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dyld(3)                  BSD Library Functions Manual                  dyld(3)

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 dur-ing during
     ing 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 parame-ter parameter
     ter 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 exe-cutable executable
     cutable 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.

SEE ALSO
     dlopen(3) dladdr(3) dyld(1) http://developer.apple.com/documentation/DeveloperTools/Concep-
     tual/MachOTopics/index.html

                               November 29, 2010

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