svlogd: do not overrun read buffer (fixes bug 439)

function                                             old     new   delta
rotate                                               513     534     +21
logdirs_reopen                                      1291    1296      +5
processorstart                                       409     385     -24

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

diff --git a/runit/svlogd.c b/runit/svlogd.c
index 25799f6..79286a3 100644 (file)
--- a/runit/svlogd.c
+++ b/runit/svlogd.c
@@ -223,7 +223,6 @@ static void processorstart(struct logdir *ld)
        while ((pid = vfork()) == -1)
                pause2cannot("vfork for processor", ld->name);
        if (!pid) {
-               char *prog[4];
                int fd;
 
                /* child */
@@ -256,11 +255,7 @@ static void processorstart(struct logdir *ld)
                xmove_fd(fd, 5);
 
 // getenv("SHELL")?
-               prog[0] = (char*)"sh";
-               prog[1] = (char*)"-c";
-               prog[2] = ld->processor;
-               prog[3] = NULL;
-               execv("/bin/sh", prog);
+               execl("/bin/sh", "/bin/sh" + 5, "-c", ld->processor, (char*) NULL);
                bb_perror_msg_and_die(FATAL"can't %s processor %s", "run", ld->name);
        }
        ld->fnsave[26] = sv_ch; /* ...restore */
@@ -398,13 +393,14 @@ static unsigned rotate(struct logdir *ld)
                        pause2cannot("rename current", ld->name);
                while ((ld->fdcur = open("current", O_WRONLY|O_NDELAY|O_APPEND|O_CREAT, 0600)) == -1)
                        pause2cannot("create new current", ld->name);
-               /* we presume this cannot fail */
-               ld->filecur = fdopen(ld->fdcur, "a"); ////
+               while ((ld->filecur = fdopen(ld->fdcur, "a")) == NULL) ////
+                       pause2cannot("create new current", ld->name); /* very unlikely */
                setvbuf(ld->filecur, NULL, _IOFBF, linelen); ////
                close_on_exec_on(ld->fdcur);
                ld->size = 0;
                while (fchmod(ld->fdcur, 0644) == -1)
                        pause2cannot("set mode of current", ld->name);
+
                rmoldest(ld);
                processorstart(ld);
        }
@@ -551,10 +547,11 @@ static unsigned logdir_open(struct logdir *ld, const char *fn)
        free(ld->processor); ld->processor = NULL;
 
        /* read config */
-       i = open_read_close("config", buf, sizeof(buf));
+       i = open_read_close("config", buf, sizeof(buf) - 1);
        if (i < 0 && errno != ENOENT)
                bb_perror_msg(WARNING"%s/config", ld->name);
        if (i > 0) {
+               buf[i] = '\0';
                if (verbose)
                        bb_error_msg(INFO"read: %s/config", ld->name);
                s = buf;