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#include <errno.h>
#include <stdlib.h>
#include <string.h>
struct env {
char *name;
char *value;
struct env *next;
};
struct env *env_head = NULL;
struct env *internal_getenv(const char *name) {
struct env *p = env_head;
for (; p; p = p->next) {
if (0 == strcmp(p->name, name)) {
return p;
}
}
return NULL;
}
int setenv(const char *name, const char *value, int overwrite) {
if (NULL == name) {
errno = -EINVAL;
return -1;
}
int name_length = strlen(name);
if (0 == name_length) {
errno = -EINVAL;
return -1;
}
int value_length = strlen(value);
struct env *p = internal_getenv(name);
if (p) {
if (!overwrite) {
return 0;
}
char *new_ptr = realloc(p->value, value_length + 1);
if (!new_ptr) {
errno = -ENOMEM;
return -1;
}
p->value = new_ptr;
strcpy(p->value, value);
return 0;
}
struct env *new_env = malloc(sizeof(struct env));
if (!new_env) {
return -ENOMEM;
}
new_env->name = malloc(name_length + 1);
if (!new_env->name) {
free(new_env);
return -ENOMEM;
}
new_env->value = malloc(value_length + 1);
if (!new_env->value) {
free(new_env->name);
free(new_env);
return -ENOMEM;
}
strcpy(new_env->name, name);
strcpy(new_env->value, value);
new_env->next = env_head;
env_head = new_env;
return 0;
}
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