allow screen blank for privacy

CMakeLists.txt

@@ -19,7 +19,7 @@ IF(NOT HAVE_LINUX_API_HEADERS)
   message(FATAL_ERROR "linux-api-headers not found")
 ENDIF()
 
-add_executable(kmsvnc kmsvnc.c drm.c input.c keymap.c va.c)
+add_executable(kmsvnc kmsvnc.c drm.c input.c keymap.c va.c drm_master.c)
 target_include_directories(kmsvnc PUBLIC
   ${LIBDRM_INCLUDEDIR}
   ${LIBDRM_INCLUDEDIR}/libdrm

drm.c

@@ -10,6 +10,7 @@
 
 #include "drm.h"
 #include "va.h"
+#include "drm_master.h"
 
 extern struct kmsvnc_data *kmsvnc;
 
@@ -154,6 +155,17 @@ void drm_sync_noop(int drmfd)
 
 void drm_cleanup() {
     if (kmsvnc->drm) {
+        if (kmsvnc->drm->gamma && kmsvnc->drm->gamma->size && kmsvnc->drm->gamma->red && kmsvnc->drm->gamma->green && kmsvnc->drm->gamma->blue) {
+            if (drmModeCrtcSetGamma(kmsvnc->drm->drm_master_fd ?: kmsvnc->drm->drm_fd, kmsvnc->drm->plane->crtc_id, kmsvnc->drm->gamma->size, kmsvnc->drm->gamma->red, kmsvnc->drm->gamma->green, kmsvnc->drm->gamma->blue)) perror("Failed to restore gamma");
+        }
+        if (kmsvnc->drm->gamma && kmsvnc->drm->gamma->red) {
+            free(kmsvnc->drm->gamma->red);
+            kmsvnc->drm->gamma->red = kmsvnc->drm->gamma->green = kmsvnc->drm->gamma->blue = NULL;
+        }
+        if (kmsvnc->drm->gamma) {
+            free(kmsvnc->drm->gamma);
+            kmsvnc->drm->gamma = NULL;
+        }
         if (kmsvnc->drm->drm_ver) {
             drmFreeVersion(kmsvnc->drm->drm_ver);
             kmsvnc->drm->drm_ver = NULL;
@@ -202,6 +214,10 @@ void drm_cleanup() {
             close(kmsvnc->drm->drm_fd);
             kmsvnc->drm->drm_fd = 0;
         }
+        if (kmsvnc->drm->drm_master_fd > 0) {
+            close(kmsvnc->drm->drm_master_fd);
+            kmsvnc->drm->drm_master_fd = 0;
+        }
         if (kmsvnc->drm->plane_res) {
             drmModeFreePlaneResources(kmsvnc->drm->plane_res);
             kmsvnc->drm->plane_res = NULL;
@@ -458,6 +474,14 @@ int drm_open() {
     {
         KMSVNC_FATAL("card %s open failed: %s\n", kmsvnc->card, strerror(errno));
     }
+    if (kmsvnc->screen_blank && !drmIsMaster(drm->drm_fd)) {
+        drm->drm_master_fd = drm_get_master_fd();
+        drm->drm_master_fd = drm->drm_master_fd > 0 ? drm->drm_master_fd : 0;
+        if (kmsvnc->debug_enabled) {
+            fprintf(stderr, "not master client, master fd %d\n", drm->drm_master_fd);
+        }
+    }
+
     drm->drm_ver = drmGetVersion(drm->drm_fd);
     printf("drm driver is %s\n", drm->drm_ver->name);
 
@@ -469,6 +493,66 @@ int drm_open() {
 
     if (drm_refresh_planes(1)) return 1;
 
