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Diffstat (limited to 'man3/dl_iterate_phdr.3')
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diff --git a/man3/dl_iterate_phdr.3 b/man3/dl_iterate_phdr.3 deleted file mode 100644 index b5cbb86..0000000 --- a/man3/dl_iterate_phdr.3 +++ /dev/null @@ -1,345 +0,0 @@ -'\" t -.\" Copyright (c) 2003, 2017 by Michael Kerrisk <mtk.manpages@gmail.com> -.\" -.\" SPDX-License-Identifier: Linux-man-pages-copyleft -.\" -.TH dl_iterate_phdr 3 2023-10-31 "Linux man-pages 6.7" -.SH NAME -dl_iterate_phdr \- walk through list of shared objects -.SH LIBRARY -Standard C library -.RI ( libc ", " \-lc ) -.SH SYNOPSIS -.nf -.BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */" -.B #include <link.h> -.P -.B int dl_iterate_phdr( -.BI " int (*" callback ")(struct dl_phdr_info *" info , -.BI " size_t " size ", void *" data ), -.BI " void *" data ); -.fi -.SH DESCRIPTION -The -.BR dl_iterate_phdr () -function allows an application to inquire at run time to find -out which shared objects it has loaded, -and the order in which they were loaded. -.P -The -.BR dl_iterate_phdr () -function walks through the list of an -application's shared objects and calls the function -.I callback -once for each object, -until either all shared objects have been processed or -.I callback -returns a nonzero value. -.P -Each call to -.I callback -receives three arguments: -.IR info , -which is a pointer to a structure containing information -about the shared object; -.IR size , -which is the size of the structure pointed to by -.IR info ; -and -.IR data , -which is a copy of whatever value was passed by the calling -program as the second argument (also named -.IR data ) -in the call to -.BR dl_iterate_phdr (). -.P -The -.I info -argument is a structure of the following type: -.P -.in +4n -.EX -struct dl_phdr_info { - ElfW(Addr) dlpi_addr; /* Base address of object */ - const char *dlpi_name; /* (Null\-terminated) name of - object */ - const ElfW(Phdr) *dlpi_phdr; /* Pointer to array of - ELF program headers - for this object */ - ElfW(Half) dlpi_phnum; /* # of items in \fIdlpi_phdr\fP */ -\& - /* The following fields were added in glibc 2.4, after the first - version of this structure was available. Check the \fIsize\fP - argument passed to the dl_iterate_phdr callback to determine - whether or not each later member is available. */ -\& - unsigned long long dlpi_adds; - /* Incremented when a new object may - have been added */ - unsigned long long dlpi_subs; - /* Incremented when an object may - have been removed */ - size_t dlpi_tls_modid; - /* If there is a PT_TLS segment, its module - ID as used in TLS relocations, else zero */ - void *dlpi_tls_data; - /* The address of the calling thread\[aq]s instance - of this module\[aq]s PT_TLS segment, if it has - one and it has been allocated in the calling - thread, otherwise a null pointer */ -}; -.EE -.in -.P -(The -.IR ElfW () -macro definition turns its argument into the name of an ELF data -type suitable for the hardware architecture. -For example, on a 32-bit platform, -.I ElfW(Addr) -yields the data type name -.IR Elf32_Addr . -Further information on these types can be found in the -.IR <elf.h> " and " <link.h> -header files.) -.P -The -.I dlpi_addr -field indicates the base address of the shared object -(i.e., the difference between the virtual memory address of -the shared object and the offset of that object in the file -from which it was