diff options
Diffstat (limited to 'libelf/libelf.h')
| -rw-r--r-- | libelf/libelf.h | 100 |
1 files changed, 97 insertions, 3 deletions
diff --git a/libelf/libelf.h b/libelf/libelf.h index 54f7c29b..c0d6389f 100644 --- a/libelf/libelf.h +++ b/libelf/libelf.h @@ -1,5 +1,5 @@ /* Interface for libelf. - Copyright (C) 1998-2010 Red Hat, Inc. + 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 @@ -35,6 +35,34 @@ /* 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 /* Known translation types. */ typedef enum @@ -64,6 +92,7 @@ typedef enum 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, ... */ /* Keep this the last entry. */ ELF_T_NUM } Elf_Type; @@ -116,6 +145,12 @@ enum #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 @@ -267,6 +302,62 @@ 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. + 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 responsibilty 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, @@ -288,8 +379,11 @@ 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. */ +/* 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. */ |