lib: fixup zlog_hexdump

* Allocate correct amount of memory
* Use snprintf() instead of sprintf()

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>

diff --git a/lib/log.c b/lib/log.c
index 9e33ef91021c020d464d29f7ec4f7066871ae933..5537d8d721fd4efb8e69b6b9e810321debbdd193 100644 (file)
--- a/lib/log.c
+++ b/lib/log.c
@@ -1092,41 +1092,48 @@ void zlog_hexdump(const void *mem, unsigned int len)
        unsigned long i = 0;
        unsigned int j = 0;
        unsigned int columns = 8;
-       char buf[(len * 4) + ((len / 4) * 20) + 30];
+       /* 19 bytes for 0xADDRESS: */
+       /* 24 bytes for data; 2 chars plus a space per data byte */
+       /*  1 byte for space */
+       /*  8 bytes for ASCII representation */
+       /*  1 byte for a newline */
+       /* ===================== */
+       /* 53 bytes per 8 bytes of data */
+       /*  1 byte for null term */
+       size_t bs = ((len / 8) + 1) * 53 + 1;
+       char buf[bs];
        char *s = buf;
 
        for (i = 0; i < len + ((len % columns) ? (columns - len % columns) : 0);
             i++) {
                /* print offset */
                if (i % columns == 0)
-                       s += sprintf(s, "0x%016lx: ", (unsigned long)mem + i);
+                       s += snprintf(s, bs - (s - buf),
+                                     "0x%016lx: ", (unsigned long)mem + i);
 
                /* print hex data */
                if (i < len)
-                       s += sprintf(s, "%02x ", 0xFF & ((const char *)mem)[i]);
+                       s += snprintf(s, bs - (s - buf), "%02x ",
+                                     0xFF & ((const char *)mem)[i]);
 
                /* end of block, just aligning for ASCII dump */
                else
-                       s += sprintf(s, "   ");
+                       s += snprintf(s, bs - (s - buf), "   ");
 
                /* print ASCII dump */
                if (i % columns == (columns - 1)) {
                        for (j = i - (columns - 1); j <= i; j++) {
-                               if (j >= len) /* end of block, not really
-                                                printing */
-                                       s += sprintf(s, " ");
-
-                               else if (isprint((int)((const char *)mem)
-                                                        [j])) /* printable char
-                                                                 */
-                                       s += sprintf(
-                                               s, "%c",
+                               /* end of block not really printing */
+                               if (j >= len)
+                                       s += snprintf(s, bs - (s - buf), " ");
+                               else if (isprint((int)((const char *)mem)[j]))
+                                       s += snprintf(
+                                               s, bs - (s - buf), "%c",
                                                0xFF & ((const char *)mem)[j]);
-
                                else /* other char */
-                                       s += sprintf(s, ".");
+                                       s += snprintf(s, bs - (s - buf), ".");
                        }
-                       s += sprintf(s, "\n");
+                       s += snprintf(s, bs - (s - buf), "\n");
                }
        }
        zlog_debug("\n%s", buf);