replace /proc scanning code by more versatile one.

Use it where appropriate.
Stop scanning /etc/passwd *for every process*!!! (uid->username)
top: reduce memory usage - we won't save unneeded fields
from /proc info anymore. Downside: ~+250 bytes of code

3 files changed, 115 insertions, 63 deletions

diff --git a/procps/kill.c b/procps/kill.c
index 9b96b4c1a..18121f06f 100644
--- a/procps/kill.c
+++ b/procps/kill.c
@@ -82,7 +82,7 @@ do_it_now:
 
 	if (killall5) {
 		pid_t sid;
-		procps_status_t* p;
+		procps_status_t* p = NULL;
 
 // Cannot happen anyway? We don't TERM ourself, we STOP
 //		/* kill(-1, sig) on Linux (at least 2.1.x)
@@ -94,8 +94,8 @@ do_it_now:
 		pid = getpid();
 		sid = getsid(pid);
 		/* Now kill all processes except our session */
-        	while ((p = procps_scan(0))!=0) {
-			if (getsid(p->pid)!=sid && p->pid!=pid && p->pid!=1)
+        	while ((p = procps_scan(p, PSSCAN_PID|PSSCAN_SID))) {
+			if (p->sid != sid && p->pid != pid && p->pid != 1)
 				kill(p->pid, signo);
 		}
 		/* And let them continue */
diff --git a/procps/ps.c b/procps/ps.c
index 9d6e42d79..2ff6e77d4 100644
--- a/procps/ps.c
+++ b/procps/ps.c
@@ -11,7 +11,7 @@
 
 int ps_main(int argc, char **argv)
 {
-	procps_status_t * p;
+	procps_status_t *p = NULL;
 	int i, len;
 	SKIP_SELINUX(const) int use_selinux = 0;
 	USE_SELINUX(security_context_t sid = NULL;)
@@ -50,7 +50,13 @@ int ps_main(int argc, char **argv)
 	else
 		puts("  PID  Uid     VmSize Stat Command");
 
-	while ((p = procps_scan(1)) != 0)  {
+	while ((p = procps_scan(p, 0
+			| PSSCAN_PID
+			| PSSCAN_UIDGID
+			| PSSCAN_STATE
+			| PSSCAN_RSS
+			| PSSCAN_CMD
+	))) {
 		char *namecmd = p->cmd;
 #if ENABLE_SELINUX
 		if (use_selinux) {
@@ -71,13 +77,18 @@ int ps_main(int argc, char **argv)
 			} else {
 				safe_strncpy(sbuf, "unknown", 7);
 			}
-			len = printf("%5u %-32s %s ", (unsigned)p->pid, sbuf, p->state);
+			len = printf("%5u %-32s %s ", p->pid, sbuf, p->state);
 		} else
 #endif
+		{
+			const char *user = get_cached_username(p->uid);
 			if (p->rss == 0)
-				len = printf("%5u %-8s        %s ", (unsigned)p->pid, p->user, p->state);
+				len = printf("%5u %-8s        %s ",
+					p->pid, user, p->state);
 			else
-				len = printf("%5u %-8s %6ld %s ", (unsigned)p->pid, p->user, p->rss, p->state);
+				len = printf("%5u %-8s %6ld %s ",
+					p->pid, user, p->rss, p->state);
+		}
 
 		i = terminal_width-len;
 
@@ -88,16 +99,15 @@ int ps_main(int argc, char **argv)
 				namecmd[i] = 0;
 			puts(namecmd);
 		} else {
-			namecmd = p->short_cmd;
+			namecmd = p->comm;
 			if (i < 2)
 				i = 2;
 			if (strlen(namecmd) > ((size_t)i-2))
 				namecmd[i-2] = 0;
 			printf("[%s]\n", namecmd);
 		}
-		/* no check needed, but to make valgrind happy.. */
-		if (ENABLE_FEATURE_CLEAN_UP && p->cmd)
-			free(p->cmd);
 	}
+	if (ENABLE_FEATURE_CLEAN_UP)
+		clear_username_cache();
 	return EXIT_SUCCESS;
 }
diff --git a/procps/top.c b/procps/top.c
index c76fdc312..8d732d4b2 100644
--- a/procps/top.c
+++ b/procps/top.c
@@ -30,37 +30,76 @@
 
 #include "busybox.h"
 
-typedef int (*cmp_t)(procps_status_t *P, procps_status_t *Q);
 
-static procps_status_t *top;   /* Hehe */
+typedef struct {
+	unsigned long rss;
+#if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
+	unsigned long ticks;
+	unsigned pcpu; /* delta of ticks */
+#endif
+	unsigned pid, ppid;
+	unsigned uid;
+	char state[4];
+	char comm[COMM_LEN];
+} top_status_t;
+static top_status_t *top;
 static int ntop;
+/* This structure stores some critical information from one frame to
+   the next. Used for finding deltas. */
+struct save_hist {
+	unsigned long ticks;
+	unsigned pid;
+};
+static struct save_hist *prev_hist;
+static int prev_hist_count;
+/* static int hist_iterations; */
+static unsigned total_pcpu;
+/* static unsigned long total_rss; */
+
+
 #define OPT_BATCH_MODE (option_mask32 & 0x4)
 