loaded). -The -.I dlpi_name -field is a null-terminated string giving the pathname -from which the shared object was loaded. -.P -To understand the meaning of the -.I dlpi_phdr -and -.I dlpi_phnum -fields, we need to be aware that an ELF shared object consists -of a number of segments, each of which has a corresponding -program header describing the segment. -The -.I dlpi_phdr -field is a pointer to an array of the program headers for this -shared object. -The -.I dlpi_phnum -field indicates the size of this array. -.P -These program headers are structures of the following form: -.P -.in +4n -.EX -typedef struct { - Elf32_Word p_type; /* Segment type */ - Elf32_Off p_offset; /* Segment file offset */ - Elf32_Addr p_vaddr; /* Segment virtual address */ - Elf32_Addr p_paddr; /* Segment physical address */ - Elf32_Word p_filesz; /* Segment size in file */ - Elf32_Word p_memsz; /* Segment size in memory */ - Elf32_Word p_flags; /* Segment flags */ - Elf32_Word p_align; /* Segment alignment */ -} Elf32_Phdr; -.EE -.in -.P -Note that we can calculate the location of a particular program header, -.IR x , -in virtual memory using the formula: -.P -.in +4n -.EX -addr == info\->dlpi_addr + info\->dlpi_phdr[x].p_vaddr; -.EE -.in -.P -Possible values for -.I p_type -include the following (see -.I <elf.h> -for further details): -.P -.in +4n -.EX -#define PT_LOAD 1 /* Loadable program segment */ -#define PT_DYNAMIC 2 /* Dynamic linking information */ -#define PT_INTERP 3 /* Program interpreter */ -#define PT_NOTE 4 /* Auxiliary information */ -#define PT_SHLIB 5 /* Reserved */ -#define PT_PHDR 6 /* Entry for header table itself */ -#define PT_TLS 7 /* Thread\-local storage segment */ -#define PT_GNU_EH_FRAME 0x6474e550 /* GCC .eh_frame_hdr segment */ -#define PT_GNU_STACK 0x6474e551 /* Indicates stack executability */ -.\" For PT_GNU_STACK, see http://www.airs.com/blog/archives/518 -#define PT_GNU_RELRO 0x6474e552 /* Read\-only after relocation */ -.EE -.in -.SH RETURN VALUE -The -.BR dl_iterate_phdr () -function returns whatever value was returned by the last call to -.IR callback . -.SH ATTRIBUTES -For an explanation of the terms used in this section, see -.BR attributes (7). -.TS -allbox; -lbx lb lb -l l l. -Interface Attribute Value -T{ -.na -.nh -.BR dl_iterate_phdr () -T} Thread safety MT-Safe -.TE -.SH VERSIONS -Various other systems provide a version of this function, -although details of the returned -.I dl_phdr_info -structure differ. -On the BSDs and Solaris, the structure includes the fields -.IR dlpi_addr , -.IR dlpi_name , -.IR dlpi_phdr , -and -.I dlpi_phnum -in addition to other implementation-specific fields. -.P -Future versions of the C library may add further fields to the -.I dl_phdr_info -structure; in that event, the -.I size -argument provides a mechanism for the callback function to discover -whether it is running on a system with added fields. -.SH STANDARDS -None. -.SH HISTORY -glibc 2.2.4. -.SH NOTES -The first object visited by -.I callback -is the main program. -For the main program, the -.I dlpi_name -field will be an empty string. -.SH EXAMPLES -The following program displays a list of pathnames of the -shared objects it has loaded. -For each shared object, the program lists some information -(virtual address, size, flags, and type) -for each of the objects ELF segments. -.P -The following shell session demonstrates the output -produced by the program on an x86-64 system. -The first shared