1 files changed, 105 insertions, 0 deletions
diff --git a/lib/rpmchroot.c b/lib/rpmchroot.c
new file mode 100644
index 0000000..81bb5e5
--- /dev/null
+++ b/lib/rpmchroot.c
@@ -0,0 +1,105 @@
+#include "system.h"
+#include <stdlib.h>
+#include <rpm/rpmstring.h>
+#include <rpm/rpmlog.h>
+#include "lib/rpmchroot.h"
+#include "debug.h"
+
+struct rootState_s {
+    char *rootDir;
+    int chrootDone;
+    int cwd;
+};
+
+/* Process global chroot state */
+static struct rootState_s rootState = {
+   .rootDir = NULL,
+   .chrootDone = 0,
+   .cwd = -1,
+}; 
+
+int rpmChrootSet(const char *rootDir)
+{
+    int rc = 0;
+
+    /* Setting same rootDir again is a no-op and not an error */
+    if (rootDir && rootState.rootDir && rstreq(rootDir, rootState.rootDir))
+	return 0;
+
+    /* Resetting only permitted in neutral state */
+    if (rootState.chrootDone != 0)
+	return -1;
+
+    rootState.rootDir = _free(rootState.rootDir);
+    if (rootState.cwd >= 0) {
+	close(rootState.cwd);
+	rootState.cwd = -1;
+    }
+
+    if (rootDir != NULL) {
+	rootState.rootDir = rstrdup(rootDir);
+	rootState.cwd = open(".", O_RDONLY);
+	if (rootState.cwd < 0) {
+	    rpmlog(RPMLOG_ERR, _("Unable to open current directory: %m\n"));
+	    rc = -1;
+	}
+    }
+
+    return rc;
+}
+
+int rpmChrootIn(void)
+{
+    int rc = 0;
+
+    if (rootState.rootDir == NULL || rstreq(rootState.rootDir, "/"))
+	return 0;
+
+    if (rootState.cwd < 0) {
+	rpmlog(RPMLOG_ERR, _("%s: chroot directory not set\n"), __func__);
+	return -1;
+    }
+
+    /* "refcounted" entry to chroot */
+    if (rootState.chrootDone > 0) {
+	rootState.chrootDone++;
+    } else if (rootState.chrootDone == 0) {
+	if (chdir("/") == 0 && chroot(rootState.rootDir) == 0) {
+	    rootState.chrootDone = 1;
+	} else {
+	    rpmlog(RPMLOG_ERR, _("Unable to change root directory: %m\n"));
+	    rc = -1;
+	}
+    }
+    return rc;
+}
+
+int rpmChrootOut(void)
+{
+    int rc = 0;
+    if (rootState.rootDir == NULL || rstreq(rootState.rootDir, "/"))
+	return 0;
+
+    if (rootState.cwd < 0) {
+	rpmlog(RPMLOG_ERR, _("%s: chroot directory not set\n"), __func__);
+	return -1;
+    }
+
+    /* "refcounted" return from chroot */
+    if (rootState.chrootDone > 1) {
+	rootState.chrootDone--;
+    } else if (rootState.chrootDone == 1) {
+	if (chroot(".") == 0 && fchdir(rootState.cwd) == 0) {
+	    rootState.chrootDone = 0;
+	} else {
+	    rpmlog(RPMLOG_ERR, _("Unable to restore root directory: %m\n"));
+	    rc = -1;
+	}
+    }
+    return rc;
+}
+
+int rpmChrootDone(void)
+{
+    return (rootState.chrootDone > 0);
+}