Mac平台上的dl_iterate_phdr等价物

Question

我希望能够遍历所有已加载的共享库，并获取它们的基地址以及文件名。这在Linux上基本上是通过dl_iterate_phdr来实现的。

但我想在Mac上做同样的事情。

- Albert

Answer 1

在dyld(3)手册中记录的函数（似乎不再在线）似乎提供类似的功能。

以下是该内容：

NAME

 _dyld_image_count, _dyld_get_image_header, _dyld_get_image_vmaddr_slide,
 _dyld_get_image_name, _dyld_register_func_for_add_image,
 _dyld_register_func_for_remove_image, NSVersionOfRunTimeLibrary,
 NSVersionOfLinkTimeLibrary _NSGetExecutablePath

SYNOPSIS

 #include <mach-o/dyld.h>

 uint32_t
 _dyld_image_count(void);

 const struct mach_header*
 _dyld_get_image_header(uint32_t image_index);

 intptr_t
 _dyld_get_image_vmaddr_slide(uint32_t image_index);

 const char*
 _dyld_get_image_name(uint32_t image_index);

 void
 _dyld_register_func_for_add_image(void (*func)(const struct mach_header* mh, intptr_t vmaddr_slide));

 void
 _dyld_register_func_for_remove_image(void (*func)(const struct mach_header* mh, intptr_t vmaddr_slide));

 int32_t
 NSVersionOfRunTimeLibrary(const char* libraryName);

 int32_t
 NSVersionOfLinkTimeLibrary(const char* libraryName);

 int
 _NSGetExecutablePath(char* buf, uint32_t* bufsize);

DESCRIPTION

These routines provide additional introspection of dyld beyond that provided by dlopen() and dladdr()

_dyld_image_count() returns the current number of images mapped in by dyld. Note that using this count to iterate all images is not thread safe, because another thread may be adding or removing images during the iteration.

_dyld_get_image_header() returns a pointer to the mach header of the image indexed by image_index. If image_index is out of range, NULL is returned.

_dyld_get_image_vmaddr_slide() returns the virtural memory address slide amount of the image indexed by image_index. If image_index is out of range zero is returned.

_dyld_get_image_name() returns the name of the image indexed by image_index. The C-string continues to be owned by dyld and should not deleted. If image_index is out of range NULL is returned.

_dyld_register_func_for_add_image() registers the specified function to be called when a new image is added (a bundle or a dynamic shared library) to the program. When this function is first registered it is called for once for each image that is currently part of the process.

_dyld_register_func_for_remove_image() registers the specified function to be called when an image is removed (a bundle or a dynamic shared library) from the process.

NSVersionOfRunTimeLibrary() returns the current_version number of the currently loaded dylib specifed by the libraryName. The libraryName parameter would be "bar" for /path/libbar.3.dylib and "Foo" for /path/Foo.framework/Versions/A/Foo. This function returns -1 if no such library is loaded.

NSVersionOfLinkTimeLibrary() returns the current_version number that the main executable was linked against at build time. The libraryName parameter would be "bar" for /path/libbar.3.dylib and "Foo" for /path/Foo.framework/Versions/A/Foo. This function returns -1 if the main executable did not link against the specified library.

_NSGetExecutablePath() copies the path of the main executable into the buffer buf. The bufsize parameter should initially be the size of the buffer. This function returns 0 if the path was successfully copied, and * bufsize is left unchanged. It returns -1 if the buffer is not large enough, and * bufsize is set to the size required. Note that _NSGetExecutablePath() will return "a path" to the executable not a "real path" to the executable. That is, the path may be a symbolic link and not the real file. With deep directories the total bufsize needed could be more than MAXPATHLEN.

- Ken Thomases

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链接已失效。 - Jean-Michaël Celerier

Answer 2

仅为完整性而言：

输入是指向某些静态内容（例如函数）的任意指针，目标是找到库及其部分。

我在这里实现了ptr_is_in_exe函数：https://github.com/albertz/openlierox/blob/0.59/src/common/Debug_extended_backtrace.cpp

static bool
ptr_is_in_exe(const void *ptr, const struct mach_header *& header, intptr_t& offset, uintptr_t& vmaddr, std::string& image_name)
{
    uint32_t i, count = _dyld_image_count();

    for (i = 0; i < count; i++) {
        header = _dyld_get_image_header(i);
        offset = _dyld_get_image_vmaddr_slide(i);

        uint32_t j = 0;
        struct load_command* cmd = (struct load_command*)((char *)header + sizeof(struct mach_header));
        if(header->magic == MH_MAGIC_64)
            cmd = (struct load_command*)((char *)header + sizeof(struct mach_header_64));

        while (j < header->ncmds) {
            if (cmd->cmd == LC_SEGMENT) {
                struct segment_command* seg = (struct segment_command*)cmd;
                if (((intptr_t)ptr >= (seg->vmaddr + offset)) && ((intptr_t)ptr < (seg->vmaddr + offset + seg->vmsize))) {
                    vmaddr = seg->vmaddr;
                    image_name = _dyld_get_image_name(i);
                    return true;
                }
            }
            if (cmd->cmd == LC_SEGMENT_64) {
                struct segment_command_64* seg = (struct segment_command_64*)cmd;
                if (((uintptr_t)ptr >= (seg->vmaddr + offset)) && ((uintptr_t)ptr < (seg->vmaddr + offset + seg->vmsize))) {
                    vmaddr = seg->vmaddr;
                    image_name = _dyld_get_image_name(i);
                    return true;
                }
            }

            j++;
            cmd = (struct load_command*)((char*)cmd + cmd->cmdsize);
        }
    }

    return false;
}

- Albert

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为了后代，鉴于您在此答案中提到的目标（但不包括您的问题），使用dladdr()要简单得多。 - Ken Thomases