Add commandline argument parser

- add several commandline options to read username, password and server
   from the commandline
 - add help output to the commandline
 - do not automatically call auth upon start-up because the user might
   want to run commands like "help" which do not require to be signed in
 - add -c option which, like for dash and bash allows to receive
   commands via the commandline instead of standard input

main.c

@@ -21,6 +21,8 @@
 #include <stdlib.h>
 #include <termios.h>
 #include <unistd.h>
+#include <getopt.h>
+#include <wordexp.h>
 
 #include <openssl/ssl.h>
 
@@ -34,16 +36,105 @@
 static void
 mfshell_run(mfshell_t *mfshell);
 
+static void
+mfshell_parse_commands(mfshell_t *mfshell, char *command);
+
 int term_resized = 0;
 int term_height = 0;
 int term_width = 0;
 
+void print_help(mfshell_t *mfshell, char *cmd)
+{
+    fprintf(stderr, "A shell to access a MediaFire account.\n");
+    fprintf(stderr, "\n");
+    fprintf(stderr, "Usage: %s [options]\n", cmd);
+    fprintf(stderr, "\n");
+    fprintf(stderr, "  -h, --help            Print this help\n");
+    fprintf(stderr, "  -v, --version         Print version information\n");
+    fprintf(stderr, "  -c, --command=<CMD>   Run command CMD and exit\n");
+    fprintf(stderr, "  -u, --username=<USER> Login username\n");
+    fprintf(stderr, "  -p, --password=<PASS> Login password\n");
+    fprintf(stderr, "  -s, --server=<SERVER> Login server\n");
+    fprintf(stderr, "\n");
+    fprintf(stderr, "Username and password are optional. If not given, they\n"
+                    "have to be entered via standard input.\n");
+    fprintf(stderr, "\n");
+    fprintf(stderr, "You should not pass your password as a commandline\n"
+                    "argument as other users with access to the list of\n"
+                    "running processes will then be able to see it.\n");
+    fprintf(stderr, "\n");
+    fprintf(stderr, "Use the \"help\" command to print a list of available\n"
+                    "commands in the interactive environment:\n");
+    fprintf(stderr, "\n");
+    fprintf(stderr, "     %s -c help\n", cmd);
+    fprintf(stderr, "\n");
+}
+
+void parse_argv(mfshell_t *mfshell, int argc, char **argv, char **username,
+        char **password, char **server, char **command)
+{
+    static struct option long_options[] = {
+        {"command",  required_argument, 0, 'c'},
+        {"username", required_argument, 0, 'u'},
+        {"password", required_argument, 0, 'p'},
+        {"server",   required_argument, 0, 's'},
+        {"help",     no_argument,       0, 'h'},
+        {"version",  no_argument,       0, 'v'}
+    };
+
+    int c;
+    for (;;) {
+        c = getopt_long(argc, argv, "c:u:p:s:hv", long_options, NULL);
+        if (c == -1)
+            break;
+
+        switch (c) {
+            case 'c':
+                *command = strdup(optarg);
+                break;
+            case 'u':
+                *username = strdup(optarg);
+                break;
+            case 'p':
+                *password = strdup(optarg);
+                break;
+            case 's':
+                *server = strdup(optarg);
+                break;
+            case 'h':
+                print_help(mfshell, argv[0]);
+                exit(0);
+            case 'v':
+                exit(0);
+            case '?':
+                exit(1);
+                break;
+            default:
+                fprintf(stderr, "getopt_long returned character code %c\n", c);
+        }
+    }
+
+    if (optind < argc) {
+        // TODO: handle non-option argv elements
+        fprintf(stderr, "Unexpected positional arguments\n");
+        exit(1);
+    }
+
+    if (*password != NULL && *username == NULL) {
+        fprintf(stderr, "You cannot pass the password without the username\n");
+        exit(1);
+    }
+}
+
 int main(int argc,char **argv)
 {
     extern int          term_height;
     extern int          term_width;
     mfshell_t           *mfshell;
     char                *server = "www.mediafire.com";
+    char                *username = NULL;
+    char                *password = NULL;
+    char                *command = NULL;
     size_t              len;
     int                 retval;
 
@@ -59,23 +150,41 @@ int main(int argc,char **argv)
 
     sig_install_SIGWINCH();
 
-    if(argc > 1)
-    {
-        if(argv[1] != NULL) server = argv[1];
-    }
+    parse_argv(mfshell, argc, argv, &username, &password, &server, &command);
 
     mfshell = mfshell_create(35860,
         "2c6dq0gb2sr8rgsue5a347lzpjnaay46yjazjcjg",server);
 
-    printf("\n\r");
-    mfshell->exec(mfshell, "auth");
-
-    // begin shell mode
-    mfshell_run(mfshell);
+    if (command == NULL) {
+        // begin shell mode
+        mfshell_run(mfshell);
+    } else {
+        // interpret command
+        mfshell_parse_commands(mfshell, command);
+    }
 
     return 0;
 }
 
+static void
+mfshell_parse_commands(mfshell_t *mfshell, char *command)
+{
+    char *next;
+    int ret;
+    wordexp_t p;
+    // FIXME: don't split by semicolon but by unescaped/unquoted semicolon
+    while ((next = strsep(&command, ";")) != NULL) {
+        // FIXME: handle non-zero return value of wordexp
+        ret = wordexp(next, &p, WRDE_SHOWERR | WRDE_UNDEF);
+        if (p.we_wordc < 1) {
+            fprintf(stderr, "Need more than zero arguments\n");
+            exit(1);
+        }
+        mfshell->exec(mfshell, p.we_wordc, p.we_wordv);
+        wordfree(&p);
+    }
+}
+
 static void
 mfshell_run(mfshell_t *mfshell)
 {
@@ -88,7 +197,10 @@ mfshell_run(mfshell_t *mfshell)
     {
         printf("\n\rmfshell > ");
 
-        getline(&cmd,&len,stdin);
+        retval = getline(&cmd,&len,stdin);
+        if (retval == -1) {
+            exit(1);
+        }
         string_chomp(cmd);
 
         printf("\n\r");
@@ -105,7 +217,7 @@ mfshell_run(mfshell_t *mfshell)
             continue;
         }
 
-        retval = mfshell->exec(mfshell,cmd);
+        retval = mfshell->exec_string(mfshell,cmd);
         free(cmd);
         cmd = NULL;
     }