libelf/libelf.h

/* Interface for libelf.
   Copyright (C) 1998-2010, 2015 Red Hat, Inc.
   This file is part of elfutils.

   This file is free software; you can redistribute it and/or modify
   it under the terms of either

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at
       your option) any later version

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at
       your option) any later version

   or both in parallel, as here.

   elfutils is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received copies of the GNU General Public License and
   the GNU Lesser General Public License along with this program.  If
   not, see <http://www.gnu.org/licenses/>.  */

#ifndef _LIBELF_H
#define _LIBELF_H 1

#include <stdint.h>
#include <sys/types.h>

/* Get the ELF types.  */
#include <elf.h>

#ifndef SHF_COMPRESSED
 /* Older glibc elf.h might not yet define the ELF compression types.  */
 #define SHF_COMPRESSED      (1 << 11)  /* Section with compressed data. */

 /* Section compression header.  Used when SHF_COMPRESSED is set.  */

 typedef struct
 {
   Elf32_Word   ch_type;        /* Compression format.  */
   Elf32_Word   ch_size;        /* Uncompressed data size.  */
   Elf32_Word   ch_addralign;   /* Uncompressed data alignment.  */
 } Elf32_Chdr;

 typedef struct
 {
   Elf64_Word   ch_type;        /* Compression format.  */
   Elf64_Word   ch_reserved;
   Elf64_Xword  ch_size;        /* Uncompressed data size.  */
   Elf64_Xword  ch_addralign;   /* Uncompressed data alignment.  */
 } Elf64_Chdr;

 /* Legal values for ch_type (compression algorithm).  */
 #define ELFCOMPRESS_ZLIB       1          /* ZLIB/DEFLATE algorithm.  */
 #define ELFCOMPRESS_LOOS       0x60000000 /* Start of OS-specific.  */
 #define ELFCOMPRESS_HIOS       0x6fffffff /* End of OS-specific.  */
 #define ELFCOMPRESS_LOPROC     0x70000000 /* Start of processor-specific.  */
 #define ELFCOMPRESS_HIPROC     0x7fffffff /* End of processor-specific.  */
#endif

#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 3)
# define __nonnull_attribute__(...) __attribute__ ((__nonnull__ (__VA_ARGS__)))
# define __deprecated_attribute__ __attribute__ ((__deprecated__))
# define __pure_attribute__ __attribute__ ((__pure__))
# define __const_attribute__ __attribute__ ((__const__))
#else
# define __nonnull_attribute__(...)
# define __deprecated_attribute__
# define __pure_attribute__
# define __const_attribute__
#endif

#if __GNUC__ < 4
#define __noreturn_attribute__
#else
#define __noreturn_attribute__ __attribute__ ((noreturn))
#endif

#ifdef __GNUC_STDC_INLINE__
# define __libdw_extern_inline extern __inline __attribute__ ((__gnu_inline__))
#else
# define __libdw_extern_inline extern __inline
#endif

/* Known translation types.  */
typedef enum
{
  ELF_T_BYTE,                   /* unsigned char */
  ELF_T_ADDR,                   /* Elf32_Addr, Elf64_Addr, ... */
  ELF_T_DYN,                    /* Dynamic section record.  */
  ELF_T_EHDR,                   /* ELF header.  */
  ELF_T_HALF,                   /* Elf32_Half, Elf64_Half, ... */
  ELF_T_OFF,                    /* Elf32_Off, Elf64_Off, ... */
  ELF_T_PHDR,                   /* Program header.  */
  ELF_T_RELA,                   /* Relocation entry with addend.  */
  ELF_T_REL,                    /* Relocation entry.  */
  ELF_T_SHDR,                   /* Section header.  */
  ELF_T_SWORD,                  /* Elf32_Sword, Elf64_Sword, ... */
  ELF_T_SYM,                    /* Symbol record.  */
  ELF_T_WORD,                   /* Elf32_Word, Elf64_Word, ... */
  ELF_T_XWORD,                  /* Elf32_Xword, Elf64_Xword, ... */
  ELF_T_SXWORD,                 /* Elf32_Sxword, Elf64_Sxword, ... */
  ELF_T_VDEF,                   /* Elf32_Verdef, Elf64_Verdef, ... */
  ELF_T_VDAUX,                  /* Elf32_Verdaux, Elf64_Verdaux, ... */
  ELF_T_VNEED,                  /* Elf32_Verneed, Elf64_Verneed, ... */
  ELF_T_VNAUX,                  /* Elf32_Vernaux, Elf64_Vernaux, ... */
  ELF_T_NHDR,                   /* Elf32_Nhdr, Elf64_Nhdr, ... */
  ELF_T_SYMINFO,		/* Elf32_Syminfo, Elf64_Syminfo, ... */
  ELF_T_MOVE,			/* Elf32_Move, Elf64_Move, ... */
  ELF_T_LIB,			/* Elf32_Lib, Elf64_Lib, ... */
  ELF_T_GNUHASH,		/* GNU-style hash section.  */
  ELF_T_AUXV,			/* Elf32_auxv_t, Elf64_auxv_t, ... */
  ELF_T_CHDR,			/* Compressed, Elf32_Chdr, Elf64_Chdr, ... */
  ELF_T_NHDR8,			/* Special GNU Properties note.  Same as Nhdr,
				   except padding.  */
  /* Keep this the last entry.  */
  ELF_T_NUM
} Elf_Type;

