Thin

This is the most common type of Mach-O files. It is composed of the following parts:

• Header: Contains general information about the file. Here is its structure according to the official source code:

struct mach_header {
     unsigned long magic; /* mach magic number identifier */
     cpu_type_t cputype; /* cpu specifier */
     cpu_subtype_t cpusubtype; /* machine specifier */
     unsigned long filetype; /* type of file */
     unsigned long ncmds; /* number of load commands */
     unsigned long sizeofcmds; /* the size of all the load commands */
      unsigned long flags; /* flags */
 };

The difference between 32-bit and 64-bit versions of this header is mainly in the extra reserved field added to the end of this structure, and the slightly different magic values used: 0xfeedface for 32-bit and 0xfeedfacf for 64-bit.

• Load commands: These can perform multiple actions, most importantly define the segments present in the file, where each block contains information about a particular...