[babl/wip/Jehan/babl-cli-tool: 3/3] bin: improve usage of the CLI tool.

[Jehan <jehanp src gnome org>]

commit 13e0c37b262f95e6b054b911c92bd7bc5345d151
Author: Jehan <jehan girinstud io>
Date:   Wed Jul 20 23:18:32 2022 +0200

    bin: improve usage of the CLI tool.
    
    - Add a --help/-h option.
    - Detect invalid options (argument starting with '-').
    - Support '--' option to indicate end of options. This can be
      particularly useful to set negative component values in floating point
      formats.
    - Print usage in various error types (when they are of wrong
      syntax/option types), additionally to printing it when --help is
      called.

 bin/babl.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 80 insertions(+), 20 deletions(-)
---
diff --git a/bin/babl.c b/bin/babl.c
index d975bd7b4..607d10b44 100644
--- a/bin/babl.c
+++ b/bin/babl.c
@@ -25,7 +25,8 @@
 #include <babl/babl.h>
 
 
-static const Babl * babl_cli_get_space (const char *path);
+static const Babl * babl_cli_get_space   (const char *path);
+static void         babl_cli_print_usage (FILE *      stream);
 
 
 int
@@ -45,6 +46,7 @@ main (int    argc,
   int         set_to           = 0;
   int         set_from_profile = 0;
   int         set_to_profile   = 0;
+  int         options_ended    = 0;
   int         n_components;
   int         data_index;
   int         c;
@@ -52,6 +54,12 @@ main (int    argc,
 
   babl_init ();
 
+  if (argc == 1)
+    {
+      babl_cli_print_usage (stderr);
+      return 2;
+    }
+
   /* Looping through arguments to get source and destination formats. */
   for (i = 1; i < argc; i++)
     {
@@ -96,6 +104,17 @@ main (int    argc,
           if (! to_space)
             return 6;
         }
+      else if (strcmp (argv[i], "--") == 0)
+        {
+          break;
+        }
+      else if (strcmp (argv[i], "--help") == 0 ||
+               strcmp (argv[i], "-h") == 0)
+        {
+          babl_cli_print_usage (stdout);
+
+          return 0;
+        }
       else if (strcmp (argv[i], "--from") == 0 ||
                strcmp (argv[i], "-f") == 0)
         {
@@ -152,25 +171,43 @@ main (int    argc,
           set_to_profile = 0;
           /* Pass. */
         }
-      else if (strcmp (argv[i], "--from") == 0 ||
-               strcmp (argv[i], "-f") == 0)
-        {
-          set_from = 1;
-        }
-      else if (strcmp (argv[i], "--to") == 0 ||
-               strcmp (argv[i], "-t") == 0)
-        {
-          set_to = 1;
-        }
-      else if (strcmp (argv[i], "--input-profile") == 0 ||
-               strcmp (argv[i], "-i") == 0)
-        {
-          set_from_profile = 1;
-        }
-      else if (strcmp (argv[i], "--output-profile") == 0 ||
-               strcmp (argv[i], "-o") == 0)
+      else if (! options_ended && strncmp (argv[i], "-", 1) == 0)
         {
-          set_to_profile = 1;
+          if (strcmp (argv[i], "--") == 0)
+            {
+              options_ended = 1;
+            }
+          else if (strcmp (argv[i], "--help") == 0 ||
+              strcmp (argv[i], "-h") == 0)
+             {
+               /* Pass. */
+             }
+          else if (strcmp (argv[i], "--from") == 0 ||
+                   strcmp (argv[i], "-f") == 0)
+            {
+              set_from = 1;
+            }
+          else if (strcmp (argv[i], "--to") == 0 ||
+                   strcmp (argv[i], "-t") == 0)
+            {
+              set_to = 1;
+            }
+          else if (strcmp (argv[i], "--input-profile") == 0 ||
+                   strcmp (argv[i], "-i") == 0)
+            {
+              set_from_profile = 1;
+            }
+          else if (strcmp (argv[i], "--output-profile") == 0 ||
+                   strcmp (argv[i], "-o") == 0)
+            {
+              set_to_profile = 1;
+            }
+          else
+            {
+              fprintf (stderr, "babl: unknown option: %s\n", argv[i]);
+              babl_cli_print_usage (stderr);
+              return 2;
+            }
         }
       else
         {
@@ -179,7 +216,8 @@ main (int    argc,
 
           if (c >= n_components)
             {
-              fprintf (stderr, "babl: unexpected argument: %s\n", argv[i]);
+              fprintf (stderr, "babl: unexpected component: %s\n", argv[i]);
+              babl_cli_print_usage (stderr);
               return 2;
             }
 
@@ -254,6 +292,7 @@ main (int    argc,
     {
       fprintf (stderr, "babl: %d components expected, %d components were passed\n",
                n_components, c);
+      babl_cli_print_usage (stderr);
       return 2;
     }
 
@@ -360,3 +399,24 @@ babl_cli_get_space (const char *path)
 
   return space;
 }
+
+static void
+babl_cli_print_usage (FILE *stream)
+{
+  fprintf (stream,
+           "usage: babl [options] [c1 ..]\n"
+           "\n"
+           "  Options:\n"
+           "     -h, --help            this help information\n"
+           "\n"
+           "     -f, --from            input Babl format\n"
+           "\n"
+           "     -t, --to              output Babl format\n"
+           "\n"
+           "     -i, --input-profile   input profile\n"
+           "\n"
+           "     -o, --output-profile  output profile\n"
+           "\n"
+           "All parameters following -- are considered components values.\n"
+           "The tool expects exactly the number of components expected by your input format.\n");
+}