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

2 files changed, 174 insertions, 93 deletions

diff --git a/libbb/find_pid_by_name.c b/libbb/find_pid_by_name.c
index 05f7f96..e986169 100644
--- a/libbb/find_pid_by_name.c
+++ b/libbb/find_pid_by_name.c
@@ -23,11 +23,11 @@ pid_t* find_pid_by_name(const char* procName)
 {
 	pid_t* pidList;
 	int i = 0;
-	procps_status_t* p;
+	procps_status_t* p = NULL;
 
 	pidList = xmalloc(sizeof(*pidList));
-	while ((p = procps_scan(0)) != 0) {
-		if (strncmp(p->short_cmd, procName, COMM_LEN-1) == 0) {
+	while ((p = procps_scan(p, PSSCAN_PID|PSSCAN_COMM))) {
+		if (strncmp(p->comm, procName, sizeof(p->comm)-1) == 0) {
 			pidList = xrealloc(pidList, sizeof(*pidList) * (i+2));
 			pidList[i++] = p->pid;
 		}
diff --git a/libbb/procps.c b/libbb/procps.c
index 15f7715..dee5638 100644
--- a/libbb/procps.c
+++ b/libbb/procps.c
@@ -11,6 +11,35 @@
 #include "libbb.h"
 
 
+typedef struct {
+	uid_t uid;
+	char username[12];
+} user_map_t;
+
+static user_map_t *username_cache;
+static int username_cache_size;
+
+void clear_username_cache(void)
+{
+	free(username_cache);
+	username_cache = NULL;
+	username_cache_size = 0;
+}
+
+const char* get_cached_username(uid_t uid)
+{
+	int i;
+	for (i = 0; i < username_cache_size; i++)
+		if (username_cache[i].uid == uid)
+			return username_cache[i].username;
+	i = username_cache_size++;
+	username_cache = xrealloc(username_cache, username_cache_size * sizeof(*username_cache));
+	username_cache[i].uid = uid;
+	bb_getpwuid(username_cache[i].username, uid, sizeof(username_cache[i].username));
+	return username_cache[i].username;
+}
+
+
 #define PROCPS_BUFSIZE 1024
 
 static int read_to_buf(const char *filename, void *buf)
@@ -21,119 +50,171 @@ static int read_to_buf(const char *filename, void *buf)
 	return ret;
 }
 
+procps_status_t* alloc_procps_scan(int flags)
+{
+	procps_status_t* sp = xzalloc(sizeof(procps_status_t));
+	sp->dir = xopendir("/proc");
+	return sp;
+}
 
-procps_status_t * procps_scan(int save_user_arg0)
+void free_procps_scan(procps_status_t* sp)
 {
-	static DIR *dir;
-	static procps_status_t ret_status;
+	closedir(sp->dir);
+	free(sp->cmd);
+	free(sp);
+}
 
+void BUG_comm_size(void);
+procps_status_t* procps_scan(procps_status_t* sp, int flags)
+{
 	struct dirent *entry;
-	char *name;
 	char buf[PROCPS_BUFSIZE];
-	char status[sizeof("/proc//cmdline") + sizeof(int)*3];
-	char *status_tail;
-	procps_status_t curstatus;
+	char filename[sizeof("/proc//cmdline") + sizeof(int)*3];
+	char *filename_tail;
 	long tasknice;
-	int pid;
+	unsigned pid;
 	int n;
 	struct stat sb;
 
-	if (!dir) {
-		dir = xopendir("/proc");
-	}
+	if (!sp)
+		sp = alloc_procps_scan(flags);
+
 	for (;;) {
-		entry = readdir(dir);
+		entry = readdir(sp->dir);
 		if (entry == NULL) {
-			closedir(dir);
-			dir = 0;
-			return 0;
+			free_procps_scan(sp);
+			return NULL;
 		}
-		name = entry->d_name;
-		if (!(*name >= '0' && *name <= '9'))
+		if (safe_strtou(entry->d_name, &pid))
 			continue;
 
