Add ability to run arbitrary commands on keypress

Action.c

@@ -33,6 +33,7 @@ in the source distribution for its full text.
 #include "ProvideCurses.h"
 #include "Row.h"
 #include "RowField.h"
+#include "RunScript.h"
 #include "Scheduling.h"
 #include "ScreenManager.h"
 #include "SignalsPanel.h"
@@ -646,6 +647,11 @@ static Htop_Reaction actionTogglePauseUpdate(State* st) {
    return HTOP_REFRESH | HTOP_REDRAW_BAR | HTOP_KEEP_FOLLOWING;
 }
 
+static Htop_Reaction actionRunScript(State* st) {
+   RunScript(st);
+   return HTOP_OK;
+}
+
 static const struct {
    const char* key;
    bool roInactive;
@@ -700,6 +706,7 @@ static const struct {
    { .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 = "      r: ", .roInactive = false, .info = "execute user script on tagged processes"},
    { .key = NULL, .info = NULL }
 };
 
@@ -939,6 +946,7 @@ void Action_setBindings(Htop_Action* keys) {
    keys['m'] = actionToggleMergedCommand;
    keys['p'] = actionToggleProgramPath;
    keys['q'] = actionQuit;
+   keys['r'] = actionRunScript;
    keys['s'] = actionStrace;
    keys['t'] = actionToggleTreeView;
    keys['u'] = actionFilterByUser;

Makefile.am

@@ -75,11 +75,13 @@ myhtopsources = \
 	ProcessLocksScreen.c \
 	ProcessTable.c \
 	Row.c \
+	RunScript.c \
 	RichString.c \
 	Scheduling.c \
 	ScreenManager.c \
 	ScreensPanel.c \
 	ScreenTabsPanel.c \
+	ScriptOutputScreen.c \
 	Settings.c \
 	SignalsPanel.c \
 	SwapMeter.c \
@@ -148,11 +150,13 @@ myhtopheaders = \
 	ProvideTerm.h \
 	RichString.h \
 	Row.h \
+	RunScript.h \
 	RowField.h \
 	Scheduling.h \
 	ScreenManager.h \
 	ScreensPanel.h \
 	ScreenTabsPanel.h \
+	ScriptOutputScreen.h \
 	Settings.h \
 	SignalsPanel.h \
 	SwapMeter.h \

