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GELF_XLATETOF(3)           Library Functions Manual           GELF_XLATETOF(3)

NAME
     elf32_xlate, elf64_xlate, gelf_xlate - translate data between files and
     memory

LIBRARY
     ELF Access Library (libelf, -lelf)

SYNOPSIS
     #include <libelf.h>

     Elf_Data *
     elf32_xlatetof(Elf_Data *dst, Elf_Data *src, unsigned int file_encoding);

     Elf_Data *
     elf32_xlatetom(Elf_Data *dst, Elf_Data *src, unsigned int file_encoding);

     Elf_Data *
     elf64_xlatetof(Elf_Data *dst, Elf_Data *src, unsigned int file_encoding);

     Elf_Data *
     elf64_xlatetom(Elf_Data *dst, Elf_Data *src, unsigned int file_encoding);

     #include <gelf.h>

     Elf_Data *
     gelf_xlatetof(Elf *elf, Elf_Data *dst, Elf_Data *src,
         unsigned int file_encoding);

     Elf_Data *
     gelf_xlatetom(Elf *elf, Elf_Data *dst, Elf_Data *src,
         unsigned int file_encoding);

DESCRIPTION
     These functions translate between the file and memory representations of
     ELF data structures.  The in-memory representation of an ELF data
     structure would conform to the byte ordering and data alignment
     restrictions dictated by the host processor.  As described in elf(3), the
     file representation of this data structure could use a different byte
     ordering from that of the host, or could use a different layout within
     the file.

     Functions elf32_xlatetom(), elf64_xlatetom(), and gelf_xlatetom()
     translate data from file representations to native, in-memory
     representations.  Functions elf32_xlatetof(), elf64_xlatetof(), and
     gelf_xlatetof() translate data from in-memory representations to file
     representations.

     Argument src denotes an Elf_Data descriptor describing the source to be
     translated.  The following elements of the descriptor need to be set
     before invoking these functions:

           d_buf   Set to a valid pointer value denoting the beginning of the
                   data area to be translated.

           d_size  Set to the total size in bytes of the source data area to
                   be translated.

           d_type  Set to the type of the source data being translated.  This
                   value is one of the values defined in the Elf_Type
                   enumeration.  The Elf_Type enumeration is described in
                   elf(3).

           d_version Set to the version number of the ELF data structures
                   being translated.  Currently only version EV_CURRENT is
                   supported.

     Argument dst describes the destination buffer.  The following elements of
     the Elf_Data descriptor need to be set before invoking these functions:

           d_buf   Set to a valid pointer value that denotes the start of the
                   destination buffer that will hold translated data.  This
                   value may be the same as that of the source buffer, in
                   which case an in-place conversion will be attempted.

           d_size  Set to the size of the destination buffer in bytes.  This
                   value will be modified if the function call succeeds.

           d_version Set to the desired version number of the destination.
                   Currently only version EV_CURRENT is supported.

     These translations routines allow the source and destination buffers to
     coincide, in which case an in-place translation will be done if the
     destination is large enough to hold the translated data.  Other kinds of
     overlap between the source and destination buffers are not permitted.

     On successful completion of the translation request the following fields
     of the dst descriptor would be modified:

           d_size  Set to the size in bytes of the translated data.

           d_type  Set to the d_type value of the source data descriptor.

     Argument file_encoding specifies the encoding in which the file objects
     are represented.  It must be one of:

           ELFDATANONE File objects use the library's native byte ordering.

           ELFDATA2LSB File objects use a little-endian ordering.

           ELFDATA2MSB File objects use a big-endian ordering.

     The functions gelf_xlatetof() and gelf_xlatetom() select the appropriate
     translation scheme based on the properties of argument elf.

RETURN VALUES
     These functions return argument dst if successful, or NULL in case of an
     error.

EXAMPLES
     To translate a GElf_Rel structure to its LSB file representation use:

           Elf_Data dst, src;
           GElf_Rel rel;
           Elf *e;

           e = ...; /* See elf_begin(3). */

           /* Set up the 'src' descriptor. */
           memset(&src, 0, sizeof src);
           src.d_buf = &rel;
           src.d_size = sizeof(rel);
           src.d_type = ELF_T_REL;
           src.d_version = EV_CURRENT;

           /* Set up the 'dst' descriptor. */
           memset(&dst, 0, sizeof dst);
           dst.d_buf = filebuf;
           dst.d_size = gelf_fsize(e, ELF_T_REL, 1, EV_CURRENT);
           dst.d_version = EV_CURRENT;

           if (gelf_xlatetof(e, &dst, &src, ELFDATA2LSB) == NULL) {
                   printf("error: %s", elf_errmsg(0));
           }

ERRORS
     These functions may fail with the following errors:

     [ELF_E_ARGUMENT]  One of arguments src, dst or elf was NULL.

     [ELF_E_ARGUMENT]  Arguments src and dst were equal.

     [ELF_E_ARGUMENT]  The desired encoding parameter was not one of
                       ELFDATANONE, ELFDATA2LSB or ELFDATA2MSB.

     [ELF_E_ARGUMENT]  The d_type field of argument src specified an
                       unsupported type.

     [ELF_E_DATA]      The src argument specified a buffer size that was not
                       an integral multiple of its underlying type.

     [ELF_E_DATA]      The dst argument specified a buffer size that was too
                       small.

     [ELF_E_DATA]      Argument dst specified a destination buffer that
                       overlaps with the source buffer.

     [ELF_E_DATA]      The destination buffer for a conversion to memory had
                       an alignment inappropriate for the underlying ELF type.

     [ELF_E_DATA]      The source buffer for a conversion to file had an
                       alignment inappropriate for the underlying ELF type.

     [ELF_E_UNIMPL]    The version numbers for arguments dst and src were not
                       identical.

     [ELF_E_UNIMPL]    The argument src requested conversion for a type which
                       is not currently supported.

     [ELF_E_VERSION]   Argument src specified an unsupported version number.

SEE ALSO
     elf(3), elf_getdata(3), gelf(3)

NetBSD 10.99                   October 11, 2018                   NetBSD 10.99