compare snprintf return value with -1. this isn't really necessary because

int promotion rules guarantee the correct result when compared with sizeof,
but it is perhaps easier for some people to understand it this way.
from Doug Hogan.

diff --git a/usr.bin/signify/signify.c b/usr.bin/signify/signify.c
index 4c33f6b..0dc9944 100644 (file)
--- a/usr.bin/signify/signify.c
+++ b/usr.bin/signify/signify.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: signify.c,v 1.90 2014/05/30 21:20:49 tedu Exp $ */
+/* $OpenBSD: signify.c,v 1.91 2014/07/13 18:59:40 tedu Exp $ */
 /*
  * Copyright (c) 2013 Ted Unangst <tedu@openbsd.org>
  *
@@ -230,11 +230,11 @@ writeb64file(const char *filename, const char *comment, const void *buf,
 {
        char header[1024];
        char b64[1024];
-       int fd, rv;
+       int fd, rv, nr;
 
        fd = xopen(filename, O_CREAT|oflags|O_NOFOLLOW|O_WRONLY, mode);
-       if (snprintf(header, sizeof(header), "%s%s\n",
-           COMMENTHDR, comment) >= sizeof(header))
+       if ((nr = snprintf(header, sizeof(header), "%s%s\n",
+           COMMENTHDR, comment)) == -1 || nr >= sizeof(header))
                errx(1, "comment too long");
        writeall(fd, header, strlen(header), filename);
        if ((rv = b64_ntop(buf, buflen, b64, sizeof(b64)-1)) == -1)
@@ -304,7 +304,7 @@ generate(const char *pubkeyfile, const char *seckeyfile, int rounds,
        uint8_t fingerprint[FPLEN];
        char commentbuf[COMMENTMAXLEN];
        SHA2_CTX ctx;
-       int i;
+       int i, nr;
 
        crypto_sign_ed25519_keypair(pubkey.pubkey, enckey.seckey);
        arc4random_buf(fingerprint, sizeof(fingerprint));
@@ -325,8 +325,8 @@ generate(const char *pubkeyfile, const char *seckeyfile, int rounds,
        explicit_bzero(digest, sizeof(digest));
        explicit_bzero(xorkey, sizeof(xorkey));
 
-       if (snprintf(commentbuf, sizeof(commentbuf), "%s secret key",
-           comment) >= sizeof(commentbuf))
+       if ((nr = snprintf(commentbuf, sizeof(commentbuf), "%s secret key",
+           comment)) == -1 || nr >= sizeof(commentbuf))
                errx(1, "comment too long");
        writeb64file(seckeyfile, commentbuf, &enckey,
            sizeof(enckey), NULL, 0, O_EXCL, 0600);
@@ -334,8 +334,8 @@ generate(const char *pubkeyfile, const char *seckeyfile, int rounds,
 
        memcpy(pubkey.pkalg, PKALG, 2);
        memcpy(pubkey.fingerprint, fingerprint, FPLEN);
-       if (snprintf(commentbuf, sizeof(commentbuf), "%s public key",
-           comment) >= sizeof(commentbuf))
+       if ((nr = snprintf(commentbuf, sizeof(commentbuf), "%s public key",
+           comment)) == -1 || nr >= sizeof(commentbuf))
                errx(1, "comment too long");
        writeb64file(pubkeyfile, commentbuf, &pubkey,
            sizeof(pubkey), NULL, 0, O_EXCL, 0666);
@@ -353,7 +353,7 @@ sign(const char *seckeyfile, const char *msgfile, const char *sigfile,
        char comment[COMMENTMAXLEN], sigcomment[COMMENTMAXLEN];
        char *secname;
        unsigned long long msglen;
-       int i, rounds;
+       int i, rounds, nr;
        SHA2_CTX ctx;
 
        readb64file(seckeyfile, &enckey, sizeof(enckey), comment);
@@ -382,12 +382,12 @@ sign(const char *seckeyfile, const char *msgfile, const char *sigfile,
        memcpy(sig.pkalg, PKALG, 2);
        secname = strstr(seckeyfile, ".sec");
        if (secname && strlen(secname) == 4) {
-               if (snprintf(sigcomment, sizeof(sigcomment), VERIFYWITH "%.*s.pub",
-                   (int)strlen(seckeyfile) - 4, seckeyfile) >= sizeof(sigcomment))
+               if ((nr = snprintf(sigcomment, sizeof(sigcomment), VERIFYWITH "%.*s.pub",
+                   (int)strlen(seckeyfile) - 4, seckeyfile)) == -1 || nr >= sizeof(sigcomment))
                        errx(1, "comment too long");
        } else {
-               if (snprintf(sigcomment, sizeof(sigcomment), "signature from %s",
-                   comment) >= sizeof(sigcomment))
+               if ((nr = snprintf(sigcomment, sizeof(sigcomment), "signature from %s",
+                   comment)) == -1 || nr >= sizeof(sigcomment))
                        errx(1, "comment too long");
        }
        if (embedded)
@@ -767,10 +767,11 @@ main(int argc, char **argv)
                usage(NULL);
 
        if (!sigfile && msgfile) {
+               int nr;
                if (strcmp(msgfile, "-") == 0)
                        usage("must specify sigfile with - message");
-               if (snprintf(sigfilebuf, sizeof(sigfilebuf), "%s.sig",
-                   msgfile) >= sizeof(sigfilebuf))
+               if ((nr = snprintf(sigfilebuf, sizeof(sigfilebuf), "%s.sig",
+                   msgfile)) == -1 || nr >= sizeof(sigfilebuf))
                        errx(1, "path too long");
                sigfile = sigfilebuf;
        }