init ci

.gitignore

@@ -0,0 +1,2 @@
+.vscode
+shperm

shperm.c

@@ -0,0 +1,90 @@
+#include <stdio.h>
+#include <linux/limits.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <libgen.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <pwd.h>
+#include <grp.h>
+
+#define PERMISSION_USER 2
+#define PERMISSION_GROUP 1
+#define PERMISSION_OTHERS 0
+
+void printPermission(char* path, int permissions, int uid, int gid) {
+    // print current path
+    printf("%s: ", path);
+
+    // print user
+    struct passwd* user = getpwuid(uid);
+    printf("%s ", user->pw_name);
+
+    // print group
+    struct group* group = getgrgid(gid);
+    printf("%s ", group->gr_name);
+
+    // print permissions
+    char permissionStr[3][4] = {"---\0", "---\0", "---\0"};
+    for (int i = 0; i < 9; i++) {
+        // clear out all permissions except the i'th bit
+        int tmpPermission = permissions & (1 << i);
+
+        // read
+        if (tmpPermission & S_IRUSR
+                || tmpPermission & S_IRGRP
+                || tmpPermission & S_IROTH) {
+            permissionStr[i / 3][(8 - i) % 3] = 'r';
+        }
+
+        // write
+        if (tmpPermission & S_IWUSR
+                || tmpPermission & S_IWGRP
+                || tmpPermission & S_IWOTH) {
+            permissionStr[i / 3][(8 - i) % 3] = 'w';
+        }
+
+        // execute
+        if (tmpPermission & S_IXUSR
+                || tmpPermission & S_IXGRP
+                || tmpPermission & S_IXOTH) {
+            permissionStr[i / 3][(8 - i) % 3] = 'x';
+        }   
+    }
+    printf("%s %s %s\n", permissionStr[PERMISSION_USER], permissionStr[PERMISSION_GROUP], permissionStr[PERMISSION_OTHERS]);
+}
+
+int main(int argc, char* argv[]) {
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <file or directory>\n", argv[0]);
+        exit(1);
+    }
+
+    char* path;
+    path = malloc(PATH_MAX);
+    
+    if (realpath(argv[1], path)) {
+        printf("Realpath: %s\n", path);
+
+        char* base;
+        do {
+            struct stat sb;
+
+            base = basename(path);
+            if (stat(path, &sb) == 0) {
+                printPermission(path, sb.st_mode, sb.st_uid, sb.st_gid);
+            } else {
+                fprintf(stderr, "Error (%d): %s\n", errno, strerror(errno));
+                exit(3);
+            }
+
+            path = dirname(path);
+        } while (strcmp(base, "/"));
+    } else {
+        fprintf(stderr, "Error (%d): %s\n", errno, strerror(errno));
+        exit(2);
+    }
+
+    free(path);
+}