top: get rid of on-stack variable buffers, use permanent one.

code shrank with and without TOPMEM:

top_main                                             828     844     +16
display_process_list                                1525    1473     -52
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 16/-52)            Total: -36 bytes

top_main                                            1150    1171     +21
display_topmem_process_list                         1150    1167     +17
display_process_list                                1525    1473     -52
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/1 up/down: 38/-52)            Total: -14 bytes

2 files changed, 25 insertions, 21 deletions

diff --git a/include/platform.h b/include/platform.h
index ff23ca18c..39809450e 100644
--- a/include/platform.h
+++ b/include/platform.h
@@ -54,6 +54,7 @@
 # define ATTRIBUTE_ALIGNED(m) __attribute__ ((__aligned__(m)))
 # if __GNUC_PREREQ (3,0)
 #  define ALWAYS_INLINE __attribute__ ((always_inline)) inline
+#  define NOINLINE      __attribute__((noinline))
 #  if !ENABLE_WERROR
 #   define ATTRIBUTE_DEPRECATED __attribute__ ((__deprecated__))
 #   define ATTRIBUTE_UNUSED_RESULT __attribute__ ((warn_unused_result))
diff --git a/procps/top.c b/procps/top.c
index a9580962a..529db5f7b 100644
--- a/procps/top.c
+++ b/procps/top.c
@@ -82,8 +82,10 @@ struct globals {
         /* int hist_iterations; */
         unsigned total_pcpu;
         /* unsigned long total_vsz; */
+        char line_buf[80];
 #endif
 };
+enum { LINE_BUF_SIZE = COMMON_BUFSIZE - offsetof(struct globals, line_buf) };
 #define G (*(struct globals*)&bb_common_bufsiz1)
 #define INIT_G() \
         do { \
@@ -102,6 +104,7 @@ struct globals {
 #define jif              (G.jif               )
 #define prev_jif         (G.prev_jif          )
 #define total_pcpu       (G.total_pcpu        )
+#define line_buf         (G.line_buf          )
 
 
 #define OPT_BATCH_MODE (option_mask32 & 0x4)
@@ -366,7 +369,7 @@ static unsigned long display_header(int scr_width)
         return total;
 }
 
-static void display_process_list(int count, int scr_width)
+static NOINLINE void display_process_list(int count, int scr_width)
 {
         enum {
                 BITS_PER_INT = sizeof(int)*8
@@ -447,7 +450,6 @@ static void display_process_list(int count, int scr_width)
         scr_width += 2; /* account for leading '\n' and trailing NUL */
         /* Ok, all preliminary data is ready, go thru the list */
         while (count-- > 0) {
-                char buf[scr_width];
                 unsigned col;
                 CALC_STAT(pmem, (s->vsz*pmem_scale + pmem_half) >> pmem_shift);
 #if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
@@ -459,7 +461,7 @@ static void display_process_list(int count, int scr_width)
                 else
                         sprintf(vsz_str_buf, "%7ld", s->vsz);
                 // PID PPID USER STAT VSZ %MEM [%CPU] COMMAND
-                col = snprintf(buf, scr_width,
+                col = snprintf(line_buf, scr_width,
                                 "\n" "%5u%6u %-8.8s %s%s" FMT
 #if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
                                 FMT
@@ -473,8 +475,8 @@ static void display_process_list(int count, int scr_width)
 #endif
                 );
                 if (col < scr_width)
-                        read_cmdline(buf + col, scr_width - col, s->pid, s->comm);
-                fputs(buf, stdout);
+                        read_cmdline(line_buf + col, scr_width - col, s->pid, s->comm);
+                fputs(line_buf, stdout);
                 /* printf(" %d/%d %lld/%lld", s->pcpu, total_pcpu,
                         jif.busy - prev_jif.busy, jif.total - prev_jif.total); */
                 s++;
@@ -722,33 +724,32 @@ static void smart_ulltoa6(unsigned long long ul, char buf[6])
         buf[5] = ' ';
 }
 
-static void display_topmem_process_list(int count, int scr_width)
+static NOINLINE void display_topmem_process_list(int count, 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;
-        char buf[scr_width | MIN_WIDTH]; /* a|b is a cheap max(a,b) */
 
         display_topmem_header(scr_width);
-        strcpy(buf, HDR_STR " COMMAND");
-        buf[5 + sort_field * 6] = '*';
-        printf(OPT_BATCH_MODE ? "%.*s" : "\e[7m%.*s\e[0m", scr_width, buf);
+        strcpy(line_buf, HDR_STR " COMMAND");
+        line_buf[5 + sort_field * 6] = '*';
+        printf(OPT_BATCH_MODE ? "%.*s" : "\e[7m%.*s\e[0m", scr_width, line_buf);
 
         while (--count >= 0) {
                 // PID VSZ VSZRW RSS (SHR) DIRTY (SHR) COMMAND
-                smart_ulltoa6(s->pid     , &buf[0*6]);
-                smart_ulltoa6(s->vsz     , &buf[1*6]);
-                smart_ulltoa6(s->vszrw   , &buf[2*6]);
-                smart_ulltoa6(s->rss     , &buf[3*6]);
-                smart_ulltoa6(s->rss_sh  , &buf[4*6]);
-                smart_ulltoa6(s->dirty   , &buf[5*6]);
-                smart_ulltoa6(s->dirty_sh, &buf[6*6]);
-                smart_ulltoa6(s->stack   , &buf[7*6]);
-                buf[8*6] = '\0';
+                smart_ulltoa6(s->pid     , &line_buf[0*6]);
+                smart_ulltoa6(s->vsz     , &line_buf[1*6]);
+                smart_ulltoa6(s->vszrw   , &line_buf[2*6]);
+                smart_ulltoa6(s->rss     , &line_buf[3*6]);
+                smart_ulltoa6(s->rss_sh  , &line_buf[4*6]);
+                smart_ulltoa6(s->dirty   , &line_buf[5*6]);
+                smart_ulltoa6(s->dirty_sh, &line_buf[6*6]);
+                smart_ulltoa6(s->stack   , &line_buf[7*6]);
+                line_buf[8*6] = '\0';
                 if (scr_width > MIN_WIDTH) {
-                        read_cmdline(&buf[8*6], scr_width - MIN_WIDTH, s->pid, s->comm);
+                        read_cmdline(&line_buf[8*6], scr_width - MIN_WIDTH, s->pid, s->comm);
                 }
-                printf("\n""%.*s", scr_width, buf);
+                printf("\n""%.*s", scr_width, line_buf);
                 s++;
         }
         putchar(OPT_BATCH_MODE ? '\n' : '\r');
@@ -848,6 +849,8 @@ int top_main(int argc, char **argv)
                         continue;
                 }
 #endif /* FEATURE_USE_TERMIOS */
+                if (col > LINE_BUF_SIZE-2) /* +2 bytes for '\n', NUL, */
+                        col = LINE_BUF_SIZE-2;
                 if (!ENABLE_FEATURE_TOP_CPU_GLOBAL_PERCENTS && scan_mask == TOP_MASK)
                         lines -= 3;
                 else