 #if ENABLE_FEATURE_USE_TERMIOS
-static int pid_sort(procps_status_t *P, procps_status_t *Q)
+static int pid_sort(top_status_t *P, top_status_t *Q)
 {
+	/* Buggy wrt pids with high bit set */
+	/* (linux pids are in [1..2^15-1]) */
 	return (Q->pid - P->pid);
 }
 #endif
 
-static int mem_sort(procps_status_t *P, procps_status_t *Q)
+static int mem_sort(top_status_t *P, top_status_t *Q)
 {
-	return (int)(Q->rss - P->rss);
+	/* We want to avoid unsigned->signed and truncation errors */
+	if (Q->rss < P->rss) return -1;
+	return Q->rss != P->rss; /* 0 if ==, 1 if > */
 }
 
-#if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
+
+typedef int (*cmp_funcp)(top_status_t *P, top_status_t *Q);
+
+#if !ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
+
+static cmp_funcp sort_function;
+
+#else
 
 enum { SORT_DEPTH = 3 };
-static cmp_t sort_function[SORT_DEPTH];
 
-static int pcpu_sort(procps_status_t *P, procps_status_t *Q)
+static cmp_funcp sort_function[SORT_DEPTH];
+
+static int pcpu_sort(top_status_t *P, top_status_t *Q)
 {
-	return (Q->pcpu - P->pcpu);
+	/* Buggy wrt ticks with high bit set */
+	/* Affects only processes for which ticks overflow */
+	return (int)Q->pcpu - (int)P->pcpu;
 }
 
-static int time_sort(procps_status_t *P, procps_status_t *Q)
+static int time_sort(top_status_t *P, top_status_t *Q)
 {
-	return (int)((Q->stime + Q->utime) - (P->stime + P->utime));
+	/* We want to avoid unsigned->signed and truncation errors */
+	if (Q->ticks < P->ticks) return -1;
+	return Q->ticks != P->ticks; /* 0 if ==, 1 if > */
 }
 
 static int mult_lvl_cmp(void* a, void* b) {
@@ -74,24 +113,6 @@ static int mult_lvl_cmp(void* a, void* b) {
 	return 0;
 }
 
-/* This structure stores some critical information from one frame to
-   the next. Mostly used for sorting. */
-struct save_hist {
-	int ticks;
-	pid_t pid;
-};
-
-/*
- * Calculates percent cpu usage for each task.
- */
-
-static struct save_hist *prev_hist;
-static int prev_hist_count;
-/* static int hist_iterations; */
-
-
-static unsigned total_pcpu;
-/* static unsigned long total_rss; */
 
 typedef struct {
 	unsigned long long usr,nic,sys,idle,iowait,irq,softirq,steal;
@@ -115,11 +136,12 @@ static void get_jiffy_counts(void)
 	jif.busy = jif.total - jif.idle - jif.iowait;
 }
 
+
 static void do_stats(void)
 {
-	procps_status_t *cur;
+	top_status_t *cur;
 	pid_t pid;
-	int total_time, i, last_i, n;
+	int i, last_i, n;
 	struct save_hist *new_hist;
 
 	get_jiffy_counts();
@@ -139,8 +161,7 @@ static void do_stats(void)
 		 * and system time
 		 */
 		pid = cur->pid;
-		total_time = cur->stime + cur->utime;
-		new_hist[n].ticks = total_time;
+		new_hist[n].ticks = cur->ticks;
 		new_hist[n].pid = pid;
 
 		/* find matching entry from previous pass */
@@ -150,13 +171,13 @@ static void do_stats(void)
 		last_i = i;
 		if (prev_hist_count) do {
 			if (prev_hist[i].pid == pid) {
-				cur->pcpu = total_time - prev_hist[i].ticks;
+				cur->pcpu = cur->ticks - prev_hist[i].ticks;
+				total_pcpu += cur->pcpu;
 				break;
 			}
 			i = (i+1) % prev_hist_count;
 			/* hist_iterations++; */
 		} while (i != last_i);
-		total_pcpu += cur->pcpu;
 		/* total_rss += cur->rss; */
 	}
 
@@ -167,10 +188,9 @@ static void do_stats(void)
 	prev_hist = new_hist;
 	prev_hist_count = ntop;
 }
-#else
-static cmp_t sort_function;
 #endif /* FEATURE_TOP_CPU_USAGE_PERCENTAGE */
 
