Add commands help

README.md

@@ -14,9 +14,6 @@ from
 [GNU Binutils](https://www.gnu.org/software/binutils/), consequently
  instructions syntax follows GAS syntax.
  
-For the moment the shell can only be used in
-[AT&T syntax](https://sourceware.org/binutils/docs-2.40/as/i386_002dVariations.html).
-
 #### Assembly syntax
 
 Informations on x86 syntax can be found in

src/shell_cmds.c

@@ -471,7 +471,36 @@ int asmsh_cmd_flags(asmsh_t *sh, asmsh_cmd_args_t *args)
 int asmsh_cmd_help_(asmsh_t *sh, asmsh_cmd_args_t *args)
 {
 	char buf[4096], abuf[64];
-	int ret;
+	int ret = 0;
+
+	if(*args->args)
+	{
+		for(size_t i=0; args->args[i]; i++)
+		{
+			const asmsh_cmd_t *cmd = asmsh_cmd_match(args->args[i],
+					strlen(args->args[i]));
+			if(!cmd)
+			{
+				dprintf(2, "Command '%s' not found\n", args->args[i]);
+				ret = 1;
+				continue;
+			}
+			dprintf(2, "Usage %s %s\n", cmd->str, cmd->usage);
+			dprintf(2, "%s\n\n", cmd->desc);
+			if(strlen(cmd->help))
+			{
+				dprintf(2, "%s\n", cmd->help);
+			}
+			if(!strcmp(cmd->str, ".help"))
+			{
+				ret=1;
+			}
+		}
+		if(!ret)
+		{
+			return 0;
+		}
+	}
 
 	ret = snprintf(buf, 4096, "Available commands :\n");
 	for(const asmsh_cmd_t *cmd = asmsh_CMDS; cmd->str; cmd++)

src/shell_cmds.h

@@ -60,6 +60,8 @@ struct asmsh_cmd_s
 	const char *usage;
 	/** Command description */
 	const char *desc;
+	/** Command help */
+	const char *help;
 };
 
 /** A command arguments with command name & NULL terminated array of args */
@@ -125,49 +127,143 @@ int asmsh_cmd_flags(asmsh_t *sh, asmsh_cmd_args_t *args);
 int asmsh_cmd_help_(asmsh_t *sh, asmsh_cmd_args_t *args);
 
