From: David Levine <levinedl@acm.org>
Date: Sun, 15 Mar 2020 21:18:58 +0000 (-0400)
Subject: Refined number of bytes copied to buffer in several places.
X-Git-Url: https://diplodocus.org/git/nmh/commitdiff_plain/361f9cbca968760822f53a80b407f24ce1713ccd?hp=283d1d6f7d1e3ef16af638b4b943e2386330e68e

Refined number of bytes copied to buffer in several places.

This fixed "output may be truncated writing up to [m] bytes
into a region of size [n]" warnings found by gcc -Wformat-truncation.
---

diff --git a/test/fakesmtp.c b/test/fakesmtp.c
index c4fa3e7c..8050e553 100644
--- a/test/fakesmtp.c
+++ b/test/fakesmtp.c
@@ -14,6 +14,10 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 
+#ifndef min
+# define min(a,b) ((a) < (b) ? (a) : (b))
+#endif
+
 #define PIDFILE "/tmp/fakesmtp.pid"
 
 #define LINESIZE 1024
@@ -155,9 +159,9 @@ getsmtp(int socket, char *data)
 		if (bytesinbuf > 0 && (p = strchr(buffer, '\r')) &&
 							*(p + 1) == '\n') {
 			*p = '\0';
-			strncpy(data, buffer, LINESIZE);
-			data[LINESIZE - 1] = '\0';
 			cc = strlen(buffer);
+			memcpy(data, buffer, min(cc + 1, LINESIZE));
+			data[LINESIZE - 1] = '\0';
 
 			/*
 			 * Shuffle leftover bytes back to the beginning
diff --git a/uip/dropsbr.c b/uip/dropsbr.c
index 630de111..4a6bb7a0 100644
--- a/uip/dropsbr.c
+++ b/uip/dropsbr.c
@@ -247,10 +247,12 @@ mbx_copy (char *mailbox, int mbx_style, int md, int fd,
 			 * If there is already a "From " line,
 			 * then leave it alone.  Else we add one.
 			 */
-			char tmpbuffer[sizeof buffer-7];
+			char tmpbuffer[sizeof buffer-21];
 			char *tp, *ep;
 
-			strncpy(tmpbuffer, buffer, sizeof(tmpbuffer));
+			(void) strncpy(tmpbuffer, buffer,
+				       min(strlen(buffer) + 1,
+					   sizeof(tmpbuffer) - 1));
 			ep = "nobody@nowhere";
 			tp = dctime(dlocaltimenow());
 			snprintf (buffer, sizeof(buffer), "From %s  %s%s", ep, tp, tmpbuffer);
diff --git a/uip/mkstemp.c b/uip/mkstemp.c
index b7fa5ae0..7a653ea8 100644
--- a/uip/mkstemp.c
+++ b/uip/mkstemp.c
@@ -88,8 +88,8 @@ build_template(const char *directory, const char *prefix, const char *suffix)
     prefix_len = strlen(prefix);
     suffix_len = strlen(suffix);
     /* sizeof pattern includes its final NULL, so don't add another. */
-    len = directory_len  +  pathsep_len  +  prefix_len  +   sizeof pattern  +
-        suffix_len;
+    len =
+        directory_len + pathsep_len + prefix_len + sizeof pattern + suffix_len;
 
     if ((template = malloc(len))) {
         char *tp = template;
@@ -102,7 +102,7 @@ build_template(const char *directory, const char *prefix, const char *suffix)
         (void) strncpy(tp, prefix, prefix_len);
         tp += prefix_len;
 
-        (void) strncpy(tp, pattern, sizeof pattern - 1);
+        (void) memcpy(tp, pattern, sizeof pattern);
         tp += sizeof pattern - 1;
 
         (void) strncpy(tp, suffix, suffix_len);
diff --git a/uip/popsbr.c b/uip/popsbr.c
index c1d520e9..3b606334 100644
--- a/uip/popsbr.c
+++ b/uip/popsbr.c
@@ -703,7 +703,8 @@ multiline (void)
         strncpy (response, buffer + LEN(TRM), sizeof(response));
     }
     else
-	strncpy (response, buffer, sizeof(response));
+	strncpy (response, buffer,
+		 min (strlen(buffer) + 1, sizeof(response) - 1));
 
     return OK;
 }