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#include <errno.h>
#include <fcntl.h>
#include <gelf.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <port.h>
static int readBPFFile(const char *fn)
{
int fd;
int rc = -1;
int idx = 0;
int text_shidx = 0;
size_t text_size = 0, offset = 0;
Elf *elf = NULL;
Elf_Data *data;
Elf_Scn *scn;
GElf_Ehdr ehdr;
GElf_Shdr shdr;
if ((fd = open64(fn, O_RDONLY)) == -1) {
fprintf(stderr, "Failed to open %s: %s\n",
fn, strerror(errno));
return -1;
}
if ((elf = elf_begin(fd, ELF_C_READ, NULL)) == NULL) {
fprintf(stderr, "Failed to open ELF in %s\n", fn);
goto err_elf;
}
if (elf_kind(elf) != ELF_K_ELF) {
fprintf(stderr, "Unsupported ELF file type for %s: %d\n",
fn, elf_kind(elf));
goto out;
}
if (gelf_getehdr(elf, &ehdr) == NULL) {
fprintf(stderr, "Failed to read EHDR from %s", fn);
goto err_elf;
}
if (ehdr.e_machine != EM_BPF) {
fprintf(stderr, "Unsupported ELF machine type %d for %s\n",
ehdr.e_machine, fn);
goto out;
}
scn = NULL;
while ((scn = elf_nextscn(elf, scn)) != NULL) {
char *name;
idx++;
if (gelf_getshdr(scn, &shdr) == NULL) {
fprintf(stderr, "Failed to get SHDR from %s", fn);
goto err_elf;
}
name = elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name);
if (name == NULL) {
fprintf(stderr, "Failed to get section name from %s\n",
fn);
goto out;
}
printf("Found section [%s], idx %d\n", name, idx);
if (shdr.sh_type == SHT_SYMTAB) {
size_t i;
if ((data = elf_getdata(scn, NULL)) == NULL) {
fprintf(stderr, "Failed to get .symtab data "
"from %s", fn);
goto err_elf;
}
for (i = 0; i < data->d_size / sizeof(GElf_Sym); i++) {
GElf_Sym sym;
char *sname;
if (!gelf_getsym(data, i, &sym))
continue;
if (GELF_ST_BIND(sym.st_info) != STB_GLOBAL)
continue;
if (sym.st_shndx != text_shidx)
continue;
sname = elf_strptr(elf, shdr.sh_link,
sym.st_name);
if (sname == NULL) {
fprintf(stderr, "Failed to get symbol "
"name from %s\n", fn);
goto out;
}
if (sym.st_value > offset) printf(" Updated previous symbol size = %lu (%lu dw)\n", sym.st_value - offset, (sym.st_value - offset) / 8);
offset = sym.st_value;
printf(" Found symbol [%s], size = %lu, val = %lu, bind %d, type %d, section %d\n", sname, sym.st_size != 0 ? sym.st_size : text_size - sym.st_value, sym.st_value, GELF_ST_BIND(sym.st_info), GELF_ST_TYPE(sym.st_info), sym.st_shndx);
}
} else if (shdr.sh_type == SHT_PROGBITS) {
if ((data = elf_getdata(scn, NULL)) == NULL) {
fprintf(stderr, "Failed to get data from %s",
fn);
goto err_elf;
}
if (!(shdr.sh_flags & SHF_EXECINSTR))
continue;
if (strcmp(name, ".text") == 0) {
text_shidx = idx;
text_size = shdr.sh_size;
}
}
}
rc = 0;
goto out;
err_elf:
fprintf(stderr, ": %s\n", elf_errmsg(elf_errno()));
out:
if (elf)
elf_end(elf);
close(fd);
return rc;
}
int main(int argc, char *argv[])
{
int i;
if (elf_version(EV_CURRENT) == EV_NONE) {
fprintf(stderr, "Invalid current ELF version.\n");
exit(1);
}
if (argc < 2) {
fprintf(stderr, "No object files specified.\n");
exit(1);
}
for (i = 1; i < argc; i++)
readBPFFile(argv[i]);
}
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