include/elf/internal.h

/* ELF support for BFD.
   Copyright (C) 1991-2024 Free Software Foundation, Inc.

   Written by Fred Fish @ Cygnus Support, from information published
   in "UNIX System V Release 4, Programmers Guide: ANSI C and
   Programming Support Tools".

   This file is part of BFD, the Binary File Descriptor library.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program 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 a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
   MA 02110-1301, USA.  */

/* This file is part of ELF support for BFD, and contains the portions
   that describe how ELF is represented internally in the BFD library.
   I.E. it describes the in-memory representation of ELF.  It requires
   the elf-common.h file which contains the portions that are common to
   both the internal and external representations.  */

/* NOTE that these structures are not kept in the same order as they appear
   in the object file.  In some cases they've been reordered for more optimal
   packing under various circumstances.  */

#ifndef _ELF_INTERNAL_H
#define _ELF_INTERNAL_H

/* Special section indices, which may show up in st_shndx fields, among
   other places.  */

#undef SHN_UNDEF
#undef SHN_LORESERVE
#undef SHN_LOPROC
#undef SHN_HIPROC
#undef SHN_LOOS
#undef SHN_HIOS
#undef SHN_ABS
#undef SHN_COMMON
#undef SHN_XINDEX
#undef SHN_HIRESERVE
#define SHN_UNDEF	0		/* Undefined section reference */
#define SHN_LORESERVE	(-0x100u)	/* Begin range of reserved indices */
#define SHN_LOPROC	(-0x100u)	/* Begin range of appl-specific */
#define SHN_HIPROC	(-0xE1u)	/* End range of appl-specific */
#define SHN_LOOS	(-0xE0u)	/* OS specific semantics, lo */
#define SHN_HIOS	(-0xC1u)	/* OS specific semantics, hi */
#define SHN_ABS		(-0xFu)		/* Associated symbol is absolute */
#define SHN_COMMON	(-0xEu)		/* Associated symbol is in common */
#define SHN_XINDEX	(-0x1u)		/* Section index is held elsewhere */
#define SHN_HIRESERVE	(-0x1u)		/* End range of reserved indices */
#define SHN_BAD		(-0x101u)	/* Used internally by bfd */

/* ELF Header */

#define EI_NIDENT	16		/* Size of e_ident[] */

typedef struct elf_internal_ehdr {
  unsigned char		e_ident[EI_NIDENT]; /* ELF "magic number" */
  bfd_vma		e_entry;	/* Entry point virtual address */
  bfd_size_type		e_phoff;	/* Program header table file offset */
  bfd_size_type		e_shoff;	/* Section header table file offset */
  unsigned long		e_version;	/* Identifies object file version */
  unsigned long		e_flags;	/* Processor-specific flags */
  unsigned short	e_type;		/* Identifies object file type */
  unsigned short	e_machine;	/* Specifies required architecture */
  unsigned int		e_ehsize;	/* ELF header size in bytes */
  unsigned int		e_phentsize;	/* Program header table entry size */
  unsigned int		e_phnum;	/* Program header table entry count */
  unsigned int		e_shentsize;	/* Section header table entry size */
  unsigned int		e_shnum;	/* Section header table entry count */
  unsigned int		e_shstrndx;	/* Section header string table index */
} Elf_Internal_Ehdr;

/* Program header */

struct elf_internal_phdr {
  unsigned long	p_type;		     /* Identifies program segment type.  */
  unsigned long	p_flags;	     /* Segment flags.  */
  bfd_vma	p_offset;	     /* Segment file offset in octets.  */
  bfd_vma	p_vaddr;	     /* Segment virtual address in octets.  */
  bfd_vma	p_paddr;	     /* Segment physical address in octets.  */
  bfd_vma	p_filesz;	     /* Segment size in file in octets.  */
  bfd_vma	p_memsz;	     /* Segment size in memory in octets.  */
  bfd_vma	p_align;	     /* Segment alignment in bytes, file
					& memory */
};

typedef struct elf_internal_phdr Elf_Internal_Phdr;

/* Section header */

typedef struct elf_internal_shdr {
  unsigned int	sh_name;		/* Section name, index in string tbl */
  unsigned int	sh_type;		/* Type of section */
  bfd_vma	sh_flags;		/* Miscellaneous section attributes */
  bfd_vma	sh_addr;		/* Section virtual addr at execution in
					   octets.  */
  file_ptr	sh_offset;		/* Section file offset in octets.  */
  bfd_size_type	sh_size;		/* Size of section in octets.  */
  unsigned int	sh_link;		/* Index of another section */
  unsigned int	sh_info;		/* Additional section information */
  bfd_vma	sh_addralign;		/* Section alignment */
  bfd_size_type	sh_entsize;		/* Entry size if section holds table */

