Add man functionality for ls command.

files/usr/share/man/ls.man

@@ -0,0 +1,14 @@
+NAME
+    ls - list directory contents
+
+SYNOPSIS
+    ls [OPTIONS] [FILE/FOLDER]
+
+DESCRIPTION
+    List information about the given file, or the files contained in the given
+    folder. If not argument is provided it will list information about files
+    inside the current folder.
+    
+OPTIONS
+    -a  : list all entries.
+    -l  : show the entries as a detailed list.

programs/man.c

@@ -3,32 +3,67 @@
 /// @copyright (c) 2014-2022 This file is distributed under the MIT License.
 /// See LICENSE.md for details.
 
-#include <strerror.h>
-#include <sys/dirent.h>
-#include <sys/unistd.h>
 #include <fcntl.h>
 #include <stdio.h>
+#include <strerror.h>
+#include <string.h>
+#include <sys/dirent.h>
+#include <sys/unistd.h>
 
 int main(int argc, char *argv[])
 {
-    int fd = open("/bin", O_RDONLY | O_DIRECTORY, 0);
-    if (fd == -1) {
-        printf("%s: cannot access '/bin': %s\n\n", argv[0], strerror(errno));
-        return 1;
-    }
-    dirent_t dent;
-    int per_line = 0;
-    while (getdents(fd, &dent, sizeof(dirent_t)) == sizeof(dirent_t)) {
-        // Shows only regular files
-        if(dent.d_type == DT_REG){
-            printf("%10s ", dent.d_name);
-            if (++per_line == 6) {
-                per_line = 0;
-                putchar('\n');
+    if (argc == 1)
+    {
+        int fd = open("/bin", O_RDONLY | O_DIRECTORY, 0);
+        if (fd == -1)
+        {
+            printf("%s: cannot access '/bin': %s\n\n", argv[0], strerror(errno));
+            return 1;
+        }
+        dirent_t dent;
+        int per_line = 0;
+        while (getdents(fd, &dent, sizeof(dirent_t)) == sizeof(dirent_t))
+        {
+            // Shows only regular files
+            if (dent.d_type == DT_REG)
+            {
+                printf("%10s ", dent.d_name);
+                if (++per_line == 6)
+                {
+                    per_line = 0;
+                    putchar('\n');
+                }
             }
         }
+        putchar('\n');
+        close(fd);
+    }
+    else if (argc == 2)
+    {
+        char filepath[PATH_MAX];
+        strcpy(filepath, "/usr/share/man/");
+        strcat(filepath, argv[1]);
+        strcat(filepath, ".man");
+        int fd = open(filepath, O_RDONLY, 42);
+        if (fd < 0)
+        {
+            printf("%s: No manual entry for %s\n\n", argv[0], argv[1]);
+        }
+        else
+        {
+            // Prepare the buffer for reading the man file.
+            char buffer[BUFSIZ];
+            // Put on the standard output the characters.
+            while (read(fd, buffer, BUFSIZ) > 0)
+            {
+                puts(buffer);
+            }
+            // Close the file descriptor.
+            close(fd);
+            // Terminate with a pair of newlines.
+            putchar('\n');
+            putchar('\n');
+        }
     }
-    putchar('\n');
-    close(fd);
     return 0;
 }