Imported Upstream version 8.17upstream/8.17

1 files changed, 227 insertions, 0 deletions

diff --git a/lib/idcache.c b/lib/idcache.c
new file mode 100644
index 00000000..8c1315f2
--- /dev/null
+++ b/lib/idcache.c
@@ -0,0 +1,227 @@
+/* idcache.c -- map user and group IDs, cached for speed
+
+   Copyright (C) 1985, 1988-1990, 1997-1998, 2003, 2005-2007, 2009-2012 Free
+   Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#include "idcache.h"
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+#include <pwd.h>
+#include <grp.h>
+
+#include <unistd.h>
+
+#include "xalloc.h"
+
+#ifdef __DJGPP__
+static char digits[] = "0123456789";
+#endif
+
+struct userid
+{
+  union
+    {
+      uid_t u;
+      gid_t g;
+    } id;
+  struct userid *next;
+  char name[FLEXIBLE_ARRAY_MEMBER];
+};
+
+/* FIXME: provide a function to free any malloc'd storage and reset lists,
+   so that an application can use code like this just before exiting:
+   #ifdef lint
+     idcache_clear ();
+   #endif
+*/
+
+static struct userid *user_alist;
+
+/* Each entry on list is a user name for which the first lookup failed.  */
+static struct userid *nouser_alist;
+
+/* Use the same struct as for userids.  */
+static struct userid *group_alist;
+
+/* Each entry on list is a group name for which the first lookup failed.  */
+static struct userid *nogroup_alist;
+
+/* Translate UID to a login name, with cache, or NULL if unresolved.  */
+
+char *
+getuser (uid_t uid)
+{
+  struct userid *tail;
+  struct userid *match = NULL;
+
+  for (tail = user_alist; tail; tail = tail->next)
+    {
+      if (tail->id.u == uid)
+        {
+          match = tail;
+          break;
+        }
+    }
+
+  if (match == NULL)
+    {
+      struct passwd *pwent = getpwuid (uid);
+      char const *name = pwent ? pwent->pw_name : "";
+      match = xmalloc (offsetof (struct userid, name) + strlen (name) + 1);
+      match->id.u = uid;
+      strcpy (match->name, name);
+
+      /* Add to the head of the list, so most recently used is first.  */
+      match->next = user_alist;
+      user_alist = match;
+    }
+
+  return match->name[0] ? match->name : NULL;
+}
+
+/* Translate USER to a UID, with cache.
+   Return NULL if there is no such user.
+   (We also cache which user names have no passwd entry,
+   so we don't keep looking them up.)  */
+
+uid_t *
+getuidbyname (const char *user)
+{
+  struct userid *tail;
+  struct passwd *pwent;
+
+  for (tail = user_alist; tail; tail = tail->next)
+    /* Avoid a function call for the most common case.  */
+    if (*tail->name == *user && !strcmp (tail->name, user))
+      return &tail->id.u;
+
+  for (tail = nouser_alist; tail; tail = tail->next)
+    /* Avoid a function call for the most common case.  */
+    if (*tail->name == *user && !strcmp (tail->name, user))
+      return NULL;
+
+  pwent = getpwnam (user);
+#ifdef __DJGPP__
+  /* We need to pretend to be the user USER, to make
+     pwd functions know about an arbitrary user name.  */
+  if (!pwent && strspn (user, digits) < strlen (user))
+    {
+      setenv ("USER", user, 1);
+      pwent = getpwnam (user);  /* now it will succeed */
+    }
+#endif
+
+  tail = xmalloc (offsetof (struct userid, name) + strlen (user) + 1);
+  strcpy (tail->name, user);
+
+  /* Add to the head of the list, so most recently used is first.  */
+  if (pwent)
+    {
+      tail->id.u = pwent->pw_uid;
+      tail->next = user_alist;
+      user_alist = tail;
+      return &tail->id.u;
+    }
+
+  tail->next = nouser_alist;
+  nouser_alist = tail;
+  return NULL;
+}
+
+/* Translate GID to a group name, with cache, or NULL if unresolved.  */
+
+char *
+getgroup (gid_t gid)
+{
+  struct userid *tail;
+  struct userid *match = NULL;
+
+  for (tail = group_alist; tail; tail = tail->next)
+    {
+      if (tail->id.g == gid)
+        {
+          match = tail;
+          break;
+        }
+    }
+
+  if (match == NULL)
+    {
+      struct group *grent = getgrgid (gid);
+      char const *name = grent ? grent->gr_name : "";
+      match = xmalloc (offsetof (struct userid, name) + strlen (name) + 1);
+      match->id.g = gid;
+      strcpy (match->name, name);
+
+      /* Add to the head of the list, so most recently used is first.  */
+      match->next = group_alist;
+      group_alist = match;
+    }
+
+  return match->name[0] ? match->name : NULL;
+}
+
+/* Translate GROUP to a GID, with cache.
+   Return NULL if there is no such group.
+   (We also cache which group names have no group entry,
+   so we don't keep looking them up.)  */
+
+gid_t *
+getgidbyname (const char *group)
+{
+  struct userid *tail;
+  struct group *grent;
+
+  for (tail = group_alist; tail; tail = tail->next)
+    /* Avoid a function call for the most common case.  */
+    if (*tail->name == *group && !strcmp (tail->name, group))
+      return &tail->id.g;
+
+  for (tail = nogroup_alist; tail; tail = tail->next)
+    /* Avoid a function call for the most common case.  */
+    if (*tail->name == *group && !strcmp (tail->name, group))
+      return NULL;
+
+  grent = getgrnam (group);
+#ifdef __DJGPP__
+  /* We need to pretend to belong to group GROUP, to make
+     grp functions know about an arbitrary group name.  */
+  if (!grent && strspn (group, digits) < strlen (group))
+    {
+      setenv ("GROUP", group, 1);
+      grent = getgrnam (group); /* now it will succeed */
+    }
+#endif
+
+  tail = xmalloc (offsetof (struct userid, name) + strlen (group) + 1);
+  strcpy (tail->name, group);
+
+  /* Add to the head of the list, so most recently used is first.  */
+  if (grent)
+    {
+      tail->id.g = grent->gr_gid;
+      tail->next = group_alist;
+      group_alist = tail;
+      return &tail->id.g;
+    }
+
+  tail->next = nogroup_alist;
+  nogroup_alist = tail;
+  return NULL;
+}