/* Descriptor for data to be converted to or from memory format.  */
typedef struct
{
  void *d_buf;			/* Pointer to the actual data.  */
  Elf_Type d_type;		/* Type of this piece of data.  */
  unsigned int d_version;	/* ELF version.  */
  size_t d_size;		/* Size in bytes.  */
  int64_t d_off;		/* Offset into section.  */
  size_t d_align;		/* Alignment in section.  */
} Elf_Data;


/* Commands for `...'.  */
typedef enum
{
  ELF_C_NULL,			/* Nothing, terminate, or compute only.  */
  ELF_C_READ,			/* Read .. */
  ELF_C_RDWR,			/* Read and write .. */
  ELF_C_WRITE,			/* Write .. */
  ELF_C_CLR,			/* Clear flag.  */
  ELF_C_SET,			/* Set flag.  */
  ELF_C_FDDONE,			/* Signal that file descriptor will not be
				   used anymore.  */
  ELF_C_FDREAD,			/* Read rest of data so that file descriptor
				   is not used anymore.  */
  /* The following are extensions.  */
  ELF_C_READ_MMAP,		/* Read, but mmap the file if possible.  */
  ELF_C_RDWR_MMAP,		/* Read and write, with mmap.  */
  ELF_C_WRITE_MMAP,		/* Write, with mmap.  */
  ELF_C_READ_MMAP_PRIVATE,	/* Read, but memory is writable, results are
				   not written to the file.  */
  ELF_C_EMPTY,			/* Copy basic file data but not the content. */
  /* Keep this the last entry.  */
  ELF_C_NUM
} Elf_Cmd;


/* Flags for the ELF structures.  */
enum
{
  ELF_F_DIRTY = 0x1,
#define ELF_F_DIRTY		ELF_F_DIRTY
  ELF_F_LAYOUT = 0x4,
#define ELF_F_LAYOUT		ELF_F_LAYOUT
  ELF_F_PERMISSIVE = 0x8
#define ELF_F_PERMISSIVE	ELF_F_PERMISSIVE
};

/* Flags for elf_compress[_gnu].  */
enum
{
  ELF_CHF_FORCE = 0x1
#define ELF_CHF_FORCE ELF_CHF_FORCE
};

/* Identification values for recognized object files.  */
typedef enum
{
  ELF_K_NONE,			/* Unknown.  */
  ELF_K_AR,			/* Archive.  */
  ELF_K_COFF,			/* Stupid old COFF.  */
  ELF_K_ELF,			/* ELF file.  */
  /* Keep this the last entry.  */
  ELF_K_NUM
} Elf_Kind;


/* Archive member header.  */
typedef struct
{
  char *ar_name;		/* Name of archive member.  */
  time_t ar_date;		/* File date.  */
  uid_t ar_uid;			/* User ID.  */
  gid_t ar_gid;			/* Group ID.  */
  mode_t ar_mode;		/* File mode.  */
  int64_t ar_size;		/* File size.  */
  char *ar_rawname;		/* Original name of archive member.  */
} Elf_Arhdr;


/* Archive symbol table entry.  */
typedef struct
{
  char *as_name;		/* Symbol name.  */
  size_t as_off;		/* Offset for this file in the archive.  */
  unsigned long int as_hash;	/* Hash value of the name.  */
} Elf_Arsym;


