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 5cd47c84f..527d9ee0c 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 15eb624cc..00cb44896 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)