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Diffstat (limited to 'names.c')
| -rw-r--r-- | names.c | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/names.c b/names.c new file mode 100644 index 000000000..61abc615d --- /dev/null +++ b/names.c @@ -0,0 +1,218 @@ +/* Look up user and/or group names. + Copyright (C) 1988, 1992 Free Software Foundation + + From GNU Tar. + + GNU Tar is free software; you can redistribute it and/or modify it + under the terms of the GNU Library General Public License as published + by the Free Software Foundation; either version 2, or (at your option) + any later version. + + GNU Tar 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 Library General Public License for more details. + + Namespace: finduname, finduid, findgname, findgid, + uid_to_uname, gid_to_gname. + */ + +/* + * Look up user and/or group names. + * + * This file should be modified for non-unix systems to do something + * reasonable. + */ + +#include <sys/types.h> +#include <string.h> +#include <unistd.h> +#define TAR_NAMES +#include "tar.h" +#include "names.h" + +#include <stdio.h> +#include <pwd.h> +#include <grp.h> + +#ifndef TUNMLEN +#define TUNMLEN 256 +#endif +#ifndef TGNMLEN +#define TGNMLEN 256 +#endif + +static int saveuid = -993; +static char saveuname[TUNMLEN]; +static int my_uid = -993; + +static int savegid = -993; +static char savegname[TGNMLEN]; +static int my_gid = -993; + +#define myuid ( my_uid < 0? (my_uid = getuid()): my_uid ) +#define mygid ( my_gid < 0? (my_gid = getgid()): my_gid ) + + +/* Make sure you link with the proper libraries if you are running the + Yellow Peril (thanks for the good laugh, Ian J.!), or, euh... NIS. + This code should also be modified for non-UNIX systems to do something + reasonable. */ + +static char cached_uname[NAMSIZ] = ""; +static char cached_gname[NAMSIZ] = ""; + +static uid_t cached_uid; /* valid only if cached_uname is not empty */ +static gid_t cached_gid; /* valid only if cached_gname is not empty */ + +#if 0 +/* These variables are valid only if nonempty. */ +static char cached_no_such_uname[NAMSIZ] = ""; +static char cached_no_such_gname[NAMSIZ] = ""; +#endif + +/* These variables are valid only if nonzero. It's not worth optimizing + the case for weird systems where 0 is not a valid uid or gid. */ +static uid_t cached_no_such_uid = 0; +static gid_t cached_no_such_gid = 0; + + +/* + * Look up a user or group name from a uid/gid, maintaining a cache. + * FIXME, for now it's a one-entry cache. + * FIXME2, the "-993" is to reduce the chance of a hit on the first lookup. + * + * This is ifdef'd because on Suns, it drags in about 38K of "yellow + * pages" code, roughly doubling the program size. Thanks guys. + */ +void finduname (char *uname, int uid) +{ + struct passwd *pw; +#ifndef HAVE_GETPWUID + extern struct passwd *getpwuid (); +#endif + + if (uid != saveuid) { + saveuid = uid; + saveuname[0] = '\0'; + pw = getpwuid (uid); + if (pw) + strncpy (saveuname, pw->pw_name, TUNMLEN); + } + strncpy (uname, saveuname, TUNMLEN); +} + +int finduid (char *uname) +{ + struct passwd *pw; + extern struct passwd *getpwnam (); + + if (uname[0] != saveuname[0]/* Quick test w/o proc call */ + ||0 != strncmp (uname, saveuname, TUNMLEN)) { + strncpy (saveuname, uname, TUNMLEN); + pw = getpwnam (uname); + if (pw) { + saveuid = pw->pw_uid; + } else { + saveuid = myuid; + } + } + return saveuid; +} + + +void findgname (char *gname, int gid) +{ + struct group *gr; +#ifndef HAVE_GETGRGID + extern struct group *getgrgid (); +#endif + + if (gid != savegid) { + savegid = gid; + savegname[0] = '\0'; + (void) setgrent (); + gr = getgrgid (gid); + if (gr) + strncpy (savegname, gr->gr_name, TGNMLEN); + } + (void) strncpy (gname, savegname, TGNMLEN); +} + + +int findgid (char *gname) +{ + struct group *gr; + extern struct group *getgrnam (); + + if (gname[0] != savegname[0]/* Quick test w/o proc call */ + ||0 != strncmp (gname, savegname, TUNMLEN)) { + strncpy (savegname, gname, TUNMLEN); + gr = getgrnam (gname); + if (gr) { + savegid = gr->gr_gid; + } else { + savegid = mygid; + } + } + return savegid; +} + + +void +uid_to_uname (uid_t uid, char uname[NAMSIZ]) +{ + struct passwd *passwd; + + if (uid != 0 && uid == cached_no_such_uid) + { + *uname = '\0'; + return; + } + + if (!cached_uname[0] || uid != cached_uid) + { + passwd = getpwuid (uid); + if (passwd) + { + cached_uid = uid; + strncpy (cached_uname, passwd->pw_name, NAMSIZ); + } + else + { + cached_no_such_uid = uid; + *uname = '\0'; + return; + } + } + strncpy (uname, cached_uname, NAMSIZ); +} + +void +gid_to_gname (gid_t gid, char gname[NAMSIZ]) +{ + struct group *group; + + if (gid != 0 && gid == cached_no_such_gid) + { + *gname = '\0'; + return; + } + + if (!cached_gname[0] || gid != cached_gid) + { + group = getgrgid (gid); + if (group) + { + cached_gid = gid; + strncpy (cached_gname, group->gr_name, NAMSIZ); + } + else + { + cached_no_such_gid = gid; + *gname = '\0'; + return; + } + } + strncpy (gname, cached_gname, NAMSIZ); +} |