Allow multiple -t interactive terminals on the command line

Think breakpoints for a series of memory operations. In this example

$ avrdude -t -U eeprom:r:dopp.eep:i -t -U eeprom:w:dopp.eep

the first -U makes a backup of the EEPROM that the second terminal can
then arbitrarily change because the second -U restores the EEPROM content.

src/avrdude.1

@@ -696,31 +696,31 @@ to the device.  Specify it more often for even quieter operations.
 These options used to control the obsolete "safemode" feature which
 is no longer present. They are silently ignored for backwards compatibility.
 .It Fl T Ar cmd
-Slots a terminal command line
+Run terminal line
 .Ar cmd
-into the intermixed list of -T terminal commands and -U memory operations.
-The terminal command line is executed when it is its turn in the mixed list.
-Except for the simplest of terminal commands the argument
+when it is its turn in relation to other -t interactive terminal shells,
+-T terminal commands and -U memory operations. Except for the simplest
+of terminal commands the argument
 .Ar cmd
 will most likely need to be set in quotes, see your OS shell manual for
-details.
+details. See below for a detailed description of all terminal commands.
 .It Fl t
 Tells
 .Nm
-to enter the interactive terminal shell before up- or downloading files
-via the -U option or processing other -T terminal commands, if any. See
-below for a detailed description of the terminal mode.
+to run an interactive terminal shell when it is its turn in relation to
+other -t interactive terminal shells, -T terminal commands and -U memory
+operations.
 .It Xo Fl U Ar memory Ns
 .Ar \&: Ns Ar op Ns
 .Ar \&: Ns Ar filename Ns
 .Op \&: Ns Ar format
 .Xc
-Perform a memory operation as indicated. Multiple -U operations are
-allowed. The
+Perform a memory operation as indicated  when it is its turn in relation to
+other -t interactive terminal shells, -T terminal commands and -U memory
+operations. The
 .Ar memory
-field specifies the memory to operate on.
-The available memory types are device-dependent, the actual
-configuration can be viewed with the
+field specifies the memory to operate on. The available memory types are
+device-dependent, the actual configuration can be viewed with the
 .Cm part
 command in terminal mode.
 Typically, a device's memory configuration at least contains

src/doc/avrdude.texi

@@ -758,26 +758,25 @@ These options used to control the obsolete "safemode" feature which
 is no longer present. They are silently ignored for backwards compatibility.
 
 @item -T @var{cmd}
-Slots a terminal command line @var{cmd} into the intermixed list of
-@code{-T} terminal commands and @code{-U} memory operations. The terminal
-command line is executed when it is its turn in the mixed list. Except for
-the simplest of terminal commands the argument @var{cmd} will most likely
-need to be set in quotes, see your OS shell manual for details.
+Run terminal line @var{cmd} when it is its turn in relation to other
+@code{-t} interactive terminal shells, @code{-T} terminal commands and
+@code{-U} memory operations. Except for the simplest of terminal commands
+the argument @var{cmd} will most likely need to be set in quotes, see your
+OS shell manual for details. See below for a detailed description of all
+terminal commands.
 
 @item -t
-Tells AVRDUDE to enter the interactive terminal shell before uploading or
-downloading files via the @code{-U} option or processing other @code{-T}
-terminal commands, if any.  See below for a detailed description of the
-terminal mode.
+Tells AVRDUDE to run an interactive terminal shell when it is its turn in
+relation to other @code{-t} interactive terminal shells, @code{-T}
+terminal commands and @code{-U} memory operations.
 
 @item -U @var{memory}:@var{op}:@var{filename}[:@var{format}]
-Perform a memory operation.
-Multiple @option{-U} options can be specified in order to operate on
-multiple memories on the same command-line invocation.  The
-@var{memory} field specifies the memory type to operate on. Use
-the @option{-v} option on the command line or the @code{part} command from
-terminal mode to display all the memory types supported by a particular
-device.
+Perform a memory operation when it is its turn in relation to other
+@code{-t} interactive terminal shells, @code{-T} terminal commands and
+@code{-U} memory operations. The @var{memory} field specifies the memory
+type to operate on. Use the @option{-T part} option on the command line or
+the @code{part} command in the interactive terminal to display all the
+memory types supported by a particular device.
 
