Hi Aaron,
On Mon, 2025-08-04 at 23:24 -0400, Aaron Merey wrote:
> Signed-off-by: Aaron Merey <[email protected]>
> ---
> v2: Mention that ELF_F_LAYOUT and ELF_F_PERMISSIVE are used with
> elf_flagelf only and mention which fields may be manually modified.
> Clarify when an error code is set. Explain exactly which check
> ELF_F_PERMISSIVE disables during elf_update.
>
> doc/Makefile.am | 6 ++
> doc/elf_flagdata.3 | 1 +
> doc/elf_flagehdr.3 | 1 +
> doc/elf_flagelf.3 | 177 +++++++++++++++++++++++++++++++++++++++++++++
> doc/elf_flagphdr.3 | 1 +
> doc/elf_flagscn.3 | 1 +
> doc/elf_flagshdr.3 | 1 +
> 7 files changed, 188 insertions(+)
> create mode 100644 doc/elf_flagdata.3
> create mode 100644 doc/elf_flagehdr.3
> create mode 100644 doc/elf_flagelf.3
> create mode 100644 doc/elf_flagphdr.3
> create mode 100644 doc/elf_flagscn.3
> create mode 100644 doc/elf_flagshdr.3
>
> diff --git a/doc/Makefile.am b/doc/Makefile.am
> index e99f685d..791a68da 100644
> --- a/doc/Makefile.am
> +++ b/doc/Makefile.am
> @@ -56,6 +56,12 @@ notrans_dist_man3_MANS= elf32_checksum.3 \
> elf_errmsg.3 \
> elf_errno.3 \
> elf_fill.3 \
> + elf_flagelf.3 \
> + elf_flagehdr.3 \
> + elf_flagphdr.3 \
> + elf_flagscn.3 \
> + elf_flagdata.3 \
> + elf_flagshdr.3 \
> elf_getarhdr.3 \
> elf_getaroff.3 \
> elf_getarsym.3 \
OK.
> diff --git a/doc/elf_flagdata.3 b/doc/elf_flagdata.3
> new file mode 100644
> index 00000000..ee84d431
> --- /dev/null
> +++ b/doc/elf_flagdata.3
> @@ -0,0 +1 @@
> +.so man3/elf_flagelf.3
> diff --git a/doc/elf_flagehdr.3 b/doc/elf_flagehdr.3
> new file mode 100644
> index 00000000..ee84d431
> --- /dev/null
> +++ b/doc/elf_flagehdr.3
> @@ -0,0 +1 @@
> +.so man3/elf_flagelf.3
OK.
> diff --git a/doc/elf_flagelf.3 b/doc/elf_flagelf.3
> new file mode 100644
> index 00000000..05a7eb84
> --- /dev/null
> +++ b/doc/elf_flagelf.3
> @@ -0,0 +1,177 @@
> +.TH ELF_FLAGELF 3 2025-06-23 "Libelf" "Libelf Programmer's Manual"
> +
> +.SH NAME
> +elf_flagelf, elf_flagdata, elf_flagehdr, elf_flagphdr, elf_flagscn,
> elf_flagshdr \- set or clear flags on ELF descriptors and components
> +.SH SYNOPSIS
> +.nf
> +#include <libelf.h>
> +
> +.B unsigned int elf_flagelf(Elf *" elf ", Elf_Cmd" cmd ", unsigned int"
> flags ");
> +.B unsigned int elf_flagehdr(Elf *" elf ", "Elf_Cmd" cmd ", unsigned int"
> flags ");
> +.B unsigned int elf_flagphdr(Elf *" elf ", Elf_Cmd" cmd ", unsigned int"
> flags ");
> +.B unsigned int elf_flagscn(Elf_Scn *" scn ", Elf_Cmd" cmd ", unsigned int"
> flags ");
> +.B unsigned int elf_flagshdr("Elf_Scn *" scn ", "Elf_Cmd" cmd ", unsigned
> int" flags ");
> +.B unsigned int elf_flagdata(Elf_Data *" data ", Elf_Cmd" cmd ", unsigned
> int" flags ");
elf_flagshdr seems to have an unbalanced '"' (twice, which makes it
balanced again?)
> +.fi
> +.SH DESCRIPTION
> +These functions allow the caller to set or clear flags on various ELF
> +components managed by
> +.B libelf .
> +They are typically used to indicate that a component has been modified
> +(dirty), or to control layout behavior during output.
OK.
> +.BR elf_flagelf ()
> +modifies flags on the top-level
> +.B Elf
> +descriptor.
> +
> +.BR elf_flagdata ()
> +modifies flags on an
> +.B Elf_Data
> +descriptor, typically retrieved using
> +.BR elf_getdata (3)
> +or created with
> +.BR elf_newdata (3).
> +
> +.BR elf_flagehdr ()
> +modifies flags on the ELF header for a ELF descriptor (e.g., the result of
> +.BR gelf_getehdr (3)).
> +
> +.BR elf_flagphdr ()
> +modifies flags on the program header table of an ELF descriptor.
