (__CYGWIN__) || defined(__INTERIX) */
+
+#define mmap dlmmap
+#define munmap dlmunmap
+
+#include "dlmalloc.c"
+
+#undef mmap
+#undef munmap
+
+#if !(defined(X86_WIN32) || defined(X86_WIN64) || defined(__OS2__)) || defined (__CYGWIN__) || defined(__INTERIX)
+
+/* A mutex used to synchronize access to *exec* variables in this file. */
+static pthread_mutex_t open_temp_exec_file_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+/* A file descriptor of a temporary file from which we'll map
+ executable pages. */
+static int execfd = -1;
+
+/* The amount of space already allocated from the temporary file. */
+static size_t execsize = 0;
+
+/* Open a temporary file name, and immediately unlink it. */
+static int
+open_temp_exec_file_name (char *name, int flags)
+{
+ int fd;
+
+#ifdef HAVE_MKOSTEMP
+ fd = mkostemp (name, flags);
+#else
+ fd = mkstemp (name);
+#endif
+
+ if (fd != -1)
+ unlink (name);
+
+ return fd;
+}
+
+/* Open a temporary file in the named directory. */
+static int
+open_temp_exec_file_dir (const char *dir)
+{
+ static const char suffix[] = "/ffiXXXXXX";
+ int lendir, flags;
+ char *tempname;
+#ifdef O_TMPFILE
+ int fd;
+#endif
+
+#ifdef O_CLOEXEC
+ flags = O_CLOEXEC;
+#else
+ flags = 0;
+#endif
+
+#ifdef O_TMPFILE
+ fd = open (dir, flags | O_RDWR | O_EXCL | O_TMPFILE, 0700);
+ /* If the running system does not support the O_TMPFILE flag then retry without it. */
+ if (fd != -1 || (errno != EINVAL && errno != EISDIR && errno != EOPNOTSUPP)) {
+ return fd;
+ } else {
+ errno = 0;
+ }
+#endif
+
+ lendir = strlen (dir);
+ tempname = __builtin_alloca (lendir + sizeof (suffix));
+
+ if (!tempname)
+ return -1;
+
+ memcpy (tempname, dir, lendir);
+ memcpy (tempname + lendir, suffix, sizeof (suffix));
+
+ return open_temp_exec_file_name (tempname, flags);
+}
+
+/* Open a temporary file in the directory in the named environment
+ variable. */
+static int
+open_temp_exec_file_env (const char *envvar)
+{
+ const char *value = getenv (envvar);
+
+ if (!value)
+ return -1;
+
+ return open_temp_exec_file_dir (value);
+}
+
+#ifdef HAVE_MNTENT
+/* Open a temporary file in an executable and writable mount point
+ listed in the mounts file. Subsequent calls with the same mounts
+ keep searching for mount points in the same file. Providing NULL
+ as the mounts file closes the file. */
+static int
+open_temp_exec_file_mnt (const char *mounts)
+{
+ static const char *last_mounts;
+ static FILE *last_mntent;
+
+ if (mounts != last_mounts)
+ {
+ if (last_mntent)
+ endmntent (last_mntent);
+
+ last_mounts = mounts;
+
+ if (mounts)
+ last_mntent = setmntent (mounts, "r");
+ else
+ last_mntent = NULL;
+ }
+
+ if (!last_mntent)
+ return -1;
+
+ for (;;)
+ {
+ int fd;
+ struct mntent mnt;
+ char buf[MAXPATHLEN * 3];
+
+ if (getmntent_r (last_mntent, &mnt, buf, sizeof (buf)) == NULL)
+ return -1;
+
+ if (hasmntopt (&mnt, "ro")
+ || hasmntopt (&mnt, "noexec")
+ || access (mnt.mnt_dir, W_OK))
+ continue;
+
+ fd = open_temp_exec_file_dir (mnt.mnt_dir);
+
+ if (fd != -1)
+ return fd;
+ }
+}
+#endif /* HAVE_MNTENT */
+
+/* Instructions to look for a location to hold a temporary file that
+ can be mapped in for execution. */
+static struct
+{
+ int (*func)(const char *);
+ const char *arg;
+ int repeat;
+} open_temp_exec_file_opts[] = {
+ { open_temp_exec_file_env, "TMPDIR", 0 },
+ { open_temp_exec_file_dir, "/tmp", 0 },
+ { open_temp_exec_file_dir, "/var/tmp", 0 },
+ { open_temp_exec_file_dir, "/dev/shm", 0 },
+ { open_temp_exec_file_env, "HOME", 0 },
+#ifdef HAVE_MNTENT
+ { open_temp_exec_file_mnt, "/etc/mtab", 1 },
+ { open_temp_exec_file_mnt, "/proc/mounts", 1 },
+#endif /* HAVE_MNTENT */
+};
+
+/* Current index into open_temp_exec_file_opts. */
+static int open_temp_exec_file_opts_idx = 0;
+
+/* Reset a current multi-call func, then advances to the next entry.
