[hackers] [ubase] Properly match (ttymaj, ttymin) pairs to tty names in /dev || sin

[git]

commit d76319f838dfb42c13c099012e72ca11d37d7178
Author: sin <s...@2f30.org>
Date:   Fri Jan 16 15:32:55 2015 +0000

    Properly match (ttymaj, ttymin) pairs to tty names in /dev
    
    For the common case where we have pts/ or tty do it straight
    away.  Otherwise traverse /dev for a match.  This fixes ps(1) when
    it is executed over a serial terminal with tty names like ttyAMA0.

diff --git a/libutil/tty.c b/libutil/tty.c
index 4bd24c0..9078e37 100644
--- a/libutil/tty.c
+++ b/libutil/tty.c
@@ -1,7 +1,13 @@
 /* See LICENSE file for copyright and license details. */
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <dirent.h>
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 
 #include "../util.h"
 
@@ -12,28 +18,63 @@ devtotty(int dev, int *tty_maj, int *tty_min)
        *tty_min = (dev & 0xff) | ((dev >> 12) & 0xfff00);
 }
 
-char *
-ttytostr(int tty_maj, int tty_min)
+int
+ttytostr(int tty_maj, int tty_min, char *str, size_t n)
 {
-       const char *pts = "pts/";
-       const char *tty = "tty";
-       char *ttystr;
-       size_t len;
-
-       /* Up to 10k ttys */
-       len = strlen(pts) + 4 + 1;
-       ttystr = emalloc(len);
+       struct stat sb;
+       struct dirent *dp;
+       DIR *dirp;
+       char path[PATH_MAX];
+
        switch (tty_maj) {
        case 136:
-               snprintf(ttystr, len, "%s%d", pts, tty_min);
-               break;
+               snprintf(str, n, "pts/%d", tty_min);
+               return 0;
        case 4:
-               snprintf(ttystr, len, "%s%d", tty, tty_min);
-               break;
+               snprintf(str, n, "tty%d", tty_min);
+               return 0;
        default:
-               ttystr[0] = '?';
-               ttystr[1] = '\0';
+               str[0] = '?';
+               str[1] = '\0';
                break;
        }
-       return ttystr;
+
+       dirp = opendir("/dev");
+       if (!dirp) {
+               weprintf("opendir /dev:");
+               return -1;
+       }
+
+       while ((dp = readdir(dirp))) {
+               if (!strcmp(dp->d_name, ".") ||
+                   !strcmp(dp->d_name, ".."))
+                       continue;
+
+               if (strlcpy(path, "/dev/", sizeof(path)) >= sizeof(path)) {
+                       weprintf("path too long\n");
+                       return -1;
+               }
+               if (strlcat(path, dp->d_name, sizeof(path)) >= sizeof(path)) {
+                       weprintf("path too long\n");
+                       return -1;
+               }
+
+               if (stat(path, &sb) < 0) {
+                       weprintf("stat %s:", dp->d_name);
+                       return -1;
+               }
+
+               if ((int)major(sb.st_rdev) == tty_maj &&
+                   (int)minor(sb.st_rdev) == tty_min) {
+                       strlcpy(str, dp->d_name, n);
+                       break;
+               }
+       }
+
+       if (closedir(dirp) < 0) {
+               weprintf("closedir /dev:");
+               return -1;
+       }
+
+       return 0;
 }
diff --git a/ps.c b/ps.c
index 2f555d8..14f95c8 100644
--- a/ps.c
+++ b/ps.c
@@ -70,7 +70,7 @@ psout(struct procstat *ps)
        struct procstatus pstatus;
        char cmdline[BUFSIZ], *cmd;
        char buf[BUFSIZ];
-       char *ttystr, *myttystr;
+       char ttystr[PATH_MAX], *myttystr;
        int tty_maj, tty_min;
        uid_t myeuid;
        unsigned sutime;
@@ -86,16 +86,13 @@ psout(struct procstat *ps)
                        return;
 
        devtotty(ps->tty_nr, &tty_maj, &tty_min);
-       ttystr = ttytostr(tty_maj, tty_min);
+       ttytostr(tty_maj, tty_min, ttystr, sizeof(ttystr));
 
        /* Only print processes that are associated with
         * a terminal and they are not session leaders */
-       if (flags & PS_aflag) {
-               if (ps->pid == ps->sid || ttystr[0] == '?') {
-                       free(ttystr);
+       if (flags & PS_aflag)
+               if (ps->pid == ps->sid || ttystr[0] == '?')
                        return;
-               }
-       }
 
        if (parsestatus(ps->pid, &pstatus) < 0)
                return;
@@ -106,10 +103,8 @@ psout(struct procstat *ps)
        if (!(flags & (PS_aflag | PS_Aflag | PS_dflag))) {
                myttystr = ttyname(0);
                if (myttystr) {
-                       if (strcmp(myttystr + strlen("/dev/"), ttystr)) {
-                               free(ttystr);
+                       if (strcmp(myttystr + strlen("/dev/"), ttystr))
                                return;
-                       }
                } else {
                        /* The invoker has no controlling terminal - just
                         * go ahead and print the processes anyway */
@@ -117,10 +112,8 @@ psout(struct procstat *ps)
                        ttystr[1] = '\0';
                }
                myeuid = geteuid();
-               if (myeuid != pstatus.euid) {
-                       free(ttystr);
+               if (myeuid != pstatus.euid)
                        return;
-               }
        }
 
        sutime = (ps->stime + ps->utime) / sysconf(_SC_CLK_TCK);
@@ -166,7 +159,6 @@ psout(struct procstat *ps)
                else
                        printf("%s\n", buf);
        }
-       free(ttystr);
 }
 
 static void
diff --git a/util.h b/util.h
index cb75bc6..d9b5f1a 100644
--- a/util.h
+++ b/util.h
@@ -50,4 +50,4 @@ size_t strlcpy(char *, const char *, size_t);
 
 /* tty.c */
 void devtotty(int, int *, int *);
-char *ttytostr(int, int);
+int ttytostr(int, int, char *, size_t);