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Updated: Thursday, June 13, 2019
 
 

elfdump(1)

Name

elfdump - dumps selected parts of an object file

Synopsis

elfdump [-cCdegGhHiklmnPrsSuvVy] [-p | -w file]
     [-F fmtopt1,fmtopt2,...] [-I index-expr]
     [-N name] [-O osabi] [-T type] file...

Description

The elfdump utility symbolically dumps selected parts of the specified object file(s). The options allow specific portions of the file to be displayed.

The elfdump utility is similar in function to the dump(1) utility. The dump utility offers an older and less user-friendly interface than elfdump, although dump might be more appropriate for certain uses such as in shell scripts.

Archive files, produced by ar(1), can also be inspected with elfdump. In this case, each object within the archive is processed using the options supplied.

elfdump can display the ELF header, program header array, and section header array for any ELF object. It is also able to display the data found in the following types of sections:

Category                   Option     ELF Section Type
Dynamic                     -d        SHT_DYNAMIC
Global Offset Table (GOT)   -G        Special, see below.
Group                       -g        SHT_GROUP
Capabilities                -H        SHT_SUNW_cap
Hash Table                  -h        SHT_HASH
Init/Fini Array                       SHT_INIT_ARRAY
                                      SHT_FINI_ARRAY
                                      SHT_PREINIT_ARRAY
Interpreter                 -i        Special, see below.
Move                        -m        SHT_SUNW_move
Note                        -n        SHT_NOTE
Relocation                  -r        SHT_RELA
                                      SHT_REL
Stack Unwind/Exceptions     -u        Special, see below.
Syminfo                     -y        SHT_SUNW_syminfo
Symbol Sort                 -S        SHT_SUNW_symsort
                                      SHT_SUNW_tlssort
Symbol Table                -s        SHT_SYMTAB
                                      SHT_DYNSYM
                                      SHT_SUNW_LDYNSYM
                                      SHT_SUNW_versym
Versioning                  -v        SHT_SUNW_verdef
                                      SHT_SUNW_verneed

The general matching options (–I, –N, –T) can be used to select the display of data for any desired section. See Matching Options. In addition, elfdump provides convenience options for the most commonly requested types of section data.

Interpreter and global offset table sections do not have a special ELF section type, but are instead implemented as SHT_PROGBITS sections with well known names (.interp and .got respectively). elfdump is able to recognize and display these special sections.

When run without options to narrow the information displayed, elfdump displays all available information for each object.

For a complete description of the displayed information, refer to the Oracle Solaris 11.4 Linkers and Libraries Guide.

Options

The following options are supported:

–c

Dumps section header information.

–C

Equivalent to –F demangle. See –F.

–d

Dumps the contents of the .dynamic section.

–e

Dumps the ELF header.

–F fmtopt1, fmtopt2,...

Alternative output format options are specified with a comma separated list of one or more of the following.

demangle

Demangles C++ symbol names.

fileprefix

Prefix every line of output with the name of the object.

fixhextab

Display hexadecimal values in tabular output as machine word sized zero-filled values. By default, elfdump displays such values in a natural format that does not include leading zeros.

notrunc

Displays long section names without truncation.

shndx | shndxonly

Alter the format used to display section indexes. The shndx format option displays sections by index and name, using the format [index]name. The shndxonly format option omits the name and displays only the section index, using the format [ index].

By default, when displaying section header information, a section index referenced by the sh_link or the sh_info field is displayed as a simple numeric value. Other displays, such as symbol table entries and relocations, display only the section name. The shndx and shndxonly format options display all section indexes in a consistent manner, using the associated format.

–g

Dumps the contents of the .group section.

–G

Dumps the contents of the .got section.

–h

Dumps the contents of the .hash section.

–H

Dumps the contents of the .SUNW_cap capabilities section.

–i

Dumps the contents of the .interp section.

