top: make it possible to feed commands via pipe

function                                             old     new   delta
handle_input                                           -     492    +492
mult_lvl_cmp                                          38      49     +11
packed_usage                                       28247   28257     +10
top_main                                            1345     928    -417
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 2/1 up/down: 513/-417)           Total: 96 bytes

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

1 files changed, 155 insertions, 110 deletions

diff --git a/procps/top.c b/procps/top.c
index ee6555188..ed8b56173 100644
--- a/procps/top.c
+++ b/procps/top.c
@@ -92,9 +92,9 @@ enum { SORT_DEPTH = 3 };
 struct globals {
         top_status_t *top;
         int ntop;
+        smallint inverted;
 #if ENABLE_FEATURE_TOPMEM
         smallint sort_field;
-        smallint inverted;
 #endif
 #if ENABLE_FEATURE_TOP_SMP_CPU
         smallint smp_cpu_info; /* one/many cpu info lines? */
@@ -194,9 +194,9 @@ static int mult_lvl_cmp(void* a, void* b)
         for (i = 0; i < SORT_DEPTH; i++) {
                 cmp_val = (*sort_function[i])(a, b);
                 if (cmp_val != 0)
-                        return cmp_val;
+                        break;
         }
-        return 0;
+        return inverted ? -cmp_val : cmp_val;
 }
 
 static NOINLINE int read_cpu_jiffy(FILE *fp, jiffy_counts_t *p_jif)
@@ -850,8 +850,105 @@ enum {
                 | PSSCAN_PID
                 | PSSCAN_SMAPS
                 | PSSCAN_COMM,
+        EXIT_MASK = (unsigned)-1,
 };
 
+#if ENABLE_FEATURE_USE_TERMIOS
+static unsigned handle_input(unsigned scan_mask, unsigned interval)
+{
+        unsigned char c, *p, buf[64];
+        int len;
+        struct pollfd pfd[1];
+
+        pfd[0].fd = 0;
+        pfd[0].events = POLLIN;
+        if (safe_poll(pfd, 1, interval * 1000) <= 0)
+                return scan_mask;
+
+        len = safe_read(STDIN_FILENO, &buf, sizeof(buf)-1);
+        if (len <= 0) { /* error/EOF? */
+                option_mask32 |= OPT_EOF;
+                return scan_mask;
+        }
+
+        buf[len] = 0;
+        p = buf;
+        while ((c = *p++) != 0) {
+                if (c == initial_settings.c_cc[VINTR])
+                        return EXIT_MASK;
+                if (c == initial_settings.c_cc[VEOF])
+                        return EXIT_MASK;
+                c |= 0x20; /* lowercase */
+                if (c == 'q')
+                        return EXIT_MASK;
+                if (c == 'n') {
+                        IF_FEATURE_TOPMEM(scan_mask = TOP_MASK;)
+                        sort_function[0] = pid_sort;
+                }
+                if (c == 'm') {
+                        IF_FEATURE_TOPMEM(scan_mask = TOP_MASK;)
+                        sort_function[0] = mem_sort;
+# if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
+                        sort_function[1] = pcpu_sort;
+                        sort_function[2] = time_sort;
+# endif
+                }
+# if ENABLE_FEATURE_SHOW_THREADS
+                if (c == 'h'
+                 IF_FEATURE_TOPMEM(&& scan_mask != TOPMEM_MASK)
+                ) {
+                        scan_mask ^= PSSCAN_TASKS;
+                }
+# endif
+# if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
+                if (c == 'p') {
+                        IF_FEATURE_TOPMEM(scan_mask = TOP_MASK;)
+                        sort_function[0] = pcpu_sort;
+                        sort_function[1] = mem_sort;
+                        sort_function[2] = time_sort;
+                }
+                if (c == 't') {
+                        IF_FEATURE_TOPMEM(scan_mask = TOP_MASK;)
+                        sort_function[0] = time_sort;
+                        sort_function[1] = mem_sort;
+                        sort_function[2] = pcpu_sort;
+                }
+#  if ENABLE_FEATURE_TOPMEM
+                if (c == 's') {
+                        scan_mask = TOPMEM_MASK;
+                        free(prev_hist);
+                        prev_hist = NULL;
+                        prev_hist_count = 0;
+                        sort_field = (sort_field + 1) % NUM_SORT_FIELD;
+                }
+#  endif
+                if (c == 'r')
+                        inverted ^= 1;
+#  if ENABLE_FEATURE_TOP_SMP_CPU
+                /* procps-2.0.18 uses 'C', 3.2.7 uses '1' */
+                if (c == 'c' || c == '1') {
+                        /* User wants to toggle per cpu <> aggregate */
+                        if (smp_cpu_info) {
+                                free(cpu_prev_jif);
+                                free(cpu_jif);
+                                cpu_jif = &cur_jif;
+                                cpu_prev_jif = &prev_jif;
+                        } else {
+                                /* Prepare for xrealloc() */
+                                cpu_jif = cpu_prev_jif = NULL;
+                        }
+                        num_cpus = 0;
+                        smp_cpu_info = !smp_cpu_info;
+                        get_jiffy_counts();
+                }
+#  endif
+# endif
+        }
+
+        return scan_mask;
+}
+#endif
+
 //usage:#if ENABLE_FEATURE_SHOW_THREADS || ENABLE_FEATURE_TOP_SMP_CPU
 //usage:# define IF_SHOW_THREADS_OR_TOP_SMP(...) __VA_ARGS__
 //usage:#else
@@ -871,8 +968,9 @@ enum {
 //usage:                IF_FEATURE_TOP_CPU_USAGE_PERCENTAGE("/cpu")
 //usage:                IF_FEATURE_TOP_CPU_USAGE_PERCENTAGE("/time")
 //usage:        IF_FEATURE_TOPMEM(
-//usage:   "\n""        S: show memory, R: reverse memory sort"
+//usage:   "\n""        S: show memory"
 //usage:        )
+//usage:   "\n""        R: reverse sort"
 //usage:        IF_SHOW_THREADS_OR_TOP_SMP(
 //usage:   "\n""        "
 //usage:                IF_FEATURE_SHOW_THREADS("H: toggle threads")
@@ -880,23 +978,34 @@ enum {
 //usage:                IF_FEATURE_TOP_SMP_CPU("1: toggle SMP")
 //usage:        )
 //usage:   "\n""        Q,^C: exit"
+//usage:   "\n"
+//usage:   "\n""Options:"
+//usage:   "\n""        -b      Batch mode"
+//usage:   "\n""        -n N    Exit after N iterations"
+//usage:   "\n""        -d N    Delay between updates"
+//usage:        IF_FEATURE_TOPMEM(
+//usage:   "\n""        -m      Same as 's' key"
+//usage:        )
+
+/* Interactive testing:
+ * echo sss | ./busybox top
+ * - shows memory screen
+ * echo sss | ./busybox top -bn1 >mem
+ * - saves memory screen - the *whole* list, not first NROWS porcesses!
+ *
+ * TODO: -i STRING param as a better alternative?
+ */
 
