top: implement scrolling up/down (_very_ useful)

function                                             old     new   delta
handle_input                                         494     564     +70
top_main                                             928     947     +19
display_topmem_process_list                          363     381     +18
display_process_list                                1442    1453     +11
clearmems                                             38      28     -10
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/1 up/down: 118/-10)           Total: 108 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 110 insertions, 74 deletions

diff --git a/procps/Config.src b/procps/Config.src
index 5cd47c8..527d9ee 100644
--- a/procps/Config.src
+++ b/procps/Config.src
@@ -140,60 +140,6 @@ config BB_SYSCTL
 	help
 	  Configure kernel parameters at runtime.
 
-config TOP
-	bool "top"
-	default y
-	help
-	  The top program provides a dynamic real-time view of a running
-	  system.
-
-config FEATURE_TOP_CPU_USAGE_PERCENTAGE
-	bool "Show CPU per-process usage percentage"
-	default y
-	depends on TOP
-	help
-	  Make top display CPU usage for each process.
-	  This adds about 2k.
-
-config FEATURE_TOP_CPU_GLOBAL_PERCENTS
-	bool "Show CPU global usage percentage"
-	default y
-	depends on FEATURE_TOP_CPU_USAGE_PERCENTAGE
-	help
-	  Makes top display "CPU: NN% usr NN% sys..." line.
-	  This adds about 0.5k.
-
-config FEATURE_TOP_SMP_CPU
-	bool "SMP CPU usage display ('c' key)"
-	default y
-	depends on FEATURE_TOP_CPU_GLOBAL_PERCENTS
-	help
-	  Allow 'c' key to switch between individual/cumulative CPU stats
-	  This adds about 0.5k.
-
-config FEATURE_TOP_DECIMALS
-	bool "Show 1/10th of a percent in CPU/mem statistics"
-	default y
-	depends on FEATURE_TOP_CPU_USAGE_PERCENTAGE
-	help
-	  Show 1/10th of a percent in CPU/mem statistics.
-	  This adds about 0.3k.
-
-config FEATURE_TOP_SMP_PROCESS
-	bool "Show CPU process runs on ('j' field)"
-	default y
-	depends on TOP
-	help
-	  Show CPU where process was last found running on.
-	  This is the 'j' field.
-
-config FEATURE_TOPMEM
-	bool "Topmem command ('s' key)"
-	default y
-	depends on TOP
-	help
-	  Enable 's' in top (gives lots of memory info).
-
 config FEATURE_SHOW_THREADS
 	bool "Support for showing threads in ps/pstree/top"
 	default y
diff --git a/procps/top.c b/procps/top.c
index 15eb624..00cb448 100644
--- a/procps/top.c
+++ b/procps/top.c
@@ -50,6 +50,60 @@
  * chroot . ./top -bn1 >top1.out
  */
 
+//config:config TOP
+//config:	bool "top"
+//config:	default y
+//config:	help
+//config:	  The top program provides a dynamic real-time view of a running
+//config:	  system.
+//config:
+//config:config FEATURE_TOP_CPU_USAGE_PERCENTAGE
+//config:	bool "Show CPU per-process usage percentage"
+//config:	default y
+//config:	depends on TOP
+//config:	help
+//config:	  Make top display CPU usage for each process.
+//config:	  This adds about 2k.
+//config:
+//config:config FEATURE_TOP_CPU_GLOBAL_PERCENTS
+//config:	bool "Show CPU global usage percentage"
+//config:	default y
+//config:	depends on FEATURE_TOP_CPU_USAGE_PERCENTAGE
+//config:	help
+//config:	  Makes top display "CPU: NN% usr NN% sys..." line.
+//config:	  This adds about 0.5k.
+//config:
+//config:config FEATURE_TOP_SMP_CPU
+//config:	bool "SMP CPU usage display ('c' key)"
+//config:	default y
+//config:	depends on FEATURE_TOP_CPU_GLOBAL_PERCENTS
+//config:	help
+//config:	  Allow 'c' key to switch between individual/cumulative CPU stats
+//config:	  This adds about 0.5k.
+//config:
+//config:config FEATURE_TOP_DECIMALS
+//config:	bool "Show 1/10th of a percent in CPU/mem statistics"
+//config:	default y
+//config:	depends on FEATURE_TOP_CPU_USAGE_PERCENTAGE
+//config:	help
+//config:	  Show 1/10th of a percent in CPU/mem statistics.
+//config:	  This adds about 0.3k.
+//config:
+//config:config FEATURE_TOP_SMP_PROCESS
+//config:	bool "Show CPU process runs on ('j' field)"
+//config:	default y
+//config:	depends on TOP
+//config:	help
+//config:	  Show CPU where process was last found running on.
+//config:	  This is the 'j' field.
+//config:
+//config:config FEATURE_TOPMEM
+//config:	bool "Topmem command ('s' key)"
+//config:	default y
+//config:	depends on TOP
+//config:	help
+//config:	  Enable 's' in top (gives lots of memory info).
+
 #include "libbb.h"
 