-		memset(&curstatus, 0, sizeof(procps_status_t));
-		pid = atoi(name);
-		curstatus.pid = pid;
+		/* After this point we have to break, not continue
+		 * ("continue" would mean that current /proc/NNN
+		 * is not a valid process info) */
 
-		status_tail = status + sprintf(status, "/proc/%d", pid);
-		if (stat(status, &sb))
-			continue;
-		bb_getpwuid(curstatus.user, sb.st_uid, sizeof(curstatus.user));
+		memset(&sp->rss, 0, sizeof(*sp) - offsetof(procps_status_t, rss));
 
-		/* see proc(5) for some details on this */
-		strcpy(status_tail, "/stat");
-		n = read_to_buf(status, buf);
-		if (n < 0)
-			continue;
-		name = strrchr(buf, ')'); /* split into "PID (cmd" and "<rest>" */
-		if (name == 0 || name[1] != ' ')
-			continue;
-		*name = 0;
-		sscanf(buf, "%*s (%15c", curstatus.short_cmd);
-		n = sscanf(name+2,
-		"%c %d "
-		"%*s %*s %*s %*s "     /* pgrp, session, tty, tpgid */
-		"%*s %*s %*s %*s %*s " /* flags, min_flt, cmin_flt, maj_flt, cmaj_flt */
-#ifdef CONFIG_FEATURE_TOP_CPU_USAGE_PERCENTAGE
-		"%lu %lu "             /* utime, stime */
-#else
-		"%*s %*s "             /* utime, stime */
-#endif
-		"%*s %*s %*s "         /* cutime, cstime, priority */
-		"%ld "                 /* nice */
-		"%*s %*s %*s "         /* timeout, it_real_value, start_time */
-		"%*s "                 /* vsize */
-		"%ld",                 /* rss */
-		curstatus.state, &curstatus.ppid,
-#ifdef CONFIG_FEATURE_TOP_CPU_USAGE_PERCENTAGE
-		&curstatus.utime, &curstatus.stime,
-#endif
-		&tasknice,
-		&curstatus.rss);
-#ifdef CONFIG_FEATURE_TOP_CPU_USAGE_PERCENTAGE
-		if (n != 6)
-#else
-		if (n != 4)
-#endif
-			continue;
+		sp->pid = pid;
+		if (!(flags & ~PSSCAN_PID)) break;
 
-		if (curstatus.rss == 0 && curstatus.state[0] != 'Z')
-			curstatus.state[1] = 'W';
-		else
-			curstatus.state[1] = ' ';
-		if (tasknice < 0)
-			curstatus.state[2] = '<';
-		else if (tasknice > 0)
-			curstatus.state[2] = 'N';
-		else
-			curstatus.state[2] = ' ';
+		filename_tail = filename + sprintf(filename, "/proc/%d", pid);
+
+		if (flags & PSSCAN_UIDGID) {
+			if (stat(filename, &sb))
+				break;
+			/* Need comment - is this effective or read UID/GID? */
+			sp->uid = sb.st_uid;
+			sp->gid = sb.st_gid;
+		}
+	
+		if (flags & PSSCAN_STAT) {
+			char *cp;
+			/* see proc(5) for some details on this */
+			strcpy(filename_tail, "/stat");
+			n = read_to_buf(filename, buf);
+			if (n < 0)
+				break;
+			cp = strrchr(buf, ')'); /* split into "PID (cmd" and "<rest>" */
+			if (!cp || cp[1] != ' ')
+				break;
+			cp[0] = '\0';
+			if (sizeof(sp->comm) < 16)
+				BUG_comm_size();
+			sscanf(buf, "%*s (%15c", sp->comm);
+			n = sscanf(cp+2,
+				"%c %u "               /* state, ppid */
+				"%u %u %*s %*s "       /* pgid, sid, tty, tpgid */
+				"%*s %*s %*s %*s %*s " /* flags, min_flt, cmin_flt, maj_flt, cmaj_flt */
+				"%lu %lu "             /* utime, stime */
+				"%*s %*s %*s "         /* cutime, cstime, priority */
+				"%ld "                 /* nice */
+				"%*s %*s %*s "         /* timeout, it_real_value, start_time */
+				"%*s "                 /* vsize */
+				"%lu",                 /* rss */
+				sp->state, &sp->ppid,
+				&sp->pgid, &sp->sid,
+				&sp->utime, &sp->stime,
+				&tasknice,
+				&sp->rss);
+			if (n != 8)
+				break;
+
+			if (sp->rss == 0 && sp->state[0] != 'Z')
+				sp->state[1] = 'W';
+			else
+				sp->state[1] = ' ';
+			if (tasknice < 0)
+				sp->state[2] = '<';
+			else if (tasknice > 0)
+				sp->state[2] = 'N';
+			else
+				sp->state[2] = ' ';
 