+    if (kmsvnc->screen_blank) {
+        drm->gamma = malloc(sizeof(struct kmsvnc_drm_gamma_data));
+        if (!drm->gamma) KMSVNC_FATAL("memory allocation error at %s:%d\n", __FILE__, __LINE__);
+        memset(drm->gamma, 0, sizeof(struct kmsvnc_drm_gamma_data));
+        drmModeCrtc *target_crtc = drmModeGetCrtc(drm->drm_fd, drm->plane->crtc_id);
+        if (target_crtc) {
+            drm->gamma->size = (uint32_t)target_crtc->gamma_size;
+            drm->gamma->red = malloc(drm->gamma->size*sizeof(uint16_t)*3);
+            if (!drm->gamma->size) {
+                fprintf(stderr, "drm->gamma->size = %u, not setting gamma.\n", drm->gamma->size);
+            }
+            else if (!drm->gamma->red) {
+                fprintf(stderr, "memory allocation error at %s:%d\n", __FILE__, __LINE__);
+                fprintf(stderr, "not setting gamma.\n");
+            }
+            else {
+                memset(drm->gamma->red, 0, drm->gamma->size*sizeof(uint16_t)*3);
+                drm->gamma->green = drm->gamma->red + drm->gamma->size;
+                drm->gamma->blue = drm->gamma->red + drm->gamma->size*2;
+                if (kmsvnc->screen_blank_restore) {
+                    int step = 0x10000 / drm->gamma->size;
+                    for (int i = 0; i < drm->gamma->size; i++) {
+                        drm->gamma->red[i] = drm->gamma->green[i] = drm->gamma->blue[i] = step * i;
+                    }
+                }
+                else {
+                    // legacy api, but weston also uses this, so whatever
+                    drmModeCrtcGetGamma(drm->drm_fd, drm->plane->crtc_id, drm->gamma->size, drm->gamma->red, drm->gamma->green, drm->gamma->blue);
+                }
+                if (kmsvnc->debug_enabled) {
+                    for (int i = 0; i < drm->gamma->size; i++) {
+                        fprintf(stderr, "gamma: %05d %05hu %05hu %05hu\n", i, drm->gamma->red[i], drm->gamma->green[i], drm->gamma->blue[i]);
+                    }
+                }
+                uint16_t *new_gamma_red = malloc(drm->gamma->size*sizeof(uint16_t)*3);
+                if (!new_gamma_red) {
+                    fprintf(stderr, "memory allocation error at %s:%d\n", __FILE__, __LINE__);
+                    fprintf(stderr, "not setting gamma.\n");
+                }
+                else {
+                    memset(new_gamma_red, 0, drm->gamma->size*sizeof(uint16_t)*3);
+                    uint16_t *new_gamma_green = new_gamma_red + drm->gamma->size;
+                    uint16_t *new_gamma_blue = new_gamma_red + drm->gamma->size*2;
+                    if (drmModeCrtcSetGamma(drm->drm_master_fd ?: drm->drm_fd, drm->plane->crtc_id, drm->gamma->size, new_gamma_red, new_gamma_green, new_gamma_blue)) perror("Failed to set gamma");
+                }
+                if (new_gamma_red) {
+                    free(new_gamma_red);
+                    new_gamma_red = NULL;
+                }
+            }
+        }
+        else {
+            fprintf(stderr, "Did not get a crtc structure, not setting gamma.\n");
+        }
+        if (target_crtc) {
+            drmModeFreeCrtc(target_crtc);
+            target_crtc = NULL;
+        }
+    }
+
     drm->mfb = drmModeGetFB2(drm->drm_fd, drm->plane->fb_id);
     if (!drm->mfb) {
         KMSVNC_FATAL("Failed to get framebuffer %u: %s\n", drm->plane->fb_id, strerror(errno));

drm_master.c

@@ -0,0 +1,99 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <dirent.h>
+#include <stdlib.h>
+
+#include "drm_master.h"
+
+extern struct kmsvnc_data *kmsvnc;
+
+
+static inline int clone_fd(pid_t pid, int target_fd) {
+    int pidfd = syscall(SYS_pidfd_open, pid, 0);
+    if (pidfd <= 0) {
+        perror("pidfd_open");
+        return -1;
+    }
+    int cloned = syscall(SYS_pidfd_getfd, pidfd, target_fd, 0);
+    if (cloned <= 0) {
+        perror("pidfd_getfd");
+    }
+    close(pidfd);
+    return cloned;
+}
+
+static inline int cmp_fds(pid_t pid, const char *drm_pth) {
+    if (pid == 1) return -1;
+    char path[PATH_MAX+1];
+    snprintf(path, PATH_MAX+1, "/proc/%d/fd", pid);
+
+    struct dirent **fdlist;
+    int count = scandir(path, &fdlist, NULL, versionsort);
+    int ret = -1;
+    if (count >= 0) {
+        for (int n = 0; n < count; n++) {
+            if (ret == -1 && fdlist[n]->d_type == DT_LNK) {
+                char link_pth[PATH_MAX+1];
+                char real_pth[PATH_MAX+1];
+                snprintf(link_pth, PATH_MAX+1, "%s/%s", path, fdlist[n]->d_name);
+                memset(real_pth, 0, PATH_MAX+1);
+                realpath(link_pth, real_pth);
+                if (!strncmp(real_pth, drm_pth, PATH_MAX)) {
+                    int fd = atoi(fdlist[n]->d_name);
+                    if (fd > 0) {
+                        int cloned = clone_fd(pid, fd);
+                        if (cloned > 0 && drmIsMaster(cloned)) {
+                            ret = cloned;
+                            //if (kmsvnc->debug_enabled) {
+                                fprintf(stderr, "found drm master pid=%d, fd=%d, cloned=%d\n", pid, fd, cloned);
+                            //}
+                        }
+                        else {
+                            if (cloned > 0) close(cloned);
+                        }
+                    }
+                }
+            }
+            free(fdlist[n]);
+            fdlist[n] = NULL;
+        }
+        free(fdlist);
+        fdlist = NULL;
+    }
+    return ret;
+}
+
+int drm_get_master_fd() {
+    char drm_pth[PATH_MAX+1];
+    memset(drm_pth, 0, PATH_MAX+1);
+    realpath(kmsvnc->card, drm_pth);
+
+    struct dirent **proclist;
+    int count = scandir("/proc", &proclist, NULL, versionsort);
+    int ret = -1;
+    if (count >= 0) {
+        for (int n = count - 1; n > 0; n--) {
+            if (ret == -1 && proclist[n]->d_type == DT_DIR) {
+                pid_t pid = (pid_t)atoi(proclist[n]->d_name);
+                if (pid > 0) {
+                    int cloned = cmp_fds(pid, drm_pth);
+                    if (cloned > 0) {
+                        ret = cloned;
+                    }
+                }
+            }
+            free(proclist[n]);
+            proclist[n] = NULL;
+        }
+        free(proclist);
+        proclist = NULL;
+    }
+    else {
+        perror("open /proc");
+    }
+    return ret;
+}

