[PATCH] Lookup users and groups in root directory instead of on host

[Daan De Meyer]

If a root directory is configured by the user, lookup users and groups
in the /etc/passwd and /etc/group of that root directory instead of the
host's /etc/passwd and /etc/group.

This is especially important when building Debian chroots on distros
that are not Debian based and where the host's /etc/passwd and /etc/group
is using passwd and group entries that differ wildly from those shipped
by Debian or its derivatives, causing dpkg stat-overrides to fail because
a group or user cannot be found in the host's passwd or group entries.
---
 lib/dpkg/db-fsys-override.c | 64 +++++++++++++++++++++++++++++++------
 1 file changed, 54 insertions(+), 10 deletions(-)

diff --git a/lib/dpkg/db-fsys-override.c b/lib/dpkg/db-fsys-override.c
index e079c5ffb..29adaf134 100644
--- a/lib/dpkg/db-fsys-override.c
+++ b/lib/dpkg/db-fsys-override.c
@@ -58,12 +58,34 @@ statdb_parse_uid(const char *str)
                        ohshit(_("invalid statoverride uid %s"), str);
                uid = (uid_t)value;
        } else {
-               struct passwd *pw = getpwnam(str);
+               char *passwd;
+               FILE *file;
+
+               uid = (uid_t)-1;
+               passwd = dpkg_fsys_get_path("etc/passwd");
+
+               file = fopen(passwd, "r");
+               free(passwd);
+               if (!file) {
+                       if (errno != ENOENT)
+                               ohshite(_("failed to open etc/passwd file"));
+               } else {
+                       struct passwd *pw;
+
+                       errno = 0;
+                       while ((pw = fgetpwent(file))) {
+                               if (strcmp(pw->pw_name, str) == 0)
+                                       break;
+                       }
 
-               if (pw == NULL)
-                       uid = (uid_t)-1;
-               else
-                       uid = pw->pw_uid;
+                       fclose(file);
+
+                       if (errno > 0)
+                               ohshite(_("failed to read passwd entry"));
+
+                       if (pw)
+                               uid = pw->pw_uid;
+               }
        }
 
        return uid;
@@ -84,12 +106,34 @@ statdb_parse_gid(const char *str)
                        ohshit(_("invalid statoverride gid %s"), str);
                gid = (gid_t)value;
        } else {
-               struct group *gr = getgrnam(str);
+               char *group;
+               FILE *file;
+
+               gid = (gid_t)-1;
+               group = dpkg_fsys_get_path("etc/group");
+
+               file = fopen(group, "r");
+               free(group);
+               if (!file) {
+                       if (errno != ENOENT)
+                               ohshite(_("failed to open etc/group file"));
+               } else {
+                       struct group *gr;
+
+                       errno = 0;
+                       while ((gr = fgetgrent(file))) {
+                               if (strcmp(gr->gr_name, str) == 0)
+                                       break;
+                       }
 
-               if (gr == NULL)
-                       gid = (gid_t)-1;
-               else
-                       gid = gr->gr_gid;
+                       fclose(file);
+
+                       if (errno > 0)
+                               ohshite(_("failed to read group entry"));
+
+                       if (gr)
+                               gid = gr->gr_gid;
+               }
        }
 
        return gid;
-- 
2.39.2