Add read-only option

Add command line option to disable all system and process changing
features.

12 files changed, 108 insertions, 42 deletions

diff --git a/Action.c b/Action.c
index c894c92f..5cffe760 100644
--- a/Action.c
+++ b/Action.c
@@ -254,11 +254,17 @@ static Htop_Reaction actionIncSearch(State* st) {
 }
 
 static Htop_Reaction actionHigherPriority(State* st) {
+   if (Settings_isReadonly())
+      return HTOP_OK;
+
    bool changed = changePriority(st->mainPanel, -1);
    return changed ? HTOP_REFRESH : HTOP_OK;
 }
 
 static Htop_Reaction actionLowerPriority(State* st) {
+   if (Settings_isReadonly())
+      return HTOP_OK;
+
    bool changed = changePriority(st->mainPanel, 1);
    return changed ? HTOP_REFRESH : HTOP_OK;
 }
@@ -292,6 +298,9 @@ static Htop_Reaction actionQuit(ATTR_UNUSED State* st) {
 }
 
 static Htop_Reaction actionSetAffinity(State* st) {
+   if (Settings_isReadonly())
+      return HTOP_OK;
+
    if (st->pl->cpuCount == 1)
       return HTOP_OK;
 
@@ -323,6 +332,9 @@ static Htop_Reaction actionSetAffinity(State* st) {
 }
 
 static Htop_Reaction actionKill(State* st) {
+   if (Settings_isReadonly())
+      return HTOP_OK;
+
    Panel* signalsPanel = SignalsPanel_new();
    const ListItem* sgn = (ListItem*) Action_pickFromVector(st, signalsPanel, 15, true);
    if (sgn && sgn->key != 0) {
@@ -370,6 +382,9 @@ static Htop_Reaction actionSetup(State* st) {
 }
 
 static Htop_Reaction actionLsof(State* st) {
+   if (Settings_isReadonly())
+      return HTOP_OK;
+
    const Process* p = (Process*) Panel_getSelected((Panel*)st->mainPanel);
    if (!p)
       return HTOP_OK;
@@ -394,6 +409,9 @@ static Htop_Reaction actionShowLocks(State* st) {
 }
 
 static Htop_Reaction actionStrace(State* st) {
+   if (Settings_isReadonly())
+      return HTOP_OK;
+
    const Process* p = (Process*) Panel_getSelected((Panel*)st->mainPanel);
    if (!p)
       return HTOP_OK;
@@ -431,49 +449,51 @@ static Htop_Reaction actionTogglePauseProcessUpdate(State* st) {
 
 static const struct {
    const char* key;
+   bool roInactive;
    const char* info;
 } helpLeft[] = {
-   { .key = " Arrows: ", .info = "scroll process list" },
-   { .key = " Digits: ", .info = "incremental PID search" },
-   { .key = "   F3 /: ", .info = "incremental name search" },
-   { .key = "   F4 \\: ",.info = "incremental name filtering" },
-   { .key = "   F5 t: ", .info = "tree view" },
-   { .key = "      p: ", .info = "toggle program path" },
-   { .key = "      m: ", .info = "toggle merged command" },
-   { .key = "      Z: ", .info = "pause/resume process updates" },
-   { .key = "      u: ", .info = "show processes of a single user" },
-   { .key = "      H: ", .info = "hide/show user process threads" },
-   { .key = "      K: ", .info = "hide/show kernel threads" },
-   { .key = "      F: ", .info = "cursor follows process" },
-   { .key = "  + - *: ", .info = "expand/collapse tree/toggle all" },
-   { .key = "N P M T: ", .info = "sort by PID, CPU%, MEM% or TIME" },
-   { .key = "      I: ", .info = "invert sort order" },
-   { .key = " F6 > .: ", .info = "select sort column" },
+   { .key = " Arrows: ",  .roInactive = false, .info = "scroll process list" },
+   { .key = " Digits: ",  .roInactive = false, .info = "incremental PID search" },
+   { .key = "   F3 /: ",  .roInactive = false, .info = "incremental name search" },
+   { .key = "   F4 \\: ", .roInactive = false, .info = "incremental name filtering" },
+   { .key = "   F5 t: ",  .roInactive = false, .info = "tree view" },
+   { .key = "      p: ",  .roInactive = false, .info = "toggle program path" },
+   { .key = "      m: ",  .roInactive = false, .info = "toggle merged command" },
+   { .key = "      Z: ",  .roInactive = false, .info = "pause/resume process updates" },
+   { .key = "      u: ",  .roInactive = false, .info = "show processes of a single user" },
+   { .key = "      H: ",  .roInactive = false, .info = "hide/show user process threads" },
+   { .key = "      K: ",  .roInactive = false, .info = "hide/show kernel threads" },
+   { .key = "      F: ",  .roInactive = false, .info = "cursor follows process" },
+   { .key = "  + - *: ",  .roInactive = false, .info = "expand/collapse tree/toggle all" },
+   { .key = "N P M T: ",  .roInactive = false, .info = "sort by PID, CPU%, MEM% or TIME" },
+   { .key = "      I: ",  .roInactive = false, .info = "invert sort order" },
+   { .key = " F6 > .: ",  .roInactive = false, .info = "select sort column" },
    { .key = NULL, .info = NULL }
 };
 