  /* The internal rep also has some cached info associated with it. */
  asection *	bfd_section;		/* Associated BFD section.  */
  unsigned char *contents;		/* Section contents.  */
} Elf_Internal_Shdr;

/* Compression header */

typedef struct elf_internal_chdr {
  unsigned int	ch_type;		/* Type of compression */
  bfd_size_type	ch_size;		/* Size of uncompressed data in bytes */
  bfd_vma	ch_addralign;		/* Alignment of uncompressed data */
} Elf_Internal_Chdr;

/* Symbol table entry */

struct elf_internal_sym {
  bfd_vma	st_value;		/* Value of the symbol */
  bfd_vma	st_size;		/* Associated symbol size */
  unsigned long	st_name;		/* Symbol name, index in string tbl */
  unsigned char	st_info;		/* Type and binding attributes */
  unsigned char	st_other;		/* Visibilty, and target specific */
  unsigned char st_target_internal;	/* Internal-only information */
  unsigned int  st_shndx;		/* Associated section index */
};

typedef struct elf_internal_sym Elf_Internal_Sym;

/* Note segments */

typedef struct elf_internal_note {
  unsigned long	namesz;			/* Size of entry's owner string */
  unsigned long	descsz;			/* Size of the note descriptor */
  unsigned long	type;			/* Interpretation of the descriptor */
  char *	namedata;		/* Start of the name+desc data */
  char *	descdata;		/* Start of the desc data */
  bfd_vma	descpos;		/* File offset of the descdata */
} Elf_Internal_Note;

/* Relocation Entries */

typedef struct elf_internal_rela {
  bfd_vma	r_offset;	/* Location at which to apply the action */
  bfd_vma	r_info;		/* Index and Type of relocation */
  bfd_vma	r_addend;	/* Constant addend used to compute value */
} Elf_Internal_Rela;

/* dynamic section structure */

typedef struct elf_internal_dyn {
  /* This needs to support 64-bit values in elf64.  */
  bfd_vma d_tag;		/* entry tag value */
  union {
    /* This needs to support 64-bit values in elf64.  */
    bfd_vma	d_val;
    bfd_vma	d_ptr;
  } d_un;
} Elf_Internal_Dyn;

/* This structure appears in a SHT_GNU_verdef section.  */

typedef struct elf_internal_verdef {
  unsigned short vd_version;	/* Version number of structure.  */
  unsigned short vd_flags;	/* Flags (VER_FLG_*).  */
  unsigned short vd_ndx;	/* Version index.  */
  unsigned short vd_cnt;	/* Number of verdaux entries.  */
  unsigned long	 vd_hash;	/* Hash of name.  */
  unsigned long	 vd_aux;	/* Offset to verdaux entries.  */
  unsigned long	 vd_next;	/* Offset to next verdef.  */

  /* These fields are set up when BFD reads in the structure.  FIXME:
     It would be cleaner to store these in a different structure.  */
  bfd			      *vd_bfd;		/* BFD.  */
  const char		      *vd_nodename;	/* Version name.  */
  struct elf_internal_verdef  *vd_nextdef;	/* vd_next as pointer.  */
  struct elf_internal_verdaux *vd_auxptr;	/* vd_aux as pointer.  */
  unsigned int		       vd_exp_refno;	/* Used by the linker.  */
} Elf_Internal_Verdef;

/* This structure appears in a SHT_GNU_verdef section.  */

typedef struct elf_internal_verdaux {
  unsigned long vda_name;	/* String table offset of name.  */
  unsigned long vda_next;	/* Offset to next verdaux.  */

  /* These fields are set up when BFD reads in the structure.  FIXME:
     It would be cleaner to store these in a different structure.  */
  const char *vda_nodename;			/* vda_name as pointer.  */
  struct elf_internal_verdaux *vda_nextptr;	/* vda_next as pointer.  */
} Elf_Internal_Verdaux;

/* This structure appears in a SHT_GNU_verneed section.  */

typedef struct elf_internal_verneed {
  unsigned short vn_version;	/* Version number of structure.  */
  unsigned short vn_cnt;	/* Number of vernaux entries.  */
  unsigned long	 vn_file;	/* String table offset of library name.  */
  unsigned long	 vn_aux;	/* Offset to vernaux entries.  */
  unsigned long	 vn_next;	/* Offset to next verneed.  */