 
@@ -101,6 +155,8 @@ struct globals {
 #endif
 #if ENABLE_FEATURE_USE_TERMIOS
 	struct termios initial_settings;
+	unsigned lines;  /* screen height */
+	int scroll_ofs;
 #endif
 #if !ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
 	cmp_funcp sort_function[1];
@@ -118,6 +174,9 @@ struct globals {
 	jiffy_counts_t *cpu_jif, *cpu_prev_jif;
 	int num_cpus;
 #endif
+#if ENABLE_FEATURE_USE_TERMIOS
+	char kbd_input[KEYCODE_BUFFER_SIZE];
+#endif
 	char line_buf[80];
 }; //FIX_ALIASING; - large code growth
 enum { LINE_BUF_SIZE = COMMON_BUFSIZE - offsetof(struct globals, line_buf) };
@@ -602,9 +661,9 @@ static NOINLINE void display_process_list(int lines_rem, int scr_width)
 
 	/* Ok, all preliminary data is ready, go through the list */
 	scr_width += 2; /* account for leading '\n' and trailing NUL */
-	if (lines_rem > ntop)
-		lines_rem = ntop;
-	s = top;
+	if (lines_rem > ntop - G.scroll_ofs)
+		lines_rem = ntop - G.scroll_ofs;
+	s = top + G.scroll_ofs;
 	while (--lines_rem >= 0) {
 		unsigned col;
 		CALC_STAT(pmem, (s->vsz*pmem_scale + pmem_half) >> pmem_shift);
@@ -649,7 +708,6 @@ static void clearmems(void)
 	clear_username_cache();
 	free(top);
 	top = NULL;
-	ntop = 0;
 }
 
 #if ENABLE_FEATURE_USE_TERMIOS
@@ -793,7 +851,7 @@ static NOINLINE void display_topmem_process_list(int lines_rem, int scr_width)
 {
 #define HDR_STR "  PID   VSZ VSZRW   RSS (SHR) DIRTY (SHR) STACK"
 #define MIN_WIDTH sizeof(HDR_STR)
-	const topmem_status_t *s = topmem;
+	const topmem_status_t *s = topmem + G.scroll_ofs;
 
 	display_topmem_header(scr_width, &lines_rem);
 	strcpy(line_buf, HDR_STR " COMMAND");
@@ -801,8 +859,8 @@ static NOINLINE void display_topmem_process_list(int lines_rem, int scr_width)
 	printf(OPT_BATCH_MODE ? "%.*s" : "\e[7m%.*s\e[0m", scr_width, line_buf);
 	lines_rem--;
 
-	if (lines_rem > ntop)
-		lines_rem = ntop;
+	if (lines_rem > ntop - G.scroll_ofs)
+		lines_rem = ntop - G.scroll_ofs;
 	while (--lines_rem >= 0) {
 		/* PID VSZ VSZRW RSS (SHR) DIRTY (SHR) COMMAND */
 		ulltoa6_and_space(s->pid     , &line_buf[0*6]);
@@ -856,26 +914,57 @@ enum {
 #if ENABLE_FEATURE_USE_TERMIOS
 static unsigned handle_input(unsigned scan_mask, unsigned interval)
 {
-	unsigned char c;
 	struct pollfd pfd[1];
 
 	pfd[0].fd = 0;
 	pfd[0].events = POLLIN;
 
 	while (1) {
-		if (safe_poll(pfd, 1, interval * 1000) <= 0)
-			return scan_mask;
-		interval = 0;
+		int32_t c;
 