RunScript.c

@@ -0,0 +1,153 @@
+/*
+htop - RunScript.h
+(C) 2025 htop dev team
+Released under the GNU GPLv2+, see the COPYING file
+in the source distribution for its full text.
+*/
+
+#include "config.h" // IWYU pragma: keep
+
+#include "RunScript.h"
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "Action.h"
+#include "InfoScreen.h"
+#include "MainPanel.h"
+#include "Object.h"
+#include "Panel.h"
+#include "Process.h"
+#include "Row.h"
+#include "ScriptOutputScreen.h"
+#include "Settings.h"
+#include "XUtils.h"
+
+
+static void write_row(Row* row, int write_fd) {
+   Process* this = (Process*) row;
+   assert(Object_isA((const Object*) this, (const ObjectClass*) &Process_class));
+
+   int pid_length = snprintf(NULL, 0, "%d", row->id);
+   char pid[pid_length + 1];
+   snprintf(pid, pid_length + 1, "%d", row->id);
+
+   char* pid_str = String_cat(pid, "\t");
+   char* user = String_cat(this->user, "\t");
+   char* cmd = String_cat(Process_getCommand(this), "\n");
+   char* user_and_cmd = String_cat(user, cmd);
+   char* line = String_cat(pid_str, user_and_cmd);
+
+   // writes PID\tUser\tCommand\n, using TSV format
+   size_t count = strlen(line);
+   char* line_start = line;
+   while (count > 0) {
+      ssize_t res = write(write_fd, line_start, strlen(line));
+      if ((res == -1 && errno != EINTR) || res == 0)
+         break;
+
+      count -= res;
+      line_start += res;
+   }
+
+   free(pid_str);
+   free(user);
+   free(cmd);
+   free(user_and_cmd);
+   free(line);
+}
+
+void RunScript(State* st) {
+   int child_read[2] = {0, 0};
+   int child_write[2] = {0, 0};
+
+   if (pipe(child_read) == -1)
+      return;
+   if (pipe(child_write) == -1) {
+      close(child_read[0]);
+      close(child_read[1]);
+      return;
+   }
+
+   pid_t child = fork();
+   if (child == -1) {
+      close(child_read[0]);
+      close(child_read[1]);
+      close(child_write[0]);
+      close(child_write[1]);
+      fprintf(stderr, "fork failed\n");
+      return;
+   } else if (child == 0) {
+      close(child_read[1]);
+      dup2(child_read[0], STDIN_FILENO);
+      close(child_read[0]);
+
+      close(child_write[0]);
+      dup2(child_write[1], STDOUT_FILENO);
+      dup2(child_write[1], STDERR_FILENO);
+      close(child_write[1]);
+
+      char* home = getenv("XDG_CONFIG_HOME");
+      if (!home)
+         home = String_cat(getenv("HOME"), "./config");
+
+      const char* path = String_cat(home, "/htop/run_script");
+      FILE* file = fopen(path, "r");
+      if (file) {
+         execl(path, path, NULL);
+         // should not reach here unless execl fails
+         fprintf(stderr, "error excuting %s\n", path);
+         perror("execl");
+      } else {
+         // check if htoprc has something
+         const char* htoprc_path = st->host->settings->scriptLocation;
+         execl(htoprc_path, htoprc_path, NULL);
+
+         // only reach here if execl fails
+         fprintf(stderr, "error executing %s from htoprc", htoprc_path);
+         fprintf(stderr, "if you expected your runscript to be executed, htop looked for it at %s", path);
+         perror("execl");
+      }
+      exit(1);
+   }
+
+   close(child_read[0]);
+   close(child_write[1]);
+
+   bool anyTagged = false;
+   Panel* super = &st->mainPanel->super;
+   for (int i = 0; i < Panel_size(super); i++) {
+      Row* row = (Row*) Panel_get(super, i);
+      if (row->tag) {
+         write_row(row, child_read[1]);
+         anyTagged = true;
+      }
+   }
+   // if nothing was tagged, operate on the highlighted row
+   if (!anyTagged) {
+      Row* row = (Row*) Panel_getSelected(super);
+      if (row)
+         write_row(row, child_read[1]);
+   }
+
+   // tell script/child we're done with sending input
+   close(child_read[1]);
+
+   const Process* p = (Process*) Panel_getSelected((Panel*)st->mainPanel);
+   if (!p)
+      return;
+
+   assert(Object_isA((const Object*) p, (const ObjectClass*) &Process_class));
+   ScriptOutputScreen* sos = ScriptOutputScreen_new(p);
+   if (fcntl(child_write[0], F_SETFL, O_NONBLOCK) >= 0) {
+      ScriptOutputScreen_SetFd(sos, child_write[0]);
+      InfoScreen_run((InfoScreen*)sos);
+   }
+   ScriptOutputScreen_delete((Object*)sos);
+}

RunScript.h

@@ -0,0 +1,21 @@
+#ifndef RUNSCRIPT_Process
+#define RUNSCRIPT_Process
+/*
+htop - RunScript.h
+(C) 2025 htop dev team
+Released under the GNU GPLv2+, see the COPYING file
+in the source distribution for its full text.
+*/
+
+#include "Action.h"
+
+
+typedef struct Node_ {
+   char* line;
+   struct Node_* next;
+} Node;
+
+
+void RunScript(State*);
+
+#endif

