cxgbetool: create one backend routine for all the loadX cmds

They are all doing almost the same thing so it makes sense to have one
common routine.  The new routine supports non-regular files too.  eg.
 # cxgbetool chnex0 loadfw <(fetch -qo - http://srv/t7fw.bin)

MFC after:	1 week
Sponsored by:	Chelsio Communications
Reviewed by:	jhb
Differential Revision:	https://reviews.freebsd.org/D55747

usr.sbin/cxgbetool/cxgbetool.c

@@ -2168,86 +2168,103 @@ get_sge_context(int argc, const char *argv[])
 	return (0);
 }
 
+static int
+real_load_file(unsigned long ioc, const char *iocname, const char *fname,
+    struct t4_bootrom *br)
+{
+	int rc, fd, n;
+	struct t4_data data = {0};
+	struct stat st = {0};
+	const int bufsz = 2 * 1024 * 1024;
+
+	if (strcmp(fname, "clear") == 0) {
+		if (br == NULL)
+			return (real_doit(ioc, &data, iocname));
+		else
+			return (real_doit(ioc, br, iocname));
+	}
+
+	fd = open(fname, O_RDONLY);
+	if (fd < 0) {
+		warn("open(%s)", fname);
+		return (errno);
+	}
+
+	if (fstat(fd, &st) < 0) {
+		warn("fstat");
+		close(fd);
+		return (errno);
+	}
+
+	if (st.st_mode & S_IFREG) {
+		data.len = st.st_size;
+		data.data = mmap(0, data.len, PROT_READ, MAP_PRIVATE, fd, 0);
+		if (data.data == MAP_FAILED) {
+			warn("mmap %u", data.len);
+			return (errno);
+		}
+	} else {
+		data.data = malloc(bufsz);
+		if (data.data == NULL) {
+			warnx("malloc failed.");
+			return (ENOMEM);
+		}
+		for (data.len = 0; data.len <= bufsz; data.len += n) {
+			n = read(fd, data.data + data.len, bufsz - data.len);
+			if (n == -1) {
+				warn("read(%s, %u)", fname, data.len);
+				free(data.data);
+				close(fd);
+				return (errno);
+			}
+			if (n == 0)
+				break;
+		}
+		if (data.len == bufsz)
+			warnx("file '%s' contents > %u ignored.", fname, bufsz);
+	}
+
+	if (br == NULL)
+		rc = real_doit(ioc, &data, iocname);
+	else {
+		br->len = data.len;
+		br->data = data.data;
+		rc = real_doit(ioc, br, iocname);
+	}
+	if (st.st_mode & S_IFREG)
+		munmap(data.data, data.len);
+	else
+		free(data.data);
+	close(fd);
+	return (rc);
+}
+#define load_file(ioc, fname) real_load_file(ioc, #ioc, fname, NULL)
+#define load_file_br(ioc, fname, br) real_load_file(ioc, #ioc, fname, br)
+
 static int
 loadfw(int argc, const char *argv[])
 {
-	int rc, fd;
-	struct t4_data data = {0};
 	const char *fname = argv[0];
-	struct stat st = {0};
 
 	if (argc != 1) {
 		warnx("loadfw: incorrect number of arguments.");
 		return (EINVAL);
 	}
 
-	fd = open(fname, O_RDONLY);
-	if (fd < 0) {
-		warn("open(%s)", fname);
-		return (errno);
-	}
-
-	if (fstat(fd, &st) < 0) {
-		warn("fstat");
-		close(fd);
-		return (errno);
-	}
-
-	data.len = st.st_size;
-	data.data = mmap(0, data.len, PROT_READ, MAP_PRIVATE, fd, 0);
-	if (data.data == MAP_FAILED) {
-		warn("mmap");
-		close(fd);
-		return (errno);
-	}
-
-	rc = doit(CHELSIO_T4_LOAD_FW, &data);
-	munmap(data.data, data.len);
-	close(fd);
-	return (rc);
+	return (load_file(CHELSIO_T4_LOAD_FW, fname));
 }
 
 static int
 loadcfg(int argc, const char *argv[])
 {
-	int rc, fd;
-	struct t4_data data = {0};
 	const char *fname = argv[0];
-	struct stat st = {0};
 
 	if (argc != 1) {
 		warnx("loadcfg: incorrect number of arguments.");
 		return (EINVAL);
 	}
 
