ELF_FLAGELF
Section: Libelf Programmer's Manual (3)
Updated: 202-0-23
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NAME
elf_flagelf, elf_flagdata, elf_flagehdr, elf_flagphdr, elf_flagscn, elf_flagshdr - set or clear flags on ELF descriptors and components
SYNOPSIS
#include <libelf.h>
unsigned int elf_flagelf(Elf * elf, Elf_Cmd cmd, unsigned int flags);
unsigned int elf_flagehdr(Elf * elf, Elf_Cmd cmd, unsigned int flags);
unsigned int elf_flagphdr(Elf * elf, Elf_Cmd cmd, unsigned int flags);
unsigned int elf_flagscn(Elf_Scn * scn, Elf_Cmd cmd, unsigned int flags);
unsigned int elf_flagshdr(Elf_Scn * scn, Elf_Cmd cmd, unsigned int flags);
unsigned int elf_flagdata(Elf_Data * data, Elf_Cmd cmd, unsigned int flags);
DESCRIPTION
These functions allow the caller to set or clear flags on various ELF
components managed by
libelf .
They are typically used to indicate that a component has been modified
(dirty), or to control layout behavior during output.
elf_flagelf()
modifies flags on the to-level
Elf
descriptor.
elf_flagdata()
modifies flags on an
Elf_Data
descriptor, typically retrieved using
elf_getdata(3)
or created with
elf_newdata(3).
elf_flagehdr()
modifies flags on the ELF header for a ELF descriptor (e.g., the result of
gelf_getehdr(3)).
elf_flagphdr()
modifies flags on the program header table of an ELF descriptor.
elf_flagscn()
modifies flags on an
Elf_Scn
(section) descriptor.
elf_flagshdr()
modifies flags on the section header of a given
Elf_Scn .
The
cmd
argument determines whether the given flags should be set (
ELF_C_SET
) or cleared (
ELF_C_CLR
).
The following flag values may be passed via the
flags
parameter:
- ELF_F_DIRTY
-
Marks the object as modified. This ensures changes to the component is written
out during
elf_update(3).
- ELF_F_LAYOUT
-
Indicates that the layout of the ELF component is managed manually. Offsets and
sizes will be preserved as provided. This flag is only used with
elf_flagelf()
and is ignored when used with other functions.
If this flag is set the user must set Ehdr
e_phoff,
e_shoff,
as well as
Elf_Data
d_off
and Shdr
sh_offset.
If not set, then these offsets will be recalculated when
elf_update
is called.
If
ELF_F_LAYOUT
is set then changes to phdr offsets will prevent elf_update from automatically
adjusting shdr offsets.
- ELF_F_PERMISSIVE
-
Enables relaxed validation of object structure. This flag permits nonstandard
layouts without strict checks. Specifically this removes a check in
elf_update()
that the section
sh_size
is a multiple of the section
sh_entsize
(if not zero). This flag is only used with
elf_flagelf()
and is ignored when used with other functions.
ELF_F_PERMISSIVE
is an elfutils libelf extention and may not be available in other libelf
implementations.
PARAMETERS
- obj
-
The object to be modified:
For
elf_flagelf,
elf_flagehdr,
elf_flagphdr,
this is an
Elf *
descriptor.
For
elf_flagscn
and
elf_flagshdr ,
this is an
Elf_Scn *
descriptor.
For
elf_flagdata ,
an
Elf_Data *
buffer.
- cmd
-
Must be either:
ELF_C_SET
to set the given flags, or
ELF_C_CLR
to clear them.
- flags
-
Bitmask of flags to modify. May include any combination of
ELF_F_DIRTY ,
ELF_F_LAYOUT ,
and
ELF_F_PERMISSIVE .
Note that
ELF_F_LAYOUT
and
ELF_F_PERMISSIVE
are only used with
elf_flagelf()
and are ignored for other functions.
RETURN VALUE
Returns the new value of the flags after the set/clear operation.
Returns 0 on error, and sets an error code retrievable via
elf_errmsg(3).
If the first argument is NULL then 0 is return and no error code is set.
If the last flag is cleared, 0 will be returned as the new flag value.
In this case 0 is not an error indicator and no error code is set.
SEE ALSO
elf_errmsg(3),
elf_update(3),
libelf(3),
elf(5)
ATTRIBUTES
| Interface | Attribute | Value
|
|
elf_flagelf(),~elf_flagehdr(),~elf_flagphdr(),~elf_flagscn(),~elf_flagshdr(),~elf_flagdata()
| Thread safety | M-Unsafe race
|
REPORTING BUGS
Report bugs to <
elfutil-devel@sourceware.org> or
https://sourceware.org/bugzilla/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- PARAMETERS
-
- RETURN VALUE
-
- SEE ALSO
-
- ATTRIBUTES
-
- REPORTING BUGS
-
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