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// SPDX-License-Identifier: MIT
/* findlib.c
* Dynamically load a shared object file and print its full path.
* Part of library-utls - https://github.com/shoogle/library-utils
* Copyright (c) 2020 Peter Jonas
*/
#define _GNU_SOURCE
#include <link.h>
#include <dlfcn.h>
#include <libgen.h>
#include <string.h>
#include <stdio.h>
char *help =
"Usage: %s LIBRARY\n"
"Print the full path to LIBRARY if it is dynamically loadable by this program.\n"
"\n"
"Exit status codes:\n"
" 0 - Success!\n"
" 1 - Failed to load LIBRARY (or one of its dependencies).\n"
" 2 - Other error(s) occurred.\n"
"\n"
"LIBRARY will fail to load if any of the following are true:\n"
" - The file is corrupt.\n"
" - It is not found in any of the library search paths (see `man ld.so`).\n"
" - It was compiled for a different architecture to that of this program.\n"
" - It depends (via DT_NEEDED) on another library that fails to load.\n"
"\n"
"Hint: You can use the `file` command to show the processor architecture that\n"
"any ELF library or executable (including this program) was compiled for.\n";
int main(int argc, char *argv[])
{
if (argc != 2) {
fprintf(stderr, help, basename(argv[0]));
return 2;
}
if ((strcmp(argv[1], "-h") == 0) || (strcmp(argv[1], "--help") == 0)) {
printf(help, basename(argv[0]));
return 0;
}
// dlopen enables us to load shared objects during execution
void *lib = dlopen(argv[1], RTLD_LAZY);
if (lib == NULL) {
fprintf(stderr, "%s: %s\n", basename(argv[0]), dlerror());
return 1;
}
struct link_map * map;
// dlinfo can return information about objects loaded with dlopen
if (dlinfo(lib, RTLD_DI_LINKMAP, &map) == -1) {
fprintf(lib, "%s: %s\n", basename(argv[0]), dlerror());
return 2;
}
printf("%s\n", map->l_name);
return 0;
}
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