scncopy.c

   1 /*
   2  * SPDX-License-Identifier: GPL-2.0-only
   3  *
   4  * Copyright 2009 Red Hat, Inc.
   5  *
   6  * Author: Peter Jones <pjones@redhat.com>
   7  */
   8 #include <gelf.h>
   9 #include <stdio.h>
  10 #include <strings.h>
  11 #include <string.h>
  12 #include <fcntl.h>
  13 #include <stdlib.h>
  14 #include <unistd.h>
  15
  16 #include "elfcreator.h"
  17 #include "dutil.h"
  18
  19 static int should_copy_scn(Elf *elf, GElf_Shdr *shdr, struct strlist *scns)
  20 {
  21         char *name;
  22         size_t shstrndx;
  23
  24         if (elf_getshdrstrndx(elf, &shstrndx) < 0)
  25                 return 0;
  26         name = elf_strptr(elf, shstrndx, shdr->sh_name);
  27         if (name == NULL)
  28                 return 0;
  29
  30         if (strlist__has_entry(scns, name))
  31                 return 1;
  32         return 0;
  33 }
  34
  35 int main(int argc, char *argv[])
  36 {
  37         int n;
  38         struct strlist *sections;
  39         char *infile = NULL, *outfile = NULL;
  40         int fd;
  41         Elf *elf;
  42         Elf_Scn *scn;
  43         int copy_all_sections = 0;
  44         ElfCreator *ctor;
  45
  46         sections = strlist__new(false);
  47         for (n = 1; n < argc; n++) {
  48                 if (!strcmp(argv[n], "-a")) {
  49                         copy_all_sections = 1;
  50                 } else if (!strcmp(argv[n], "-s")) {
  51                         if (n == argc-1) {
  52                                 fprintf(stderr, "Missing argument to -s\n");
  53                                 return -1;
  54                         }
  55                         n++;
  56                         strlist__add(sections, argv[n]);
  57                         continue;
  58                 } else if (!strcmp(argv[n], "-o")) {
  59                         if (n == argc-1) {
  60                                 fprintf(stderr, "Missing argument to -o\n");
  61                                 return -1;
  62                         }
  63                         n++;
  64                         outfile = argv[n];
  65                         continue;
  66                 } else if (!strcmp(argv[n], "-?") ||
  67                                 !strcmp(argv[n], "--help") ||
  68                                 !strcmp(argv[n], "--usage")) {
  69                         printf("usage: scncopy [-s section0 [[-s section1] ... -s sectionN] | -a ] -o outfile infile\n");
  70                         return 0;
  71                 } else if (n == argc-1) {
  72                         infile = argv[n];
  73                 } else {
  74                         fprintf(stderr, "usage: pjoc -s section 0 [[-s section1] ... -s sectionN] -o outfile infile\n");
  75                         return 1;
  76                 }
  77         }
  78         if (!infile || !outfile) {
  79                 fprintf(stderr, "usage: pjoc -s section 0 [[-s section1] ... -s sectionN] -o outfile infile\n");
  80                 return 1;
  81         }
  82
  83         if (!(fd = open(infile, O_RDONLY))) {
  84                 fprintf(stderr, "Could not open \"%s\" for reading: %m\n", infile);
  85                 return 1;
  86         }
  87
  88         elf_version(EV_CURRENT);
  89
  90         if ((elf = elf_begin(fd, ELF_C_READ_MMAP_PRIVATE, NULL)) == NULL) {
  91                 fprintf(stderr, "cannot get elf descriptor for \"%s\": %s\n",
  92                                 infile, elf_errmsg(-1));
  93                 close(fd);
  94                 return 1;
  95         }
  96
  97         if (elf_kind(elf) != ELF_K_ELF) {
  98                 fprintf(stderr, "\"%s\" is not an ELF file\n", infile);
  99 err:
 100                 elf_end(elf);
 101                 close(fd);
 102                 return 1;
 103         }
 104
 105         if ((ctor = elfcreator_begin(outfile, elf)) == NULL) {
 106                 fprintf(stderr, "could not initialize ELF creator\n");
 107                 goto err;
 108         }
 109
 110         scn = NULL;
 111         while ((scn = elf_nextscn(elf, scn)) != NULL) {
 112                 GElf_Shdr shdr_mem, *shdr;
 113
 114                 shdr = gelf_getshdr(scn, &shdr_mem);
 115                 if (shdr == NULL)
 116                         continue;
 117
 118                 if (!should_copy_scn(elf, shdr, sections) && !copy_all_sections)
 119                         continue;
 120
 121                 elfcreator_copy_scn(ctor, scn);
 122         }
 123         elfcreator_end(ctor);
 124         return 0;
 125 }