 Typically, a device's memory configuration at least contains the memory
 types @code{flash}, @code{eeprom}, @code{signature} and @code{lock}, which

src/main.c

@@ -240,12 +240,11 @@ static void usage(void)
     "  -F                     Override invalid signature or initial checks\n"
     "  -e                     Perform a chip erase\n"
     "  -O                     Perform RC oscillator calibration (see AVR053)\n"
-    "  -t                     Enter terminal shell before processing -U/T\n"
-    "  -T <terminal cmd line> Slot terminal line into a list and run in turn\n"
+    "  -t                     Run an interactive terminal when it is its turn\n"
+    "  -T <terminal cmd line> Run terminal line when it is its turn\n"
     "  -U <memtype>:r|w|v:<filename>[:format]\n"
-    "                         Memory operation specification\n"
-    "                         Multiple -U/T options are allowed; each request\n"
-    "                         is performed in the specified intermixed order\n"
+    "                         Carry out memory operation when it is its turn\n"
+    "                         Multiple -t, -T and -U options can be specified\n"
     "  -n                     Do not write to the device whilst processing -U\n"
     "  -V                     Do not automatically verify during -U\n"
     "  -E <exitsp>[,<exitsp>] List programmer exit specifications\n"
@@ -511,11 +510,10 @@ int main(int argc, char * argv [])
   int     erase;       /* 1=erase chip, 0=don't */
   int     calibrate;   /* 1=calibrate RC oscillator, 0=don't */
   char  * port;        /* device port (/dev/xxx) */
-  int     terminal;    /* 1=enter terminal mode, 0=don't */
   const char *exitspecs; /* exit specs string from command line */
   const char *programmer; /* programmer id */
-  int     explicit_c;  /* 1=explicit -c on command line, 0=not spcified  there */
-  int     explicit_e;  /* 1=explicit -e on command line, 0=not spcified  there */
+  int     explicit_c;  /* 1=explicit -c on command line, 0=not specified there */
+  int     explicit_e;  /* 1=explicit -e on command line, 0=not specified there */
   char    sys_config[PATH_MAX]; /* system wide config file */
   char    usr_config[PATH_MAX]; /* per-user config file */
   char    executable_abspath[PATH_MAX]; /* absolute path to avrdude executable */
@@ -603,7 +601,6 @@ int main(int argc, char * argv [])
   calibrate     = 0;
   p             = NULL;
   ovsigck       = 0;
-  terminal      = 0;
   quell_progress = 0;
   exitspecs     = NULL;
   pgm           = NULL;
@@ -767,7 +764,7 @@ int main(int argc, char * argv [])
         break;
 
       case 't': /* enter terminal mode */
-        terminal = 1;
+        ladd(updates, cmd_update("interactive terminal"));
         break;
 
       case 's':
@@ -1249,7 +1246,6 @@ int main(int argc, char * argv [])
         upd->filename, mtype);
       upd->memtype = cfg_strdup("main()", mtype);
     }
-
     rc = update_dryrun(p, upd);
     if (rc && rc != LIBAVRDUDE_SOFTFAIL)
       doexit = 1;
@@ -1486,15 +1482,6 @@ int main(int argc, char * argv [])
     }
   }
 
-  if (terminal) {
-    /*
-     * terminal mode
-     */
-    if (uflags & UF_NOWRITE)
-      pmsg_warning("the terminal ignores option -n, that is, it writes to the device\n");
-    exitrc = terminal_mode(pgm, p);
-  }
-
   if (!init_ok) {
     /*
      * If we came here by the -tF options, bail out now.
@@ -1504,7 +1491,7 @@ int main(int argc, char * argv [])
   }
 
 
-  int wrmem = 0;
+  int wrmem = 0, terminal = 0;
   for (ln=lfirst(updates); ln; ln=lnext(ln)) {
     upd = ldata(ln);
     if(upd->cmdline && wrmem) { // Invalidate cache if device was written to
@@ -1514,6 +1501,8 @@ int main(int argc, char * argv [])
       pgm->flush_cache(pgm, p);
       wrmem |= upd->op == DEVICE_WRITE;
     }
+    if((uflags & UF_NOWRITE) && !terminal++ && upd->cmdline)
+      pmsg_warning("the terminal ignores option -n, that is, it writes to the device\n");
     rc = do_op(pgm, p, upd, uflags);
     if (rc && rc != LIBAVRDUDE_SOFTFAIL) {
       exitrc = 1;

src/update.c

@@ -147,7 +147,8 @@ void free_update(UPDATE * u)
 
 char *update_str(const UPDATE *upd) {
   if(upd->cmdline)
-    return str_sprintf("-T %s", upd->cmdline);
+    return str_sprintf("-%c %s",
+      str_eq("interactive terminal", upd->cmdline)? 't': 'T', upd->cmdline);
   return str_sprintf("-U %s:%c:%s:%c",
     upd->memtype,
     upd->op == DEVICE_READ? 'r': upd->op == DEVICE_WRITE? 'w': 'v',
@@ -375,8 +376,13 @@ int do_op(const PROGRAMMER *pgm, const AVRPART *p, const UPDATE *upd, enum updat
   pmsg_info("processing %s\n", tofree = update_str(upd));
   free(tofree);
 
-  if(upd->cmdline)
-    return terminal_line(pgm, p, upd->cmdline);
+  if(upd->cmdline) {
+    if(!str_eq(upd->cmdline, "interactive terminal"))
+      return terminal_line(pgm, p, upd->cmdline);
+    // Interactive terminal shell
+    clearerr(stdin);
+    return terminal_mode(pgm, p);
+  }
 
   mem = avr_locate_mem(p, upd->memtype);
   if (mem == NULL) {