–I index-expr

Qualifies the sections or program headers to examine with a specific index or index range. For example, the third section header in a file can be displayed using:

example% elfdump -c -I 3 filename

An index-expr can be a single non-negative integer value that specifies a specific item, as shown in the previous example. Alternatively, an index-expr can consist of two such values separated by a colon (:), indicating a range of items. The following example displays the third, fourth, and fifth program headers in a file:

example% elfdump -p -I 3:5 filename

When specifying an index range, the second value can be omitted to indicate the final item in the file. For example, the following statement lists all section headers from the tenth to the end:

example% elfdump -c -I 10: filename

See Matching Options for additional information about the matching options (–I, –N, –T).

–k

Calculates the ELF checksum. See gelf_checksum(3ELF).

–l

Equivalent to –F notrunc. See –F.

–m

Dumps the contents of the .SUNW_move section.

–n

Dumps the contents of .note sections. By default, elfdump displays this data without interpretation in hexadecimal form. Core files are an exception. A subset of the core file notes described in core(5) are interpreted by elfdump and displayed in a high level format: NT_PLATFORM, NT_AUXV, NT_ASRS, NT_PSTATUS, NT_PSINFO, NT_PRCRED, NT_UTSNAME, NT_LWPSTATUS, NT_LWPSINFO, NT_PRPRIV, NT_PRPRIVINFO, NT_CONTENT, NT_ZONENAME, NT_SIGACTION and NT_FDINFO.

–N name

Qualifies the sections or program headers to examine with a specific name. For example, in a file that contains more than one symbol table, the .dynsym symbol table can be displayed by itself using:

example% elfdump -N .dynsym filename

ELF program headers do not have names. If the –p option is specified, name refers to the program header type, and the behavior of the –N option is identical to that of the –T option. For example, the program header that identifies an interpreter can be displayed using:

example% elfdump -p -N PT_INTERP filename

See Matching Options for additional information about the matching options (–I, –N, –T).

–O osabi

Specifies the Operating System ABI to apply when interpreting the object. osabi can be the name or value of any of the ELFOSABI_ constants found in /usr/include/sys/elf.h . For convenience, the ELFOSABI_ prefix may be omitted from these names. Two osabi values are fully supported: solaris is the native ABI of the Solaris operating system. none is the generic ELF ABI. Support for other operating system ABIs may be incomplete or missing. Items for which strings are unavailable are displayed in numeric form.

If –O is not used, and the object ELF header specifies a non-generic ABI, the ABI specified by the object is used. If the object specifies the generic ELF ABI, elfdump searches for a .note.ABI-tag section, and if found, identifies the object as having the linux ABI. Otherwise, an object that specifies the generic ELF ABI is assumed to conform to the solaris ABI.

–p

Dumps the program headers. Individual program headers can be specified using the matching options (–I, –N, – T). See Matching Options for additional information.

The –p and –w options are mutually exclusive. Only one of these options can be used in a given elfdump invocation.

–P

Generate and use alternative section header information based on the information from the program headers, ignoring any section header information contained in the file. If the file has no section headers a warning message is printed and this option is automatically selected. Section headers are not used by the system to execute a program. As such, a malicious program can have its section headers stripped or altered to provide misleading information. In contrast the program headers must be accurate for the program to be runnable. The use of synthetic section header information derived from the program headers allows files with altered section headers to be examined.

–r

Dumps the contents of the .rel[a] relocation sections.

–s

Dumps the contents of the .SUNW_ldynsym, .dynsym, and .symtab symbol table sections. For archives, the archive symbol table is also dumped. Individual sections can be specified with the matching options (–I, –N, – T). An archive symbol table can be specified using the special section name –N ARSYM.

In the case of core files, the shndx field has the value “unknown” since the field does not contain the valid values.

In addition to the standard symbol table information, the version definition index of the symbol is also provided under the ver heading.

See Matching Options for additional information about the matching options (–I, –N, –T).

–S

Dumps the contents of the .SUNW_ldynsym and .dynsym symbol table sections sorted in the order given by the .SUNW_dynsymsort and .SUNW_dyntlssort symbol sort sections. Thread Local Storage (TLS) symbols are sorted by offset. Regular symbols are sorted by address. Symbols not referenced by the sort sections are not displayed.