 int top_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int top_main(int argc UNUSED_PARAM, char **argv)
 {
         int iterations;
         unsigned lines, col;
-        int lines_rem;
         unsigned interval;
         char *str_interval, *str_iterations;
         unsigned scan_mask = TOP_MASK;
 #if ENABLE_FEATURE_USE_TERMIOS
         struct termios new_settings;
-        struct pollfd pfd[1];
-        unsigned char c;
-
-        pfd[0].fd = 0;
-        pfd[0].events = POLLIN;
 #endif
 
         INIT_G();
@@ -933,15 +1042,6 @@ int top_main(int argc UNUSED_PARAM, char **argv)
 
         /* change to /proc */
         xchdir("/proc");
-#if ENABLE_FEATURE_USE_TERMIOS
-        tcgetattr(0, (void *) &initial_settings);
-        memcpy(&new_settings, &initial_settings, sizeof(new_settings));
-        /* unbuffered input, turn off echo */
-        new_settings.c_lflag &= ~(ISIG | ICANON | ECHO | ECHONL);
-
-        bb_signals(BB_FATAL_SIGS, sig_catcher);
-        tcsetattr_stdin_TCSANOW(&new_settings);
-#endif
 
 #if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
         sort_function[0] = pcpu_sort;
@@ -951,21 +1051,41 @@ int top_main(int argc UNUSED_PARAM, char **argv)
         sort_function[0] = mem_sort;
 #endif
 
-        while (1) {
+#if ENABLE_FEATURE_USE_TERMIOS
+        tcgetattr(0, (void *) &initial_settings);
+        memcpy(&new_settings, &initial_settings, sizeof(new_settings));
+        if (!OPT_BATCH_MODE) {
+                /* unbuffered input, turn off echo */
+                new_settings.c_lflag &= ~(ISIG | ICANON | ECHO | ECHONL);
+                tcsetattr_stdin_TCSANOW(&new_settings);
+        }
+
+        bb_signals(BB_FATAL_SIGS, sig_catcher);
+
+        /* Eat initial input, if any */
+        scan_mask = handle_input(scan_mask, 0);
+#endif
+
+        while (scan_mask != EXIT_MASK) {
                 procps_status_t *p = NULL;
 