 
+static const char asmsh_cmd_help_help[] = "\
+asmsh details:\n\
+=============\n\
+\n\
+This shell allows to execute assembly instructions in a real Linux process.\n\
+This process will be named \"child process\".\n\
+\n\
+The shell uses the GNU assembler as from binutils. Consequently, instructions\n\
+syntax follows GAS syntax.\n\
+\n\
+child process details:\n\
+----------------------\n\
+In order to execute assembly instructions we have to be able to write them.\n\
+The bytecode will be written in a dedicated memory map (mmap). This memory\n\
+map is created by the child process when spawned, the the child jump in\n\
+the memory map and pauses.\n\
+At this moment the shell can prompt the user for a new instruction to\n\
+execute. The instructions is compiled using GNU as. The resulting bytecode\n\
+is written at the %rip (next instruction pointer register on x86_64), in\n\
+the memory map we just jumped into. Once written an implicit .step is called\n\
+and the instruction is executed.\n\
+";
+
+static const char asmsh_cmd_breakpoint_help[] = "\
+Breakpoint management commands.\n\
+    add (default) : add a breakpoint at given address (. by default)\n\
+    del           : remove a breakpoint at given address (. by default)\n\
+    list          : list breakpoints set\
+";
+
+static const char asmsh_cmd_bcode_help[] = "\
+Print the bytecode of the instruction given in argument or, by default\n\
+the last instruction bytecode.\n\
+\n\
+Exemple :\n\
+---------\n\
+\n\
+.bytecode xor %rax, %rax\n\
+";
+
+static const char asmsh_cmd_label_help[] = "\
+Set a label at given address (. by default)\n\
+\n\
+Note :\n\
+------\n\
+Label names must be uniq (?)\n\
+\n\
+Example :\n\
+---------\n\
+.label some_name ; name current address \"some_name\"\n\
+.label foobar 0x123456 ; name address 0x123456 \"foobar\"\n\
+";
+
+static const char asmsh_cmd_syntax_help[] = "\
+Allows to change between AT&T (att argument) or Intel (intel argument)\n\
+syntaxes.\n\
+\n\
+More informations can be found in GNU as documentation :\n\
+ https://ftp.gnu.org/old-gnu/Manuals/gas/html_chapter/as_16.html#SEC198\n\
+\n\
+Example:\n\
+--------\n\
+.syntax intel\n\
+.syn att\n\
+";
+
+static const char asmsh_cmd_reset_help[] = "\
+Kill underlying child process and start a new one.\n\
+\n\
+see .help .help for more informations\n\
+";
+
+static const char asmsh_cmd_step_help[] = "";
+static const char asmsh_cmd_run_help[] = "";
+
+static const char asmsh_cmd_syscalls_help[] = "";
+static const char asmsh_cmd_maps_help[] = "";
+static const char asmsh_cmd_print_regs_help[] = "";
+static const char asmsh_cmd_flags_help[] = "";
+static const char asmsh_cmd_quit_help[] = "";
+
 /* 
  * The list of shell commands
  */
 static const asmsh_cmd_t asmsh_CMDS[] = {
 	{".breakpoint", asmsh_cmd_breakpoint, 3,
 	 ".br(eakpoint)", "[add|del|list] [addr]",
-	 "Set a breakpoint"},
+	 "manage breakpoints",
+	 asmsh_cmd_breakpoint_help},
 	{".bytecode", asmsh_cmd_bcode, 2,
-	 ".b(ytecode)", "",
-	 "display last instruction bytecode"},
+	 ".b(ytecode)", "[instruction]",
+	 "display instruction bytecode",
+	 asmsh_cmd_bcode_help},
 	{".flags", asmsh_cmd_flags, 2,
 	 ".f(lags)", "",
-	 "display CPU flags"},
+	 "display CPU flags",
+	 asmsh_cmd_flags_help},
 	{".help", asmsh_cmd_help_, 2,
 	 ".h(elp)","[cmd]",
-	 "display this help or the help of specified command"},
+	 "display this help or the help of specified command",
+	 asmsh_cmd_help_help},
 	{".label", asmsh_cmd_label, 2,
 	 ".l(abel)", "label_name [addr]",
-	 "Set a label at given address (or . if none given)"},
+	 "set a label",
+	 asmsh_cmd_label_help},
 	{".maps", asmsh_cmd_maps, 2,
 	 ".m(aps)", "",
-	 "display memory maps"},
+	 "display memory maps",
+	 asmsh_cmd_maps_help},
 	{".quit", asmsh_cmd_quit, 2,
 	 ".q(uit)","",
-	 "quit asmsh"},
+	 "quit asmsh",
+	 asmsh_cmd_quit_help},
 	{".regs", asmsh_cmd_print_regs, 1,
 	".(regs)", "",
-	"display registers value"},
+	"display registers value",
+	asmsh_cmd_print_regs_help},
 	{".run", asmsh_cmd_run, 3,
 	 ".ru(n)", "",
-	 "Run until a breakpoint is reached"},
+	 "Run until a breakpoint is reached",
+	 asmsh_cmd_run_help},
 	{".step", asmsh_cmd_step, 2,
 	 ".s(tep)", "",
-	 "Run the instruction pointed by RIP"},
+	 "Run the instruction pointed by RIP",
+	 asmsh_cmd_step_help},
 	{".syntax", asmsh_cmd_syntax, 4,
 	 ".syn(tax)", "(att)|(intel)",
-	 "Change syntax AT&T (att) or Intel (intel)"},
+	 "Change syntax AT&T (att) or Intel (intel)",
+	 asmsh_cmd_syntax_help},
 	{".syscalls", asmsh_cmd_syscalls, 4,
 	 ".sys(calls)", "",
-	 "print syscalls name & numbers"},
+	 "print syscalls name & numbers",
+	 asmsh_cmd_syscalls_help},
 	{".reset", asmsh_cmd_reset, 0,
 	 ".reset", "",
-	 "reset the shell"},
+	 "reset the shell",
+	 asmsh_cmd_reset_help},
 	{NULL, NULL, 0},
 };