diff options
Diffstat (limited to 'libelf/libelf.h')
| -rw-r--r-- | libelf/libelf.h | 64 |
1 files changed, 62 insertions, 2 deletions
diff --git a/libelf/libelf.h b/libelf/libelf.h index 49234c8a..364e7767 100644 --- a/libelf/libelf.h +++ b/libelf/libelf.h @@ -117,6 +117,12 @@ 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 @@ -274,6 +280,57 @@ extern Elf64_Shdr *elf64_getshdr (Elf_Scn *__scn); 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, unsigned int __flags); @@ -294,8 +351,11 @@ 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. */ |