Refactor the command line interface

Select operation by its name instead of by number of the arguments.

1 files changed, 165 insertions, 57 deletions

diff --git a/src/options.c b/src/options.c
index 002b36c..e2fcfdb 100644
--- a/src/options.c
+++ b/src/options.c
@@ -38,22 +38,126 @@
  */
 #include "program_info.h"
 
+#define OPTIONS_MAX_OPERATION_NAME_LENGTH 8
 #define OPTIONS_DEFAULT_SECTOR_SIZE 512
 #define OPTIONS_DEFAULT_BUFFER_SIZE (4 * 1024 * 1024)
 
-static void options_init(options_t *const opts);
+struct common_options {
+    bool help;
+    uint32_t sector_size;
+    uint32_t buffer_size;
+};
+
 static int options_parse_unsigned(const char *const arg, uint32_t *const value);
+static void options_parse_operation(const char *const argv,
+                                    options_t *const opts);
+static bool options_parse_common(int *const argc, char ***const argv,
+                                 struct common_options *const opts);
+static bool options_parse_backup(int *const argc, char ***const argv,
+                                 options_t *const opts);
+static bool options_parse_restore(int *const argc, char ***const argv,
+                                  options_t *const opts);
 
-int
+bool
 options_parse(int argc, char **argv, options_t *const opts)
 {
-    options_init(opts);
+    // Skip the executable name
+    --argc;
+    ++argv;
+
+    options_parse_operation(argv[0], opts);
+
+    if (options_is_operation(opts, OPERATION_ID_UNKNOWN)) {
+        return false;
+    }
+
+    if (options_is_operation(opts, OPERATION_ID_BACKUP)) {
+        if (!options_parse_backup(&argc, &argv, opts)) {
+            return false;
+        }
+    } else if (options_is_operation(opts, OPERATION_ID_RESTORE)) {
+        if (!options_parse_restore(&argc, &argv, opts)) {
+            return false;
+        }
+    }
+    return true;
+}
+
+void
+options_usage(int exit_code)
+{
+    printf("Usage: %s [-s SECTOR_SIZE] [-b BUFFER_SIZE] [INFILE] REFFILE "
+           "OUTFILE\n",
+           PROGRAM_NAME_STR);
+    exit(exit_code);
+}
+
+bool
+options_is_operation(const options_t *const opts, operation_id_t operation_id)
+{
+    return (opts->operation_id == operation_id);
+}
+
+const options_backup_t *
+options_get_for_backup(const options_t *const opts)
+{
+    return &(opts->op.backup);
+}
+
+const options_restore_t *
+options_get_for_restore(const options_t *const opts)
+{
+    return &(opts->op.restore);
+}
+
+static int
+options_parse_unsigned(const char *const arg, uint32_t *const value)
+{
+    char *end;
+
+    errno = 0;
+
+    *value = strtoul(arg, &end, 0);
+
+    return ((*end != '\0') || (errno != 0)) ? -1 : 0;
+}
+
+static void
+options_parse_operation(const char *const op_name, options_t *const opts)
+{
+    if (op_name == NULL) {
+        opts->operation_id = OPERATION_ID_UNKNOWN;
+    } else if (strncmp(op_name, "help", OPTIONS_MAX_OPERATION_NAME_LENGTH) ==
+               0) {
+        opts->operation_id = OPERATION_ID_HELP;
+    } else if (strncmp(op_name, "backup", OPTIONS_MAX_OPERATION_NAME_LENGTH) ==
+               0) {
+        opts->operation_id = OPERATION_ID_BACKUP;
+    } else if (strncmp(op_name, "restore", OPTIONS_MAX_OPERATION_NAME_LENGTH) ==
+               0) {
+        opts->operation_id = OPERATION_ID_RESTORE;
+    } else {
+        opts->operation_id = OPERATION_ID_UNKNOWN;
+    }
+}
+
+static void
+options_init_common(struct common_options *const opts)
+{
+    opts->help = false;
+    opts->sector_size = OPTIONS_DEFAULT_SECTOR_SIZE;
+    opts->buffer_size = OPTIONS_DEFAULT_BUFFER_SIZE;
+}
 
+static bool
+options_parse_common(int *const argc, char ***const argv,
+                     struct common_options *const opts)
+{
     int ch;
     char *arg_sector_size = NULL;
     char *arg_buffer_size = NULL;
 
-    while ((ch = getopt(argc, argv, ":b:hs:")) != -1) {
+    while ((ch = getopt(*argc, *argv, ":b:hs:")) != -1) {
         switch (ch) {
         case 'b':
             arg_buffer_size = optarg;
@@ -69,90 +173,94 @@ options_parse(int argc, char **argv, options_t *const opts)
 
         case ':':
             print_error("missing argument for option '-%c'", optopt);
-            return 1;
-
+            return false;
         default:
             print_error("unknown option '-%c'", optopt);
-            return 1;
+            return false;
         }
     }
 
