detect drawable linux framebuffer #1369

src/lib/internal.h

@@ -1123,8 +1123,6 @@ int ncvisual_blit(struct ncvisual* ncv, int rows, int cols,
 
 void nclog(const char* fmt, ...);
 
-bool is_linux_console(int fd, unsigned no_font_changes, bool* quadrants);
-
 // logging
 extern int loglevel;
 

src/lib/linux.c

@@ -1,6 +1,11 @@
+#include "linux.h"
 #include "internal.h"
 
 #ifdef __linux__
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <linux/fb.h>
 #include <linux/kd.h>
 #include <sys/ioctl.h>
 
@@ -411,6 +416,26 @@ bool is_linux_console(int fd, unsigned no_font_changes, bool* quadrants){
   reprogram_console_font(fd, no_font_changes, quadrants);
   return true;
 }
+
+bool is_linux_framebuffer(tinfo* ti){
+  // FIXME there might be multiple framebuffers present; how do we determine
+  // which one is ours?
+  const char* dev = "/dev/fb0";
+  int fd = open(dev, O_RDWR | O_CLOEXEC);
+  if(fd < 0){
+    logdebug("Couldn't open framebuffer device %s\n", dev);
+    return false;
+  }
+  struct fb_var_screeninfo fbi = {};
+  if(ioctl(fd, FBIOGET_VSCREENINFO, &fbi)){
+    logdebug("Couldn't get framebuffer info from %s (%s?)\n", dev, strerror(errno));
+    close(fd);
+    return false;
+  }
+  loginfo("Linux framebuffer detected at %s: %dx%d\n", dev, fbi.yres, fbi.xres);
+  ti->linux_fb_fd = fd;
+  return true;
+}
 #else
 bool is_linux_console(int fd, unsigned no_font_changes, bool* quadrants){
   (void)fd;
@@ -418,4 +443,9 @@ bool is_linux_console(int fd, unsigned no_font_changes, bool* quadrants){
   (void)quadrants;
   return false;
 }
+
+bool is_linux_framebuffer(tinfo* ti){
+  (void)ti;
+  return false;
+}
 #endif

src/lib/linux.h

@@ -0,0 +1,22 @@
+#ifndef NOTCURSES_LINUX
+#define NOTCURSES_LINUX
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdbool.h>
+
+struct tinfo;
+
+bool is_linux_console(int fd, unsigned no_font_changes, bool* quadrants);
+
+// if is_linux_console returned true, call this to determine whether it is
+// a drawable framebuffer console. do not call if not is_linux_console!
+bool is_linux_framebuffer(struct tinfo* ti);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

src/lib/termdesc.c

@@ -5,6 +5,7 @@
 #include <sys/utsname.h>
 #include "internal.h"
 #include "input.h"
+#include "linux.h"
 
 // there does not exist any true standard terminal size. with that said, we
 // need assume *something* for the case where we're not actually attached to
@@ -155,6 +156,9 @@ void free_terminfo_cache(tinfo* ti){
   ncinputlayer_stop(&ti->input);
   free(ti->termversion);
   free(ti->esctable);
+  if(ti->linux_fb_fd >= 0){
+    close(ti->linux_fb_fd);
+  }
 }
 
 // compare one terminal version against another. numerics, separated by
@@ -416,7 +420,11 @@ apply_term_heuristics(tinfo* ti, const char* termname, int fd,
     if(uname(&un) == 0){
       ti->termversion = strdup(un.release);
     }
-    termname = "Linux console";
+    if(ti->linux_fb_fd >= 0){
+      termname = "Linux framebuffer";
+    }else{
+      termname = "Linux console";
+    }
     ti->caps.braille = false; // no caps.braille, no caps.sextants in linux console
   }
   // run a wcwidth(⣿) to guarantee libc Unicode 3 support, independent of term
@@ -478,9 +486,13 @@ int interrogate_terminfo(tinfo* ti, int fd, const char* termname, unsigned utf8,
                          int* cursor_y, int* cursor_x){
   queried_terminals_e qterm = TERMINAL_UNKNOWN;
   memset(ti, 0, sizeof(*ti));
+  ti->linux_fb_fd = -1;
   // we might or might not program quadrants into the console font
   if(is_linux_console(fd, nonewfonts, &ti->caps.quadrants)){
     qterm = TERMINAL_LINUX;
+    if(is_linux_framebuffer(ti)){
+      // FIXME set up pixel-drawing API for framebuffer #1369
+    }
   }
   if(fd >= 0){
     if(qterm == TERMINAL_UNKNOWN){

src/lib/termdesc.h

@@ -159,6 +159,8 @@ typedef struct tinfo {
 
   int default_rows; // LINES environment var / lines terminfo / 24
   int default_cols; // COLUMNS environment var / cols terminfo / 80
+
+  int linux_fb_fd;  // linux framebuffer device fd
 } tinfo;
 
 // retrieve the terminfo(5)-style escape 'e' from tdesc (NULL if undefined).