我在 Windows 8 上遇到了类似的问题 - tmpfile() 导致 win32 ERROR_ACCESS_DENIED 错误代码 - 是的,如果您以管理员权限运行应用程序 - 那么它工作正常。
我想这里提到了问题:
https ://lists.gnu.org/archive/html/bug-gnulib/2007-02/msg00162.html
在 Windows 下,tmpfile 函数被定义为始终在根目录中创建其临时文件。大多数用户没有这样做的权限,所以它经常会失败。
我怀疑这是一个不完整的 Windows 端口问题 - 所以这应该是向 Microsoft 报告的错误。(如果没有用,为什么要编写 tmpfile 函数?)
但是谁有时间和微软风车搏斗呢?!:-)
我已经使用 GetTempPathW / GetModuleFileNameW / _wfopen 编写了类似的实现。我遇到此问题的代码来自 libjpeg - 我在此处附加了整个源代码,但您可以从 jpeg_open_backing_store 获取代码。
jmemwin.cpp:
//
// Windows port for jpeg lib functions.
//
#define JPEG_INTERNALS
#include <Windows.h> // GetTempFileName
#undef FAR // Will be redefined - disable warning
#include "jinclude.h"
#include "jpeglib.h"
extern "C" {
#include "jmemsys.h" // jpeg_ api interface.
//
// Memory allocation and freeing are controlled by the regular library routines malloc() and free().
//
GLOBAL(void *) jpeg_get_small (j_common_ptr cinfo, size_t sizeofobject)
{
return (void *) malloc(sizeofobject);
}
GLOBAL(void) jpeg_free_small (j_common_ptr cinfo, void * object, size_t sizeofobject)
{
free(object);
}
/*
* "Large" objects are treated the same as "small" ones.
* NB: although we include FAR keywords in the routine declarations,
* this file won't actually work in 80x86 small/medium model; at least,
* you probably won't be able to process useful-size images in only 64KB.
*/
GLOBAL(void FAR *) jpeg_get_large (j_common_ptr cinfo, size_t sizeofobject)
{
return (void FAR *) malloc(sizeofobject);
}
GLOBAL(void) jpeg_free_large (j_common_ptr cinfo, void FAR * object, size_t sizeofobject)
{
free(object);
}
//
// Used only by command line applications, not by static library compilation
//
#ifndef DEFAULT_MAX_MEM /* so can override from makefile */
#define DEFAULT_MAX_MEM 1000000L /* default: one megabyte */
#endif
GLOBAL(long) jpeg_mem_available (j_common_ptr cinfo, long min_bytes_needed, long max_bytes_needed, long already_allocated)
{
// jmemansi.c's jpeg_mem_available implementation was insufficient for some of .jpg loads.
MEMORYSTATUSEX status = { 0 };
status.dwLength = sizeof(status);
GlobalMemoryStatusEx(&status);
if( status.ullAvailPhys > LONG_MAX )
// Normally goes here since new PC's have more than 4 Gb of ram.
return LONG_MAX;
return (long) status.ullAvailPhys;
}
/*
Backing store (temporary file) management.
Backing store objects are only used when the value returned by
jpeg_mem_available is less than the total space needed. You can dispense
with these routines if you have plenty of virtual memory; see jmemnobs.c.
*/
METHODDEF(void) read_backing_store (j_common_ptr cinfo, backing_store_ptr info, void FAR * buffer_address, long file_offset, long byte_count)
{
if (fseek(info->temp_file, file_offset, SEEK_SET))
ERREXIT(cinfo, JERR_TFILE_SEEK);
size_t readed = fread( buffer_address, 1, byte_count, info->temp_file);
if (readed != (size_t) byte_count)
ERREXIT(cinfo, JERR_TFILE_READ);
}
METHODDEF(void)
write_backing_store (j_common_ptr cinfo, backing_store_ptr info, void FAR * buffer_address, long file_offset, long byte_count)
{
if (fseek(info->temp_file, file_offset, SEEK_SET))
ERREXIT(cinfo, JERR_TFILE_SEEK);
if (JFWRITE(info->temp_file, buffer_address, byte_count) != (size_t) byte_count)
ERREXIT(cinfo, JERR_TFILE_WRITE);
// E.g. if you need to debug writes.
//if( fflush(info->temp_file) != 0 )
// ERREXIT(cinfo, JERR_TFILE_WRITE);
}
METHODDEF(void)
close_backing_store (j_common_ptr cinfo, backing_store_ptr info)
{
fclose(info->temp_file);
// File is deleted using 'D' flag on open.
}
static HMODULE DllHandle()
{
MEMORY_BASIC_INFORMATION info;
VirtualQuery(DllHandle, &info, sizeof(MEMORY_BASIC_INFORMATION));
return (HMODULE)info.AllocationBase;
}
GLOBAL(void) jpeg_open_backing_store(j_common_ptr cinfo, backing_store_ptr info, long total_bytes_needed)
{
// Generate unique filename.
wchar_t path[ MAX_PATH ] = { 0 };
wchar_t dllPath[ MAX_PATH ] = { 0 };
GetTempPathW( MAX_PATH, path );
// Based on .exe or .dll filename
GetModuleFileNameW( DllHandle(), dllPath, MAX_PATH );
wchar_t* p = wcsrchr( dllPath, L'\\');
wchar_t* ext = wcsrchr( p + 1, L'.');
if( ext ) *ext = 0;
wchar_t* outFile = path + wcslen(path);
static int iTempFileId = 1;
// Based on process id (so processes would not fight with each other)
// Based on some process global id.
wsprintfW(outFile, L"%s_%d_%d.tmp",p + 1, GetCurrentProcessId(), iTempFileId++ );
// 'D' - temporary file.
if ((info->temp_file = _wfopen(path, L"w+bD") ) == NULL)
ERREXITS(cinfo, JERR_TFILE_CREATE, "");
info->read_backing_store = read_backing_store;
info->write_backing_store = write_backing_store;
info->close_backing_store = close_backing_store;
} //jpeg_open_backing_store
/*
* These routines take care of any system-dependent initialization and
* cleanup required.
*/
GLOBAL(long)
jpeg_mem_init (j_common_ptr cinfo)
{
return DEFAULT_MAX_MEM; /* default for max_memory_to_use */
}
GLOBAL(void)
jpeg_mem_term (j_common_ptr cinfo)
{
/* no work */
}
}
我故意忽略了一些函数的错误——你见过 GetTempPathW 或 GetModuleFileNameW 失败吗?