-		if (safe_read(STDIN_FILENO, &c, 1) != 1) { /* error/EOF? */
+		c = read_key(STDIN_FILENO, G.kbd_input, interval * 1000);
+		if (c == -1 && errno != EAGAIN) {
+			/* error/EOF */
 			option_mask32 |= OPT_EOF;
-			return scan_mask;
+			break;
 		}
+		interval = 0;
 
 		if (c == initial_settings.c_cc[VINTR])
 			return EXIT_MASK;
 		if (c == initial_settings.c_cc[VEOF])
 			return EXIT_MASK;
+
+		if (c == KEYCODE_UP) {
+			G.scroll_ofs--;
+			goto normalize_ofs;
+		}
+		if (c == KEYCODE_DOWN) {
+			G.scroll_ofs++;
+			goto normalize_ofs;
+		}
+		if (c == KEYCODE_HOME) {
+			G.scroll_ofs = 0;
+			break;
+		}
+		if (c == KEYCODE_END) {
+			G.scroll_ofs = ntop - G.lines / 2;
+			goto normalize_ofs;
+		}
+		if (c == KEYCODE_PAGEUP) {
+			G.scroll_ofs -= G.lines / 2;
+			goto normalize_ofs;
+		}
+		if (c == KEYCODE_PAGEDOWN) {
+			G.scroll_ofs += G.lines / 2;
+ normalize_ofs:
+			if (G.scroll_ofs >= ntop)
+				G.scroll_ofs = ntop - 1;
+			if (G.scroll_ofs < 0)
+				G.scroll_ofs = 0;
+			break;
+		}
+
 		c |= 0x20; /* lowercase */
 		if (c == 'q')
 			return EXIT_MASK;
@@ -1011,7 +1100,7 @@ int top_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int top_main(int argc UNUSED_PARAM, char **argv)
 {
 	int iterations;
-	unsigned lines, col;
+	unsigned col;
 	unsigned interval;
 	char *str_interval, *str_iterations;
 	unsigned scan_mask = TOP_MASK;
@@ -1081,15 +1170,15 @@ int top_main(int argc UNUSED_PARAM, char **argv)
 		procps_status_t *p = NULL;
 
 		if (OPT_BATCH_MODE) {
-			lines = INT_MAX;
+			G.lines = INT_MAX;
 			col = LINE_BUF_SIZE - 2; /* +2 bytes for '\n', NUL */
 		} else {
-			lines = 24; /* default */
+			G.lines = 24; /* default */
 			col = 79;
 #if ENABLE_FEATURE_USE_TERMIOS
 			/* We output to stdout, we need size of stdout (not stdin)! */
-			get_terminal_width_height(STDOUT_FILENO, &col, &lines);
-			if (lines < 5 || col < 10) {
+			get_terminal_width_height(STDOUT_FILENO, &col, &G.lines);
+			if (G.lines < 5 || col < 10) {
 				sleep(interval);
 				continue;
 			}
@@ -1099,6 +1188,7 @@ int top_main(int argc UNUSED_PARAM, char **argv)
 		}
 
 		/* read process IDs & status for all the processes */
+		ntop = 0;
 		while ((p = procps_scan(p, scan_mask)) != NULL) {
 			int n;
 #if ENABLE_FEATURE_TOPMEM
@@ -1165,10 +1255,10 @@ int top_main(int argc UNUSED_PARAM, char **argv)
 		}
 #endif
 		if (scan_mask != TOPMEM_MASK)
-			display_process_list(lines, col);
+			display_process_list(G.lines, col);
 #if ENABLE_FEATURE_TOPMEM
 		else
-			display_topmem_process_list(lines, col);
+			display_topmem_process_list(G.lines, col);
 #endif
 		clearmems();
 		if (iterations >= 0 && !--iterations)