> +
> +.BR elf_flagscn ()
> +modifies flags on an
> +.B Elf_Scn
> +(section) descriptor.
> +
> +.BR elf_flagshdr ()
> +modifies flags on the section header of a given
> +.B Elf_Scn .
OK.
> +The
> +.I cmd
> +argument determines whether the given flags should be set (
> +.B ELF_C_SET
> +) or cleared (
> +.B ELF_C_CLR
> +).
OK.
> +The following flag values may be passed via the
> +.I flags
> +parameter:
> +
> +.TP
> +.B ELF_F_DIRTY
> +Marks the object as modified. This ensures changes to the component is
> written
> +out during
> +.BR elf_update (3).
> +
> +.TP
> +.B 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
> +.BR elf_flagelf ()
> +and is ignored when used with other functions. The user may set
> +Ehdr
> +.IR e_phoff ,
> +.IR e_shoff ,
> +as well as
> +.B Elf_Data
> +.I d_off
> +and
> +Shdr
> +.IR sh_offset .
> +If not set, then these offsets will be recaculated when
> +.B elf_update
> +is called.
s/recaculated/recalculated/
Also I would make this a little stronger.
"If set the user is must setup ..."
Maybe hint that if the phdrs have been setup then setting ELF_F_LAYOUT
will prevent libelf from updating/changing the shdr offsets when
elf_update is called (which would most likely invalidate the offsets
set in the phdrs).
> +.TP
> +.B ELF_F_PERMISSIVE
> +Enables relaxed validation of object structure. This flag permits
> nonstandard layouts
> +without strict checks. Specifically this removes a check in
> +.BR elf_update ()
> +that the section
> +.I sh_size
> +is a multiple of the section
> +.I sh_entsize
> +(if not zero). This flag is only used with
> +.BR elf_flagelf ()
> +and is ignored when used with other functions.
OK. Maybe mention this is an elfutils libelf extension?
> +.SH PARAMETERS
> +.TP
> +.I obj
> +The object to be modified:
> +For
> +.BR elf_flagelf ,
> +.BR elf_flagehdr ,
> +.BR elf_flagphdr ,
> +this is an
> +.B Elf *
> +descriptor.
> +For
> +.B elf_flagscn
> +and
> +.B elf_flagshdr ,
> +this is an
> +.B Elf_Scn *
> +descriptor.
> +For
> +.B elf_flagdata ,
> +an
> +.B Elf_Data *
> +buffer.
OK.
> +.TP
> +.I cmd
> +Must be either:
> +.B ELF_C_SET
> +to set the given flags, or
> +.B ELF_C_CLR
> +to clear them.
OK.
> +.TP
> +.I flags
> +Bitmask of flags to modify. May include any combination of
> +.B ELF_F_DIRTY ,
> +.B ELF_F_LAYOUT ,
> +and
> +.B ELF_F_PERMISSIVE .
> +
> +Note that
> +.B ELF_F_LAYOUT
> +and
> +.B ELF_F_PERMISSIVE
> +are only used with
> +.BR elf_flagelf ()
> +and are ignored for other functions.
OK.
> +.SH 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
> +.BR elf_errmsg (3).
> +If the first argument is NULL then 0 is return and no error code is set.
OK. (Just a sidenote, this is pretty useless given that most functions
can only take one flag, ELF_F_DIRTY which happens to be 1. So the
return value will be either zero or one. So zero is also a valid return
value...)
> +.SH SEE ALSO
> +.BR elf_errmsg (3),
> +.BR elf_update (3),
> +.BR libelf (3),
> +.BR elf (5)
OK.
> +.SH ATTRIBUTES
> +.TS
> +allbox;
> +lbx lb lb
> +l l l.
> +Interface Attribute Value
> +T{
> +.na
> +.nh
> +.BR elf_flagelf
> (),\~elf_flagehdr(),\~elf_flagphdr(),\~elf_flagscn(),\~elf_flagshdr(),\~elf_flagdata()
> +T} Thread safety MT-Unsafe race
> +.TE
> +
> +.SH REPORTING BUGS
> +Report bugs to <[email protected]> or
> https://sourceware.org/bugzilla/.
OK.
> diff --git a/doc/elf_flagphdr.3 b/doc/elf_flagphdr.3
> new file mode 100644
> index 00000000..ee84d431
> --- /dev/null
> +++ b/doc/elf_flagphdr.3
> @@ -0,0 +1 @@
> +.so man3/elf_flagelf.3
> diff --git a/doc/elf_flagscn.3 b/doc/elf_flagscn.3
> new file mode 100644
> index 00000000..ee84d431
> --- /dev/null
> +++ b/doc/elf_flagscn.3
> @@ -0,0 +1 @@
> +.so man3/elf_flagelf.3
> diff --git a/doc/elf_flagshdr.3 b/doc/elf_flagshdr.3
> new file mode 100644
> index 00000000..ee84d431
> --- /dev/null
> +++ b/doc/elf_flagshdr.3
> @@ -0,0 +1 @@
> +.so man3/elf_flagelf.3
OK.
