1 files changed, 99 insertions, 0 deletions
diff --git a/library/pwcache.c b/library/pwcache.c
new file mode 100644
index 0000000..f75e207
--- /dev/null
+++ b/library/pwcache.c
@@ -0,0 +1,99 @@
+/*
+ * pwcache.c - memory cache passwd file handling
+ *
+ * Copyright © 2011-2023 Jim Warner <james.warner@comcast.net>
+ * Copyright © 2015-2023 Craig Small <csmall@dropbear.xyz>
+ * Copyright © 2002      Albert Cahalan
+ *
+ * Older version:
+ * Copyright © 1992-1998 Michael K. Johnson <johnsonm@redhat.com>
+ * Note: most likely none of his code remains
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <stdlib.h>
+#include <pwd.h>
+#include <grp.h>
+
+#include "pwcache.h"
+#include "procps-private.h"
+
+// might as well fill cache lines... else we waste memory anyway
+
+#define HASHSIZE  64              /* power of 2 */
+#define HASH(x)   ((x) & (HASHSIZE - 1))
+
+static char ERRname[] = "?";
+
+static __thread struct pwbuf {
+    struct pwbuf *next;
+    uid_t uid;
+    char name[P_G_SZ];
+} *pwhash[HASHSIZE];
+
+char *pwcache_get_user(uid_t uid) {
+    struct pwbuf **p;
+    struct passwd *pw;
+
+    p = &pwhash[HASH(uid)];
+    while (*p) {
+        if ((*p)->uid == uid)
+            return((*p)->name);
+        p = &(*p)->next;
+    }
+    if (!(*p = (struct pwbuf *)malloc(sizeof(struct pwbuf))))
+        return ERRname;
+    (*p)->uid = uid;
+    pw = getpwuid(uid);
+    if(!pw || strlen(pw->pw_name) >= P_G_SZ)
+        sprintf((*p)->name, "%u", uid);
+    else
+        strcpy((*p)->name, pw->pw_name);
+
+    (*p)->next = NULL;
+    return((*p)->name);
+}
+
+static __thread struct grpbuf {
+    struct grpbuf *next;
+    gid_t gid;
+    char name[P_G_SZ];
+} *grphash[HASHSIZE];
+
+char *pwcache_get_group(gid_t gid) {
+    struct grpbuf **g;
+    struct group *gr;
+
+    g = &grphash[HASH(gid)];
+    while (*g) {
+        if ((*g)->gid == gid)
+            return((*g)->name);
+        g = &(*g)->next;
+    }
+    if (!(*g = (struct grpbuf *)malloc(sizeof(struct grpbuf))))
+        return ERRname;;
+    (*g)->gid = gid;
+    gr = getgrgid(gid);
+    if (!gr || strlen(gr->gr_name) >= P_G_SZ)
+        sprintf((*g)->name, "%u", gid);
+    else
+        strcpy((*g)->name, gr->gr_name);
+    (*g)->next = NULL;
+    return((*g)->name);
+}