doc/man/man3/dyld.3

   1 .Dd June 20, 2019
   2 .Dt dyld 3
   3 .Sh NAME
   4 .Nm _dyld_image_count,
   5 .Nm _dyld_get_image_header,
   6 .Nm _dyld_get_image_vmaddr_slide,
   7 .Nm _dyld_get_image_name,
   8 .Nm _dyld_register_func_for_add_image,
   9 .Nm _dyld_register_func_for_remove_image,
  10 .Nm NSVersionOfRunTimeLibrary,
  11 .Nm NSVersionOfLinkTimeLibrary
  12 .Nm _NSGetExecutablePath
  13 .Sh SYNOPSIS
  14 .In mach-o/dyld.h
  15 .Ft uint32_t
  16 .Fo _dyld_image_count
  17 .Fa "void"
  18 .Fc
  19 .Ft const struct mach_header*
  20 .Fo _dyld_get_image_header
  21 .Fa "uint32_t image_index"
  22 .Fc
  23 .Ft intptr_t
  24 .Fo _dyld_get_image_vmaddr_slide
  25 .Fa "uint32_t image_index"
  26 .Fc
  27 .Ft const char*
  28 .Fo _dyld_get_image_name
  29 .Fa "uint32_t image_index"
  30 .Fc
  31 .Ft void
  32 .Fo _dyld_register_func_for_add_image
  33 .Fa "void \*[lp]*func\*[rp]\*[lp]const struct mach_header* mh, intptr_t vmaddr_slide\*[rp]"
  34 .Fc
  35 .Ft void
  36 .Fo _dyld_register_func_for_remove_image
  37 .Fa "void \*[lp]*func\*[rp]\*[lp]const struct mach_header* mh, intptr_t vmaddr_slide\*[rp]"
  38 .Fc
  39 .Ft int32_t
  40 .Fo NSVersionOfRunTimeLibrary
  41 .Fa "const char* libraryName"
  42 .Fc
  43 .Ft int32_t
  44 .Fo NSVersionOfLinkTimeLibrary
  45 .Fa "const char* libraryName"
  46 .Fc
  47 .Ft int
  48 .Fo _NSGetExecutablePath
  49 .Fa "char* buf"
  50 .Fa "uint32_t* bufsize"
  51 .Fc
  52 .Sh DESCRIPTION
  53 These routines provide additional introspection of dyld beyond that provided by
  54 .Fn dlopen
  55 and
  56 .Fn dladdr
  57 .
  58 .Pp
  59 .Fn _dyld_image_count
  60 returns the current number of images mapped in by dyld. Note that using this
  61 count to iterate all images is not thread safe, because another thread
  62 may be adding or removing images during the iteration.
  63 .Pp
  64 .Fn _dyld_get_image_header
  65 returns a pointer to the mach header of the image indexed by image_index.  If
  66 .Fa image_index
  67 is out of range, NULL is returned.
  68 .Pp
  69 .Fn _dyld_get_image_vmaddr_slide
  70 returns the virtural memory address slide amount of the image indexed by
  71 .Fa image_index.
  72 If
  73 .Fa image_index
  74 is out of range zero is returned.
  75 .Pp
  76 .Fn _dyld_get_image_name
  77 returns the name of the image indexed by
  78 .Fa image_index.
  79 The C-string continues to be owned by dyld and should not be deleted.
  80 If
  81 .Fa image_index
  82 is out of range NULL is returned.
  83 .Pp
  84 .Fn _dyld_register_func_for_add_image
  85 registers the specified function to be called when a new image is added
  86 (a bundle or a dynamic shared library) to the program.  When this function is
  87 first registered it is called for once for each image that is currently part of
  88 the process.  The function is called with the dyld lock held.  This blocks other
  89 threads from using dlopen().  Therefore, the function should do minimal work and
  90 return.
  91 .Pp
  92 .Fn _dyld_register_func_for_remove_image
  93 registers the specified function to be called when an image is removed
  94 (a bundle or a dynamic shared library) from the process.
  95 .Pp
  96 .Fn NSVersionOfRunTimeLibrary
  97 returns the current_version number of the currently loaded dylib
  98 specifed by the libraryName.  The libraryName parameter would be "bar" for /path/libbar.3.dylib and
  99 "Foo" for /path/Foo.framework/Versions/A/Foo.  This function returns -1 if no such library is loaded.
 100 .Pp
 101 .Fn NSVersionOfLinkTimeLibrary
 102 returns the current_version number that the main executable was linked
 103 against at build time.  The libraryName parameter would be "bar" for /path/libbar.3.dylib and
 104 "Foo" for /path/Foo.framework/Versions/A/Foo.  This function returns -1 if the main executable did not link
 105 against the specified library.
 106 .Pp
 107 .Fn _NSGetExecutablePath
 108 copies the path of the main executable into the buffer
 109 .Fa buf .
 110 The
 111 .Fa bufsize
 112 parameter should initially be the size of the buffer.  This function returns 0 if the path was successfully copied,
 113 and  *
 114 .Fa bufsize
 115 is left unchanged.
 116 It returns -1 if the buffer is not large enough, and *
 117 .Fa bufsize
 118 is set to the size required.
 119 Note that
 120 .Fn _NSGetExecutablePath
 121 will return "a path" to the executable not a "real path" to the executable.
 122 That is, the path may be a symbolic link and not the real file. With deep directories the total bufsize
 123 needed could be more than MAXPATHLEN.
 124 .Sh SEE ALSO
 125 .Xr dlopen 3
 126 .Xr dladdr 3
 127 .Xr dyld 1
 128 https://developer.apple.com/library/archive/documentation/DeveloperTools/Conceptual/MachOTopics/0-Introduction/introduction.html