[2/4,v3] doc: Add elf_memory.3
Commit Message
Signed-off-by: Aaron Merey <amerey@redhat.com>
---
v3: Mention that the underlying memory image should be writable since
libelf may attempt to modify it. Remove some implementation details.
doc/Makefile.am | 1 +
doc/elf_memory.3 | 85 ++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 86 insertions(+)
create mode 100644 doc/elf_memory.3
Comments
Hi Aaron,
On Sun, Sep 14, 2025 at 07:21:00PM -0400, Aaron Merey wrote:
> Signed-off-by: Aaron Merey <amerey@redhat.com>
>
> ---
> v3: Mention that the underlying memory image should be writable since
> libelf may attempt to modify it. Remove some implementation details.
>
> doc/Makefile.am | 1 +
> doc/elf_memory.3 | 85 ++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 86 insertions(+)
> create mode 100644 doc/elf_memory.3
>
> diff --git a/doc/Makefile.am b/doc/Makefile.am
> index 81566664..96d35d20 100644
> --- a/doc/Makefile.am
> +++ b/doc/Makefile.am
> @@ -78,6 +78,7 @@ notrans_dist_man3_MANS= elf32_checksum.3 \
> elf_hash.3 \
> elf_gnu_hash.3 \
> elf_kind.3 \
> + elf_memory.3 \
> elf_ndxscn.3 \
> elf_newdata.3 \
> elf_newscn.3 \
OK.
> diff --git a/doc/elf_memory.3 b/doc/elf_memory.3
> new file mode 100644
> index 00000000..8f4efced
> --- /dev/null
> +++ b/doc/elf_memory.3
> @@ -0,0 +1,85 @@
> +.TH ELF_MEMORY 3 2025-06-23 "Libelf" "Libelf Programmer's Manual"
> +
> +.SH NAME
> +elf_memory \- create an ELF descriptor from a memory buffer
> +.SH SYNOPSIS
> +.nf
> +#include <libelf.h>
> +
> +.B Elf * elf_memory(char *" image ", size_t" size ");
OK.
> +.fi
> +.SH DESCRIPTION
> +The
> +.BR elf_memory ()
> +function creates a new ELF descriptor from a memory region containing an ELF
> +object. This function is used when the ELF data is already present in memory
> +rather than being read from a file descriptor.
> +
> +The memory pointed to by
> +.I image
> +must contain a complete ELF file or archive. The contents must remain valid
> +and unmodified for the lifetime of the resulting ELF descriptor.
> +
> +The ELF descriptor returned by
> +.BR elf_memory ()
> +is opened in read-only mode using ELF_C_READ_MMAP_PRIVATE (see
> +.BR elf_begin ).
> +The underlying memory image should not be directly modified by the application
> +while its ELF descriptor is open. Some libelf functions, such as
> +.BR elf_compress ()
> +and
> +.BR gelf_update_* (),
> +may internally modify the underlying image and therefore require that the
> +underlying image be writable. The use of a read-only image (e.g., memory
> +mapped with
> +.BR PROT_READ
> +only) may result in failures or crashes.
Nice.
> +
> +.SH PARAMETERS
> +.TP
> +.I image
> +A pointer to a memory buffer that contains the complete contents of an ELF file
> +or archive. If NULL, this function fails and returns NULL.
OK.
> +.TP
> +.I size
> +The size in bytes of the memory region pointed to by
> +.IR image .
> +Must be at least as much as a full ELF header and should cover the entire ELF
> +object.
OK.
> +.SH RETURN VALUE
> +On success,
> +.BR elf_memory ()
> +returns a pointer to an
> +.B Elf
> +descriptor representing the archive or ELF file contained in
> +.IR image .
> +
> +On failure, it returns NULL and sets an error code retrievable by
> +.BR elf_errmsg (3).
OK.
> +.SH SEE ALSO
> +.BR elf_begin (3),
> +.BR elf_errmsg (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_memory ()
> +T} Thread safety MT-Safe
> +.TE
> +
> +.SH REPORTING BUGS
> +Report bugs to <elfutils-devel@sourceware.org> or https://sourceware.org/bugzilla/.
> +
OK.
Thanks,
Mark
@@ -78,6 +78,7 @@ notrans_dist_man3_MANS= elf32_checksum.3 \
elf_hash.3 \
elf_gnu_hash.3 \
elf_kind.3 \
+ elf_memory.3 \
elf_ndxscn.3 \
elf_newdata.3 \
elf_newscn.3 \
new file mode 100644
@@ -0,0 +1,85 @@
+.TH ELF_MEMORY 3 2025-06-23 "Libelf" "Libelf Programmer's Manual"
+
+.SH NAME
+elf_memory \- create an ELF descriptor from a memory buffer
+.SH SYNOPSIS
+.nf
+#include <libelf.h>
+
+.B Elf * elf_memory(char *" image ", size_t" size ");
+
+.fi
+.SH DESCRIPTION
+The
+.BR elf_memory ()
+function creates a new ELF descriptor from a memory region containing an ELF
+object. This function is used when the ELF data is already present in memory
+rather than being read from a file descriptor.
+
+The memory pointed to by
+.I image
+must contain a complete ELF file or archive. The contents must remain valid
+and unmodified for the lifetime of the resulting ELF descriptor.
+
+The ELF descriptor returned by
+.BR elf_memory ()
+is opened in read-only mode using ELF_C_READ_MMAP_PRIVATE (see
+.BR elf_begin ).
+The underlying memory image should not be directly modified by the application
+while its ELF descriptor is open. Some libelf functions, such as
+.BR elf_compress ()
+and
+.BR gelf_update_* (),
+may internally modify the underlying image and therefore require that the
+underlying image be writable. The use of a read-only image (e.g., memory
+mapped with
+.BR PROT_READ
+only) may result in failures or crashes.
+
+.SH PARAMETERS
+.TP
+.I image
+A pointer to a memory buffer that contains the complete contents of an ELF file
+or archive. If NULL, this function fails and returns NULL.
+
+.TP
+.I size
+The size in bytes of the memory region pointed to by
+.IR image .
+Must be at least as much as a full ELF header and should cover the entire ELF
+object.
+
+.SH RETURN VALUE
+On success,
+.BR elf_memory ()
+returns a pointer to an
+.B Elf
+descriptor representing the archive or ELF file contained in
+.IR image .
+
+On failure, it returns NULL and sets an error code retrievable by
+.BR elf_errmsg (3).
+
+
+.SH SEE ALSO
+.BR elf_begin (3),
+.BR elf_errmsg (3),
+.BR libelf (3),
+.BR elf (5)
+
+.SH ATTRIBUTES
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface Attribute Value
+T{
+.na
+.nh
+.BR elf_memory ()
+T} Thread safety MT-Safe
+.TE
+
+.SH REPORTING BUGS
+Report bugs to <elfutils-devel@sourceware.org> or https://sourceware.org/bugzilla/.
+