add dynamic linesig control #1228

NEWS.md

@@ -1,6 +1,9 @@
 This document attempts to list user-visible changes and any major internal
 rearrangements of Notcurses.
 
+* 2.1.2 (not yet released)
+  * Add `notcurses_linesigs_enable()` and `notcurses_linesigs_disable()`.
+
 * 2.1.1 (2020-12-16)
   * Progress bars via `ncprogbar`, using the standard widget API.
 

USAGE.md

@@ -554,12 +554,6 @@ nckey_supppuab_p(char32_t w){
   return w >= 0x100000 && w <= 0x10fffd;
 }
 
-// Is the event a synthesized mouse event?
-static inline bool
-nckey_mouse_p(char32_t r){
-  return r >= NCKEY_BUTTON1 && r <= NCKEY_RELEASE;
-}
-
 // An input event. Cell coordinates are currently defined only for mouse events.
 typedef struct ncinput {
   char32_t id;     // identifier. Unicode codepoint or synthesized NCKEY event
@@ -601,6 +595,20 @@ notcurses_getc_blocking(struct notcurses* n, ncinput* ni){
 }
 ```
 
+By default, certain keys are mapped to signals by the terminal's line
+discipline. This can be disabled with `notcurses_linesigs_disable()`, and
+reenabled with `notcurses_linesigs_enable()`.
+
+```
+// Disable signals originating from the terminal's line discipline, i.e.
+// SIGINT (^C), SIGQUIT (^\), and SIGTSTP (^Z). They are enabled by default.
+int notcurses_linesigs_disable(struct notcurses* n);
+
+// Restore signals originating from the terminal's line discipline, i.e.
+// SIGINT (^C), SIGQUIT (^\), and SIGTSTP (^Z), if disabled.
+int notcurses_linesigs_enable(struct notcurses* n);
+```
+
 ## Mice
 
 notcurses supports mice, though only through brokers such as X or
@@ -616,6 +624,12 @@ int notcurses_mouse_enable(struct notcurses* n);
 
 // Disable mouse events. Any events in the input queue can still be delivered.
 int notcurses_mouse_disable(struct notcurses* n);
+
+// Is the event a synthesized mouse event?
+static inline bool
+nckey_mouse_p(char32_t r){
+  return r >= NCKEY_BUTTON1 && r <= NCKEY_RELEASE;
+}
 ```
 
 "Button-event tracking mode" implies the ability to detect mouse button

doc/man/man3/notcurses_input.3.md

@@ -41,6 +41,10 @@ typedef struct ncinput {
 
 **static inline bool ncinput_equal_p(const struct ncinput* ***n1***, const struct ncinput* ***n2***);**
 
+**int notcurses_linesigs_disable(struct notcurses* ***n***);**
+
+**int notcurses_linesigs_enable(struct notcurses* ***n***);**
+
 # DESCRIPTION
 
 notcurses supports input from keyboards and mice, and any device that looks
@@ -73,6 +77,13 @@ be called without the possibility of blocking.
 not considering padding or the **seqnum** field), returning **true** if they
 represent the same input (though not necessarily the same input event).
 
+**notcurses_linesigs_disable** disables conversion of inputs **INTR**, **QUIT**,
+**SUSP**, and **DSUSP** into **SIGINT**, **SIGQUIT**, and **SIGTSTP**. These
+conversions are enabled by default. **notcurses_linesigs_enable** undoes this
+action, but signals in the interim are permanently lost.
+
+**int notcurses_linesigs_enable(struct notcurses* ***n***);**
+
 ## Mice
 
 For mouse events, the additional fields **y** and **x** are set. These fields

include/notcurses/notcurses.h

@@ -1012,6 +1012,14 @@ API int notcurses_mouse_enable(struct notcurses* n);
 // Disable mouse events. Any events in the input queue can still be delivered.
 API int notcurses_mouse_disable(struct notcurses* n);
 
+// Disable signals originating from the terminal's line discipline, i.e.
+// SIGINT (^C), SIGQUIT (^\), and SIGTSTP (^Z). They are enabled by default.
+API int notcurses_linesigs_disable(struct notcurses* n);
+
+// Restore signals originating from the terminal's line discipline, i.e.
+// SIGINT (^C), SIGQUIT (^\), and SIGTSTP (^Z), if disabled.
+API int notcurses_linesigs_enable(struct notcurses* n);
+
 // Refresh the physical screen to match what was last rendered (i.e., without
 // reflecting any changes since the last call to notcurses_render()). This is
 // primarily useful if the screen is externally corrupted, or if an

src/lib/input.c

@@ -28,7 +28,7 @@ int cbreak_mode(int ttyfd, const struct termios* tpreserved){
   // etc. still have their typical effects. ICRNL maps return to 13 (Ctrl+M)
   // instead of 10 (Ctrl+J).
   modtermios.c_lflag &= (~ECHO & ~ICANON);
-  modtermios.c_iflag &= (~ICRNL);
+  modtermios.c_iflag &= ~ICRNL;
   if(tcsetattr(ttyfd, TCSANOW, &modtermios)){
     fprintf(stderr, "Error disabling echo / canonical on %d (%s)\n", ttyfd, strerror(errno));
     return -1;
@@ -36,6 +36,44 @@ int cbreak_mode(int ttyfd, const struct termios* tpreserved){
   return 0;
 }
 
+// Disable signals originating from the terminal's line discipline, i.e.
+// SIGINT (^C), SIGQUIT (^\), and SIGTSTP (^Z). They are enabled by default.
+int notcurses_linesigs_disable(notcurses* n){
+  if(n->ttyfd < 0){
+    return 0;
+  }
+  struct termios tios;
+  if(tcgetattr(n->ttyfd, &tios)){
+    logerror(n, "Couldn't preserve terminal state for %d (%s)\n", n->ttyfd, strerror(errno));
+    return -1;
+  }
+  tios.c_lflag &= ~ISIG;
+  if(tcsetattr(n->ttyfd, TCSANOW, &tios)){
+    logerror(n, "Error disabling signals on %d (%s)\n", n->ttyfd, strerror(errno));
+    return -1;
+  }
+  return 0;
+}
+
+// Restore signals originating from the terminal's line discipline, i.e.
+// SIGINT (^C), SIGQUIT (^\), and SIGTSTP (^Z), if disabled.
+int notcurses_linesigs_enable(notcurses* n){
+  if(n->ttyfd < 0){
+    return 0;
+  }
+  struct termios tios;
+  if(tcgetattr(n->ttyfd, &tios)){
+    logerror(n, "Couldn't preserve terminal state for %d (%s)\n", n->ttyfd, strerror(errno));
+    return -1;
+  }
+  tios.c_lflag |= ~ISIG;
+  if(tcsetattr(n->ttyfd, TCSANOW, &tios)){
+    logerror(n, "Error disabling signals on %d (%s)\n", n->ttyfd, strerror(errno));
+    return -1;
+  }
+  return 0;
+}
+
 static inline int
 pop_input_keypress(ncinputlayer* nc){
   int candidate = nc->inputbuf[nc->inputbuf_valid_starts];