+ If we're at the last, go back to the first and return nonzero,
+ otherwise return zero. */
+static int
+open_temp_exec_file_opts_next (void)
+{
+ if (open_temp_exec_file_opts[open_temp_exec_file_opts_idx].repeat)
+ open_temp_exec_file_opts[open_temp_exec_file_opts_idx].func (NULL);
+
+ open_temp_exec_file_opts_idx++;
+ if (open_temp_exec_file_opts_idx
+ == (sizeof (open_temp_exec_file_opts)
+ / sizeof (*open_temp_exec_file_opts)))
+ {
+ open_temp_exec_file_opts_idx = 0;
+ return 1;
+ }
+
+ return 0;
+}
+
+/* Return a file descriptor of a temporary zero-sized file in a
+ writable and executable filesystem. */
+static int
+open_temp_exec_file (void)
+{
+ int fd;
+
+ do
+ {
+ fd = open_temp_exec_file_opts[open_temp_exec_file_opts_idx].func
+ (open_temp_exec_file_opts[open_temp_exec_file_opts_idx].arg);
+
+ if (!open_temp_exec_file_opts[open_temp_exec_file_opts_idx].repeat
+ || fd == -1)
+ {
+ if (open_temp_exec_file_opts_next ())
+ break;
+ }
+ }
+ while (fd == -1);
+
+ return fd;
+}
+
+/* Map in a chunk of memory from the temporary exec file into separate
+ locations in the virtual memory address space, one writable and one
+ executable. Returns the address of the writable portion, after
+ storing an offset to the corresponding executable portion at the
+ last word of the requested chunk. */
+static void *
+dlmmap_locked (void *start, size_t length, int prot, int flags, off_t offset)
+{
+ void *ptr;
+
+ if (execfd == -1)
+ {
+ open_temp_exec_file_opts_idx = 0;
+ retry_open:
+ execfd = open_temp_exec_file ();
+ if (execfd == -1)
+ return MFAIL;
+ }
+
+ offset = execsize;
+
+ if (ftruncate (execfd, offset + length))
+ return MFAIL;
+
+ flags &= ~(MAP_PRIVATE | MAP_ANONYMOUS);
+ flags |= MAP_SHARED;
+
+ ptr = mmap (NULL, length, (prot & ~PROT_WRITE) | PROT_EXEC,
+ flags, execfd, offset);
+ if (ptr == MFAIL)
+ {
+ if (!offset)
+ {
+ close (execfd);
+ goto retry_open;
+ }
+ ftruncate (execfd, offset);
+ return MFAIL;
+ }
+ else if (!offset
+ && open_temp_exec_file_opts[open_temp_exec_file_opts_idx].repeat)
+ open_temp_exec_file_opts_next ();
+
+ start = mmap (start, length, prot, flags, execfd, offset);
+
+ if (start == MFAIL)
+ {
+ munmap (ptr, length);
+ ftruncate (execfd, offset);
+ return start;
+ }
+
+ mmap_exec_offset ((char *)start, length) = (char*)ptr - (char*)start;
+
+ execsize += length;
+
+ return start;
+}
+
+/* Map in a writable and executable chunk of memory if possible.
+ Failing that, fall back to dlmmap_locked. */
+static void *
+dlmmap (void *start, size_t length, int prot,
+ int flags, int fd, off_t offset)
+{
+ void *ptr;
+
+ assert (start == NULL && length % malloc_getpagesize == 0
+ && prot == (PROT_READ | PROT_WRITE)
+ && flags == (MAP_PRIVATE | MAP_ANONYMOUS)
+ && fd == -1 && offset == 0);
+
+#if FFI_CLOSURE_TEST
+ printf ("mapping in %zi\n", length);
+#endif
+
+ if (execfd == -1 && is_emutramp_enabled ())
+ {
+ ptr = mmap (start, length, prot & ~PROT_EXEC, flags, fd, offset);
+ return ptr;
+ }
+
+ if (execfd == -1 && !is_selinux_enabled ())
+ {
+ ptr = mmap (start, length, prot | PROT_EXEC, flags, fd, offset);
+
+ if (ptr != MFAIL || (errno != EPERM && errno != EACCES))
+ /* Cool, no need to mess with separate segments. */
+ return ptr;
+
+ /* If MREMAP_DUP is ever introduced and implemented, try mmap
+ with ((prot & ~PROT_WRITE) | PROT_EXEC) and mremap with
+ MREMAP_DUP and prot at this point. */
+ }
+
+ if (execsize == 0 || execfd == -1)
+ {
+ pthread_mutex_lock (&open_temp_exec_file_mutex);
+ ptr = dlmmap_locked (start, length, prot, flags, offset);
+ pthread_mutex_unlock (&open_temp_exec_file_mutex);
+
+ return ptr;
+ }
+
+ return dlmmap_locked (start, length, prot, flags, offset);
+}
+
+/* Release memory at the given address, as well as the corresponding
+ executable page if it's separate. */
+static int
+dlmunmap (void *start, size_t length)
+{
+ /* We don't bother decreasing execsize or truncating the file, since
+ we can't quite tell whether we're unmapping the end of the file.