 static const struct {
    const char* key;
+   bool roInactive;
    const char* info;
 } helpRight[] = {
-   { .key = "  Space: ", .info = "tag process" },
-   { .key = "      c: ", .info = "tag process and its children" },
-   { .key = "      U: ", .info = "untag all processes" },
-   { .key = "   F9 k: ", .info = "kill process/tagged processes" },
-   { .key = "   F7 ]: ", .info = "higher priority (root only)" },
-   { .key = "   F8 [: ", .info = "lower priority (+ nice)" },
+   { .key = "  Space: ", .roInactive = false, .info = "tag process" },
+   { .key = "      c: ", .roInactive = false, .info = "tag process and its children" },
+   { .key = "      U: ", .roInactive = false, .info = "untag all processes" },
+   { .key = "   F9 k: ", .roInactive = true,  .info = "kill process/tagged processes" },
+   { .key = "   F7 ]: ", .roInactive = true,  .info = "higher priority (root only)" },
+   { .key = "   F8 [: ", .roInactive = false, .info = "lower priority (+ nice)" },
 #if (defined(HAVE_LIBHWLOC) || defined(HAVE_LINUX_AFFINITY))
-   { .key = "      a: ", .info = "set CPU affinity" },
+   { .key = "      a: ", .roInactive = true, .info = "set CPU affinity" },
 #endif
-   { .key = "      e: ", .info = "show process environment" },
-   { .key = "      i: ", .info = "set IO priority" },
-   { .key = "      l: ", .info = "list open files with lsof" },
-   { .key = "      x: ", .info = "list file locks of process" },
-   { .key = "      s: ", .info = "trace syscalls with strace" },
-   { .key = "      w: ", .info = "wrap process command in multiple lines" },
-   { .key = " F2 C S: ", .info = "setup" },
-   { .key = "   F1 h: ", .info = "show this help screen" },
-   { .key = "  F10 q: ", .info = "quit" },
+   { .key = "      e: ", .roInactive = false, .info = "show process environment" },
+   { .key = "      i: ", .roInactive = true,  .info = "set IO priority" },
+   { .key = "      l: ", .roInactive = true,  .info = "list open files with lsof" },
+   { .key = "      x: ", .roInactive = false, .info = "list file locks of process" },
+   { .key = "      s: ", .roInactive = true,  .info = "trace syscalls with strace" },
+   { .key = "      w: ", .roInactive = false, .info = "wrap process command in multiple lines" },
+   { .key = " F2 C S: ", .roInactive = false, .info = "setup" },
+   { .key = "   F1 h: ", .roInactive = false, .info = "show this help screen" },
+   { .key = "  F10 q: ", .roInactive = false, .info = "quit" },
    { .key = NULL, .info = NULL }
 };
 
@@ -549,26 +569,28 @@ static Htop_Reaction actionHelp(State* st) {
 
    line++;
 
+   const bool readonly = Settings_isReadonly();
+
    int item;
    for (item = 0; helpLeft[item].key; item++) {
-      attrset(CRT_colors[DEFAULT_COLOR]);
+      attrset((helpLeft[item].roInactive && readonly) ? CRT_colors[HELP_SHADOW] : CRT_colors[DEFAULT_COLOR]);
       mvaddstr(line + item, 10, helpLeft[item].info);
-      attrset(CRT_colors[HELP_BOLD]);
+      attrset((helpLeft[item].roInactive && readonly) ? CRT_colors[HELP_SHADOW] : CRT_colors[HELP_BOLD]);
       mvaddstr(line + item, 1,  helpLeft[item].key);
       if (String_eq(helpLeft[item].key, "      H: ")) {
-         attrset(CRT_colors[PROCESS_THREAD]);
+         attrset((helpLeft[item].roInactive && readonly) ? CRT_colors[HELP_SHADOW] : CRT_colors[PROCESS_THREAD]);
          mvaddstr(line + item, 33, "threads");
       } else if (String_eq(helpLeft[item].key, "      K: ")) {
-         attrset(CRT_colors[PROCESS_THREAD]);
+         attrset((helpLeft[item].roInactive && readonly) ? CRT_colors[HELP_SHADOW] : CRT_colors[PROCESS_THREAD]);
          mvaddstr(line + item, 27, "threads");
       }
    }
    int leftHelpItems = item;
 
