add groups and id commands

readme.md

@@ -4,7 +4,7 @@
 A terrible busybox/gnu coreutils clone.
 
 Currently the only supported commands are: 
-`dd`, `cat`, `yes`, `echo`, `printf`
+`dd`, `cat`, `yes`, `echo`, `printf`, `id`, `groups`
  
 ## How to
 

src/command.h

@@ -7,9 +7,12 @@
 #define ARGUMENTS int argc, char** argv
 #define NEXT_ARGS argc - 1, &argv[1]
 #define COMMAND(name) int name (ARGUMENTS) 
+#define COMMAND_EMPTY(name) int name (void)
 
 COMMAND(dd);
 COMMAND(cat);
 COMMAND(yes);
 COMMAND(echo);
 COMMAND(print);
+COMMAND_EMPTY(groups);
+COMMAND_EMPTY(user_id);

src/commands/groups.c

@@ -0,0 +1,32 @@
+#include "../command.h"
+
+#include <grp.h>
+#include <pwd.h>
+#include <unistd.h>
+
+COMMAND_EMPTY(groups) {
+
+    __uid_t uid = getuid();
+    
+    struct passwd* pw = getpwuid(uid);
+    if(pw == NULL){
+        perror("error: failed to fetch groups: ");
+    }
+    
+    int ngroups = 0;
+    getgrouplist(pw->pw_name, pw->pw_gid, NULL, &ngroups);
+    
+    __gid_t groups[ngroups];
+    getgrouplist(pw->pw_name, pw->pw_gid, groups, &ngroups);
+    
+    for (int i = 0; i < ngroups; i++){
+        struct group* gr = getgrgid(groups[i]);
+        if(gr == NULL){
+            perror("error: failed to fetch groups: ");
+        }
+        printf("%s ",gr->gr_name);
+    }
+    printf("\n");
+
+    return EXIT_SUCCESS;
+}

src/commands/id.c

@@ -0,0 +1,42 @@
+#include "../command.h"
+
+#include <grp.h>
+#include <pwd.h>
+#include <unistd.h>
+
+COMMAND_EMPTY(user_id) {
+
+    __uid_t uid = getuid();
+    __gid_t gid = getgid();
+    
+    struct passwd* pw = getpwuid(uid);
+    if(pw == NULL){
+        perror("error: failed to fetch groups: ");
+    }
+    
+    int ngroups = 0;
+    getgrouplist(pw->pw_name, pw->pw_gid, NULL, &ngroups);
+    
+    __gid_t groups[ngroups];
+    getgrouplist(pw->pw_name, pw->pw_gid, groups, &ngroups);
+   
+    struct group* ugr = getgrgid(gid);
+    printf("uid=%d(%s) gid=%d(%s) ",
+           uid, ugr->gr_name, gid, ugr->gr_name);
+    
+    if (ngroups > 0) {
+        printf("groups=");
+    }
+
+    for (int i = 0; i < ngroups; i++){
+        struct group* gr = getgrgid(groups[i]);
+        if(gr == NULL){
+            perror("error: failed to fetch groups: ");
+        }
+        printf("%d(%s)", gr->gr_gid, gr->gr_name);
+        if (i + 1 < ngroups) putchar(',');
+    }
+    printf("\b\n");
+
+    return EXIT_SUCCESS;
+}

src/main.c

@@ -20,7 +20,7 @@ int main (ARGUMENTS) {
         if (argc < 2) {
             printf("usage: lazysphere [function [arguments]...]\n\n");
             printf("currently defined functions:\n");
-            printf("\tdd, cat, yes, echo, printf\n");
+            printf("\tdd, cat, yes, echo, printf, id, groups\n");
             return EXIT_SUCCESS;
         }
         argc--;
@@ -44,6 +44,10 @@ int main (ARGUMENTS) {
         return echo(NEXT_ARGS);
     } else if (streql(cmd, "printf")) {
         return print(NEXT_ARGS);
+    } else if (streql(cmd, "groups")) {
+        return groups();
+    } else if (streql(cmd, "id")) {
+        return user_id();
     } else {
         error("error: invalid command %s", cmd);
     }