–T type

Qualifies the sections or program headers to examine with a specific type. For example, in a file that contains more than one symbol table, the .dynsym symbol table can be displayed by itself using:

example% elfdump -T SHT_DYNSYM filename

The value of type can be a numeric value, or any of the SHT_ symbolic names defined in /usr/include/sys/elf.h . The SHT_ prefix is optional, and type is case insensitive. Therefore, the above example can also be written as:

example% elfdump -T dynsym filename

If the –p option is specified, type refers to the program header type, which allows for the display of specific program headers. For example, the program header that identifies an interpreter can be displayed using:

example% elfdump -p -T PT_INTERP filename

The value of type can be a numeric value, or any of the PT_ symbolic names defined in /usr/include/sys/elf.h . The PT_ prefix is optional, and type is case insensitive. Therefore, the above example can also be written as:

example% elfdump -p -T interp filename

See Matching Options for additional information about the matching options (–I, –N, –T).

–u

Dumps the contents of sections used for stack frame unwinding and exception processing.

–v

Dumps the contents of the .SUNW_version version sections.

–V
–-version

Print version information and immediately exit.

–w file

Writes the contents of sections which are specified with the matching options (–I, –N, –T) to the named file. For example, extracting the .text section of a file can be carried out with:

example% elfdump -w text.out -N .text filename

See Matching Options for additional information about the matching options (–I, –N, –T).

The –p and –w options are mutually exclusive. Only one of these options can be used in a given elfdump invocation.

–y

Dumps the contents of the .SUNW_syminfo section. Symbol attributes are conveyed by the following keywords.

AUXILIARY

Symbol definition acts as an auxiliary filter.

CAP

Symbol is associated with capabilities.

COPY

Symbol definition is the result of a copy-relocation.

DEFERRED

Symbol is associated with a deferred dependency.

DEPEND

Symbol reference has a dependency on the associated object.

DIRECT

Symbol reference is directly bound to the associated dependency. Always set in conjunction with DEPEND.

FILTER

Symbol definition acts as a standard filter.

INTERPOSE

Symbol definition acts as an interposer.

LAZY

Symbol reference is to a dependency that should be lazily loaded. Always set in conjunction with DEPEND.

NODIRECT

External references can not directly bind to this symbol definition.

WEAK

Symbol definition acts as a weak standard filter. Always set in conjunction with FILTER.

–?
–-help

Print usage message and immediately exit.

Operands

The following operand is supported:

file

The name of the specified object file.

Usage

Matching Options

The options –I, –N, and –T are collectively referred to as the matching options. These options are used to narrow the range of program headers or sections to examine, by index, name, or type.

The exact interpretation of the matching options depends on the other options used:

  • When used with the –p option, the matching options reference program headers. –I refers to program header indexes. –T refers to program header types. As program headers do not have names, the –N option behaves identically to –T for program headers.

  • The matching options are used to select sections by index, name, or type when used with any of the options –c, –g, –m, –n, –r, –s, –S, –u, or –w.

  • If matching options are used alone without any of the options –c, –g, –m, –n, –p, –r, –s, –S, –u, or –w, then elfdump examines each object, and displays the contents of any sections matched.

Any number and type of matching option can be mixed in a given invocation of elfdump. In this case, elfdump displays the superset of all items matched by any of the matching options used. This feature allows for the selection of complex groupings of items using the most convenient form for specifying each item.

Files

liblddbg.so

linker debugging library

libproc.so

process control library

Attributes

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Availability
system/linker
Interface Stability
Committed

See Also

ar(1), dump(1), elffile(1), file(1), nm(1), pvs(1), elf(3ELF), libproc(3LIB), core(5), attributes(7)

Oracle Solaris 11.4 Linkers and Libraries Guide

Notes

Sections used for stack unwinding and exception handling can have the ELF section type SHT_PROGBITS, or SHT_AMD64_UNWIND, depending on the compiler and platform involved. These sections are recognized by name: .eh_frame, .eh_frame_hdr, and .exception_ranges.

Core files contain information from multiple objects, each represented by a program header. elfdump uses libproc to determine the object name and mapping attributes that correspond to each program header. Program headers are augmented with pr_mapname and pr_mflags fields to display this information. Section names are augmented with the name of the object to which they apply.