Question

I want to iterate through all loaded shared libraries and get their base addresses as well as their file names. This is basically dl_iterate_phdr on Linux.

But I want to do the same for Mac.

Answer 1

The functions documented in the dyld(3) man page (which no longer seem to be online) seem to provide the analogous functionality.

Here’s that content:

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.