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-rw-r--r--lib/env.c115
1 files changed, 115 insertions, 0 deletions
diff --git a/lib/env.c b/lib/env.c
new file mode 100644
index 00000000..94ea0a4e
--- /dev/null
+++ b/lib/env.c
@@ -0,0 +1,115 @@
+// 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()
+{
+ 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)
+{
+ toys.envc = 0;
+ *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)
+void xsetenv(char *name, char *val)
+{
+ unsigned i, len, envc;
+ char *new;
+
+ // If we haven't snapshot initial environment state yet, do so now.
+ if (!toys.envc) {
+ while (environ[toys.envc++]);
+ memcpy(new = xmalloc(((toys.envc|0xff)+1)*sizeof(char *)),
+ environ, toys.envc*sizeof(char *));
+ environ = (void *)new;
+ }
+
+ new = strchr(name, '=');
+ if (new) {
+ len = new-name;
+ if (val) error_exit("xsetenv %s to %s", name, val);
+ new = name;
+ } else {
+ len = strlen(name);
+ if (val) new = xmprintf("%s=%s", name, val);
+ }
+
+ envc = toys.envc-1;
+ 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>=envc) free(environ[i]);
+ else {
+ char **delete = environ+i;
+
+ // move old entries down, add at end of old data
+ toys.envc = envc--;
+ for (i=0; new ? i<envc : !!delete[i]; i++) delete[i] = delete[i+1];
+ i = envc;
+ }
+ break;
+ }
+ }
+
+ if (!new) return;
+
+ // resize and null terminate if expanding
+ if (!environ[i]) {
+ len = i+1;
+ if (!(len&255)) environ = xrealloc(environ, len*sizeof(char *));
+ environ[len] = 0;
+ }
+ environ[i] = new;
+}
+
+// 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);
+}