Create "mmc" utility

This commit was made by Chris Ball, but reuses framework code from
Goffredo's btrfs-progs/btrfs.c.
Signed-off-by: Chris Ball <cjb@laptop.org>

Makefile

+CC = gcc
+AM_CFLAGS = -D_FILE_OFFSET_BITS=64 -D_FORTIFY_SOURCE=2
+CFLAGS = -g -O0
+objects = mmc.o
+
+CHECKFLAGS= -Wall -Werror -Wuninitialized -Wundef
+
+DEPFLAGS = -Wp,-MMD,$(@D)/.$(@F).d,-MT,$@
+
+INSTALL = install
+prefix ?= /usr/local
+bindir = $(prefix)/bin
+LIBS=
+RESTORE_LIBS=
+
+progs = mmc
+
+# make C=1 to enable sparse
+ifdef C
+	check = sparse $(CHECKFLAGS)
+endif
+
+all: $(progs) manpages
+
+.c.o:
+ifdef C
+	$(check) $<
+endif
+	$(CC) $(CHECKFLAGS) $(AM_CFLAGS) $(DEPFLAGS) $(CFLAGS) -c $<
+
+mmc: $(objects)
+	$(CC) $(CFLAGS) -o $@ $(objects) $(LDFLAGS) $(LIBS)
+
+manpages:
+	cd man && make
+
+install-man:
+	cd man && make install
+
+clean:
+	rm -f $(progs) $(objects)
+	cd man && make clean
+
+install: $(progs) install-man
+	$(INSTALL) -m755 -d $(DESTDIR)$(bindir)
+	$(INSTALL) $(progs) $(DESTDIR)$(bindir)

man/Makefile

+all: 
+clean: 