/* Descriptor for the ELF file.  */
typedef struct Elf Elf;

/* Descriptor for ELF file section.  */
typedef struct Elf_Scn Elf_Scn;


#ifdef __cplusplus
extern "C" {
#endif

/* Return descriptor for ELF file to work according to CMD.  */
extern Elf *elf_begin (int __fildes, Elf_Cmd __cmd, Elf *__ref);

/* Create a clone of an existing ELF descriptor.  */
  extern Elf *elf_clone (Elf *__elf, Elf_Cmd __cmd);

/* Create descriptor for memory region.  */
extern Elf *elf_memory (char *__image, size_t __size);

/* Advance archive descriptor to next element.  */
extern Elf_Cmd elf_next (Elf *__elf);

/* Free resources allocated for ELF.  */
extern int elf_end (Elf *__elf);

/* Update ELF descriptor and write file to disk.  */
extern int64_t elf_update (Elf *__elf, Elf_Cmd __cmd);

/* Determine what kind of file is associated with ELF.  */
extern Elf_Kind elf_kind (Elf *__elf) __pure_attribute__;

/* Get the base offset for an object file.  */
extern int64_t elf_getbase (Elf *__elf);


/* Retrieve file identification data.  */
extern char *elf_getident (Elf *__elf, size_t *__nbytes);

/* Retrieve class-dependent object file header.  */
extern Elf32_Ehdr *elf32_getehdr (Elf *__elf);
/* Similar but this time the binary calls is ELFCLASS64.  */
extern Elf64_Ehdr *elf64_getehdr (Elf *__elf);

/* Create ELF header if none exists.  */
extern Elf32_Ehdr *elf32_newehdr (Elf *__elf);
/* Similar but this time the binary calls is ELFCLASS64.  */
extern Elf64_Ehdr *elf64_newehdr (Elf *__elf);

/* Get the number of program headers in the ELF file.  If the file uses
   more headers than can be represented in the e_phnum field of the ELF
   header the information from the sh_info field in the zeroth section
   header is used.  */
extern int elf_getphdrnum (Elf *__elf, size_t *__dst);

/* Retrieve class-dependent program header table.  */
extern Elf32_Phdr *elf32_getphdr (Elf *__elf);
/* Similar but this time the binary calls is ELFCLASS64.  */
extern Elf64_Phdr *elf64_getphdr (Elf *__elf);

/* Create ELF program header.  */
extern Elf32_Phdr *elf32_newphdr (Elf *__elf, size_t __cnt);
/* Similar but this time the binary calls is ELFCLASS64.  */
extern Elf64_Phdr *elf64_newphdr (Elf *__elf, size_t __cnt);


/* Get section at INDEX.  */
extern Elf_Scn *elf_getscn (Elf *__elf, size_t __index);

/* Get section at OFFSET.  */
extern Elf_Scn *elf32_offscn (Elf *__elf, Elf32_Off __offset);
/* Similar bug this time the binary calls is ELFCLASS64.  */
extern Elf_Scn *elf64_offscn (Elf *__elf, Elf64_Off __offset);

/* Get index of section.  */
extern size_t elf_ndxscn (Elf_Scn *__scn);

/* Get section with next section index.  */
extern Elf_Scn *elf_nextscn (Elf *__elf, Elf_Scn *__scn);

/* Create a new section and append it at the end of the table.  */
extern Elf_Scn *elf_newscn (Elf *__elf);

/* Get the section index of the extended section index table for the
   given symbol table.  */
extern int elf_scnshndx (Elf_Scn *__scn);

/* Get the number of sections in the ELF file.  If the file uses more
   sections than can be represented in the e_shnum field of the ELF
   header the information from the sh_size field in the zeroth section
   header is used.  */
extern int elf_getshdrnum (Elf *__elf, size_t *__dst);
/* Sun messed up the implementation of 'elf_getshnum' in their implementation.
   It was agreed to make the same functionality available under a different
   name and obsolete the old name.  */
extern int elf_getshnum (Elf *__elf, size_t *__dst)
     __deprecated_attribute__;


