diff options
Diffstat (limited to 'src/lib/fs/mmap.c')
| -rw-r--r-- | src/lib/fs/mmap.c | 234 |
1 files changed, 234 insertions, 0 deletions
diff --git a/src/lib/fs/mmap.c b/src/lib/fs/mmap.c new file mode 100644 index 0000000000..6d69fd5e78 --- /dev/null +++ b/src/lib/fs/mmap.c @@ -0,0 +1,234 @@ +/* Copyright (c) 2003-2004, Roger Dingledine + * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. + * Copyright (c) 2007-2018, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +#include "lib/fs/mmap.h" +#include "lib/fs/files.h" +#include "lib/log/torlog.h" +#include "lib/log/util_bug.h" +#include "lib/log/win32err.h" +#include "lib/string/compat_string.h" +#include "lib/malloc/util_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. */ +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). */ +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) +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 */ +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) || ... || ... */ |