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#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <unistd.h>
#include <stdlib.h>
#include <assert.h>
#include <stdio.h>
#define assert_success(e) do { if ((e) < 0) { perror(#e); abort(); } } while (0)
void set_env_prefix(char *env, char *sep, char *prefix) {
char *existing = getenv(env);
if (existing) {
char *val;
assert_success(asprintf(&val, "%s%s%s", prefix, sep, existing));
assert_success(setenv(env, val, 1));
free(val);
} else {
assert_success(setenv(env, prefix, 1));
}
}
void set_env_suffix(char *env, char *sep, char *suffix) {
char *existing = getenv(env);
if (existing) {
char *val;
assert_success(asprintf(&val, "%s%s%s", existing, sep, suffix));
assert_success(setenv(env, val, 1));
free(val);
} else {
assert_success(setenv(env, suffix, 1));
}
}
int main(int argc, char **argv) {
assert_success(setenv("MESSAGE", "HELLO", 0));
set_env_prefix("PATH", ":", "/usr/bin/");
set_env_suffix("PATH", ":", "/usr/local/bin/");
putenv("MESSAGE2=WORLD");
char **argv_tmp = calloc(4 + argc, sizeof(*argv_tmp));
assert(argv_tmp != NULL);
argv_tmp[0] = argv[0];
argv_tmp[1] = "-x";
argv_tmp[2] = "-y";
argv_tmp[3] = "-z";
for (int i = 1; i < argc; ++i) {
argv_tmp[3 + i] = argv[i];
}
argv_tmp[3 + argc] = NULL;
argv = argv_tmp;
argv[0] = "my-wrapper";
return execv("/send/me/flags", argv);
}
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