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/* Copyright (c) 2003-2004, Roger Dingledine
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2020, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file mmap.c
*
* \brief Cross-platform support for mapping files into our address space.
**/
#include "lib/fs/mmap.h"
#include "lib/fs/files.h"
#include "lib/log/log.h"
#include "lib/log/util_bug.h"
#include "lib/log/win32err.h"
#include "lib/string/compat_string.h"
#include "lib/malloc/malloc.h"
#ifdef HAVE_MMAP
#include <sys/mman.h>
#endif
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef _WIN32
#include <windows.h>
#endif
#include <errno.h>
#include <string.h>
#if defined(HAVE_MMAP) || defined(RUNNING_DOXYGEN)
/** Try to create a memory mapping for <b>filename</b> and return it. On
* failure, return NULL. Sets errno properly, using ERANGE to mean
* "empty file". Must only be called on trusted Tor-owned files, as changing
* the underlying file's size causes unspecified behavior. */
MOCK_IMPL(tor_mmap_t *,
tor_mmap_file,(const char *filename))
{
int fd; /* router file */
char *string;
int result;
tor_mmap_t *res;
size_t size, filesize;
struct stat st;
tor_assert(filename);
fd = tor_open_cloexec(filename, O_RDONLY, 0);
if (fd<0) {
int save_errno = errno;
int severity = (errno == ENOENT) ? LOG_INFO : LOG_WARN;
log_fn(severity, LD_FS,"Could not open \"%s\" for mmap(): %s",filename,
strerror(errno));
errno = save_errno;
return NULL;
}
/* Get the size of the file */
result = fstat(fd, &st);
if (result != 0) {
int save_errno = errno;
log_warn(LD_FS,
"Couldn't fstat opened descriptor for \"%s\" during mmap: %s",
filename, strerror(errno));
close(fd);
errno = save_errno;
return NULL;
}
size = filesize = (size_t)(st.st_size);
if (st.st_size > SSIZE_T_CEILING || (off_t)size < st.st_size) {
log_warn(LD_FS, "File \"%s\" is too large. Ignoring.",filename);
errno = EFBIG;
close(fd);
return NULL;
}
if (!size) {
/* Zero-length file. If we call mmap on it, it will succeed but
* return NULL, and bad things will happen. So just fail. */
log_info(LD_FS,"File \"%s\" is empty. Ignoring.",filename);
errno = ERANGE;
close(fd);
return NULL;
}
string = mmap(0, size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
if (string == MAP_FAILED) {
int save_errno = errno;
log_warn(LD_FS,"Could not mmap file \"%s\": %s", filename,
strerror(errno));
errno = save_errno;
return NULL;
}
res = tor_malloc_zero(sizeof(tor_mmap_t));
res->data = string;
res->size = filesize;
res->mapping_size = size;
return res;
}
/** Release storage held for a memory mapping; returns 0 on success,
* or -1 on failure (and logs a warning). */
MOCK_IMPL(int,
tor_munmap_file,(tor_mmap_t *handle))
{
int res;
if (handle == NULL)
return 0;
res = munmap((char*)handle->data, handle->mapping_size);
if (res == 0) {
/* munmap() succeeded */
tor_free(handle);
} else {
log_warn(LD_FS, "Failed to munmap() in tor_munmap_file(): %s",
strerror(errno));
res = -1;
}
return res;
}
#elif defined(_WIN32)
MOCK_IMPL(tor_mmap_t *,
tor_mmap_file,(const char *filename))
{
TCHAR tfilename[MAX_PATH]= {0};
tor_mmap_t *res = tor_malloc_zero(sizeof(tor_mmap_t));
int empty = 0;
HANDLE file_handle = INVALID_HANDLE_VALUE;
DWORD size_low, size_high;
uint64_t real_size;
res->mmap_handle = NULL;
#ifdef UNICODE
mbstowcs(tfilename,filename,MAX_PATH);
#else
strlcpy(tfilename,filename,MAX_PATH);
#endif
file_handle = CreateFile(tfilename,
GENERIC_READ, FILE_SHARE_READ,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
0);
if (file_handle == INVALID_HANDLE_VALUE)
goto win_err;
size_low = GetFileSize(file_handle, &size_high);
if (size_low == INVALID_FILE_SIZE && GetLastError() != NO_ERROR) {
log_warn(LD_FS,"Error getting size of \"%s\".",filename);
goto win_err;
}
if (size_low == 0 && size_high == 0) {
log_info(LD_FS,"File \"%s\" is empty. Ignoring.",filename);
empty = 1;
goto err;
}
real_size = (((uint64_t)size_high)<<32) | size_low;
if (real_size > SIZE_MAX) {
log_warn(LD_FS,"File \"%s\" is too big to map; not trying.",filename);
goto err;
}
res->size = real_size;
res->mmap_handle = CreateFileMapping(file_handle,
NULL,
PAGE_READONLY,
size_high,
size_low,
NULL);
if (res->mmap_handle == NULL)
goto win_err;
res->data = (char*) MapViewOfFile(res->mmap_handle,
FILE_MAP_READ,
0, 0, 0);
if (!res->data)
goto win_err;
CloseHandle(file_handle);
return res;
win_err: {
DWORD e = GetLastError();
int severity = (e == ERROR_FILE_NOT_FOUND || e == ERROR_PATH_NOT_FOUND) ?
LOG_INFO : LOG_WARN;
char *msg = format_win32_error(e);
log_fn(severity, LD_FS, "Couldn't mmap file \"%s\": %s", filename, msg);
tor_free(msg);
if (e == ERROR_FILE_NOT_FOUND || e == ERROR_PATH_NOT_FOUND)
errno = ENOENT;
else
errno = EINVAL;
}
err:
if (empty)
errno = ERANGE;
if (file_handle != INVALID_HANDLE_VALUE)
CloseHandle(file_handle);
tor_munmap_file(res);
return NULL;
}
/* Unmap the file, and return 0 for success or -1 for failure */
MOCK_IMPL(int,
tor_munmap_file,(tor_mmap_t *handle))
{
if (handle == NULL)
return 0;
if (handle->data) {
/* This is an ugly cast, but without it, "data" in struct tor_mmap_t would
have to be redefined as non-const. */
BOOL ok = UnmapViewOfFile( (LPVOID) handle->data);
if (!ok) {
log_warn(LD_FS, "Failed to UnmapViewOfFile() in tor_munmap_file(): %d",
(int)GetLastError());
}
}
if (handle->mmap_handle != NULL)
CloseHandle(handle->mmap_handle);
tor_free(handle);
return 0;
}
#else
#error "cannot implement tor_mmap_file"
#endif /* defined(HAVE_MMAP) || defined(RUNNING_DOXYGEN) || ... */
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