On Mon, 2025-02-10 at 13:51 +0000, Mykyta Yatsenko wrote:
[...]
> @@ -363,6 +378,24 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state)
> return -ENOMEM;
> env.filename_cnt++;
> break;
> + case 'G': {
> + static int presets_cap;
> + char *expr = strdup(arg);
> +
> + if (expr[0] == '@') {
> + if (parse_var_presets_from_file(expr + 1, &env.presets,
> + &presets_cap, &env.npresets)) {
Nit: I'd modify 'env' directly in parse_var_presets{,_from_file} and
add presets_cap field to 'env': to avoid static variable and to
avoid '(*presets)[*size].name = ...' below.
> + fprintf(stderr, "Could not parse global variables preset: %s\n",
> + arg);
> + argp_usage(state);
> + }
> + } else if (parse_var_presets(expr, &env.presets, &presets_cap, &env.npresets)) {
> + fprintf(stderr, "Could not parse global variables preset: %s\n", arg);
> + argp_usage(state);
> + }
> + free(expr);
> + break;
> + }
> default:
> return ARGP_ERR_UNKNOWN;
> }
> @@ -1292,6 +1325,273 @@ static int process_prog(const char *filename, struct bpf_object *obj, struct bpf
> return 0;
> };
>
> +static int parse_var_presets(char *expr, struct var_preset **presets, int *capacity, int *size)
> +{
> + char *eq_ptr = strchr(expr, '=');
> + char *name_ptr = expr;
> + char *name_end = eq_ptr - 1;
> + char *val_ptr = eq_ptr + 1;
> + long long value;
> +
> + if (!eq_ptr) {
> + fprintf(stderr, "No assignment in expression\n");
> + return -EINVAL;
> + }
> +
> + while (isspace(*name_ptr))
> + ++name_ptr;
> + while (isspace(*name_end))
> + --name_end;
I think this loop has to be capped by string start check,
otherwise for -G ' = 10' it might read some uninitialized memory.
> + while (isspace(*val_ptr))
> + ++val_ptr;
> +
> + if (name_ptr > name_end) {
> + fprintf(stderr, "Empty variable name in expression %s\n", expr);
> + return -EINVAL;
> + }
> +
> + if (*size >= *capacity) {
> + *capacity = max(*capacity * 2, 1);
> + *presets = realloc(*presets, *capacity * sizeof(**presets));
Nit: if realloc() fails it returns NULL,
so the pointer to older *presets would be lost and never freed
(but we exit the program in case of an error, so not really an issue).
Also, check for NULL and return -ENOMEM?
> + }
> +
> + if (isalpha(*val_ptr)) {
> + char *value_end = val_ptr + strlen(val_ptr) - 1;
> +
> + while (isspace(*value_end))
> + --value_end;
> + *(value_end + 1) = '\0';
> +
> + (*presets)[*size].svalue = strdup(val_ptr);
Silly question, why strdup here and for .name?
Keeping pointers to argv should be fine as far as I know.
> + (*presets)[*size].type = NAME;
> + } else if (*val_ptr == '-' || isdigit(*val_ptr)) {
> + errno = 0;
> + value = strtoll(val_ptr, NULL, 0);
> + if (errno == ERANGE) {
> + errno = 0;
> + value = strtoull(val_ptr, NULL, 0);
> + }
> + (*presets)[*size].ivalue = value;
> + (*presets)[*size].type = INTEGRAL;
> + if (errno) {
> + fprintf(stderr, "Could not parse integer value %s\n", val_ptr);
> + return -EINVAL;
> + }
> + } else {
> + fprintf(stderr, "Could not parse value %s\n", val_ptr);
> + return -EINVAL;
> + }
> + *(name_end + 1) = '\0';
> + (*presets)[*size].name = strdup(name_ptr);
> + (*size)++;
> + return 0;
> +}
> +
> +static int parse_var_presets_from_file(const char *filename, struct var_preset **presets,
> + int *capacity, int *size)
Thank you for adding this!
> +{
> + FILE *f;
> + char line[256];
> + int err = 0;
> +
> + f = fopen(filename, "rt");
> + if (!f) {
> + fprintf(stderr, "Could not open file %s\n", filename);
> + return -EINVAL;
> + }
> +
> + while (fgets(line, sizeof(line), f)) {
> + int err = parse_var_presets(line, presets, capacity, size);
> +
> + if (err)
> + goto cleanup;
> + }
> +
> +cleanup:
Nit: I'd check for ferror(f) and write something to stderr here.
> + fclose(f);
> + return err;
> +}
> +
> +static bool is_signed_type(const struct btf_type *t)
> +{
> + if (btf_is_int(t))
> + return btf_int_encoding(t) & BTF_INT_SIGNED;
> + if (btf_is_enum(t))
> + return btf_kflag(t);
> + return true;
> +}
[...]
> +static int set_global_vars(struct bpf_object *obj, struct var_preset *presets, int npresets)
> +{
> + struct btf_var_secinfo *sinfo;
> + const char *sec_name;
> + const struct btf_type *type;
> + struct bpf_map *map;
> + struct btf *btf;
> + bool *set_var;
> + int i, j, k, n, cnt, err = 0;
> +
> + if (npresets == 0)
> + return 0;
> +
> + btf = bpf_object__btf(obj);
> + if (!btf)
> + return -EINVAL;
> +
> + set_var = calloc(npresets, sizeof(bool));
> + for (i = 0; i < npresets; ++i)
> + set_var[i] = false;
As Andrii writes in a sibling thread, I'd keep this flag in the
'struct var_preset'.
> +
> + cnt = btf__type_cnt(btf);
> + for (i = 0; i != cnt; ++i) {
> + type = btf__type_by_id(btf, i);
> +
> + if (!btf_is_datasec(type))
> + continue;
> +
> + sinfo = btf_var_secinfos(type);
> + sec_name = btf__name_by_offset(btf, type->name_off);
> + map = bpf_object__find_map_by_name(obj, sec_name);
> + if (!map)
> + continue;
> +
> + n = btf_vlen(type);
> + for (j = 0; j < n; ++j, ++sinfo) {
> + const struct btf_type *var_type = btf__type_by_id(btf, sinfo->type);
> + const char *var_name = btf__name_by_offset(btf, var_type->name_off);
> +
> + if (!btf_is_var(var_type))
> + continue;
> +
> + for (k = 0; k < npresets; ++k) {
> + if (strcmp(var_name, presets[k].name) != 0)
> + continue;
> +
> + if (set_var[k]) {
> + fprintf(stderr, "Variable %s is set more than once",
> + var_name);
> + }
> +
> + err = set_global_var(obj, btf, var_type, map, sinfo, presets + k);
> + if (err)
> + goto out;
> +
> + set_var[k] = true;
> + break;
> + }
> + }
> + }
> + for (i = 0; i < npresets; ++i) {
> + if (!set_var[i]) {
> + fprintf(stderr, "Global variable preset %s has not been applied\n",
> + presets[i].name);
> + }
> + }
> +out:
> + free(set_var);
> + return err;
> +}
> +
[...]
