1.\" Copyright (c) 2005 Mark Kettenis 2.\" Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org> 3.\" 4.\" Permission to use, copy, modify, and distribute this software for any 5.\" purpose with or without fee is hereby granted, provided that the above 6.\" copyright notice and this permission notice appear in all copies. 7.\" 8.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 9.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 10.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 11.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 12.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 13.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 14.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 15.\" 16.\" $OpenBSD: dl_iterate_phdr.3,v 1.3 2007/05/31 19:19:48 jmc Exp $ 17.\" $FreeBSD$ 18.Dd February 15, 2012 19.Dt DL_ITERATE_PHDR 3 20.Os 21.Sh NAME 22.Nm dl_iterate_phdr 23.Nd iterate over program headers 24.Sh LIBRARY 25For the dynamically linked binaries, the service is provided by 26.Xr ld-elf.so.1 1 27dynamic linker. 28Statically linked programs use an implementation of 29.Fn dl_iterate_phdr 30from libc. 31.Sh SYNOPSIS 32.In link.h 33.Ft int 34.Fn dl_iterate_phdr "int (*callback)(struct dl_phdr_info *, size_t, void *)" "void *data" 35.Sh DESCRIPTION 36The 37.Fn dl_iterate_phdr 38function iterates over all ELF objects loaded into a process's 39address space, calling 40.Fa callback 41for each object, passing it information about the object's 42program headers and the 43.Fa data 44argument. 45The iteration is aborted when all objects are passed, or when the next 46.Fa callback 47call returns non-zero value. 48The information about the program headers is passed in a structure 49that is defined as: 50.Bd -literal 51struct dl_phdr_info { 52 Elf_Addr dlpi_addr; 53 const char *dlpi_name; 54 const Elf_Phdr *dlpi_phdr; 55 Elf_Half dlpi_phnum; 56 unsigned long long int dlpi_adds; 57 unsigned long long int dlpi_subs; 58 size_t dlpi_tls_modid; 59 void *dlpi_tls_data; 60}; 61.Ed 62.Pp 63The members of 64.Li struct dl_phdr_info 65have the following meaning: 66.Bl -tag -width dlpi_tls_modid 67.It Fa dlpi_addr 68The base address at which the object is mapped into the address 69space of the calling process. 70.It Fa dlpi_name 71The name of the ELF object. 72.It Fa dlpi_phdr 73A pointer to the object's program headers. 74.It Fa dlpi_phnum 75The number of program headers in the object. 76.It Fa dlpi_adds 77The counter of the object loads performed by the dynamic linker. 78.It Fa dlpi_subs 79The counter of the object unloads performed by the dynamic linker. 80.It Fa dlpi_tls_modid 81The TLS index of the object. 82.It Fa dlpi_tls_data 83A pointer to the initialization data for the object TLS segment. 84.El 85.Pp 86Future versions of 87.Fx 88might add more members to this structure. 89To make it possible for programs to check whether any new members have 90been added, the size of the structure is passed as an second argument to 91.Fa callback . 92.Pp 93The third argument to callback is the 94.Fa data 95value passed to the call to 96.Fn dl_iterate_phdr , 97allowing the 98.Fa callback 99to have a context. 100.Sh RETURN VALUES 101The 102.Fn dl_iterate_phdr 103returns the value returned by the last 104.Fa callback 105call executed. 106.Sh SEE ALSO 107.Xr ld 1 , 108.Xr ld-elf.so.1 1 , 109.Xr dlopen 3 , 110.Xr elf 5 111.Sh HISTORY 112The 113.Nm 114function first appeared in 115.Fx 7.0 . 116