    for (item = 0; helpRight[item].key; item++) {
-      attrset(CRT_colors[HELP_BOLD]);
+      attrset((helpRight[item].roInactive && readonly) ? CRT_colors[HELP_SHADOW] : CRT_colors[HELP_BOLD]);
       mvaddstr(line + item, 41, helpRight[item].key);
-      attrset(CRT_colors[DEFAULT_COLOR]);
+      attrset((helpRight[item].roInactive && readonly) ? CRT_colors[HELP_SHADOW] : CRT_colors[DEFAULT_COLOR]);
       mvaddstr(line + item, 50, helpRight[item].info);
    }
    line += MAXIMUM(leftHelpItems, item);
diff --git a/CRT.c b/CRT.c
index acf21bb6..481e16c1 100644
--- a/CRT.c
+++ b/CRT.c
@@ -166,6 +166,7 @@ static int CRT_colorSchemes[LAST_COLORSCHEME][LAST_COLORELEMENT] = {
       [LOAD_AVERAGE_ONE] = A_BOLD | ColorPair(White, Black),
       [LOAD] = A_BOLD,
       [HELP_BOLD] = A_BOLD | ColorPair(Cyan, Black),
+      [HELP_SHADOW] = A_BOLD | ColorPairGrayBlack,
       [CLOCK] = A_BOLD,
       [DATE] = A_BOLD,
       [DATETIME] = A_BOLD,
@@ -258,6 +259,7 @@ static int CRT_colorSchemes[LAST_COLORSCHEME][LAST_COLORELEMENT] = {
       [LOAD_AVERAGE_ONE] = A_BOLD,
       [LOAD] = A_BOLD,
       [HELP_BOLD] = A_BOLD,
+      [HELP_SHADOW] = A_DIM,
       [CLOCK] = A_BOLD,
       [DATE] = A_BOLD,
       [DATETIME] = A_BOLD,
@@ -350,6 +352,7 @@ static int CRT_colorSchemes[LAST_COLORSCHEME][LAST_COLORELEMENT] = {
       [LOAD_AVERAGE_ONE] = ColorPair(Black, White),
       [LOAD] = ColorPair(Black, White),
       [HELP_BOLD] = ColorPair(Blue, White),
+      [HELP_SHADOW] = A_BOLD | ColorPair(Black, White),
       [CLOCK] = ColorPair(Black, White),
       [DATE] = ColorPair(Black, White),
       [DATETIME] = ColorPair(Black, White),
@@ -442,6 +445,7 @@ static int CRT_colorSchemes[LAST_COLORSCHEME][LAST_COLORELEMENT] = {
       [LOAD_AVERAGE_ONE] = ColorPair(Black, Black),
       [LOAD] = ColorPairWhiteDefault,
       [HELP_BOLD] = ColorPair(Blue, Black),
+      [HELP_SHADOW] = A_BOLD | ColorPairGrayBlack,
       [CLOCK] = ColorPairWhiteDefault,
       [DATE] = ColorPairWhiteDefault,
       [DATETIME] = ColorPairWhiteDefault,
@@ -534,6 +538,7 @@ static int CRT_colorSchemes[LAST_COLORSCHEME][LAST_COLORELEMENT] = {
       [LOAD_AVERAGE_ONE] = A_BOLD | ColorPair(White, Blue),
       [LOAD] = A_BOLD | ColorPair(White, Blue),
       [HELP_BOLD] = A_BOLD | ColorPair(Cyan, Blue),
+      [HELP_SHADOW] = A_BOLD | ColorPair(Black, Blue),
       [CLOCK] = ColorPair(White, Blue),
       [DATE] = ColorPair(White, Blue),
       [DATETIME] = ColorPair(White, Blue),
@@ -626,6 +631,7 @@ static int CRT_colorSchemes[LAST_COLORSCHEME][LAST_COLORELEMENT] = {
       [LOAD_AVERAGE_ONE] = A_BOLD | ColorPair(Green, Black),
       [LOAD] = A_BOLD,
       [HELP_BOLD] = A_BOLD | ColorPair(Cyan, Black),
+      [HELP_SHADOW] = A_BOLD | ColorPairGrayBlack,
       [CLOCK] = ColorPair(Green, Black),
       [CHECK_BOX] = ColorPair(Green, Black),
       [CHECK_MARK] = A_BOLD | ColorPair(Green, Black),
diff --git a/CRT.h b/CRT.h
index 92357528..e85247bd 100644
--- a/CRT.h
+++ b/CRT.h
@@ -109,6 +109,7 @@ typedef enum ColorElements_ {
    DATE,
    DATETIME,
    HELP_BOLD,
+   HELP_SHADOW,
    HOSTNAME,
    CPU_NICE,
    CPU_NICE_TEXT,
diff --git a/CommandLine.c b/CommandLine.c
index 796018af..16ded1fa 100644
--- a/CommandLine.c
+++ b/CommandLine.c
@@ -53,6 +53,7 @@ static void printHelpFlag(const char* name) {
          "-H --highlight-changes[=DELAY]  Highlight new and old processes\n"
          "-M --no-mouse                   Disable the mouse\n"
          "-p --pid=PID[,PID,PID...]       Show only the given PIDs\n"
+         "   --readonly                   Disable all system and process changing features\n"
          "-s --sort-key=COLUMN            Sort by COLUMN in list view (try --sort-key=help for a list)\n"
          "-t --tree                       Show the tree view (can be combined with -s)\n"
          "-u --user[=USERNAME]            Show only processes for a given user (or $USER)\n"
@@ -79,6 +80,7 @@ typedef struct CommandLineSettings_ {
    bool allowUnicode;
    bool highlightChanges;
    int highlightDelaySecs;
+   bool readonly;
 } CommandLineSettings;
 
