pyrox.dev
1#define _GNU_SOURCE /* See feature_test_macros(7) */
2#include <unistd.h>
3#include <stdlib.h>
4#include <assert.h>
5#include <stdio.h>
6
7#define assert_success(e) do { if ((e) < 0) { perror(#e); abort(); } } while (0)
8
9void set_env_prefix(char *env, char *sep, char *prefix) {
10 char *existing = getenv(env);
11 if (existing) {
12 char *val;
13 assert_success(asprintf(&val, "%s%s%s", prefix, sep, existing));
14 assert_success(setenv(env, val, 1));
15 free(val);
16 } else {
17 assert_success(setenv(env, prefix, 1));
18 }
19}
20
21void set_env_suffix(char *env, char *sep, char *suffix) {
22 char *existing = getenv(env);
23 if (existing) {
24 char *val;
25 assert_success(asprintf(&val, "%s%s%s", existing, sep, suffix));
26 assert_success(setenv(env, val, 1));
27 free(val);
28 } else {
29 assert_success(setenv(env, suffix, 1));
30 }
31}
32
33int main(int argc, char **argv) {
34 assert_success(setenv("MESSAGE", "HELLO", 0));
35 set_env_prefix("PATH", ":", "/usr/bin/");
36 set_env_suffix("PATH", ":", "/usr/local/bin/");
37 putenv("MESSAGE2=WORLD");
38
39 char **argv_tmp = calloc(3 + argc + 0 + 1, sizeof(*argv_tmp));
40 assert(argv_tmp != NULL);
41 argv_tmp[0] = argv[0];
42 argv_tmp[1] = "-x";
43 argv_tmp[2] = "-y";
44 argv_tmp[3] = "-z";
45 for (int i = 1; i < argc; ++i) {
46 argv_tmp[3 + i] = argv[i];
47 }
48 argv_tmp[3 + argc + 0] = NULL;
49 argv = argv_tmp;
50
51 argv[0] = "my-wrapper";
52 return execv("/send/me/flags", argv);
53}