pkg: refactor out a pkg_read_fd()

We already have to do this for reading the pubkey, just pull it out for
other uses.  The ECC signer will use this to verify the bootstrap if
the PUBKEY mechanism is used.

Reviewed by:	bapt, emaste
Differential Revision:	https://reviews.freebsd.org/D48107

usr.sbin/pkg/pkg.c

@@ -451,32 +451,46 @@ load_fingerprints(const char *path, int *count)
 	return (fingerprints);
 }
 
+char *
+pkg_read_fd(int fd, size_t *osz)
+{
+	char *obuf;
+	char buf[4096];
+	FILE *fp;
+	ssize_t r;
+
+	obuf = NULL;
+	*osz = 0;
+	fp = open_memstream(&obuf, osz);
+	if (fp == NULL)
+		err(EXIT_FAILURE, "open_memstream()");
+
+	while ((r = read(fd, buf, sizeof(buf))) >0) {
+		fwrite(buf, 1, r, fp);
+	}
+
+	if (ferror(fp))
+		errx(EXIT_FAILURE, "reading file");
+
+	fclose(fp);
+
+	return (obuf);
+}
+
 static struct pubkey *
 read_pubkey(int fd)
 {
 	struct pubkey *pk;
 	char *sigb;
 	size_t sigsz;
-	FILE *sig;
-	char buf[4096];
-	int r;
 
 	if (lseek(fd, 0, 0) == -1) {
 		warn("lseek");
 		return (NULL);
 	}
 
-	sigsz = 0;
-	sigb = NULL;
-	sig = open_memstream(&sigb, &sigsz);
-	if (sig == NULL)
-		err(EXIT_FAILURE, "open_memstream()");
+	sigb = pkg_read_fd(fd, &sigsz);
 
-	while ((r = read(fd, buf, sizeof(buf))) >0) {
-		fwrite(buf, 1, r, sig);
-	}
-
-	fclose(sig);
 	pk = calloc(1, sizeof(struct pubkey));
 	pk->siglen = sigsz;
 	pk->sig = calloc(1, pk->siglen);

usr.sbin/pkg/pkg.h

@@ -63,4 +63,6 @@ struct pubkey {
 	int siglen;
 };
 
+char *pkg_read_fd(int fd, size_t *osz);
+
 #endif /* _PKG_H */