1.7 - Better arg parsing

Changes

@@ -1,3 +1,14 @@
+may 2024
+    - 1.7
+    - Heavily refactored arg parsing to use a simple search-and-dispatch pattern
+    - The argument order no longer matters. The last filename entered is the one used.
+    - longopts can now take arguments in --key=value or --key value format
+    - Added -c to --color
+    - -h/--help is now a canon option
+    - -- now disables opt parsing instead of merely exiting the arg parsing loop
+    - updated man page to explain what -s/--sector does
+    - made an effort to keep code style as similar to pixel's as possible (next line brace, 2-space indent)
+
 april 2022
     - 1.6
     - configure script must error-out when (n)curses isn't found

configure.ac

@@ -9,7 +9,7 @@ AC_INIT
 AC_CONFIG_SRCDIR([hexedit.c])
 AC_CONFIG_HEADERS(config.h)
 
-define(TheVERSION, 1.6)
+define(TheVERSION, 1.7)
 
 PRODUCT=hexedit
 VERSION=TheVERSION

hexedit.c

@@ -41,13 +41,182 @@ const modeParams modes[LAST] = {
 modeType mode = maximized;
 int colored = FALSE;
 int isReadOnly = FALSE;
+int disableOpts = FALSE;
 
 const char * const usage = "usage: %s [-s | --sector] [-m | --maximize] [-l<n> | --linelength <n>] [-r | --readonly]"
 #ifdef HAVE_COLORS 
-     " [--color]"
+     " [-c | --color]"
 #endif 
      " [-h | --help] filename\n";
 
+typedef void (*ParseArgCallbackFn)(const char *nextArg);
+
+static void pacallback_sector      (const char *unused);
+static void pacallback_readOnly    (const char *unused);
+static void pacallback_maximize    (const char *unused);
+#ifdef HAVE_COLORS
+static void pacallback_color       (const char *unused);
+#endif
+static void pacallback_lineLength  (const char *nextArg);
+static void pacallback_disableOpts (const char *unused);
+static void pacallback_usage       (const char *unused);
+
+static inline int parseArg_matchOpt (const char *arg, const char *shortName, const char *longName);
+static inline int parseArg          (const char **argv);
+
+/* name:    pacallback_*
+ * nextArg: argument for option, if applicable
+ * desc:    these are callbacks per ParseArgCallbackFn, used by parseArg
+ */
+static void pacallback_sector(const char *unused)
+{
+  (void) unused;
+  mode = bySector;
+}
+
+static void pacallback_readOnly(const char *unused)
+{
+  (void) unused;
+  isReadOnly = TRUE;
+}
+
+static void pacallback_maximize(const char *unused)
+{
+  (void) unused;
+  mode = maximized;
+  lineLength = 0;
+}
+
+#ifdef HAVE_COLORS
+static void pacallback_color(const char *unused)
+{
+  (void) unused;
+  colored = TRUE;
+}
+#endif
+
+static void pacallback_lineLength(const char *nextArg)
+{
+  lineLength = atoi(nextArg);
+
+  if (lineLength < 0 || lineLength > 4096)
+    DIE("%s: illegal line length\n")
+}
+
+static void pacallback_disableOpts(const char *unused)
+{
+  (void) unused;
+  disableOpts = TRUE;
+}
+
+static void pacallback_usage(const char *unused)
+{
+  (void) unused;
+  DIE(usage);
+}
+
+/* name:      parseArg_matchOpt
+ * arg:       current argument
+ * shortName: short name to check against
+ * longName:  long name to check against
+ * return:    number indicating status
+ *            0: no match
+ *            1: short match
+ *            2: long match
+ */
+static inline int parseArg_matchOpt(const char *arg, const char *shortName, const char *longName)
+{
+  if (shortName != NULL && strbeginswith(arg, shortName))
+    return 1;
+
+  if (longName != NULL && strbeginswith(arg, longName))
+    return 2;
+
+  return 0;
+}
+
+/* name:   parseArg
+ * argvp:  pointer to current argv offset
+ * return: number of arguments to advance
+ * desc:   parses arguments according to embedded argument list.
+ *         Execution is handled by callback functions.
+ * notes:
+ *
+ * 1. This can be canonized as a type in a future update, but is left
+ *    anonymous for now
+ *
+ * 2. Adds support for the --longopt=value convention
+ *
+ * 3. if a filename was already selected, free the existing one and
+ *    replace it. Note that file scope variables are guaranteed to be
+ *    zero initialized per the standard.
+ *
+ * 4. Fixes issue #70 -- if no options match the argument, it is assumed
+ *    to be the filename. The effect is that the most recent "naked"
+ *    argument is used as the filename.
+ */
+static inline int parseArg(const char **argvp)
+{
+  static const struct { // 1
+    const char *       shortName;
+    const char *       longName;
+    int                hasArg;
+    ParseArgCallbackFn callback;
+  } opts[] = {
+    {"-s", "--sector",     FALSE, pacallback_sector},
+    {"-r", "--readonly",   FALSE, pacallback_readOnly},
+    {"-m", "--maximize",   FALSE, pacallback_maximize},
+#ifdef HAVE_COLORS
+    {"-c", "--color",      FALSE, pacallback_color},
+#endif
+    {"-l", "--linelength", TRUE,  pacallback_lineLength},
+    {"-h", "--help",       FALSE, pacallback_usage},
+    {"--", NULL,           FALSE, pacallback_disableOpts},
+    {"-",  NULL,           FALSE, pacallback_usage},
+  };
+  static const size_t opts_len = sizeof opts / sizeof *opts;
+
+  const char *curArg = argvp[0];
+  const char *nextArg = NULL;
+  int advanceBy = 1;
+
+  if (disableOpts)
+    goto exit_disableOpts;
+
+  for (size_t i = 0; i < opts_len; ++i)
+  {
+    int matchOpt = parseArg_matchOpt(curArg, opts[i].shortName, opts[i].longName);
+    const char *strchrMatch;
+
+    if (matchOpt == 0)
+      continue;
+
+    if (opts[i].hasArg)
+    {
+      if (matchOpt == 1 && strlen(curArg) > 2)
+        nextArg = curArg + 2;
+
+      else if (matchOpt == 2 && (strchrMatch = strchr(curArg, '=')) != NULL) // 2
+        nextArg = strchrMatch + 1;
+
+      else
+      {
+        nextArg = argvp[1];
+        advanceBy = 2;
+      }
+    }
+
+    opts[i].callback(nextArg);
+    return advanceBy;
+  }
+
+exit_disableOpts:
+  if (fileName != NULL) // 3
+    free(fileName);
+
+  fileName = strdup(curArg); // 4
+  return 1;
+}
 
