elf_getident(3elf)

1elf_getident(3ELF)           ELF Library Functions          elf_getident(3ELF)
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NAME

6       elf_getident,    elf_getphdrnum,   elf_getshdrnum,   elf_getshdrstrndx,
7       elf_getphnum, elf_getshnum, elf_getshstrndx - retrieve ELF header data
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SYNOPSIS

10       cc [ flag ... ] file ... -lelf [ library ... ]
11       #include <libelf.h>
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13       char *elf_getident(Elf *elf, size_t *dst);
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16       int elf_getphdrnum(Elf *elf, size_t *dst);
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19       int elf_getshdrnum(Elf *elf, size_t *dst);
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22       int elf_getshdrstrndx(Elf *elf, size_t *dst);
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25   Obsolete Interfaces
26       int elf_getphnum(Elf *elf, size_t *dst);
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29       int elf_getshnum(Elf *elf, size_t *dst);
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32       int elf_getshstrndx(Elf *elf, size_t *dst);
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DESCRIPTION

36       As elf(3ELF) explains, ELF provides a framework for various classes  of
37       files,  where  basic  objects  might have 32 or 64 bits. To accommodate
38       these  differences,  without  forcing  the  larger  sizes  on   smaller
39       machines, the initial bytes in an ELF file hold identification informa‐
40       tion common to all file classes. The e_ident of every  ELF  header  has
41       EI_NIDENT bytes with interpretations described in the following table.
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46       e_ident Index        Value                 Purpose
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48       EI_MAG0              ELFMAG0               File identification
49       EI_MAG1              ELFMAG1
50       EI_MAG2              ELFMAG2
51       EI_MAG3              ELFMAG3
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53       EI_CLASS             ELFCLASSNONE          File class
54                            ELFCLASS32
55                            ELFCLASS64
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57       EI_DATA              ELFDATANONE           Data encoding
58                            ELFDATA2LSB
59                            ELFDATA2MSB
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61       EI_VERSION           EV_CURRENT            File version
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63       7-15                 0                     Unused, set to zero
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67       Other  kinds of files might have identification data, though they would
68       not conform to e_ident. See elf_kind(3ELF)  for  information  on  other
69       kinds of files.
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72       The  elf_getident()  function returns a pointer to the initial bytes of
73       the file. If the library recognizes the file,  a  conversion  from  the
74       file  image to the memory image can occur. The identification bytes are
75       guaranteed to be unmodified, though the size  of  the  unmodified  area
76       depends  on the file type. If the dst argument is non-null, the library
77       stores the number of identification bytes in the location to which  dst
78       points.  If  no  data are present, elf is NULL, or an error occurs, the
79       return value is a null pointer, with 0 stored through dst,  if  dst  is
80       non-null.
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83       The  elf_getphdrnum()  function  obtains  the number of program headers
84       recorded in the ELF file. The number of sections in a file is typically
85       recorded  in  the e_phnum field of the ELF header. A file that requires
86       the ELF extended program  header  records  the  value  PN_XNUM  in  the
87       e_phnum  field  and records the number of sections in the sh_info field
88       of section header 0. See USAGE. The dst argument points to the location
89       where  the  number  of  sections  is stored. If elf is NULL or an error
90       occurs, elf_getphdrnum() returns −1.
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93       The elf_getshdrnum() function obtains the number of  sections  recorded
94       in the ELF file. The number of sections in a file is typically recorded
95       in the e_shnum field of the  ELF  header.  A  file  that  requires  ELF
96       extended  section  records the value 0 in the e_shnum field and records
97       the number of sections in the sh_size field of section  header  0.  See
98       USAGE. The dst argument points to the location where the number of sec‐
99       tions is stored. If a call to elf_newscn(3ELF) that uses the  same  elf
100       descriptor  is performed, the value obtained by elf_getshnum() is valid
101       only after a successful call to elf_update(3ELF). If elf is NULL or  an
102       error occurs, elf_getshdrnum() returns −1.
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105       The  elf_getshdrstrndx()  function  obtains  the  section  index of the
106       string table associated with the section headers in the ELF  file.  The
107       section  header  string  table  index  is  typically  recorded  in  the
108       e_shstrndx field of the ELF header. A file that requires  ELF  extended
109       section  records  the  value  SHN_XINDEX  in  the  e_shstrndx field and
110       records the string table index in the sh_link field of  section  header
111       0. See USAGE. The dst argument points to the location where the section
112       header string table index is stored. If elf is NULL or an error occurs,
113       elf_getshdrstrndx() returns −1.
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116       The  elf_getphnum(),  elf_getshnum(),  and  elf_getshstrndx() functions
117       behave in a manner similar to elf_getphdrnum(),  elf_getshdrnum(),  and
118       elf_getshdrstrndx(),  respectively, except that they return 0 if elf is
119       NULL or an error occurs. Because these return values differ from  those
120       used  by  some other systems, they are therefore non-portable and their
121       use  is  discouraged.  The  elf_getphdrnum(),   elf_getshdrnum(),   and
122       elf_getshdrstrndx() functions should be used instead.
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USAGE

125       ELF  extended  sections  allow  an ELF file to contain more than 0xff00
126       (SHN_LORESERVE) section. ELF extended program headers allow an ELF file
127       to contain 0xffff (PN_XNUM) or more program headers. See the Linker and
128       Libraries Guide for more information.
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RETURN VALUES

131       Upon successful completion, the elf_getident() function returns 1. Oth‐
132       erwise, it return 0.
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135       Upon successful completion, the elf_getphdrnum(), elf_getshdrnum(), and
136       elf_getshdrstrndx()  functions return 0. Otherwise, they return -1.
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139       Upon successful completion,  the  elf_getphnum(),  elf_getshnum(),  and
140       elf_getshstrndx()  functions return 1. Otherwise, they return 0.
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ATTRIBUTES

143       See attributes(5) for descriptions of the following attributes:
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148       ┌─────────────────────────────┬─────────────────────────────┐
149       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
150       ├─────────────────────────────┼─────────────────────────────┤
151       │Interface Stability          │See below.                   │
152       ├─────────────────────────────┼─────────────────────────────┤
153       │MT-Level                     │MT-Safe                      │
154       └─────────────────────────────┴─────────────────────────────┘
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157       The  elf_getident(),  elf_getphdrnum(), elf_getshdrnum(), and  elf_get‐
158       shdrstrndx() functions  are  Committed.  The  elf_getphnum(),  elf_get‐
159       shnum(), and  elf_getshstrndx() functions are Committed (Obsolete).
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NAME

SYNOPSIS

DESCRIPTION

USAGE

RETURN VALUES

ATTRIBUTES

SEE ALSO