mmc.c

+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ *
+ * (This code is based on btrfs-progs/btrfs.c.)
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define MMC_VERSION	"0.1"
+
+#define BASIC_HELP 0
+#define ADVANCED_HELP 1
+
+typedef int (*CommandFunction)(int argc, char **argv);
+
+struct Command {
+	CommandFunction	func;	/* function which implements the command */
+	int	nargs;		/* if == 999, any number of arguments
+				   if >= 0, number of arguments,
+				   if < 0, _minimum_ number of arguments */
+	char	*verb;		/* verb */
+	char	*help;		/* help lines; from the 2nd line onward they 
+                                   are automatically indented */
+        char    *adv_help;      /* advanced help message; from the 2nd line 
+                                   onward they are automatically indented */
+
+	/* the following fields are run-time filled by the program */
+	char	**cmds;		/* array of subcommands */
+	int	ncmds;		/* number of subcommand */
+};
+
+static struct Command commands[] = {
+	/*
+	 *	avoid short commands different for the case only
+	 */
+	{ 0, 0, 0, 0 }
+};
+
+static char *get_prgname(char *programname)
+{
+	char	*np;
+	np = strrchr(programname,'/');
+	if(!np)
+		np = programname;
+	else
+		np++;
+
+	return np;
+}
+
+static void print_help(char *programname, struct Command *cmd, int helptype)
+{
+	char	*pc;
+
+	printf("\t%s %s ", programname, cmd->verb );
+
+	if (helptype == ADVANCED_HELP && cmd->adv_help)
+		for(pc = cmd->adv_help; *pc; pc++){
+			putchar(*pc);
+			if(*pc == '\n')
+				printf("\t\t");
+		}
+	else
+		for(pc = cmd->help; *pc; pc++){
+			putchar(*pc);
+			if(*pc == '\n')
+				printf("\t\t");
+		}
+
+	putchar('\n');
+}
+
+static void help(char *np)
+{
+	struct Command *cp;
+
+	printf("Usage:\n");
+	for( cp = commands; cp->verb; cp++ )
+		print_help(np, cp, BASIC_HELP);
+
+	printf("\n\t%s help|--help|-h\n\t\tShow the help.\n",np);
+	printf("\n\t%s <cmd> --help\n\t\tShow detailed help for a command or subset of commands.\n",np);
+	printf("\n%s\n", MMC_VERSION);
+}
+
+static int split_command(char *cmd, char ***commands)
+{
+	int	c, l;
+	char	*p, *s;
+
+	for( *commands = 0, l = c = 0, p = s = cmd ; ; p++, l++ ){
+		if ( *p && *p != ' ' )
+			continue;
+
+		/* c + 2 so that we have room for the null */
+		(*commands) = realloc( (*commands), sizeof(char *)*(c + 2));
+		(*commands)[c] = strndup(s, l);
+		c++;
+		l = 0;
+		s = p+1;
+		if( !*p ) break;
+	}
+
+	(*commands)[c] = 0;
+	return c;
+}
+
+/*
+	This function checks if the passed command is ambiguous
+*/
+static int check_ambiguity(struct Command *cmd, char **argv){
+	int		i;
+	struct Command	*cp;
+	/* check for ambiguity */
+	for( i = 0 ; i < cmd->ncmds ; i++ ){
+		int match;
+		for( match = 0, cp = commands; cp->verb; cp++ ){
+			int	j, skip;
+			char	*s1, *s2;
+
+			if( cp->ncmds < i )
+				continue;
+
+			for( skip = 0, j = 0 ; j < i ; j++ )
+				if( strcmp(cmd->cmds[j], cp->cmds[j])){
+					skip=1;
+					break;
+				}
+			if(skip)
+				continue;
+
+			if( !strcmp(cmd->cmds[i], cp->cmds[i]))
+				continue;
+			for(s2 = cp->cmds[i], s1 = argv[i+1];
+				*s1 == *s2 && *s1; s1++, s2++ ) ;
+			if( !*s1 )
+				match++;
+		}
+		if(match){
+			int j;
+			fprintf(stderr, "ERROR: in command '");
+			for( j = 0 ; j <= i ; j++ )
+				fprintf(stderr, "%s%s",j?" ":"", argv[j+1]);
+			fprintf(stderr, "', '%s' is ambiguous\n",argv[j]);
+			return -2;
+		}
+	}
+	return 0;
+}
+
+/*
+ * This function, compacts the program name and the command in the first
+ * element of the '*av' array
+ */
+static int prepare_args(int *ac, char ***av, char *prgname, struct Command *cmd ){
+
+	char	**ret;
+	int	i;
+	char	*newname;
+
+	ret = (char **)malloc(sizeof(char*)*(*ac+1));
+	newname = (char*)malloc(strlen(prgname)+strlen(cmd->verb)+2);
+	if( !ret || !newname ){
+		free(ret);
+		free(newname);
+		return -1;
+	}
+
+	ret[0] = newname;
+	for(i=0; i < *ac ; i++ )
+		ret[i+1] = (*av)[i];
+
+	strcpy(newname, prgname);
+	strcat(newname, " ");
+	strcat(newname, cmd->verb);
+
+	(*ac)++;
+	*av = ret;
+
+	return 0;
+
+}
+
+/*
+	This function performs the following jobs:
+	- show the help if '--help' or 'help' or '-h' are passed
+	- verify that a command is not ambiguous, otherwise show which
+	  part of the command is ambiguous
+	- if after a (even partial) command there is '--help' show detailed help
+	  for all the matching commands
+	- if the command doesn't match show an error
+	- finally, if a command matches, they return which command matched and
+	  the arguments
+
+	The function return 0 in case of help is requested; <0 in case
+	of uncorrect command; >0 in case of matching commands
+	argc, argv are the arg-counter and arg-vector (input)
+	*nargs_ is the number of the arguments after the command (output)
+	**cmd_  is the invoked command (output)
+	***args_ are the arguments after the command
+
+*/
+static int parse_args(int argc, char **argv,
+		      CommandFunction *func_,
+		      int *nargs_, char **cmd_, char ***args_ )
+{
+	struct Command	*cp;
+	struct Command	*matchcmd=0;
+	char		*prgname = get_prgname(argv[0]);
+	int		i=0, helprequested=0;
+
+	if( argc < 2 || !strcmp(argv[1], "help") ||
+		!strcmp(argv[1], "-h") || !strcmp(argv[1], "--help")){
+		help(prgname);
+		return 0;
+	}
+
+	for( cp = commands; cp->verb; cp++ )
+		if( !cp->ncmds)
+			cp->ncmds = split_command(cp->verb, &(cp->cmds));
+
+	for( cp = commands; cp->verb; cp++ ){
+		int     match;
+
+		if( argc-1 < cp->ncmds )
+			continue;
+		for( match = 1, i = 0 ; i < cp->ncmds ; i++ ){
+			char	*s1, *s2;
+			s1 = cp->cmds[i];
+			s2 = argv[i+1];
+
+			for(s2 = cp->cmds[i], s1 = argv[i+1];
+				*s1 == *s2 && *s1;
+				s1++, s2++ ) ;
+			if( *s1 ){
+				match=0;
+				break;
+			}
+		}
+
+		/* If you understand why this code works ...
+			you are a genious !! */
+		if(argc>i+1 && !strcmp(argv[i+1],"--help")){
+			if(!helprequested)
+				printf("Usage:\n");
+			print_help(prgname, cp, ADVANCED_HELP);
+			helprequested=1;
+			continue;
+		}
+
+		if(!match)
+			continue;
+
+		matchcmd = cp;
+		*nargs_  = argc-matchcmd->ncmds-1;
+		*cmd_ = matchcmd->verb;
+		*args_ = argv+matchcmd->ncmds+1;
+		*func_ = cp->func;
+
+		break;
+	}
+
+	if(helprequested){
+		printf("\n%s\n", MMC_VERSION);
+		return 0;
+	}
+
+	if(!matchcmd){
+		fprintf( stderr, "ERROR: unknown command '%s'\n",argv[1]);
+		help(prgname);
+		return -1;
+	}
+
+	if(check_ambiguity(matchcmd, argv))
+		return -2;
+
+	/* check the number of argument */
+	if (matchcmd->nargs < 0 && matchcmd->nargs < -*nargs_ ){
+		fprintf(stderr, "ERROR: '%s' requires minimum %d arg(s)\n",
+			matchcmd->verb, -matchcmd->nargs);
+			return -2;
+	}
+	if(matchcmd->nargs >= 0 && matchcmd->nargs != *nargs_ && matchcmd->nargs != 999){
+		fprintf(stderr, "ERROR: '%s' requires %d arg(s)\n",
+			matchcmd->verb, matchcmd->nargs);
+			return -2;
+	}
+	
+        if (prepare_args( nargs_, args_, prgname, matchcmd )){
+                fprintf(stderr, "ERROR: not enough memory\\n");
+		return -20;
+        }
+
+
+	return 1;
+}
+int main(int ac, char **av )
+{
+	char		*cmd=0, **args=0;
+	int		nargs=0, r;
+	CommandFunction func=0;
+
+	r = parse_args(ac, av, &func, &nargs, &cmd, &args);
+	if( r <= 0 ){
+		/* error or no command to parse*/
+		exit(-r);
+	}
+
+	exit(func(nargs, args));
+}
+