 /*******************************************************************************/
 /* main */
@@ -57,52 +226,21 @@ int main(int argc, char **argv)
   progName = basename(argv[0]);
   argv++; argc--;
 
-  for (; argc > 0; argv++, argc--) 
-    {
-      if (streq(*argv, "-s") || streq(*argv, "--sector"))
-	mode = bySector;
-      else if (streq(*argv, "-r") || streq(*argv, "--readonly"))
-	isReadOnly = TRUE;
-      else if (streq(*argv, "-m") || streq(*argv, "--maximize")) {
-	mode = maximized;
-	lineLength = 0;
-      }
-#ifdef HAVE_COLORS
-      else if (streq(*argv, "--color"))
-	colored = TRUE;
-#endif
-      else if (strbeginswith(*argv, "-l") || strbeginswith(*argv, "--linelength")) {
-	if (strbeginswith(*argv, "-l") && strlen(*argv) > 2)
-	  lineLength = atoi(*argv + 2);
-	else {
-	  argv++; argc--;
-	  lineLength = atoi(*argv);
-	}
-	if (lineLength < 0 || lineLength > 4096)
-	  DIE("%s: illegal line length\n")
-      } else if (streq(*argv, "--")) {
-	argv++; argc--;
-	break;
-      } else if (*argv[0] == '-')
-
-	DIE(usage)
-      else break;
-    }
-  if (argc > 1) DIE(usage);
+  for (; argc > 0;)
+  {
+    int advanceBy = parseArg((const char **)argv);
 
-  init();
-  if (argc == 1) {
-    fileName = strdup(*argv);
-    openFile();
+    argv += advanceBy;
+    argc -= advanceBy;
   }
+
+  init();
   initCurses();
-  if (fileName == NULL) {
-    if (!findFile()) {
-      exitCurses();
-      DIE("%s: No such file\n");
-    }
-    openFile();
+  if (fileName == NULL && !findFile()) {
+    exitCurses();
+    DIE("%s: No such file\n");
   }
+  openFile();
   readFile();
   do display();
   while (key_to_function(getch()));