-.\" Copyright (c) 2003 by Michael Kerrisk <mtk-manpages@gmx.net>
+.\" Copyright (c) 2003, 2017 by Michael Kerrisk <mtk.manpages@gmail.com>
.\"
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-.TH DL_ITERATE_PHDR 3 2007-05-18 "Linux 2.4.21" "Linux Programmer's Manual"
+.TH DL_ITERATE_PHDR 3 2017-07-13 "GNU" "Linux Programmer's Manual"
.SH NAME
dl_iterate_phdr \- walk through list of shared objects
.SH SYNOPSIS
.nf
-#define _GNU_SOURCE
+.BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */"
.B #include <link.h>
-\fBint dl_iterate_phdr(\fP
- \fBint (*\fPcallback\fB) \
-(struct dl_phdr_info *\fPinfo\fB,\fP
- \fBsize_t\fP size\fB, void *\fPdata\fB),\fP
- \fBvoid *\fPdata\fB);\fP
+.BI "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.
+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.
The
.BR dl_iterate_phdr ()
once for each object,
until either all shared objects have been processed or
.I callback
-returns a non-zero value.
+returns a nonzero value.
Each call to
.I callback
.I info
argument is a structure of the following type:
+.in +4n
.nf
- struct dl_phdr_info {
+struct dl_phdr_info {
ElfW(Addr) dlpi_addr; /* Base address of object */
const char *dlpi_name; /* (Null-terminated) name of
- object
+ object */
const ElfW(Phdr) *dlpi_phdr; /* Pointer to array of
ELF program headers
for this object */
- ElfW(Half) dlpi_phnum; /* # of items in 'dlpi_phdr' */
- };
+ 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 int dlpi_adds;
+ /* Incremented when a new object may
+ have been added */
+ unsigned long long int 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's instance
+ of this module's PT_TLS segment, if it has
+ one and it has been allocated in the calling
+ thread, otherwise a null pointer */
+};
.fi
+.in
(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,
-ElfW(Addr) yields the data type name Elf32_Addr.
+.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.)
field indicates the size of this array.
These program headers are structures of the following form:
+.in +4n
.nf
- typedef struct
- {
+typedef struct {
Elf32_Word p_type; /* Segment type */
Elf32_Off p_offset; /* Segment file offset */
Elf32_Addr p_vaddr; /* Segment virtual address */
Elf32_Word p_memsz; /* Segment size in memory */
Elf32_Word p_flags; /* Segment flags */
Elf32_Word p_align; /* Segment alignment */
- } Elf32_Phdr;
+} Elf32_Phdr;
.fi
+.in
Note that we can calculate the location of a particular program header,
.IR x ,
in virtual memory using the formula:
.nf
- addr == info->dlpi_addr + info->dlpi_phdr[x].p_vaddr;
+ addr == info\->dlpi_addr + info\->dlpi_phdr[x].p_vaddr;
+.fi
+
+Possible values for
+.I p_type
+include the following (see
+.IR <elf.h>
+for further details):
+
+.nf
+.in +4n
+#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 */
+.in
.fi
.SH RETURN VALUE
The
.BR dl_iterate_phdr ()
function returns whatever value was returned by the last call to
.IR callback .
-.SH "CONFORMING TO"
+.SH VERSIONS
+.BR dl_iterate_phdr ()
+has been supported in glibc since version 2.2.4.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lb
+l l l.
+Interface Attribute Value
+T{
+.BR dl_iterate_phdr ()
+T} Thread safety MT-Safe
+.TE
+
+.SH CONFORMING TO
The
.BR dl_iterate_phdr ()
-function is Linux specific and should be avoided in portable applications.
+function is not specified in any standard.
+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
+.IR dlpi_phnum
+in addition to other implementation-specific fields.
+.SH NOTES
+Future versions of the C library may add further fields to the
+.IR 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.
+
+The first object visited by
+.IR callback
+is the main program.
+For the main program, the
+.I dlpi_name
+field will be an empty string.
.SH EXAMPLE
The following program displays a list of pathnames of the
shared objects it has loaded.
-For each shared object, the program lists the virtual addresses
-at which the object's ELF segments are loaded.
+For each shared object, the program lists some information
+(virtual address, size, flags, and type)
+for each of the objects ELF segments.
+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.
+.nf
+.in +4n
+$ \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
+.in
+.fi
+
+.SS Program source
+\&
.nf
#define _GNU_SOURCE
#include <link.h>
static int
callback(struct dl_phdr_info *info, size_t size, void *data)
{
- int j;
+ char *type;
+ int p_type, j;
- printf("name=%s (%d segments)\\n", info->dlpi_name,
- info->dlpi_phnum);
+ printf("Name: \\"%s\\" (%d segments)\\n", info\->dlpi_name,
+ info\->dlpi_phnum);
+
+ for (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(" %2d: [%14p; memsz:%7lx] flags: 0x%x; ", j,
+ (void *) (info\->dlpi_addr + info\->dlpi_phdr[j].p_vaddr),
+ info\->dlpi_phdr[j].p_memsz,
+ info\->dlpi_phdr[j].p_flags);
+ if (type != NULL)
+ printf("%s\\n", type);
+ else
+ printf("[other (0x%x)]\\n", p_type);
+ }
- for (j = 0; j < info->dlpi_phnum; j++)
- printf("\\t\\t header %2d: address=%10p\\n", j,
- (void *) (info->dlpi_addr + info->dlpi_phdr[j].p_vaddr));
return 0;
}
exit(EXIT_SUCCESS);
}
.fi
-.SH "SEE ALSO"
+.SH SEE ALSO
.BR ldd (1),
.BR objdump (1),
.BR readelf (1),
+.BR dladdr (3),
.BR dlopen (3),
-.BR feature_test_macros (7),
-.BR ld.so (8),
-and the
-.I "Executable and Linking Format Specification"
+.BR elf (5),
+.BR ld.so (8)
+
+.IR "Executable and Linking Format Specification" ,
available at various locations online.
projects / thirdparty / man-pages.git / blobdiff