github.com/afumu/libc@v0.0.6/musl/src/env/setenv.c (about)

     1  #include <stdlib.h>
     2  #include <string.h>
     3  #include <errno.h>
     4  
     5  void __env_rm_add(char *old, char *new)
     6  {
     7  	static char **env_alloced;
     8  	static size_t env_alloced_n;
     9  	//TODO for (size_t i=0; i < env_alloced_n; i++)
    10  	size_t i=0;
    11  	for (; i < env_alloced_n; i++)
    12  		if (env_alloced[i] == old) {
    13  			env_alloced[i] = new;
    14  			free(old);
    15  			return;
    16  		} else if (!env_alloced[i] && new) {
    17  			env_alloced[i] = new;
    18  			new = 0;
    19  		}
    20  	if (!new) return;
    21  	char **t = realloc(env_alloced, sizeof *t * (env_alloced_n+1));
    22  	if (!t) return;
    23  	(env_alloced = t)[env_alloced_n++] = new;
    24  }
    25  
    26  int setenv(const char *var, const char *value, int overwrite)
    27  {
    28  	char *s;
    29  	size_t l1, l2;
    30  
    31  	if (!var || !(l1 = __strchrnul(var, '=') - var) || var[l1]) {
    32  		errno = EINVAL;
    33  		return -1;
    34  	}
    35  	if (!overwrite && getenv(var)) return 0;
    36  
    37  	l2 = strlen(value);
    38  	s = malloc(l1+l2+2);
    39  	if (!s) return -1;
    40  	memcpy(s, var, l1);
    41  	s[l1] = '=';
    42  	memcpy(s+l1+1, value, l2+1);
    43  	return __putenv(s, l1, s);
    44  }