-    argc -= optind;
-    argv += optind;
-
-    if (opts->help) {
-        return 0;
-    } else if (argc < 2) {
-        print_error("missing arguments");
-        return 1;
-    } else if (argc > 3) {
-        print_error("too many arguments");
-        return 1;
-    }
+    *argc -= optind;
+    *argv += optind;
 
     /* Convert numbers in the arguments */
     if ((arg_sector_size != NULL) &&
         options_parse_unsigned(arg_sector_size, &(opts->sector_size))) {
         print_error("incorrect sector size");
-        return 1;
+        return false;
     } else if ((arg_buffer_size != NULL) &&
                options_parse_unsigned(arg_buffer_size, &(opts->buffer_size))) {
         print_error("incorrect buffer size");
-        return 1;
+        return false;
     } else if (opts->sector_size == 0) {
         print_error("sector size cannot be 0");
-        return 1;
+        return false;
     } else if (opts->buffer_size == 0) {
         print_error("buffer size cannot be 0");
-        return 1;
+        return false;
     } else if (opts->sector_size > opts->buffer_size) {
         print_error("sector size cannot larger than buffer size");
-        return 1;
+        return false;
     } else if ((opts->buffer_size % opts->sector_size) != 0) {
         print_error("buffer size is not multiple of sector size");
-        return 1;
+        return false;
     }
 
-    /* Pick the file paths */
-    int last_path_index = argc - 1;
-    opts->out_file_path = argv[last_path_index--];
-    opts->ref_file_path = argv[last_path_index--];
-    if (last_path_index >= 0) {
-        opts->in_file_path = argv[last_path_index];
-    }
-
-    return 0;
+    return true;
 }
 
-void
-options_usage(int exit_code)
+static bool
+options_parse_backup(int *const argc, char ***const argv, options_t *const opts)
 {
-    printf("Usage: %s [-s SECTOR_SIZE] [-b BUFFER_SIZE] [INFILE] REFFILE "
-           "OUTFILE\n",
-           PROGRAM_NAME_STR);
-    exit(exit_code);
-}
+    struct common_options common_opts;
+    options_init_common(&common_opts);
+    if (!options_parse_common(argc, argv, &common_opts)) {
+        return false;
+    }
 
-static void
-options_init(options_t *const opts)
-{
-    opts->help = false;
-    opts->sector_size = OPTIONS_DEFAULT_SECTOR_SIZE;
-    opts->buffer_size = OPTIONS_DEFAULT_BUFFER_SIZE;
+    if (common_opts.help) {
+        opts->operation_id = OPERATION_ID_HELP;
+    } else if (*argc < 3) {
+        print_error("missing arguments");
+        return false;
+    } else if (*argc > 3) {
+        print_error("too many arguments");
+        return false;
+    } else {
+        opts->op.backup.sector_size = common_opts.sector_size;
+        opts->op.backup.buffer_size = common_opts.buffer_size;
+        opts->op.backup.in_file_path = (*argv)[0];
+        opts->op.backup.ref_file_path = (*argv)[1];
+        opts->op.backup.out_file_path = (*argv)[2];
+    }
 
-    opts->in_file_path = NULL;
-    opts->ref_file_path = NULL;
-    opts->out_file_path = NULL;
+    return true;
 }
 
-static int
-options_parse_unsigned(const char *const arg, uint32_t *const value)
+static bool
+options_parse_restore(int *const argc, char ***const argv,
+                      options_t *const opts)
 {
-    char *end;
-
-    errno = 0;
+    struct common_options common_opts;
+    options_init_common(&common_opts);
+    if (!options_parse_common(argc, argv, &common_opts)) {
+        return false;
+    }
 
-    *value = strtoul(arg, &end, 0);
+    if (common_opts.help) {
+        opts->operation_id = OPERATION_ID_HELP;
+    } else if (*argc < 2) {
+        print_error("missing arguments");
+        return false;
+    } else if (*argc > 2) {
+        print_error("too many arguments");
+        return false;
+    } else {
+        opts->op.restore.sector_size = common_opts.sector_size;
+        opts->op.restore.buffer_size = common_opts.buffer_size;
+        opts->op.restore.in_file_path = (*argv)[0];
+        opts->op.restore.out_file_path = (*argv)[1];
+    }
 
-    return ((*end != '\0') || (errno != 0)) ? -1 : 0;
+    return true;
 }