object for which output is displayed -(where the name is an empty string) -is the main program. -.P -.in +4n -.EX -$ \fB./a.out\fP -Name: "" (9 segments) - 0: [ 0x400040; memsz: 1f8] flags: 0x5; PT_PHDR - 1: [ 0x400238; memsz: 1c] flags: 0x4; PT_INTERP - 2: [ 0x400000; memsz: ac4] flags: 0x5; PT_LOAD - 3: [ 0x600e10; memsz: 240] flags: 0x6; PT_LOAD - 4: [ 0x600e28; memsz: 1d0] flags: 0x6; PT_DYNAMIC - 5: [ 0x400254; memsz: 44] flags: 0x4; PT_NOTE - 6: [ 0x400970; memsz: 3c] flags: 0x4; PT_GNU_EH_FRAME - 7: [ (nil); memsz: 0] flags: 0x6; PT_GNU_STACK - 8: [ 0x600e10; memsz: 1f0] flags: 0x4; PT_GNU_RELRO -Name: "linux\-vdso.so.1" (4 segments) - 0: [0x7ffc6edd1000; memsz: e89] flags: 0x5; PT_LOAD - 1: [0x7ffc6edd1360; memsz: 110] flags: 0x4; PT_DYNAMIC - 2: [0x7ffc6edd17b0; memsz: 3c] flags: 0x4; PT_NOTE - 3: [0x7ffc6edd17ec; memsz: 3c] flags: 0x4; PT_GNU_EH_FRAME -Name: "/lib64/libc.so.6" (10 segments) - 0: [0x7f55712ce040; memsz: 230] flags: 0x5; PT_PHDR - 1: [0x7f557145b980; memsz: 1c] flags: 0x4; PT_INTERP - 2: [0x7f55712ce000; memsz: 1b6a5c] flags: 0x5; PT_LOAD - 3: [0x7f55716857a0; memsz: 9240] flags: 0x6; PT_LOAD - 4: [0x7f5571688b80; memsz: 1f0] flags: 0x6; PT_DYNAMIC - 5: [0x7f55712ce270; memsz: 44] flags: 0x4; PT_NOTE - 6: [0x7f55716857a0; memsz: 78] flags: 0x4; PT_TLS - 7: [0x7f557145b99c; memsz: 544c] flags: 0x4; PT_GNU_EH_FRAME - 8: [0x7f55712ce000; memsz: 0] flags: 0x6; PT_GNU_STACK - 9: [0x7f55716857a0; memsz: 3860] flags: 0x4; PT_GNU_RELRO -Name: "/lib64/ld\-linux\-x86\-64.so.2" (7 segments) - 0: [0x7f557168f000; memsz: 20828] flags: 0x5; PT_LOAD - 1: [0x7f55718afba0; memsz: 15a8] flags: 0x6; PT_LOAD - 2: [0x7f55718afe10; memsz: 190] flags: 0x6; PT_DYNAMIC - 3: [0x7f557168f1c8; memsz: 24] flags: 0x4; PT_NOTE - 4: [0x7f55716acec4; memsz: 604] flags: 0x4; PT_GNU_EH_FRAME - 5: [0x7f557168f000; memsz: 0] flags: 0x6; PT_GNU_STACK - 6: [0x7f55718afba0; memsz: 460] flags: 0x4; PT_GNU_RELRO -.EE -.in -.SS Program source -\& -.\" SRC BEGIN (dl_iterate_phdr.c) -.EX -#define _GNU_SOURCE -#include <link.h> -#include <stdint.h> -#include <stdio.h> -#include <stdlib.h> -\& -static int -callback(struct dl_phdr_info *info, size_t size, void *data) -{ - char *type; - int p_type; -\& - printf("Name: \e"%s\e" (%d segments)\en", info\->dlpi_name, - info\->dlpi_phnum); -\& - for (size_t j = 0; j < info\->dlpi_phnum; j++) { - p_type = info\->dlpi_phdr[j].p_type; - type = (p_type == PT_LOAD) ? "PT_LOAD" : - (p_type == PT_DYNAMIC) ? "PT_DYNAMIC" : - (p_type == PT_INTERP) ? "PT_INTERP" : - (p_type == PT_NOTE) ? "PT_NOTE" : - (p_type == PT_INTERP) ? "PT_INTERP" : - (p_type == PT_PHDR) ? "PT_PHDR" : - (p_type == PT_TLS) ? "PT_TLS" : - (p_type == PT_GNU_EH_FRAME) ? "PT_GNU_EH_FRAME" : - (p_type == PT_GNU_STACK) ? "PT_GNU_STACK" : - (p_type == PT_GNU_RELRO) ? "PT_GNU_RELRO" : NULL; -\& - printf(" %2zu: [%14p; memsz:%7jx] flags: %#jx; ", j, - (void *) (info\->dlpi_addr + info\->dlpi_phdr[j].p_vaddr), - (uintmax_t) info\->dlpi_phdr[j].p_memsz, - (uintmax_t) info\->dlpi_phdr[j].p_flags); - if (type != NULL) - printf("%s\en", type); - else - printf("[other (%#x)]\en", p_type); - } -\& - return 0; -} -\& -int -main(void) -{ - dl_iterate_phdr(callback, NULL); -\& - exit(EXIT_SUCCESS); -} -.EE -.\" SRC END -.SH SEE ALSO -.BR ldd (1), -.BR objdump (1), -.BR readelf (1), -.BR dladdr (3), -.BR dlopen (3), -.BR elf (5), -.BR ld.so (8) -.P -.IR "Executable and Linking Format Specification" , -available at various locations online. |