-	if (strcmp(fname, "clear") == 0)
-		return (doit(CHELSIO_T4_LOAD_CFG, &data));
-
-	fd = open(fname, O_RDONLY);
-	if (fd < 0) {
-		warn("open(%s)", fname);
-		return (errno);
-	}
-
-	if (fstat(fd, &st) < 0) {
-		warn("fstat");
-		close(fd);
-		return (errno);
-	}
-
-	data.len = st.st_size;
-	data.len &= ~3;		/* Clip off to make it a multiple of 4 */
-	data.data = mmap(0, data.len, PROT_READ, MAP_PRIVATE, fd, 0);
-	if (data.data == MAP_FAILED) {
-		warn("mmap");
-		close(fd);
-		return (errno);
-	}
-
-	rc = doit(CHELSIO_T4_LOAD_CFG, &data);
-	munmap(data.data, data.len);
-	close(fd);
-	return (rc);
+	return (load_file(CHELSIO_T4_LOAD_CFG, fname));
 }
 
 static int
@@ -2317,12 +2334,10 @@ read_mem(uint32_t addr, uint32_t len, void (*output)(uint32_t *, uint32_t))
 static int
 loadboot(int argc, const char *argv[])
 {
-	int rc, fd;
 	long l;
 	char *p;
 	struct t4_bootrom br = {0};
 	const char *fname = argv[0];
-	struct stat st = {0};
 
 	if (argc == 1) {
 		br.pf_offset = 0;
@@ -2344,75 +2359,20 @@ loadboot(int argc, const char *argv[])
 		return (EINVAL);
 	}
 
-	if (strcmp(fname, "clear") == 0)
-		return (doit(CHELSIO_T4_LOAD_BOOT, &br));
-
-	fd = open(fname, O_RDONLY);
-	if (fd < 0) {
-		warn("open(%s)", fname);
-		return (errno);
-	}
-
-	if (fstat(fd, &st) < 0) {
-		warn("fstat");
-		close(fd);
-		return (errno);
-	}
-
-	br.len = st.st_size;
-	br.data = mmap(0, br.len, PROT_READ, MAP_PRIVATE, fd, 0);
-	if (br.data == MAP_FAILED) {
-		warn("mmap");
-		close(fd);
-		return (errno);
-	}
-
-	rc = doit(CHELSIO_T4_LOAD_BOOT, &br);
-	munmap(br.data, br.len);
-	close(fd);
-	return (rc);
+	return (load_file_br(CHELSIO_T4_LOAD_BOOT, fname, &br));
 }
 
 static int
 loadbootcfg(int argc, const char *argv[])
 {
-	int rc, fd;
-	struct t4_data bc = {0};
 	const char *fname = argv[0];
-	struct stat st = {0};
 
 	if (argc != 1) {
 		warnx("loadbootcfg: incorrect number of arguments.");
 		return (EINVAL);
 	}
 
-	if (strcmp(fname, "clear") == 0)
-		return (doit(CHELSIO_T4_LOAD_BOOTCFG, &bc));
-
-	fd = open(fname, O_RDONLY);
-	if (fd < 0) {
-		warn("open(%s)", fname);
-		return (errno);
-	}
-
-	if (fstat(fd, &st) < 0) {
-		warn("fstat");
-		close(fd);
-		return (errno);
-	}
-
-	bc.len = st.st_size;
-	bc.data = mmap(0, bc.len, PROT_READ, MAP_PRIVATE, fd, 0);
-	if (bc.data == MAP_FAILED) {
-		warn("mmap");
-		close(fd);
-		return (errno);
-	}
-
-	rc = doit(CHELSIO_T4_LOAD_BOOTCFG, &bc);
-	munmap(bc.data, bc.len);
-	close(fd);
-	return (rc);
+	return (load_file(CHELSIO_T4_LOAD_BOOTCFG, fname));
 }
 
 /*