[PATCH v2 4/5] x86: Use getopt to handle command line args

[Fouad Hilly <fouad.hilly@cloud.com>]

Use getopt_long() to handle command line arguments.
Introduce ext_err for common exit with errors.

[v2]
1- Removed unnecessary NULL initialization.
2- Used static at the beginning of type struct declaration.
3- Corrected switch\case indentations.
4- Removed redundant checks.
5- Corrected label indentation.

Signed-off-by: Fouad Hilly <fouad.hilly@cloud.com>
---
 tools/misc/xen-ucode.c | 43 ++++++++++++++++++++++++++++++------------
 1 file changed, 31 insertions(+), 12 deletions(-)

diff --git a/tools/misc/xen-ucode.c b/tools/misc/xen-ucode.c
index 0c0b2337b4ea..e3c1943e3633 100644
--- a/tools/misc/xen-ucode.c
+++ b/tools/misc/xen-ucode.c
@@ -11,6 +11,7 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <xenctrl.h>
+#include <getopt.h>
 
 static xc_interface *xch;
 
@@ -22,7 +23,8 @@ static void usage(const char *name)
     printf("%s: Xen microcode updating tool\n"
            "Usage: %s [microcode file] [options]\n"
            "Options:\n"
-           "show-cou-info   show CPU information and exit\n",
+           "  -h, --help            display this help and exit\n"
+           "  -s, --show-cpu-info   show CPU information and exit\n",
            name, name);
 }
 
@@ -86,6 +88,13 @@ int main(int argc, char *argv[])
     char *filename, *buf;
     size_t len;
     struct stat st;
+    int opt;
+
+    static const struct option options[] = {
+        {"help", no_argument, NULL, 'h'},
+        {"show-cpu-info", no_argument, NULL, 's'},
+        {NULL, no_argument, NULL, 0}
+    };
 
     xch = xc_interface_open(NULL, NULL, 0);
     if ( xch == NULL )
@@ -95,19 +104,22 @@ int main(int argc, char *argv[])
         exit(1);
     }
 
-    if ( argc < 2 )
-    {
-        fprintf(stderr,
-                "xen-ucode: Xen microcode updating tool\n"
-                "Usage: %s [<microcode file> | show-cpu-info]\n", argv[0]);
-        show_curr_cpu(stderr);
-        exit(2);
-    }
+    if ( argc != 2 )
+        goto ext_err;
 
-    if ( !strcmp(argv[1], "show-cpu-info") )
+    while ( (opt = getopt_long(argc, argv, "hs", options, NULL)) != -1 )
     {
-        show_curr_cpu(stdout);
-        return 0;
+        switch (opt)
+        {
+        case 'h':
+            usage(argv[0]);
+            exit(EXIT_SUCCESS);
+        case 's':
+            show_curr_cpu(stdout);
+            exit(EXIT_SUCCESS);
+        default:
+            goto ext_err;
+        }
     }
 
     filename = argv[1];
@@ -152,4 +164,11 @@ int main(int argc, char *argv[])
     close(fd);
 
     return 0;
+
+ ext_err:
+    fprintf(stderr,
+            "xen-ucode: Xen microcode updating tool\n"
+            "Usage: %s [microcode file] [options]\n", argv[0]);
+    show_curr_cpu(stderr);
+    exit(STDERR_FILENO);
 }
-- 
2.42.0