git: 7e1a2e46aa9a - main - kboot: Create routines to read Linux tiny files

The branch main has been updated by imp:

URL: https://cgit.FreeBSD.org/src/commit/?id=7e1a2e46aa9a2f834c33b5c50de0437ac19d7b41

commit 7e1a2e46aa9a2f834c33b5c50de0437ac19d7b41
Author:     Warner Losh <imp@FreeBSD.org>
AuthorDate: 2022-12-02 18:05:58 +0000
Commit:     Warner Losh <imp@FreeBSD.org>
CommitDate: 2022-12-02 18:08:11 +0000

    kboot: Create routines to read Linux tiny files
    
    Most of the files in /sys/ and /proc/ are small with one value. Create
    two routines to help us read the file and decode that value.
    
    Sponsored by:           Netflix
---
 stand/kboot/Makefile |  3 ++-
 stand/kboot/kboot.h  |  4 ++++
 stand/kboot/util.c   | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/stand/kboot/Makefile b/stand/kboot/Makefile
index c8bd313d1d1d..42385c9caf76 100644
--- a/stand/kboot/Makefile
+++ b/stand/kboot/Makefile
@@ -30,7 +30,8 @@ SRCS=	\
 		kbootfdt.c \
 		main.c \
 		termios.c \
-		vers.c \
+		util.c \
+		vers.c
 
 CFLAGS.gfx_fb_stub.c += -I${SRCTOP}/contrib/pnglite -I${SRCTOP}/sys/teken
 
diff --git a/stand/kboot/kboot.h b/stand/kboot/kboot.h
index 5441c90eaecc..e3d169ee5ac0 100644
--- a/stand/kboot/kboot.h
+++ b/stand/kboot/kboot.h
@@ -19,4 +19,8 @@ void fdt_arch_fixups(void *fdtp);
 uint64_t kboot_get_phys_load_segment(void);
 uint8_t kboot_get_kernel_machine_bits(void);
 
+/* util.c */
+bool file2str(const char *fn, char *buffer, size_t buflen);
+bool file2u64(const char *fn, uint64_t *val);
+
 #endif /* KBOOT_H */
diff --git a/stand/kboot/util.c b/stand/kboot/util.c
new file mode 100644
index 000000000000..938aad599e19
--- /dev/null
+++ b/stand/kboot/util.c
@@ -0,0 +1,46 @@
+/*-
+ * Copyright 2022 Netflix, Inc
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "stand.h"
+#include "host_syscall.h"
+#include "kboot.h"
+
+bool
+file2str(const char *fn, char *buffer, size_t buflen)
+{
+	int fd;
+	ssize_t len;
+
+	fd = host_open(fn, HOST_O_RDONLY, 0);
+	if (fd == -1)
+		return false;
+	len = host_read(fd, buffer, buflen - 1);
+	if (len < 0) {
+		host_close(fd);
+		return false;
+	}
+	buffer[len] = '\0';
+	/*
+	 * Trim trailing white space
+	 */
+	while (isspace(buffer[len - 1]))
+		buffer[--len] = '\0';
+	host_close(fd);
+	return true;
+}
+
+bool
+file2u64(const char *fn, uint64_t *val)
+{
+	unsigned long v;
+	char buffer[80];
+
+	if (!file2str(fn, buffer, sizeof(buffer)))
+		return false;
+	v = strtoull(buffer, NULL, 0);	/* XXX check return values? */
+	*val = v;
+	return true;
+}