 static CommandLineSettings parseArguments(const char* program, int argc, char** argv) {
@@ -95,6 +97,7 @@ static CommandLineSettings parseArguments(const char* program, int argc, char**
       .allowUnicode = true,
       .highlightChanges = false,
       .highlightDelaySecs = -1,
+      .readonly = false,
    };
 
    const struct option long_opts[] =
@@ -112,6 +115,7 @@ static CommandLineSettings parseArguments(const char* program, int argc, char**
       {"pid",        required_argument,   0, 'p'},
       {"filter",     required_argument,   0, 'F'},
       {"highlight-changes", optional_argument, 0, 'H'},
+      {"readonly",   no_argument,         0, 128},
       PLATFORM_LONG_OPTIONS
       {0,0,0,0}
    };
@@ -231,6 +235,9 @@ static CommandLineSettings parseArguments(const char* program, int argc, char**
             flags.highlightChanges = true;
             break;
          }
+         case 128:
+            flags.readonly = true;
+            break;
 
          default:
            if (Platform_getLongOption(opt, argc, argv) == false)
@@ -273,6 +280,9 @@ int CommandLine_run(const char* name, int argc, char** argv) {
 
    CommandLineSettings flags = parseArguments(name, argc, argv);
 
+   if (flags.readonly)
+      Settings_enableReadonly();
+
    Platform_init();
 
    Process_setupColumnWidths();
diff --git a/MainPanel.c b/MainPanel.c
index 842e8e15..cf7392e4 100644
--- a/MainPanel.c
+++ b/MainPanel.c
@@ -21,7 +21,8 @@ in the source distribution for its full text.
 #include "XUtils.h"
 
 
-static const char* const MainFunctions[]  = {"Help  ", "Setup ", "Search", "Filter", "Tree  ", "SortBy", "Nice -", "Nice +", "Kill  ", "Quit  ", NULL};
+static const char* const MainFunctions[]     = {"Help  ", "Setup ", "Search", "Filter", "Tree  ", "SortBy", "Nice -", "Nice +", "Kill  ", "Quit  ", NULL};
+static const char* const MainFunctions_ro[]  = {"Help  ", "Setup ", "Search", "Filter", "Tree  ", "SortBy", "      ", "      ", "      ", "Quit  ", NULL};
 
 void MainPanel_updateTreeFunctions(MainPanel* this, bool mode) {
    FunctionBar* bar = MainPanel_getFunctionBar(this);
@@ -195,7 +196,7 @@ const PanelClass MainPanel_class = {
 
