From 0ae929fa94a0d9d88014b0ff46fe6b9a99d4925b Mon Sep 17 00:00:00 2001
From: David Howells <dhowells@redhat.com>
Date: Tue, 22 Jan 2019 17:47:31 +0000
Subject: [PATCH] Honour 'sysname' setting in preload

If a defaults section exists in the configuration and this contains a
setting for the workstation's @sys substitution list, e.g.:

        [defaults]
        sysname = fedora28_x86 amd64_linux

then load this into kernel after the cell list has been preloaded.

Signed-off-by: David Howells <dhowells@redhat.com>
---
 src/include/kafs/cellserv.h |  1 +
 src/lib_cell_lookup.c       |  6 ++++
 src/preload-cells.c         | 62 +++++++++++++++++++++----------------
 3 files changed, 42 insertions(+), 27 deletions(-)

diff --git a/src/include/kafs/cellserv.h b/src/include/kafs/cellserv.h
index 00e081e..a232b0b 100644
--- a/src/include/kafs/cellserv.h
+++ b/src/include/kafs/cellserv.h
@@ -147,6 +147,7 @@ extern int kafs_dns_lookup_vlservers(struct kafs_server_list *vsl,
 extern struct kafs_profile kafs_config_profile;
 extern struct kafs_cell_db *kafs_cellserv_db;
 extern const char *kafs_this_cell;
+extern const char *kafs_sysname;
 extern int kafs_read_config(const char *const *files,
 			    struct kafs_report *report);
 extern struct kafs_cell *kafs_lookup_cell(const char *cell_name,
diff --git a/src/lib_cell_lookup.c b/src/lib_cell_lookup.c
index 2029707..f048151 100644
--- a/src/lib_cell_lookup.c
+++ b/src/lib_cell_lookup.c
@@ -24,6 +24,7 @@ static const char *const kafs_std_config[] = {
 struct kafs_profile kafs_config_profile = { .name = "<kafsconfig>" };
 struct kafs_cell_db *kafs_cellserv_db;
 const char *kafs_this_cell;
+const char *kafs_sysname;
 
 #define verbose(r, fmt, ...)						\
 	do {								\
@@ -72,6 +73,11 @@ static void kafs_read_defaults(struct kafs_profile *prof, struct kafs_report *re
 	p = kafs_profile_get_string(def, "thiscell", report);
 	if (p)
 		kafs_this_cell = p;
+
+	/* Find the @sys substitutions (sysname = <sub> <sub> ...) */
+	p = kafs_profile_get_string(def, "sysname", report);
+	if (p)
+		kafs_sysname = p;
 }
 
 /*
diff --git a/src/preload-cells.c b/src/preload-cells.c
index c51bba3..d0db1c6 100644
--- a/src/preload-cells.c
+++ b/src/preload-cells.c
@@ -61,6 +61,39 @@ static void _error(const char *fmt, ...)
 	va_end(va);
 }
 
+/*
+ * Write a string to a proc file.
+ */
+static void write_to_proc(const char *file, const char *str, bool redirect_to_stdout)
+{
+	int fd = 1, n;
+
+	if (!str)
+		return;
+
+	if (redirect_to_stdout) {
+		printf("WRITE '%s' TO %s\n", str, file);
+		return;
+	}
+
+	fd = open(file, O_WRONLY);
+	if (fd == -1) {
+		_error("Can't open %s: %m", file);
+		exit(1);
+	}
+
+	n = strlen(str);
+	if (write(fd, str, n) != n) {
+		_error("Can't write '%s' to %s: %m", str, file);
+		exit(1);
+	}
+
+	if (close(fd) == -1) {
+		_error("Can't close %s: %m", file);
+		exit(1);
+	}
+}
+
 /*
  * Parse the cell database file
  */
@@ -104,33 +137,8 @@ int do_preload(const struct kafs_cell_db *db, bool redirect_to_stdout)
 		}
 	}
 
-	if (kafs_this_cell) {
-		if (!redirect_to_stdout) {
-			fd = open("/proc/net/afs/rootcell", O_WRONLY);
-			if (fd == -1) {
-				_error("Can't open /proc/fs/afs/rootcell: %m");
-				exit(1);
-			}
-		}
-
-		n = strlen(kafs_this_cell);
-		if (write(fd, kafs_this_cell, n) != n) {
-			_error("Can't set root cell '%s': %m", kafs_this_cell);
-			exit(1);
-		}
-
-		if (!redirect_to_stdout) {
-			if (close(fd) == -1) {
-				_error("Can't close /proc/fs/afs/rootcell: %m");
-				exit(1);
-			}
-		} else {
-			if (write(1, "\n", 1) == -1)
-				perror("stdout");
-		}
-
-	}
-
+	write_to_proc("/proc/net/afs/rootcell", kafs_this_cell, redirect_to_stdout);
+	write_to_proc("/proc/net/afs/sysname", kafs_sysname, redirect_to_stdout);
 	exit(0);
 }
 
-- 
2.49.0