+ We don't expect frequent deallocation anyway. If we did, we
+ could locate pages in the file by writing to the pages being
+ deallocated and checking that the file contents change.
+ Yuck. */
+ msegmentptr seg = segment_holding (gm, start);
+ void *code;
+
+#if FFI_CLOSURE_TEST
+ printf ("unmapping %zi\n", length);
+#endif
+
+ if (seg && (code = add_segment_exec_offset (start, seg)) != start)
+ {
+ int ret = munmap (code, length);
+ if (ret)
+ return ret;
+ }
+
+ return munmap (start, length);
+}
+
+#if FFI_CLOSURE_FREE_CODE
+/* Return segment holding given code address. */
+static msegmentptr
+segment_holding_code (mstate m, char* addr)
+{
+ msegmentptr sp = &m->seg;
+ for (;;) {
+ if (addr >= add_segment_exec_offset (sp->base, sp)
+ && addr < add_segment_exec_offset (sp->base, sp) + sp->size)
+ return sp;
+ if ((sp = sp->next) == 0)
+ return 0;
+ }
+}
+#endif
+
+#endif /* !(defined(X86_WIN32) || defined(X86_WIN64) || defined(__OS2__)) || defined (__CYGWIN__) || defined(__INTERIX) */
+
+/* Allocate a chunk of memory with the given size. Returns a pointer
+ to the writable address, and sets *CODE to the executable
+ corresponding virtual address. */
+void *
+ffi_closure_alloc (size_t size, void **code)
+{
+ void *ptr;
+
+ if (!code)
+ return NULL;
+
+ ptr = dlmalloc (size);
+
+ if (ptr)
+ {
+ msegmentptr seg = segment_holding (gm, ptr);
+
+ *code = add_segment_exec_offset (ptr, seg);
+ }
+
+ return ptr;
+}
+
+/* Release a chunk of memory allocated with ffi_closure_alloc. If
+ FFI_CLOSURE_FREE_CODE is nonzero, the given address can be the
+ writable or the executable address given. Otherwise, only the
+ writable address can be provided here. */
+void
+ffi_closure_free (void *ptr)
+{
+#if FFI_CLOSURE_FREE_CODE
+ msegmentptr seg = segment_holding_code (gm, ptr);
+
+ if (seg)
+ ptr = sub_segment_exec_offset (ptr, seg);
+#endif
+
+ dlfree (ptr);
+}
+
+
+#if FFI_CLOSURE_TEST
+/* Do some internal sanity testing to make sure allocation and
+ deallocation of pages are working as intended. */
+int main ()
+{
+ void *p[3];
+#define GET(idx, len) do { p[idx] = dlmalloc (len); printf ("allocated %zi for p[%i]\n", (len), (idx)); } while (0)
+#define PUT(idx) do { printf ("freeing p[%i]\n", (idx)); dlfree (p[idx]); } while (0)
+ GET (0, malloc_getpagesize / 2);
+ GET (1, 2 * malloc_getpagesize - 64 * sizeof (void*));
+ PUT (1);
+ GET (1, 2 * malloc_getpagesize);
+ GET (2, malloc_getpagesize / 2);
+ PUT (1);
+ PUT (0);
+ PUT (2);
+ return 0;
+}
+#endif /* FFI_CLOSURE_TEST */
+# else /* ! FFI_MMAP_EXEC_WRIT */
+
+/* On many systems, memory returned by malloc is writable and
+ executable, so just use it. */
+
+#include <stdlib.h>
+
+void *
+ffi_closure_alloc (size_t size, void **code)
+{
+ if (!code)
+ return NULL;
+
+ return *code = malloc (size);
+}
+
+void
+ffi_closure_free (void *ptr)
+{
+ free (ptr);
+}
+
+# endif /* ! FFI_MMAP_EXEC_WRIT */
+#endif /* FFI_CLOSURES */
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