 MainPanel* MainPanel_new() {
    MainPanel* this = AllocThis(MainPanel);
-   Panel_init((Panel*) this, 1, 1, 1, 1, Class(Process), false, FunctionBar_new(MainFunctions, NULL, NULL));
+   Panel_init((Panel*) this, 1, 1, 1, 1, Class(Process), false, FunctionBar_new(Settings_isReadonly() ? MainFunctions_ro : MainFunctions, NULL, NULL));
    this->keys = xCalloc(KEY_MAX, sizeof(Htop_Action));
    this->inc = IncSet_new(MainPanel_getFunctionBar(this));
 
diff --git a/Process.c b/Process.c
index 1ca942a3..e7431cec 100644
--- a/Process.c
+++ b/Process.c
@@ -482,6 +482,9 @@ bool Process_isTomb(const Process* this) {
 }
 
 bool Process_setPriority(Process* this, int priority) {
+   if (Settings_isReadonly())
+      return false;
+
    int old_prio = getpriority(PRIO_PROCESS, this->pid);
    int err = setpriority(PRIO_PROCESS, this->pid, priority);
 
diff --git a/Settings.c b/Settings.c
index 8baad6a7..0606df30 100644
--- a/Settings.c
+++ b/Settings.c
@@ -472,3 +472,13 @@ void Settings_setSortKey(Settings* this, ProcessField sortKey) {
       this->treeDirection = (Process_fields[sortKey].defaultSortDesc) ? -1 : 1;
    }
 }
+
+static bool readonly = false;
+
+void Settings_enableReadonly(void) {
+   readonly = true;
+}
+
+bool Settings_isReadonly(void) {
+   return readonly;
+}
diff --git a/Settings.h b/Settings.h
index f10b3055..7313ce38 100644
--- a/Settings.h
+++ b/Settings.h
@@ -95,4 +95,8 @@ void Settings_invertSortOrder(Settings* this);
 
 void Settings_setSortKey(Settings* this, ProcessField sortKey);
 
+void Settings_enableReadonly(void);
+
+bool Settings_isReadonly(void);
+
 #endif
diff --git a/htop.1.in b/htop.1.in
index 5408dbb4..e8cfc3f6 100644
--- a/htop.1.in
+++ b/htop.1.in
@@ -54,6 +54,9 @@ Do not use unicode but ASCII characters for graph meters
 \fB\-M \-\-no-mouse\fR
 Disable support of mouse control
 .TP
+\fB\-\-readonly\fR
+Disable all system and process changing features
+.TP
 \fB\-V \-\-version
 Output version information and exit
 .TP
diff --git a/linux/Platform.c b/linux/Platform.c
index 831ea273..af3fa277 100644
--- a/linux/Platform.c
+++ b/linux/Platform.c
@@ -130,6 +130,9 @@ static enum CapMode Platform_capabilitiesMode = CAP_MODE_BASIC;
 #endif
 
 static Htop_Reaction Platform_actionSetIOPriority(State* st) {
+   if (Settings_isReadonly())
+      return HTOP_OK;
+
    const LinuxProcess* p = (const LinuxProcess*) Panel_getSelected((Panel*)st->mainPanel);
    if (!p)
       return HTOP_OK;
@@ -873,7 +876,7 @@ bool Platform_getLongOption(int opt, int argc, char** argv) {
 
    switch (opt) {
 #ifdef HAVE_LIBCAP
-      case 128: {
+      case 160: {
          const char* mode = optarg;
          if (!mode && optind < argc && argv[optind] != NULL &&
             (argv[optind][0] != '\0' && argv[optind][0] != '-')) {
diff --git a/linux/Platform.h b/linux/Platform.h
index 78a44275..2506fae5 100644
--- a/linux/Platform.h
+++ b/linux/Platform.h
@@ -85,7 +85,7 @@ static inline void Platform_getRelease(char** string) {
 
 #ifdef HAVE_LIBCAP
    #define PLATFORM_LONG_OPTIONS \
-      {"drop-capabilities", optional_argument, 0, 128},
+      {"drop-capabilities", optional_argument, 0, 160},
 #else
    #define PLATFORM_LONG_OPTIONS
 #endif
diff --git a/linux/SystemdMeter.c b/linux/SystemdMeter.c
index 24a47f74..a891eb11 100644
--- a/linux/SystemdMeter.c
+++ b/linux/SystemdMeter.c
@@ -195,6 +195,9 @@ dlfailure:
 #endif /* !BUILD_STATIC || HAVE_LIBSYSTEMD */
 
 static void updateViaExec(void) {
+   if (Settings_isReadonly())
+      return;
+
    int fdpair[2];
    if (pipe(fdpair) < 0)
       return;