 #ifdef PAGE_SHIFT
-		curstatus.rss <<= (PAGE_SHIFT - 10);     /* 2**10 = 1kb */
+			sp->rss <<= (PAGE_SHIFT - 10);     /* 2**10 = 1kb */
 #else
-		curstatus.rss *= (getpagesize() >> 10);     /* 2**10 = 1kb */
+			sp->rss *= (getpagesize() >> 10);     /* 2**10 = 1kb */
 #endif
+		}
 
-		if (save_user_arg0) {
-			strcpy(status_tail, "/cmdline");
-			n = read_to_buf(status, buf);
-			if (n > 0) {
-				if (buf[n-1]=='\n')
-					buf[--n] = 0;
-				name = buf;
-				while (n) {
-					if (((unsigned char)*name) < ' ')
-						*name = ' ';
-					name++;
-					n--;
-				}
-				*name = 0;
-				if (buf[0])
-					curstatus.cmd = strdup(buf);
-				/* if NULL it work true also */
+		if (flags & PSSCAN_CMD) {
+			free(sp->cmd);
+			sp->cmd = NULL;
+			strcpy(filename_tail, "/cmdline");
+			n = read_to_buf(filename, buf);
+			if (n <= 0)
+				break;
+			if (buf[n-1] == '\n') {
+				if (!--n)
+					break;
+				buf[n] = '\0';
 			}
+			do {
+				n--;
+				if ((unsigned char)(buf[n]) < ' ')
+					buf[n] = ' ';
+			} while (n);
+			sp->cmd = strdup(buf);
 		}
-		return memcpy(&ret_status, &curstatus, sizeof(procps_status_t));
+		break;
 	}
+	return sp;
 }
+/* from kernel:
+	//             pid comm S ppid pgid sid tty_nr tty_pgrp flg
+        sprintf(buffer,"%d (%s) %c %d  %d   %d  %d     %d       %lu %lu \
+%lu %lu %lu %lu %lu %ld %ld %ld %ld %d 0 %llu %lu %ld %lu %lu %lu %lu %lu \
+%lu %lu %lu %lu %lu %lu %lu %lu %d %d %lu %lu %llu\n",
+                task->pid,
+                tcomm,
+                state,
+                ppid,
+                pgid,
+                sid,
+                tty_nr,
+                tty_pgrp,
+                task->flags,
+                min_flt,
+
+                cmin_flt,
+                maj_flt,
+                cmaj_flt,
+                cputime_to_clock_t(utime),
+                cputime_to_clock_t(stime),
+                cputime_to_clock_t(cutime),
+                cputime_to_clock_t(cstime),
+                priority,
+                nice,
+                num_threads,
+	// 0,
+                start_time,
+                vsize,
+                mm ? get_mm_rss(mm) : 0,
+                rsslim,
+                mm ? mm->start_code : 0,
+                mm ? mm->end_code : 0,
+                mm ? mm->start_stack : 0,
+                esp,
+                eip,
+the rest is some obsolete cruft
+*/