/* Get the section index of the section header string table in the ELF
   file.  If the index cannot be represented in the e_shstrndx field of
   the ELF header the information from the sh_link field in the zeroth
   section header is used.  */
extern int elf_getshdrstrndx (Elf *__elf, size_t *__dst);
/* Sun messed up the implementation of 'elf_getshstrndx' in their
   implementation.  It was agreed to make the same functionality available
   under a different name and obsolete the old name.  */
extern int elf_getshstrndx (Elf *__elf, size_t *__dst)
     __deprecated_attribute__;


/* Retrieve section header of ELFCLASS32 binary.  */
extern Elf32_Shdr *elf32_getshdr (Elf_Scn *__scn);
/* Similar for ELFCLASS64.  */
extern Elf64_Shdr *elf64_getshdr (Elf_Scn *__scn);

/* Returns compression header for a section if section data is
   compressed.  Returns NULL and sets elf_errno if the section isn't
   compressed or an error occurred.  */
extern Elf32_Chdr *elf32_getchdr (Elf_Scn *__scn);
extern Elf64_Chdr *elf64_getchdr (Elf_Scn *__scn);

/* Compress or decompress the data of a section and adjust the section
   header.

   elf_compress works by setting or clearing the SHF_COMPRESS flag
   from the section Shdr and will encode or decode a Elf32_Chdr or
   Elf64_Chdr at the start of the section data.  elf_compress_gnu will
   encode or decode any section, but is traditionally only used for
   sections that have a name starting with ".debug" when
   uncompressed or ".zdebug" when compressed and stores just the
   uncompressed size.  The GNU compression method is deprecated and
   should only be used for legacy support.

   elf_compress takes a compression type that should be either zero to
   decompress or an ELFCOMPRESS algorithm to use for compression.
   Currently only ELFCOMPRESS_ZLIB is supported.  elf_compress_gnu
   will compress in the traditional GNU compression format when
   compress is one and decompress the section data when compress is
   zero.

   The FLAGS argument can be zero or ELF_CHF_FORCE.  If FLAGS contains
   ELF_CHF_FORCE then it will always compress the section, even if
   that would not reduce the size of the data section (including the
   header).  Otherwise elf_compress and elf_compress_gnu will compress
   the section only if the total data size is reduced.

   On successful compression or decompression the function returns
   one.  If (not forced) compression is requested and the data section
   would not actually reduce in size, the section is not actually
   compressed and zero is returned.  Otherwise -1 is returned and
   elf_errno is set.

   It is an error to request compression for a section that already
   has SHF_COMPRESSED set, or (for elf_compress) to request
   decompression for an section that doesn't have SHF_COMPRESSED set.
   If a section has SHF_COMPRESSED set then calling elf_compress_gnu
   will result in an error.  The section has to be decompressed first
   using elf_compress.  Calling elf_compress on a section compressed
   with elf_compress_gnu is fine, but probably useless.

   It is always an error to call these functions on SHT_NOBITS
   sections or if the section has the SHF_ALLOC flag set.
   elf_compress_gnu will not check whether the section name starts
   with ".debug" or .zdebug".  It is the responsibility of the caller
   to make sure the deprecated GNU compression method is only called
   on correctly named sections (and to change the name of the section
   when using elf_compress_gnu).

   All previous returned Shdrs and Elf_Data buffers are invalidated by
   this call and should no longer be accessed.

   Note that although this changes the header and data returned it
   doesn't mark the section as dirty.  To keep the changes when
   calling elf_update the section has to be flagged ELF_F_DIRTY.  */
extern int elf_compress (Elf_Scn *scn, int type, unsigned int flags);
extern int elf_compress_gnu (Elf_Scn *scn, int compress, unsigned int flags);

/* Set or clear flags for ELF file.  */
extern unsigned int elf_flagelf (Elf *__elf, Elf_Cmd __cmd,
				 unsigned int __flags);
/* Similarly for the ELF header.  */
extern unsigned int elf_flagehdr (Elf *__elf, Elf_Cmd __cmd,
				  unsigned int __flags);
/* Similarly for the ELF program header.  */
extern unsigned int elf_flagphdr (Elf *__elf, Elf_Cmd __cmd,
				  unsigned int __flags);
/* Similarly for the given ELF section.  */
extern unsigned int elf_flagscn (Elf_Scn *__scn, Elf_Cmd __cmd,
				 unsigned int __flags);
/* Similarly for the given ELF data.  */
extern unsigned int elf_flagdata (Elf_Data *__data, Elf_Cmd __cmd,
				  unsigned int __flags);
/* Similarly for the given ELF section header.  */
extern unsigned int elf_flagshdr (Elf_Scn *__scn, Elf_Cmd __cmd,
				  unsigned int __flags);