-                lines = 24; /* default */
-                col = 79;
+                if (OPT_BATCH_MODE) {
+                        lines = INT_MAX;
+                        col = LINE_BUF_SIZE - 2; /* +2 bytes for '\n', NUL */
+                } else {
+                        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) {
-                        sleep(interval);
-                        continue;
-                }
+                        /* We output to stdout, we need size of stdout (not stdin)! */
+                        get_terminal_width_height(STDOUT_FILENO, &col, &lines);
+                        if (lines < 5 || col < 10) {
+                                sleep(interval);
+                                continue;
+                        }
 #endif
-                if (col > LINE_BUF_SIZE-2) /* +2 bytes for '\n', NUL, */
-                        col = LINE_BUF_SIZE-2;
+                        if (col > LINE_BUF_SIZE - 2)
+                                col = LINE_BUF_SIZE - 2;
+                }
 
                 /* read process IDs & status for all the processes */
                 while ((p = procps_scan(p, scan_mask)) != NULL) {
@@ -1033,15 +1153,11 @@ int top_main(int argc UNUSED_PARAM, char **argv)
                         qsort(topmem, ntop, sizeof(topmem_status_t), (void*)topmem_sort);
                 }
 #endif
-                lines_rem = lines;
-                if (OPT_BATCH_MODE) {
-                        lines_rem = INT_MAX;
-                }
                 if (scan_mask != TOPMEM_MASK)
-                        display_process_list(lines_rem, col);
+                        display_process_list(lines, col);
 #if ENABLE_FEATURE_TOPMEM
                 else
-                        display_topmem_process_list(lines_rem, col);
+                        display_topmem_process_list(lines, col);
 #endif
                 clearmems();
                 if (iterations >= 0 && !--iterations)
@@ -1052,81 +1168,10 @@ int top_main(int argc UNUSED_PARAM, char **argv)
                 if (option_mask32 & (OPT_b|OPT_EOF))
                          /* batch mode, or EOF on stdin ("top </dev/null") */
                         sleep(interval);
-                else if (safe_poll(pfd, 1, interval * 1000) > 0) {
-                        if (safe_read(STDIN_FILENO, &c, 1) != 1) { /* error/EOF? */
-                                option_mask32 |= OPT_EOF;
-                                continue;
-                        }
-                        if (c == initial_settings.c_cc[VINTR])
-                                break;
-                        c |= 0x20; /* lowercase */
-                        if (c == 'q')
-                                break;
-                        if (c == 'n') {
-                                IF_FEATURE_TOPMEM(scan_mask = TOP_MASK;)
-                                sort_function[0] = pid_sort;
-                        }
-                        if (c == 'm') {
-                                IF_FEATURE_TOPMEM(scan_mask = TOP_MASK;)
-                                sort_function[0] = mem_sort;
-# if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
-                                sort_function[1] = pcpu_sort;
-                                sort_function[2] = time_sort;
-# endif
-                        }
-# if ENABLE_FEATURE_SHOW_THREADS
-                        if (c == 'h'
-                         IF_FEATURE_TOPMEM(&& scan_mask != TOPMEM_MASK)
-                        ) {
-                                scan_mask ^= PSSCAN_TASKS;
-                        }
-# endif
-# if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
-                        if (c == 'p') {
-                                IF_FEATURE_TOPMEM(scan_mask = TOP_MASK;)
-                                sort_function[0] = pcpu_sort;
-                                sort_function[1] = mem_sort;
-                                sort_function[2] = time_sort;
-                        }
-                        if (c == 't') {
-                                IF_FEATURE_TOPMEM(scan_mask = TOP_MASK;)
-                                sort_function[0] = time_sort;
-                                sort_function[1] = mem_sort;
-                                sort_function[2] = pcpu_sort;
-                        }
-#  if ENABLE_FEATURE_TOPMEM
-                        if (c == 's') {
-                                scan_mask = TOPMEM_MASK;
-                                free(prev_hist);
-                                prev_hist = NULL;
-                                prev_hist_count = 0;
-                                sort_field = (sort_field + 1) % NUM_SORT_FIELD;
-                        }
-                        if (c == 'r')
-                                inverted ^= 1;
-#  endif
-#  if ENABLE_FEATURE_TOP_SMP_CPU
-                        /* procps-2.0.18 uses 'C', 3.2.7 uses '1' */
-                        if (c == 'c' || c == '1') {
-                                /* User wants to toggle per cpu <> aggregate */
-                                if (smp_cpu_info) {
-                                        free(cpu_prev_jif);
-                                        free(cpu_jif);
-                                        cpu_jif = &cur_jif;
-                                        cpu_prev_jif = &prev_jif;
-                                } else {
-                                        /* Prepare for xrealloc() */
-                                        cpu_jif = cpu_prev_jif = NULL;
-                                }
-                                num_cpus = 0;
-                                smp_cpu_info = !smp_cpu_info;
-                                get_jiffy_counts();
-                        }
-#  endif
-# endif
-                }
+                else
+                        scan_mask = handle_input(scan_mask, interval);
 #endif /* FEATURE_USE_TERMIOS */
-        } /* end of "while (1)" */
+        } /* end of "while (not Q)" */
 
         bb_putchar('\n');
 #if ENABLE_FEATURE_USE_TERMIOS