+
 /* display generic info (meminfo / loadavg) */
 static unsigned long display_generic(int scr_width)
 {
@@ -265,7 +285,7 @@ static void display_status(int count, int scr_width)
 		bits_per_int = sizeof(int)*8
 	};
 
-	procps_status_t *s = top;
+	top_status_t *s = top;
 	char rss_str_buf[8];
 	unsigned long total_memory = display_generic(scr_width); /* or use total_rss? */
 	unsigned pmem_shift, pmem_scale;
@@ -333,14 +353,19 @@ static void display_status(int count, int scr_width)
 			sprintf(rss_str_buf, "%6ldM", s->rss/1024);
 		else
 			sprintf(rss_str_buf, "%7ld", s->rss);
-		USE_FEATURE_TOP_CPU_USAGE_PERCENTAGE(pcpu = div((s->pcpu*pcpu_scale) >> pcpu_shift, 10);)
-		col -= printf("\n%5u %-8s %s  %s%6u%3u.%c" \
-				USE_FEATURE_TOP_CPU_USAGE_PERCENTAGE("%3u.%c") " ",
-				(unsigned)s->pid, s->user, s->state, rss_str_buf, (unsigned)s->ppid,
+		USE_FEATURE_TOP_CPU_USAGE_PERCENTAGE(
+		pcpu = div((s->pcpu*pcpu_scale) >> pcpu_shift, 10);
+		)
+		col -= printf("\n%5u %-8s %s  "
+				"%s%6u"
+				USE_FEATURE_TOP_CPU_USAGE_PERCENTAGE("%3u.%c")
+				"%3u.%c ",
+				s->pid, get_cached_username(s->uid), s->state,
+				rss_str_buf, s->ppid,
 				USE_FEATURE_TOP_CPU_USAGE_PERCENTAGE(pcpu.quot, '0'+pcpu.rem,)
 				pmem.quot, '0'+pmem.rem);
 		if (col > 0)
-			printf("%.*s", col, s->short_cmd);
+			printf("%.*s", col, s->comm);
 		/* printf(" %d/%d %lld/%lld", s->pcpu, total_pcpu,
 			jif.busy - prev_jif.busy, jif.total - prev_jif.total); */
 		s++;
@@ -350,18 +375,20 @@ static void display_status(int count, int scr_width)
 	fflush(stdout);
 }
 
+
 static void clearmems(void)
 {
+	clear_username_cache();
 	free(top);
 	top = 0;
 	ntop = 0;
 }
 
+
 #if ENABLE_FEATURE_USE_TERMIOS
 #include <termios.h>
 #include <signal.h>
 
-
 static struct termios initial_settings;
 
 static void reset_term(void)
@@ -427,7 +454,7 @@ int top_main(int argc, char **argv)
 #endif /* FEATURE_TOP_CPU_USAGE_PERCENTAGE */
 
 	while (1) {
-		procps_status_t *p;
+		procps_status_t *p = NULL;
 
 		/* Default to 25 lines - 5 lines for status */
 		lines = 24 - 3;
@@ -442,11 +469,26 @@ int top_main(int argc, char **argv)
 #endif /* FEATURE_USE_TERMIOS */
 
 		/* read process IDs & status for all the processes */
-		while ((p = procps_scan(0)) != 0) {
+		while ((p = procps_scan(p, 0
+				| PSSCAN_PID
+				| PSSCAN_PPID
+				| PSSCAN_RSS
+				| PSSCAN_STIME
+				| PSSCAN_UTIME
+				| PSSCAN_STATE
+				| PSSCAN_COMM
+				| PSSCAN_SID
+				| PSSCAN_UIDGID
+		))) {
 			int n = ntop;
-
-			top = xrealloc(top, (++ntop)*sizeof(procps_status_t));
-			memcpy(top + n, p, sizeof(procps_status_t));
+			top = xrealloc(top, (++ntop)*sizeof(top_status_t));
+			top[n].pid = p->pid;
+			top[n].ppid = p->ppid;
+			top[n].rss = p->rss;
+			top[n].ticks = p->stime + p->utime;
+			top[n].uid = p->uid;
+			strcpy(top[n].state, p->state);
+			strcpy(top[n].comm, p->comm);
 		}
 		if (ntop == 0) {
 			bb_error_msg_and_die("can't find process info in /proc");
@@ -459,9 +501,9 @@ int top_main(int argc, char **argv)
 			continue;
 		}
 		do_stats();
-		qsort(top, ntop, sizeof(procps_status_t), (void*)mult_lvl_cmp);
+		qsort(top, ntop, sizeof(top_status_t), (void*)mult_lvl_cmp);
 #else
-		qsort(top, ntop, sizeof(procps_status_t), (void*)sort_function);
+		qsort(top, ntop, sizeof(top_status_t), (void*)sort_function);
 #endif /* FEATURE_TOP_CPU_USAGE_PERCENTAGE */
 		count = lines;
 		if (OPT_BATCH_MODE || count > ntop) {