cosmopolitan/libc/elf/getelfsectionheaderaddress.c
Jōshin e16a7d8f3b
flip et / noet in modelines
`et` means `expandtab`.

```sh
rg 'vi: .* :vi' -l -0 | \
  xargs -0 sed -i '' 's/vi: \(.*\) et\(.*\)  :vi/vi: \1 xoet\2:vi/'
rg 'vi: .*  :vi' -l -0 | \
  xargs -0 sed -i '' 's/vi: \(.*\)noet\(.*\):vi/vi: \1et\2  :vi/'
rg 'vi: .*  :vi' -l -0 | \
  xargs -0 sed -i '' 's/vi: \(.*\)xoet\(.*\):vi/vi: \1noet\2:vi/'
```
2023-12-07 22:17:11 -05:00

48 lines
3 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/elf/def.h"
#include "libc/elf/elf.h"
#include "libc/elf/scalar.h"
#include "libc/elf/struct/shdr.h"
/**
* Returns section header object at `elf.section[i]`.
*
* @param elf points to the start of the executable image data
* @param mapsize is the number of bytes past `elf` we can access
* @param i is the index of the section header
* @return pointer to section header within image, or null if
* 1. `i` was a magic number, i.e. `i >= SHN_LORESERVE`, or
* 2. `e_shoff` was zero (image has no section headers), or
* 3. `e_shentsize` had fewer than the mandatory 60 bytes, or
* 4. section header wasn't contained by `[elf,elf+mapsize)`, or
* 5. an arithmetic overflow occurred
*/
Elf64_Shdr *GetElfSectionHeaderAddress(const Elf64_Ehdr *elf, //
size_t mapsize, //
Elf64_Half i) { //
Elf64_Off off;
if (i >= SHN_LORESERVE) return 0;
if (i >= elf->e_shnum) return 0;
if (elf->e_shoff <= 0) return 0;
if (elf->e_shoff >= mapsize) return 0;
if (elf->e_shentsize < sizeof(Elf64_Shdr)) return 0;
if ((off = elf->e_shoff + (unsigned)i * elf->e_shentsize) > mapsize) return 0;
return (Elf64_Shdr *)((char *)elf + off);
}