ScriptOutputScreen.c

@@ -0,0 +1,133 @@
+/*
+htop - ScriptOutputScreen.c
+(C) 2025 htop dev team
+Released under the GNU GPLv2+, see the COPYING file
+in the source distribution for its full text.
+*/
+
+#include "config.h" // IWYU pragma: keep
+
+#include "ScriptOutputScreen.h"
+
+#include <assert.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "Panel.h"
+#include "ProvideCurses.h"
+#include "XUtils.h"
+
+
+ScriptOutputScreen* ScriptOutputScreen_new(const Process* process) {
+   ScriptOutputScreen* this = xCalloc(1, sizeof(ScriptOutputScreen));
+   Object_setClass(this, Class(ScriptOutputScreen));
+   // this fd needs to be set later
+   this->read_fd = -1;
+   this->data_head = NULL;
+   this->data_tail = &this->data_head;
+   return (ScriptOutputScreen*) InfoScreen_init(&this->super, process, NULL, LINES - 2, " ");
+}
+
+void ScriptOutputScreen_SetFd(ScriptOutputScreen* this, int fd) {
+   this->read_fd = fd;
+}
+
+void ScriptOutputScreen_delete(Object* this) {
+   // free the linked list and close fd
+   assert(Object_isA((const Object*) this, (const ObjectClass*) &ScriptOutputScreen_class));
+   Node* walk = ((ScriptOutputScreen*)this)->data_head;
+   while (walk) {
+      free(walk->line);
+      Node* next = walk->next;
+      free(walk);
+      walk = next;
+   }
+   close(((ScriptOutputScreen*)this)->read_fd);
+   free(InfoScreen_done((InfoScreen*)this));
+}
+
+static void ScriptOutputScreen_scan(InfoScreen* super) {
+   Panel* panel = super->display;
+   int idx = Panel_getSelectedIndex(panel);
+   Panel_prune(panel);
+
+   char buffer[8192];
+   ScriptOutputScreen* sos = ((ScriptOutputScreen*)super);
+   assert(Object_isA((const Object*) sos, (const ObjectClass*) &ScriptOutputScreen_class));
+
+   // redraw existing stuff in the screen first
+   Node* walk = sos->data_head;
+   while (walk) {
+      InfoScreen_addLine(super, walk->line);
+      walk = walk->next;
+   }
+
+   for (;;) {
+      ssize_t res = read(sos->read_fd, buffer, sizeof(buffer) - 1);
+      if (res < 0) {
+         if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)
+            continue;
+
+         break;
+      }
+
+      if (res == 0) {
+         break;
+      }
+
+      if (res > 0) {
+         int start = 0;
+         int num_tabs = 0;
+         for (int i = 0; i <= res; i++) {
+            num_tabs += (buffer[i] == '\t');
+            // split line when find \n or exhaust buffer
+            if (i == res || buffer[i] == '\n') {
+               buffer[i] = '\0';
+               char* str;
+               if (num_tabs > 0) {
+                  // manually replace all \t with TABSIZE spaces
+                  str = xMalloc((num_tabs * TABSIZE + i - start + 1) * sizeof(char));
+                  int index = 0;
+                  for (int j = start; j <= i; j++) {
+                     if (buffer[j] == '\t') {
+                        for (int k = 0; k < TABSIZE; k++) {
+                           str[index++] = ' ';
+                        }
+                     } else {
+                        str[index++] = buffer[j];
+                     }
+                  }
+               } else {
+                  str = buffer + start;
+               }
+               InfoScreen_addLine(super, str);
+               // store line for next redraw
+               *(sos->data_tail) = xMalloc(sizeof(Node));
+               (*sos->data_tail)->line = xStrdup(str);
+               (*sos->data_tail)->next = NULL;
+               *(&sos->data_tail) = &((*sos->data_tail)->next);
+
+               if (num_tabs > 0)
+                  free(str);
+               start = i + 1;
+               num_tabs = 0;
+            }
+         }
+      }
+   }
+   Panel_setSelected(panel, idx);
+}
+
+static void ScriptOutputScreen_draw(InfoScreen* this ) {
+   InfoScreen_drawTitled(this, "Output of script for process %d - %s", Process_getPid(this->process), Process_getCommand(this->process));
+}
+
+const InfoScreenClass ScriptOutputScreen_class = {
+   .super = {
+      .extends = Class(Object),
+      .delete = ScriptOutputScreen_delete
+   },
+   .scan = ScriptOutputScreen_scan,
+   .draw = ScriptOutputScreen_draw
+};