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// Can't trust libc not to leak enviornment variable memory, so...
#include "toys.h"
// In libc, populated by start code, used by getenv() and exec() and friends.
extern char **environ;
// Returns the number of bytes taken by the environment variables. For use
// when calculating the maximum bytes of environment+argument data that can
// be passed to exec for find(1) and xargs(1).
long environ_bytes(void)
{
long bytes = sizeof(char *);
char **ev;
for (ev = environ; *ev; ev++) bytes += sizeof(char *) + strlen(*ev) + 1;
return bytes;
}
// This will clear the inherited environment if called first thing.
// Use this instead of envc so we keep track of what needs to be freed.
void xclearenv(void)
{
if (toys.envc) {
int i;
for (i = 0; environ[i]; i++) if (i>=toys.envc) free(environ[i]);
} else environ = xmalloc(256*sizeof(char *));
toys.envc = 1;
*environ = 0;
}
// Frees entries we set earlier. Use with libc getenv but not setenv/putenv.
// if name has an equals and !val, act like putenv (name=val must be malloced!)
// if !val unset name. (Name with = and val is an error)
// returns pointer to new name=value environment string, NULL if none
char *xsetenv(char *name, char *val)
{
unsigned i, j = 0, len;
char *new;
// If we haven't snapshot initial environment state yet, do so now.
if (!toys.envc) {
// envc is size +1 so even if env empty it's nonzero after initialization
while (environ[toys.envc++]);
memcpy(new = xmalloc(((toys.envc|31)+1)*sizeof(char *)), environ,
toys.envc*sizeof(char *));
environ = (void *)new;
}
if (!(new = strchr(name, '='))) {
len = strlen(name);
if (val) new = xmprintf("%s=%s", name, val);
} else {
len = new-name;
if (val) error_exit("xsetenv %s to %s", name, val);
new = name;
}
for (i = 0; environ[i]; i++) {
// Drop old entry, freeing as appropriate. Assumes no duplicates.
if (!memcmp(name, environ[i], len) && environ[i][len]=='=') {
if (i<toys.envc-1) toys.envc--;
else free(environ[i]);
j++;
}
// move data down to fill hole, including null terminator
if (j && !(environ[i] = environ[i+1])) break;
}
if (!new) return 0;
// resize and null terminate if expanding
if (!j && !environ[i]) {
len = i+1;
if (!(len&31)) environ = xrealloc(environ, (len+32)*sizeof(char *));
environ[len] = 0;
}
return environ[i] = new;
}
void xunsetenv(char *name)
{
if (strchr(name, '=')) error_exit("xunsetenv %s name has =", name);
xsetenv(name, 0);
}
// remove entry and return pointer instead of freeing
char *xpop_env(char *name)
{
int len, i;
char *s = 0;
for (len = 0; name[len] && name[len]!='='; len++);
for (i = 0; environ[i]; i++) {
if (!s && !strncmp(name, environ[i], len) && environ[i][len] == '=') {
s = environ[i];
if (toys.envc-1>i) {
s = xstrdup(s);
toys.envc--;
}
}
if (s) environ[i] = environ[i+1];
}
return s;
}
// reset environment for a user, optionally clearing most of it
void reset_env(struct passwd *p, int clear)
{
int i;
if (clear) {
char *s, *stuff[] = {"TERM", "DISPLAY", "COLORTERM", "XAUTHORITY"};
for (i=0; i<ARRAY_LEN(stuff); i++)
stuff[i] = (s = getenv(stuff[i])) ? xmprintf("%s=%s", stuff[i], s) : 0;
xclearenv();
for (i=0; i < ARRAY_LEN(stuff); i++) if (stuff[i]) xsetenv(stuff[i], 0);
if (chdir(p->pw_dir)) {
perror_msg("chdir %s", p->pw_dir);
xchdir("/");
}
} else {
char **ev1, **ev2;
// remove LD_*, IFS, ENV, and BASH_ENV from environment
for (ev1 = ev2 = environ;;) {
while (*ev2 && (strstart(ev2, "LD_") || strstart(ev2, "IFS=") ||
strstart(ev2, "ENV=") || strstart(ev2, "BASH_ENV="))) ev2++;
if (!(*ev1++ = *ev2++)) break;
}
}
setenv("PATH", _PATH_DEFPATH, 1);
setenv("HOME", p->pw_dir, 1);
setenv("SHELL", p->pw_shell, 1);
setenv("USER", p->pw_name, 1);
setenv("LOGNAME", p->pw_name, 1);
}
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