liminix

commit 61dc5beca8804b70fb10559d38017526523452be
parent f3225c2bd5d9ea2ab8aea66da4276a0e9787cfad
Author: Daniel Barlow <dan@telent.net>
Date:   Thu, 19 Oct 2023 18:56:09 +0100

preinit: parse rootfstype from kernel command line

Diffstat:
A
pkgs/preinit/Makefile
 | 
4
++++
M
pkgs/preinit/default.nix
 | 
1
-
A
pkgs/preinit/parseopts.c
 | 
97
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
M
pkgs/preinit/preinit.c
 | 
22
++++++++++------------
A
pkgs/preinit/shell.nix
 | 
5
+++++

5 files changed, 116 insertions(+), 13 deletions(-)
diff --git a/pkgs/preinit/Makefile b/pkgs/preinit/Makefile
@@ -0,0 +1,4 @@
+CFLAGS+=-Os -DPREINIT_USE_LIBC  -fno-stack-protector -fpic -fPIC
+LDFLAGS=-static
+
+preinit: preinit.o parseopts.o
diff --git a/pkgs/preinit/default.nix b/pkgs/preinit/default.nix
@@ -15,7 +15,6 @@ stdenv.mkDerivation {
 
 #  NIX_DEBUG=2;
   hardeningDisable = [ "all" ];
-  CFLAGS = "-Os -static -DPREINIT_USE_LIBC  -fno-stack-protector -fpic -fPIC -I ./ -I ${kernel}/tools/include/nolibc";
 
   postBuild = ''
     $STRIP  --remove-section=.note --remove-section=.comment preinit
diff --git a/pkgs/preinit/parseopts.c b/pkgs/preinit/parseopts.c
@@ -0,0 +1,97 @@
+#include <string.h>
+#include <unistd.h>
+
+static int begins_with(char * str, char * prefix)
+{
+	while(*prefix) {
+		if(*str == '\0') return 0;
+		if(*str != *prefix) return 0;
+		str++;
+		prefix++;
+	}
+	return 1;
+}
+
+
+void parseopts(char * cmdline, char **root, char **rootfstype) {
+    *root = 0;
+    *rootfstype = 0;
+
+    for(char *p = cmdline; *p; p++) {
+	if(begins_with(p, "root=")) {
+	    *root = p + strlen("root=");
+	    while(*p && (*p != ' ')) p++;
+	    
+	    if(*p) {
+		*p = '\0';
+		p++;
+	    };
+	};
+	if(begins_with(p, "rootfstype=")) {
+	    *rootfstype = p + strlen("rootfstype=");
+	    while(*p && (*p != ' ')) p++;
+	    if(*p) {
+		*p = '\0';
+		p++;
+	    };
+	};
+    };
+}
+
+#ifdef TESTS
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#define die(fmt, ...) do { printf(fmt, __VA_ARGS__); exit(1); } while(0)
+#define S(x) #x
+#define expect_equal(actual, expected) \
+    if(!actual || strcmp(actual, expected)) die("%d: expected \"%s\", got \"%s\"", __LINE__, expected, actual);
+
+
+int main()
+{
+    char * root = "/dev/hda1";
+    char * rootfstype = "xiafs";
+    char *buf;
+
+    // finds root= and rootfstype= options
+    buf = strdup("liminix console=ttyS0,115200 panic=10 oops=panic init=/bin/init loglevel=8 root=/dev/ubi0_4 rootfstype=ubifs fw_devlink=off mtdparts=phram0:18M(rootfs) phram.phram=phram0,0x40400000,18874368,65536 root=/dev/mtdblock0 foo");
+    parseopts(buf, &root, &rootfstype);
+    expect_equal(root, "/dev/mtdblock0");
+    expect_equal(rootfstype, "ubifs");
+
+    // in case of duplicates, chooses the latter
+    // also: works if the option is end of string
+    buf = strdup("liminix console=ttyS0,115200 panic=10 oops=panic init=/bin/init loglevel=8 root=/dev/ubi0_4 rootfstype=ubifs fw_devlink=off mtdparts=phram0:18M(rootfs) phram.phram=phram0,0x40400000,18874368,65536 root=/dev/mtdblock0");
+    parseopts(buf, &root, &rootfstype);
+    expect_equal(root, "/dev/mtdblock0");
+    expect_equal(rootfstype, "ubifs");
+
+    // options may appear in either order
+    buf = strdup("liminix fw_devlink=off root=/dev/hda1 rootfstype=ubifs  foo");
+    parseopts(buf, &root, &rootfstype);
+    expect_equal(root, "/dev/hda1");
+    expect_equal(rootfstype, "ubifs");
+
+    buf = strdup("liminix rootfstype=ubifs fw_devlink=off root=/dev/hda1 foo");
+    parseopts(buf, &root, &rootfstype);
+    expect_equal(rootfstype, "ubifs");
+    expect_equal(root, "/dev/hda1");
+
+    // provides NULL for missing options
+    buf = strdup("liminix rufustype=ubifs fw_devlink=off foot=/dev/hda1");
+    parseopts(buf, &root, &rootfstype);
+    if(rootfstype) die("expected null rootfstype, got \"%s\"", rootfstype);
+    if(root) die("expected null root, got \"%s\"", root);
+
+    // provides empty strings for empty options
+    buf = strdup("liminix rootfstype= fw_devlink=off root= /dev/hda1");
+    parseopts(buf, &root, &rootfstype);
+    if(strlen(rootfstype)) die("expected empty rootfstype, got \"%s\"", rootfstype);
+    if(strlen(root)) die("expected null root, got \"%s\"", root);
+
+}
+
+
+#endif
diff --git a/pkgs/preinit/preinit.c b/pkgs/preinit/preinit.c
@@ -10,6 +10,8 @@
 #endif
 #include <asm/setup.h>
 
