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DL_ITERATE_PHDR(3)	    Library Functions Manual	    DL_ITERATE_PHDR(3)

NAME
       dl_iterate_phdr -- iterate over program headers

LIBRARY
       For  the	 dynamically  linked  binaries,	 the  service  is  provided by
       ld-elf.so.1(1) dynamic linker.  Statically linked programs use  an  im-
       plementation of dl_iterate_phdr() from libc.

SYNOPSIS
       #include	<link.h>

       int
       dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *),
	   void	*data);

DESCRIPTION
       The  dl_iterate_phdr()  function	 iterates  over	all ELF	objects	loaded
       into a process's	address	space, calling callback	for each object, pass-
       ing it information about	the object's program headers and the data  ar-
       gument.	 The iteration is aborted when all objects are passed, or when
       the next	callback call returns non-zero value.  The  information	 about
       the program headers is passed in	a structure that is defined as:

       struct dl_phdr_info {
	       Elf_Addr	       dlpi_addr;
	       const char      *dlpi_name;
	       const Elf_Phdr  *dlpi_phdr;
	       Elf_Half	       dlpi_phnum;
	       unsigned	long long int dlpi_adds;
	       unsigned	long long int dlpi_subs;
	       size_t	       dlpi_tls_modid;
	       void	       *dlpi_tls_data;
       };

       The members of struct dl_phdr_info have the following meaning:

       dlpi_addr       The base	address	at which the object is mapped into the
		       address space of	the calling process.

       dlpi_name       The pathname of the ELF object.

       dlpi_phdr       A pointer to the	object's program headers.

       dlpi_phnum      The number of program headers in	the object.

       dlpi_adds       The  counter  of	 the object loads performed by the dy-
		       namic linker.

       dlpi_subs       The counter of the object unloads performed by the  dy-
		       namic linker.

       dlpi_tls_modid  The TLS index of	the object.

       dlpi_tls_data   A  pointer  to the calling thread' TLS data segment for
		       this module, if it was allocated, NULL otherwise.

       Future versions of FreeBSD might	add more members  to  this  structure.
       To  make	it possible for	programs to check whether any new members have
       been added, the size of the structure is	passed as an  second  argument
       to callback.

       The  third argument to callback is the data value passed	to the call to
       dl_iterate_phdr(), allowing the callback	to have	a context.

RETURN VALUES
       The dl_iterate_phdr() returns the value returned	by the	last  callback
       call executed.

SEE ALSO
       ld(1), ld-elf.so.1(1), dlopen(3), elf(5)

HISTORY
       The dl_iterate_phdr function first appeared in FreeBSD 7.0.

FreeBSD	14.3			 April 5, 2021		    DL_ITERATE_PHDR(3)

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