/* Get data from section while translating from file representation to
   memory representation.  The Elf_Data d_type is set based on the
   section type if known.  Otherwise d_type is set to ELF_T_BYTE.  If
   the section contains compressed data then d_type is always set to
   ELF_T_CHDR.  */
extern Elf_Data *elf_getdata (Elf_Scn *__scn, Elf_Data *__data);

/* Get uninterpreted section content.  */
extern Elf_Data *elf_rawdata (Elf_Scn *__scn, Elf_Data *__data);

/* Create new data descriptor for section SCN.  */
extern Elf_Data *elf_newdata (Elf_Scn *__scn);

/* Get data translated from a chunk of the file contents as section data
   would be for TYPE.  The resulting Elf_Data pointer is valid until
   elf_end (ELF) is called.  */
extern Elf_Data *elf_getdata_rawchunk (Elf *__elf,
				       int64_t __offset, size_t __size,
				       Elf_Type __type);


/* Return pointer to string at OFFSET in section INDEX.  */
extern char *elf_strptr (Elf *__elf, size_t __index, size_t __offset);


/* Return header of archive.  */
extern Elf_Arhdr *elf_getarhdr (Elf *__elf);

/* Return offset in archive for current file ELF.  */
extern int64_t elf_getaroff (Elf *__elf);

/* Select archive element at OFFSET.  */
extern size_t elf_rand (Elf *__elf, size_t __offset);

/* Get symbol table of archive.  */
extern Elf_Arsym *elf_getarsym (Elf *__elf, size_t *__narsyms);


/* Control ELF descriptor.  */
extern int elf_cntl (Elf *__elf, Elf_Cmd __cmd);

/* Retrieve uninterpreted file contents.  */
extern char *elf_rawfile (Elf *__elf, size_t *__nbytes);


/* Return size of array of COUNT elements of the type denoted by TYPE
   in the external representation.  The binary class is taken from ELF.
   The result is based on version VERSION of the ELF standard.  */
extern size_t elf32_fsize (Elf_Type __type, size_t __count,
			   unsigned int __version)
       __const_attribute__;
/* Similar but this time the binary calls is ELFCLASS64.  */
extern size_t elf64_fsize (Elf_Type __type, size_t __count,
			   unsigned int __version)
       __const_attribute__;


/* Convert data structure from the representation in the file represented
   by ELF to their memory representation.  */
extern Elf_Data *elf32_xlatetom (Elf_Data *__dest, const Elf_Data *__src,
				 unsigned int __encode);
/* Same for 64 bit class.  */
extern Elf_Data *elf64_xlatetom (Elf_Data *__dest, const Elf_Data *__src,
				 unsigned int __encode);

/* Convert data structure from to the representation in memory
   represented by ELF file representation.  */
extern Elf_Data *elf32_xlatetof (Elf_Data *__dest, const Elf_Data *__src,
				 unsigned int __encode);
/* Same for 64 bit class.  */
extern Elf_Data *elf64_xlatetof (Elf_Data *__dest, const Elf_Data *__src,
				 unsigned int __encode);


/* Return error code of last failing function call.  This value is kept
   separately for each thread.  */
extern int elf_errno (void);

/* Return error string for ERROR.  If ERROR is zero, return error string
   for most recent error or NULL is none occurred.  If ERROR is -1 the
   behaviour is similar to the last case except that not NULL but a legal
   string is returned.  */
extern const char *elf_errmsg (int __error);


/* Coordinate ELF library and application versions.  */
extern unsigned int elf_version (unsigned int __version);

/* Set fill bytes used to fill holes in data structures.  */
extern void elf_fill (int __fill);

/* Compute hash value.  */
extern unsigned long int elf_hash (const char *__string)
       __pure_attribute__;

/* Compute hash value using the GNU-specific hash function.  */
extern unsigned long int elf_gnu_hash (const char *__string)
       __pure_attribute__;


/* Compute simple checksum from permanent parts of the ELF file.  */
extern long int elf32_checksum (Elf *__elf);
/* Similar but this time the binary calls is ELFCLASS64.  */
extern long int elf64_checksum (Elf *__elf);

#ifdef __cplusplus
}
#endif

#endif  /* libelf.h */