drm_master.h

@@ -0,0 +1,5 @@
+#pragma once
+
+#include "kmsvnc.h"
+
+int drm_get_master_fd();

kmsvnc.c

@@ -238,6 +238,8 @@ static struct argp_option kmsvnc_main_options[] = {
     {"input-height", 0xff07, "0", 0, "Explicitly set input height"},
     {"input-offx", 0xff08, "0", 0, "Set input offset of x axis on a multi display system"},
     {"input-offy", 0xff09, "0", 0, "Set input offset of y axis on a multi display system"},
+    {"screen-blank", 0xff0a, 0, OPTION_ARG_OPTIONAL, "Blank screen with gamma set on crtc"},
+    {"screen-blank-restore-linear", 0xff0b, 0, OPTION_ARG_OPTIONAL, "Restore linear values on exit in case of messed up gamma"},
     {"wakeup", 'w', 0, OPTION_ARG_OPTIONAL, "Move mouse to wake the system up before start"},
     {"disable-input", 'i', 0, OPTION_ARG_OPTIONAL, "Disable uinput"},
     {"desktop-name", 'n', "kmsvnc", 0, "Specify vnc desktop name"},
@@ -337,6 +339,12 @@ static error_t parse_opt(int key, char *arg, struct argp_state *state) {
                 kmsvnc->input_offy = offset_y;
             }
             break;
+        case 0xff0a:
+            kmsvnc->screen_blank = 1;
+            break;
+        case 0xff0b:
+            kmsvnc->screen_blank_restore = 1;
+            break;
         case 'w':
             kmsvnc->input_wakeup = 1;
             break;

kmsvnc.h

@@ -42,6 +42,8 @@ struct kmsvnc_data
     int input_height;
     int input_offx;
     int input_offy;
+    char screen_blank;
+    char screen_blank_restore;
     struct kmsvnc_drm_data *drm;
     struct kmsvnc_input_data *input;
     struct kmsvnc_keymap_data *keymap;
@@ -85,9 +87,18 @@ struct kmsvnc_drm_funcs
     void (*convert)(const char *, int, int, char *);
 };
 
+struct kmsvnc_drm_gamma_data
+{
+    uint32_t size;
+    uint16_t *red;
+    uint16_t *green;
+    uint16_t *blue;
+};
+
 struct kmsvnc_drm_data
 {
     int drm_fd;
+    int drm_master_fd;
     drmVersionPtr drm_ver;
     int prime_fd;
     drmModePlane *plane;
@@ -95,7 +106,7 @@ struct kmsvnc_drm_data
     drmModePlaneRes *plane_res;
     drmModeFB2 *mfb;
     drmModeFB2 *cursor_mfb;
-    u_int32_t plane_id;
+    uint32_t plane_id;
     int mmap_fd;
     size_t mmap_size;
     off_t mmap_offset;
@@ -113,6 +124,7 @@ struct kmsvnc_drm_data
     size_t kms_cpy_tmp_buf_len;
     char *kms_cursor_buf;
     size_t kms_cursor_buf_len;
+    struct kmsvnc_drm_gamma_data *gamma;
 };
 
 struct kmsvnc_va_data