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	id.c - ubase - suckless linux base utils
	git clone git://git.suckless.org/ubase
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	---
	id.c (2942B)
	---
	1 /* See LICENSE file for copyright and license details. */
	2 #include <sys/types.h>
	3
	4 #include <ctype.h>
	5 #include <errno.h>
	6 #include <grp.h>
	7 #include <limits.h>
	8 #include <pwd.h>
	9 #include <stdio.h>
	10 #include <stdlib.h>
	11 #include <unistd.h>
	12
	13 #include "util.h"
	14
	15 static void groupid(struct passwd *pw);
	16 static void user(struct passwd *pw);
	17 static void userid(uid_t id);
	18 static void usernam(const char *nam);
	19
	20 static int gflag = 0;
	21 static int uflag = 0;
	22 static int Gflag = 0;
	23 static int nflag = 0;
	24
	25 static void
	26 groupid(struct passwd *pw)
	27 {
	28 gid_t gid, groups[NGROUPS_MAX];
	29 struct group *gr;
	30 int ngroups;
	31 int i;
	32
	33 ngroups = NGROUPS_MAX;
	34 getgrouplist(pw->pw_name, pw->pw_gid, groups, &ngroups);
	35 for (i = 0; i < ngroups; i++) {
	36 gid = groups[i];
	37 if (nflag) {
	38 if (!(gr = getgrgid(gid)))
	39 eprintf("getgrgid:");
	40 printf("%s", gr->gr_name);
	41 } else
	42 printf("%u", gid);
	43
	44 if (i < ngroups - 1)
	45 putchar(' ');
	46 }
	47 putchar('\n');
	48 }
	49
	50 static void
	51 user(struct passwd *pw)
	52 {
	53 struct group *gr;
	54 gid_t gid, groups[NGROUPS_MAX];
	55 int ngroups;
	56 int i;
	57
	58 if (uflag) {
	59 if (nflag)
	60 printf("%s\n", pw->pw_name);
	61 else
	62 printf("%u\n", pw->pw_uid);
	63 return;
	64 } else if (gflag) {
	65 if (nflag) {
	66 if (!(gr = getgrgid(pw->pw_gid)))
	67 eprintf("getgrgid:");
	68 printf("%s\n", gr->gr_name);
	69 } else
	70 printf("%u\n", pw->pw_gid);
	71 return;
	72 }
	73
	74 printf("uid=%u(%s)", pw->pw_uid, pw->pw_name);
	75 printf(" gid=%u", pw->pw_gid);
	76 if (!(gr = getgrgid(pw->pw_gid)))
	77 eprintf("getgrgid:");
	78 printf("(%s)", gr->gr_name);
	79
	80 ngroups = NGROUPS_MAX;
	81 getgrouplist(pw->pw_name, pw->pw_gid, groups, &ngroups);
	82 for (i = 0; i < ngroups; i++) {
	83 gid = groups[i];
	84 printf("%s%u", !i ? " groups=" : ",", gid);
	85 if (!(gr = getgrgid(gid)))
	86 eprintf("getgrgid:");
	87 printf("(%s)", gr->gr_name);
	88 }
	89 putchar('\n');
	90 }
	91
	92 static void
	93 usernam(const char *nam)
	94 {
	95 struct passwd *pw;
	96
	97 errno = 0;
	98 pw = getpwnam(nam);
	99 if (!pw) {
	100 if (errno)
	101 eprintf("getpwnam %s:", nam);
	102 else
	103 eprintf("getpwnam %s: no such user\n", nam);
	104 }
	105 if (Gflag)
	106 groupid(pw);
	107 else
	108 user(pw);
	109 }
	110
	111 static void
	112 userid(uid_t id)
	113 {
	114 struct passwd *pw;
	115
	116 errno = 0;
	117 pw = getpwuid(id);
	118 if (!pw) {
	119 if (errno)
	120 eprintf("getpwuid %d:", id);
	121 else
	122 eprintf("getpwuid %d: no such user\n", id);
	123 }
	124 if (Gflag)
	125 groupid(pw);
	126 else
	127 user(pw);
	128 }
	129
	130 static void
	131 usage(void)
	132 {
	133 eprintf("usage: %s [-n] [-g \| -u \| -G] [user \| uid]\n", argv0);
	134 }
	135
	136 int
	137 main(int argc, char *argv[])
	138 {
	139 ARGBEGIN {
	140 case 'g':
	141 gflag = 1;
	142 break;
	143 case 'u':
	144 uflag = 1;
	145 break;
	146 case 'G':
	147 Gflag = 1;
	148 break;
	149 case 'n':
	150 nflag = 1;
	151 break;
	152 default:
	153 usage();
	154 } ARGEND;
	155
	156 /* ensure that only one of -g, -u, or -G was specified */
	157 if (gflag + uflag + Gflag > 1)
	158 usage();
	159
	160 switch (argc) {
	161 case 0:
	162 userid(getuid());
	163 break;
	164 case 1:
	165 /* user names can't begin [0-9] */
	166 if (isdigit(argv[0][0]))
	167 userid(estrtol(argv[0], 0));
	168 else
	169 usernam(argv[0]);
	170 break;
	171 default:
	172 usage();
	173 }
	174
	175 return 0;
	176 }