Adapt help to terminal size

If the error stream is a terminal, and we can retrieve the terminal
size, wrap the lines at terminal boundaries.

app/meson.build

@@ -29,6 +29,7 @@ src = [
     'src/util/process.c',
     'src/util/strbuf.c',
     'src/util/str_util.c',
+    'src/util/term.c',
     'src/util/thread.c',
     'src/util/tick.c',
 ]
@@ -189,6 +190,7 @@ if get_option('buildtype') == 'debug'
             'src/options.c',
             'src/util/strbuf.c',
             'src/util/str_util.c',
+            'src/util/term.c',
         ]],
         ['test_clock', [
             'tests/test_clock.c',

app/src/cli.c

@@ -4,15 +4,14 @@
 #include <getopt.h>
 #include <stdint.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <unistd.h>
 
 #include "options.h"
 #include "util/log.h"
 #include "util/strbuf.h"
 #include "util/str_util.h"
-
-#include <termios.h>
-#include <sys/ioctl.h>
+#include "util/term.h"
 
 #define STR_IMPL_(x) #x
 #define STR(x) STR_IMPL_(x)
@@ -743,13 +742,16 @@ print_shortcut(const struct sc_shortcut *shortcut, unsigned cols) {
 
 void
 scrcpy_print_usage(const char *arg0) {
-    unsigned cols = 80;
+#define SC_TERM_COLS_DEFAULT 80
+    unsigned cols;
 
-    struct winsize ws;
-    if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) != -1) {
-        cols = ws.ws_col;
-        if (cols < 20) {
-            cols = 20;
+    if (!isatty(STDERR_FILENO)) {
+        // Not a tty, use a default value
+        cols = SC_TERM_COLS_DEFAULT;
+    } else {
+        bool ok = sc_term_get_size(NULL, &cols);
+        if (!ok) {
+            cols = SC_TERM_COLS_DEFAULT; // default value
         }
     }
 

app/src/util/term.c

@@ -0,0 +1,51 @@
+#include "term.h"
+
+#include <assert.h>
+
+#ifdef _WIN32
+# include <windows.h>
+#else
+# include <unistd.h>
+# include <sys/ioctl.h>
+#endif
+
+bool
+sc_term_get_size(unsigned *rows, unsigned *cols) {
+#ifdef _WIN32
+    CONSOLE_SCREEN_BUFFER_INFO csbi;
+
+    bool ok =
+        GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &csbi);
+    if (!ok) {
+        return false;
+    }
+
+    if (rows) {
+        assert(csbi.srWindow.Bottom >= csbi.srWindow.Top);
+        *rows = csbi.srWindow.Bottom - csbi.srWindow.Top + 1;
+    }
+
+    if (cols) {
+        assert(csbi.srWindow.Right >= csbi.srWindow.Left);
+        *cols = csbi.srWindow.Right - csbi.srWindow.Left + 1;
+    }
+
+    return true;
+#else
+    struct winsize ws;
+    int r = ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws);
+    if (r == -1) {
+        return false;
+    }
+
+    if (rows) {
+        *rows = ws.ws_row;
+    }
+
+    if (cols) {
+        *cols = ws.ws_col;
+    }
+
+    return true;
+#endif
+}

app/src/util/term.h

@@ -0,0 +1,11 @@
+#ifndef SC_TERM_H
+#define SC_TERM_H
+
+#include "common.h"
+
+#include <stdbool.h>
+
+bool
+sc_term_get_size(unsigned *rows, unsigned *cols);
+
+#endif