show selected command wrapped in a separate window

For a process with a very long command, especially with many long
command line arguments, inspecting the command and its arguments could
become inconvenient.

Meanwhile htop supports the concept of "screen", or window, which is
extended here to create a dedicated "CommandScreen", making it possible
to display the command of the selected process in a separate window
meanwhile being wrapped into multiple lines.

Another benefit of using a command screen is, the user can navigate
through the wrapped lines of the command and perform actions like
searching and filtering.

Action.c

@@ -13,6 +13,7 @@ in the source distribution for its full text.
 #include "CategoriesPanel.h"
 #include "CRT.h"
 #include "EnvScreen.h"
+#include "CommandScreen.h"
 #include "MainPanel.h"
 #include "OpenFilesScreen.h"
 #include "Process.h"
@@ -422,8 +423,8 @@ static const struct { const char* key; const char* info; } helpRight[] = {
    { .key = "      e: ", .info = "show process environment" },
    { .key = "      i: ", .info = "set IO priority" },
    { .key = "      l: ", .info = "list open files with lsof" },
+   { .key = "      M: ", .info = "show process command in multiple lines" },
    { .key = "      s: ", .info = "trace syscalls with strace" },
-   { .key = "         ", .info = "" },
    { .key = " F2 C S: ", .info = "setup" },
    { .key = "   F1 h: ", .info = "show this help screen" },
    { .key = "  F10 q: ", .info = "quit" },
@@ -530,6 +531,16 @@ static Htop_Reaction actionShowEnvScreen(State* st) {
    return HTOP_REFRESH | HTOP_REDRAW_BAR;
 }
 
+static Htop_Reaction actionShowCommandScreen(State* st) {
+   Process* p = (Process*) Panel_getSelected(st->panel);
+   if (!p) return HTOP_OK;
+   CommandScreen* cmdScr = CommandScreen_new(p);
+   InfoScreen_run((InfoScreen*)cmdScr);
+   CommandScreen_delete((Object*)cmdScr);
+   clear();
+   CRT_enableDelay();
+   return HTOP_REFRESH | HTOP_REDRAW_BAR;
+}
 
 void Action_setBindings(Htop_Action* keys) {
    keys[KEY_RESIZE] = actionResize;
@@ -584,4 +595,5 @@ void Action_setBindings(Htop_Action* keys) {
    keys['U'] = actionUntagAll;
    keys['c'] = actionTagAllChildren;
    keys['e'] = actionShowEnvScreen;
+   keys['M'] = actionShowCommandScreen;
 }

CommandScreen.c

@@ -0,0 +1,74 @@
+#include "CommandScreen.h"
+
+#include "config.h"
+#include "CRT.h"
+#include "IncSet.h"
+#include "ListItem.h"
+#include "Platform.h"
+#include "StringUtils.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+
+static void CommandScreen_addLine(InfoScreen* this, char* line, const char* p, int line_offset, int len) {
+   memcpy(line, p - line_offset, len);
+   line[len] = '\0';
+   InfoScreen_addLine(this, line);
+}
+
+static void CommandScreen_scan(InfoScreen* this) {
+   Panel* panel = this->display;
+   int idx = MAXIMUM(Panel_getSelectedIndex(panel), 0);
+
+   Panel_prune(panel);
+
+   const char* p = this->process->comm;
+   char* line = xMalloc(COLS + 1);
+   int line_offset = 0, last_spc = -1, len;
+   for (; *p != '\0'; p++, line_offset++) {
+      if (*p == ' ') last_spc = line_offset;
+
+      if (line_offset == COLS) {
+         len = (last_spc == -1) ? line_offset : last_spc;
+         CommandScreen_addLine(this, line, p, line_offset, len);
+         line_offset -= len;
+         last_spc = -1;
+      }
+   }
+
+   if (line_offset > 0) CommandScreen_addLine(this, line, p, line_offset, line_offset);
+
+   free(line);
+   Panel_setSelected(panel, idx);
+}
+
+static void CommandScreen_draw(InfoScreen* this) {
+   char* title = xMalloc(COLS + 1);
+   int len = snprintf(title, COLS + 1, "Command of process %d - %s", this->process->pid, this->process->comm);
+   if (len > COLS) {
+      memset(&title[COLS - 3], '.', 3);
+   }
+
+   InfoScreen_drawTitled(this, "%s", title);
+   free(title);
+}
+
+InfoScreenClass CommandScreen_class = {
+   .super = {
+      .extends = Class(Object),
+      .delete = CommandScreen_delete
+   },
+   .scan = CommandScreen_scan,
+   .draw = CommandScreen_draw
+};
+
+CommandScreen* CommandScreen_new(Process* process) {
+   CommandScreen* this = AllocThis(CommandScreen);
+   return (CommandScreen*) InfoScreen_init(&this->super, process, NULL, LINES - 3, " ");
+}
+
+void CommandScreen_delete(Object* this) {
+   free(InfoScreen_done((InfoScreen*)this));
+}

CommandScreen.h

@@ -0,0 +1,16 @@
+#ifndef HEADER_CommandScreen
+#define HEADER_CommandScreen
+
+#include "InfoScreen.h"
+
+typedef struct CommandScreen_ {
+   InfoScreen super;
+} CommandScreen;
+
+extern InfoScreenClass CommandScreen_class;
+
+CommandScreen* CommandScreen_new(Process* process);
+
+void CommandScreen_delete(Object* this);
+
+#endif

Makefile.am

@@ -22,7 +22,7 @@ BatteryMeter.c Process.c ProcessList.c RichString.c ScreenManager.c Settings.c \
 SignalsPanel.c StringUtils.c SwapMeter.c TasksMeter.c UptimeMeter.c \
 TraceScreen.c UsersTable.c Vector.c AvailableColumnsPanel.c AffinityPanel.c \
 HostnameMeter.c OpenFilesScreen.c Affinity.c IncSet.c Action.c EnvScreen.c \
-InfoScreen.c XAlloc.c
+InfoScreen.c CommandScreen.c XAlloc.c
 
 myhtopheaders = AvailableColumnsPanel.h AvailableMetersPanel.h \
 CategoriesPanel.h CheckItem.h ClockMeter.h ColorsPanel.h ColumnsPanel.h \
@@ -32,7 +32,7 @@ BatteryMeter.h Meter.h MetersPanel.h Object.h Panel.h ProcessList.h RichString.h
 ScreenManager.h Settings.h SignalsPanel.h StringUtils.h SwapMeter.h \
 TasksMeter.h UptimeMeter.h TraceScreen.h UsersTable.h Vector.h Process.h \
 AffinityPanel.h HostnameMeter.h OpenFilesScreen.h Affinity.h IncSet.h Action.h \
-EnvScreen.h InfoScreen.h XAlloc.h Macros.h
+EnvScreen.h InfoScreen.h CommandScreen.h XAlloc.h Macros.h
 
 # Linux
 # -----

htop.1.in

@@ -116,6 +116,9 @@ update of system calls issued by the process.
 Display open files for a process: if lsof(1) is installed, pressing this key
 will display the list of file descriptors opened by the process.
 .TP
+.B M
+Display the command line of the highlighted process in multiple lines.
+.TP
 .B F1, h, ?
 Go to the help screen
 .TP