+void parseopts(char * cmdline, char **root, char **rootfstype);
+
 #define ERR(x) write(2, x, strlen(x))
 #define AVER(c) do { if(c < 0) ERR("failed: "  #c); } while(0)
 
@@ -40,6 +42,7 @@ char buf[COMMAND_LINE_SIZE];
 int main(int argc, char *argv[], char *envp[])
 {
 	char *rootdevice = 0;
+	char *rootfstype = 0;
 	char *p = buf;
 	write(1, banner, strlen(banner));
 
@@ -54,22 +57,17 @@ int main(int argc, char *argv[], char *envp[])
 		write(1, buf, len);
 	};
 
-	while(*p) {
-		if(begins_with(p, "root=")) {
-			rootdevice = p + 5;
-			while(*p && (*p != ' ')) p++;
-			*p= '\0';
-		}
-		while(*p && (*p != ' ')) p++;
-		p++;
-	}
-
+	parseopts(buf, &rootdevice, &rootfstype);
+	
 	if(rootdevice) {
+    	        if(!rootfstype) rootfstype = "jffs2"; /* backward compatibility */
 		write(1, "rootdevice ", 11);
 		write(1, rootdevice, strlen(rootdevice));
-		write(1, "\n", 1);
+		write(1, " (", 2);
+		write(1, rootfstype, strlen(rootfstype));
+		write(1, ")\n", 1);
 
-		AVER(mount(rootdevice, "/target/persist", "ubifs", 0, NULL));
+		AVER(mount(rootdevice, "/target/persist", rootfstype, 0, NULL));
 		AVER(mount("/target/persist/nix", "/target/nix",
 			   "bind", MS_BIND, NULL));
 
diff --git a/pkgs/preinit/shell.nix b/pkgs/preinit/shell.nix
@@ -0,0 +1,5 @@
+with import <nixpkgs> {};
+mkShell {
+  name = "preinit-env";
+  src = ./.;
+}