  /* These fields are set up when BFD reads in the structure.  FIXME:
     It would be cleaner to store these in a different structure.  */
  bfd			      *vn_bfd;		/* BFD.  */
  const char                  *vn_filename;	/* vn_file as pointer.  */
  struct elf_internal_vernaux *vn_auxptr;	/* vn_aux as pointer.  */
  struct elf_internal_verneed *vn_nextref;	/* vn_nextref as pointer.  */
} Elf_Internal_Verneed;

/* This structure appears in a SHT_GNU_verneed section.  */

typedef struct elf_internal_vernaux {
  unsigned long	 vna_hash;	/* Hash of dependency name.  */
  unsigned short vna_flags;	/* Flags (VER_FLG_*).  */
  unsigned short vna_other;	/* Unused.  */
  unsigned long	 vna_name;	/* String table offset to version name.  */
  unsigned long	 vna_next;	/* Offset to next vernaux.  */

  /* These fields are set up when BFD reads in the structure.  FIXME:
     It would be cleaner to store these in a different structure.  */
  const char                  *vna_nodename;	/* vna_name as pointer.  */
  struct elf_internal_vernaux *vna_nextptr;	/* vna_next as pointer.  */
} Elf_Internal_Vernaux;

/* This structure appears in a SHT_GNU_versym section.  This is not a
   standard ELF structure; ELF just uses Elf32_Half.  */

typedef struct elf_internal_versym {
  unsigned short vs_vers;
} Elf_Internal_Versym;

/* Structure for syminfo section.  */
typedef struct
{
  unsigned short int 	si_boundto;
  unsigned short int	si_flags;
} Elf_Internal_Syminfo;

/* This structure appears on the stack and in NT_AUXV core file notes.  */
typedef struct
{
  bfd_vma a_type;
  bfd_vma a_val;
} Elf_Internal_Auxv;


/* This structure is used to describe how sections should be assigned
   to program segments.  */

struct elf_segment_map
{
  /* Next program segment.  */
  struct elf_segment_map *next;
  /* Program segment type.  */
  unsigned long p_type;
  /* Program segment flags.  */
  unsigned long p_flags;
  /* Program segment physical address in octets.  */
  bfd_vma p_paddr;
  /* Program segment virtual address offset from section vma in bytes.  */
  bfd_vma p_vaddr_offset;
  /* Program segment alignment.  */
  bfd_vma p_align;
  /* Segment size in file and memory in octets.  */
  bfd_vma p_size;
  /* Whether the p_flags field is valid; if not, the flags are based
     on the section flags.  */
  unsigned int p_flags_valid : 1;
  /* Whether the p_paddr field is valid; if not, the physical address
     is based on the section lma values.  */
  unsigned int p_paddr_valid : 1;
  /* Whether the p_align field is valid; if not, PT_LOAD segment
     alignment is based on the default maximum page size.  */
  unsigned int p_align_valid : 1;
  /* Whether the p_size field is valid; if not, the size are based
     on the section sizes.  */
  unsigned int p_size_valid : 1;
  /* Whether this segment includes the file header.  */
  unsigned int includes_filehdr : 1;
  /* Whether this segment includes the program headers.  */
  unsigned int includes_phdrs : 1;
  /* Assume this PT_LOAD header has an lma of zero when sorting
     headers before assigning file offsets.  PT_LOAD headers with this
     flag set are placed after one with includes_filehdr set, and
     before PT_LOAD headers without this flag set.  */
  unsigned int no_sort_lma : 1;
  /* Index holding original order before sorting segments.  */
  unsigned int idx;
  /* Number of sections (may be 0).  */
  unsigned int count;
  /* Sections.  Actual number of elements is in count field.  */
  asection *sections[1];
};

/* .tbss is special.  It doesn't contribute memory space to normal
   segments and it doesn't take file space in normal segments.  */
#define ELF_TBSS_SPECIAL(sec_hdr, segment)			\
  (((sec_hdr)->sh_flags & SHF_TLS) != 0				\
   && (sec_hdr)->sh_type == SHT_NOBITS				\
   && (segment)->p_type != PT_TLS)

#define ELF_SECTION_SIZE(sec_hdr, segment)			\
  (ELF_TBSS_SPECIAL(sec_hdr, segment) ? 0 : (sec_hdr)->sh_size)

