-/* populate_stack fills the stack with an argv, envp, and auxv.
- * We assume the stack pointer is backed by real memory.
- * It will go hard with you if it does not. For your own health,
- * stack should be 16-byte aligned. */
-void *populate_stack(uintptr_t *stack, int argc, char *argv[],
- int envc, char *envp[],
- int auxc, struct elf_aux auxv[])
-{
- /* Function to get the lengths of the argument and environment strings. */
- int get_lens(int argc, char *argv[], int arg_lens[])
- {
- int total = 0;
-
- if (!argc)
- return 0;
- for (int i = 0; i < argc; i++) {
- arg_lens[i] = strlen(argv[i]) + 1;
- total += arg_lens[i];
- }
- return total;
- }
-
- /* Function to help map the argument and environment strings, to their
- * final location. */
- int remap(int argc, char *argv[], char *new_argv[],
- char new_argbuf[], int arg_lens[])
- {
- int offset = 0;
-
- if (!argc)
- return 0;
- for (int i = 0; i < argc; i++) {
- memcpy(new_argbuf + offset, argv[i], arg_lens[i]);
- if (dune_debug) {
- fprintf(stderr, "data: memcpy(%p, %p, %ld)\n",
- new_argbuf + offset, argv[i], arg_lens[i]);
- fprintf(stderr, "arg: set arg %d, @%p, to %p\n", i,
- &new_argv[i], new_argbuf + offset);
- }
- new_argv[i] = new_argbuf + offset;
- offset += arg_lens[i];
- }
- new_argv[argc] = NULL;
- return offset;
- }
-
- /* Start tracking the size of the buffer necessary to hold all of our data
- * on the stack. Preallocate space for argc, argv, envp, and auxv in this
- * buffer. */
- int bufsize = 0;
-
- bufsize += 1 * sizeof(size_t);
- bufsize += (auxc + 1) * sizeof(struct elf_aux);
- bufsize += (envc + 1) * sizeof(char**);
- bufsize += (argc + 1) * sizeof(char**);
- if (dune_debug)
- fprintf(stderr, "Bufsize for pointers and argc is %d\n", bufsize);
-
- /* Add in the size of the env and arg strings. */
- int arg_lens[argc];
- int env_lens[envc];
-
- bufsize += get_lens(argc, argv, arg_lens);
- bufsize += get_lens(envc, envp, env_lens);
- if (dune_debug)
- fprintf(stderr, "Bufsize for pointers, argc, and strings is %d\n",
- bufsize);
-
- /* Adjust bufsize so that our buffer will ultimately be 16 byte aligned. */
- bufsize = (bufsize + 15) & ~0xf;
- if (dune_debug)
- fprintf(stderr,
- "Bufsize for pointers, argc, and strings is rounded is %d\n",
- bufsize);
-
- /* Set up pointers to all of the appropriate data regions we map to. */
- size_t *new_argc = (size_t*)((uint8_t*)stack - bufsize);
- char **new_argv = (char**)(new_argc + 1);
- char **new_envp = new_argv + argc + 1;
- struct elf_aux *new_auxv = (struct elf_aux*)(new_envp + envc + 1);
- char *new_argbuf = (char*)(new_auxv + auxc + 1);
-
- if (dune_debug) {
- fprintf(stderr, "There are %d args, %d env, and %d aux\n", new_argc,
- envc, auxc);
- fprintf(stderr, "Locations: argc: %p, argv: %p, envp: %p, auxv: %p\n",
- new_argc, new_argv, new_envp, new_auxv);
- fprintf(stderr, "Locations: argbuf: %p, ", new_argbuf);
- fprintf(stderr, "Sizeof argc is %d\n", sizeof(size_t));
- }
- /* Map argc into its final location. */
- *new_argc = argc;
-
- /* Map all data for argv and envp into its final location. */
- int offset = 0;
-
- offset = remap(argc, argv, new_argv, new_argbuf, arg_lens);
- if (offset == -1)
- return 0;
- if (dune_debug) {
- fprintf(stderr, "Locations: argbuf: %p, envbuf: %p, ", new_argbuf,
- new_argbuf + offset);
-
- }
- offset = remap(envc, envp, new_envp, new_argbuf + offset, env_lens);
- if (offset == -1)
- return 0;
-
- /* Map auxv into its final location. */
- struct elf_aux null_aux = {0, 0};
-
- memcpy(new_auxv, auxv, auxc * sizeof(struct elf_aux));
- memcpy(new_auxv + auxc, &null_aux, sizeof(struct elf_aux));
- if (dune_debug) {
- fprintf(stderr, "auxbuf: %p\n", new_auxv);
- hexdump(stdout, new_auxv, auxc * sizeof(struct elf_aux));
- }
- return (uint8_t*)stack - bufsize;
-}
-
projects / akaros.git / blobdiff