/* Decide if the section SEC_HDR is in SEGMENT.  If CHECK_VMA, then
   VMAs are checked for alloc sections.  If STRICT, then a zero size
   section won't match at the end of a segment, unless the segment
   is also zero size.  Regardless of STRICT and CHECK_VMA, zero size
   sections won't match at the start or end of PT_DYNAMIC nor PT_NOTE,
   unless PT_DYNAMIC and PT_NOTE are themselves zero sized.  */
#define ELF_SECTION_IN_SEGMENT_1(sec_hdr, segment, check_vma, strict)	\
  ((/* Only PT_LOAD, PT_GNU_RELRO and PT_TLS segments can contain	\
       SHF_TLS sections.  */						\
    ((((sec_hdr)->sh_flags & SHF_TLS) != 0)				\
     && ((segment)->p_type == PT_TLS					\
	 || (segment)->p_type == PT_GNU_RELRO				\
	 || (segment)->p_type == PT_LOAD))				\
    /* PT_TLS segment contains only SHF_TLS sections, PT_PHDR no	\
       sections at all.  */						\
    || (((sec_hdr)->sh_flags & SHF_TLS) == 0				\
	&& (segment)->p_type != PT_TLS					\
	&& (segment)->p_type != PT_PHDR))				\
   /* PT_LOAD and similar segments only have SHF_ALLOC sections.  */	\
   && !(((sec_hdr)->sh_flags & SHF_ALLOC) == 0				\
	&& ((segment)->p_type == PT_LOAD				\
	    || (segment)->p_type == PT_DYNAMIC				\
	    || (segment)->p_type == PT_GNU_EH_FRAME			\
	    || (segment)->p_type == PT_GNU_STACK			\
	    || (segment)->p_type == PT_GNU_RELRO			\
	    || (segment)->p_type == PT_GNU_SFRAME			\
	    || ((segment)->p_type >= PT_GNU_MBIND_LO			\
		&& (segment)->p_type <= PT_GNU_MBIND_HI)))		\
   /* Any section besides one of type SHT_NOBITS must have file		\
      offsets within the segment.  */					\
   && ((sec_hdr)->sh_type == SHT_NOBITS					\
       || ((bfd_vma) (sec_hdr)->sh_offset >= (segment)->p_offset	\
	   && (!(strict)						\
	       || ((sec_hdr)->sh_offset - (segment)->p_offset		\
		   <= (segment)->p_filesz - 1))				\
	   && (((sec_hdr)->sh_offset - (segment)->p_offset		\
		+ ELF_SECTION_SIZE(sec_hdr, segment))			\
	       <= (segment)->p_filesz)))				\
   /* SHF_ALLOC sections must have VMAs within the segment.  */		\
   && (!(check_vma)							\
       || ((sec_hdr)->sh_flags & SHF_ALLOC) == 0			\
       || ((sec_hdr)->sh_addr >= (segment)->p_vaddr			\
	   && (!(strict)						\
	       || ((sec_hdr)->sh_addr - (segment)->p_vaddr		\
		   <= (segment)->p_memsz - 1))				\
	   && (((sec_hdr)->sh_addr - (segment)->p_vaddr			\
		+ ELF_SECTION_SIZE(sec_hdr, segment))			\
	       <= (segment)->p_memsz)))					\
   /* No zero size sections at start or end of PT_DYNAMIC nor		\
      PT_NOTE.  */							\
   && (((segment)->p_type != PT_DYNAMIC					\
	&& (segment)->p_type != PT_NOTE)				\
       || (sec_hdr)->sh_size != 0					\
       || (segment)->p_memsz == 0					\
       || (((sec_hdr)->sh_type == SHT_NOBITS				\
	    || ((bfd_vma) (sec_hdr)->sh_offset > (segment)->p_offset	\
	        && ((sec_hdr)->sh_offset - (segment)->p_offset		\
		    < (segment)->p_filesz)))				\
	   && (((sec_hdr)->sh_flags & SHF_ALLOC) == 0			\
	       || ((sec_hdr)->sh_addr > (segment)->p_vaddr		\
		   && ((sec_hdr)->sh_addr - (segment)->p_vaddr		\
		       < (segment)->p_memsz))))))

#define ELF_SECTION_IN_SEGMENT(sec_hdr, segment)			\
  (ELF_SECTION_IN_SEGMENT_1 (sec_hdr, segment, 1, 0))

#define ELF_SECTION_IN_SEGMENT_STRICT(sec_hdr, segment)			\
  (ELF_SECTION_IN_SEGMENT_1 (sec_hdr, segment, 1, 1))

#endif /* _ELF_INTERNAL_H */