hexagonrpcd/rpcd_builder: introduce /system/vendor mapping

Needed for some Xiaomi phones such as the Poco F1.
Based on https://gitlab.com/sdm670-mainline/hexagonrpc/-/merge_requests/1.
Thanks to the initial work of @longnoserob in the above MR!

README.md

@@ -133,6 +133,7 @@ These files are searched for in:
     /usr/share/qcom/sensors/config		/vendor/etc/sensors/config
     /usr/share/qcom/sensors/registry	/mnt/vendor/persist/sensors/registry/registry
     /usr/share/qcom/sensors/sns_reg.conf	/vendor/etc/sensors/sns_reg_config
+    /usr/share/qcom/socinfo			/sys/devices/soc0
 
 These files and directories should be populated with files from your device's
 Android firmware.

hexagonrpcd/hexagonfs.h

@@ -33,7 +33,7 @@ struct hexagonfs_fd;
 
 struct hexagonfs_file_ops {
 	void (*close)(void *fd_data);
-	int (*from_dirent)(void *dirent_data, bool dir, void **fd_data);
+	int (*from_dirent)(const void *dirent_data, bool dir, void **fd_data);
 	int (*openat)(struct hexagonfs_fd *dir,
 		      const char *segment,
 		      bool expect_dir,

hexagonrpcd/hexagonfs_mapped.c

@@ -47,7 +47,7 @@ static void mapped_close(void *fd_data)
 	free(ctx);
 }
 
-static int mapped_from_dirent(void *dirent_data, bool dir, void **fd_data)
+static int mapped_from_dirent(const void *dirent_data, bool dir, void **fd_data)
 {
 	struct mapped_ctx *ctx;
 	const char *name = dirent_data;
@@ -222,7 +222,7 @@ static void mapped_or_empty_close(void *fd_data)
 		mapped_close(fd_data);
 }
 
-static int mapped_or_empty_from_dirent(void *dirent_data, bool dir, void **fd_data)
+static int mapped_or_empty_from_dirent(const void *dirent_data, bool dir, void **fd_data)
 {
 	int ret;
 

hexagonrpcd/hexagonfs_plat_subtype_name.c

@@ -41,7 +41,7 @@ static void plat_subtype_name_close(void *fd_data)
 		free(ctx->name);
 }
 
-static int plat_subtype_name_from_dirent(void *dirent_data,
+static int plat_subtype_name_from_dirent(const void *dirent_data,
 					 bool dir,
 					 void **fd_data)
 {
@@ -54,7 +54,7 @@ static int plat_subtype_name_from_dirent(void *dirent_data,
 	if (ctx == NULL)
 		return -ENOMEM;
 
-	ctx->fd = open((const char *) dirent_data, O_RDONLY);
+	ctx->fd = open(dirent_data, O_RDONLY);
 	if (ctx->fd == -1)
 		return -errno;
 

hexagonrpcd/hexagonfs_virt_dir.c

@@ -31,10 +31,10 @@
  * This function searches for the relevant path segment in the path directory.
  * It is not optimized because it is dealing with small directories.
  */
-static struct hexagonfs_dirent *walk_dir(struct hexagonfs_dirent **dir,
+static const struct hexagonfs_dirent *walk_dir(const struct hexagonfs_dirent *const *dir,
 					 const char *segment)
 {
-	struct hexagonfs_dirent **curr = dir;
+	const struct hexagonfs_dirent *const *curr = dir;
 
 	while (*curr != NULL) {
 		if (!strcmp(segment, (*curr)->name))
@@ -46,9 +46,17 @@ static struct hexagonfs_dirent *walk_dir(struct hexagonfs_dirent **dir,
 	return *curr;
 }
 
-static int virt_dir_from_dirent(void *dirent_data, bool dir, void **fd_data)
+static int virt_dir_from_dirent(const void *dirent_data, bool dir, void **fd_data)
 {
-	*fd_data = dirent_data;
+	const struct hexagonfs_dirent *const **wrapper;
+
+	wrapper = malloc(sizeof(*wrapper));
+	if (wrapper == NULL)
+		return -ENOMEM;
+
+	*wrapper = dirent_data;
+	*fd_data = wrapper;
+
 	return 0;
 }
 
@@ -57,12 +65,12 @@ static int virt_dir_openat(struct hexagonfs_fd *dir,
 			   bool expect_dir,
 			   struct hexagonfs_fd **out)
 {
+	const struct hexagonfs_dirent *const **dirlist = dir->data;
+	const struct hexagonfs_dirent *ent;
 	struct hexagonfs_fd *fd;
-	struct hexagonfs_dirent *ent;
-	struct hexagonfs_dirent **dirlist = dir->data;
 	int ret;
 
-	ent = walk_dir(dirlist, segment);
+	ent = walk_dir(*dirlist, segment);
 	if (ent == NULL)
 		return -ENOENT;
 
@@ -89,6 +97,7 @@ err:
 
 static void virt_dir_close(void *fd_data)
 {
+	free(fd_data);
 }
 
 static int virt_dir_stat(struct hexagonfs_fd *fd, struct stat *stats)

hexagonrpcd/rpcd_builder.c

@@ -31,6 +31,7 @@
 #define SENSORS_CONFIG		"/sensors/config/"
 #define SENSORS_REGISTRY	"/sensors/registry/"
 #define SNS_REG_CONFIG		"/sensors/sns_reg.conf"
+#define SYSFS_SOCINFO		"/socinfo/"
 
 static struct hexagonfs_dirent *hfs_mkdir(const char *name, size_t n_ents, ...)
 {
@@ -110,9 +111,9 @@ static struct hexagonfs_dirent *hfs_map_or_empty(const char *name, const char *p
  */
 struct hexagonfs_dirent *construct_root_dir(const char *prefix, const char *dsp)
 {
-	char *acdbdata, *dsp_libs, *sns_cfg, *sns_reg, *sns_reg_config;
+	char *acdbdata, *dsp_libs, *sns_cfg, *sns_reg, *sns_reg_config, *socinfo;
 	size_t n_prefix;
-	struct hexagonfs_dirent *persist_dir;
+	struct hexagonfs_dirent *persist_dir, *vendor_dir;
 
 	n_prefix = strlen(prefix);
 
@@ -120,6 +121,7 @@ struct hexagonfs_dirent *construct_root_dir(const char *prefix, const char *dsp)
 	sns_cfg = malloc(n_prefix + strlen(SENSORS_CONFIG) + 1);
 	sns_reg = malloc(n_prefix + strlen(SENSORS_REGISTRY) + 1);
 	sns_reg_config = malloc(n_prefix + strlen(SNS_REG_CONFIG) + 1);
+	socinfo = malloc(n_prefix + strlen(SYSFS_SOCINFO) + 1);
 
 	dsp_libs = malloc(n_prefix + strlen(DSP_LIBS) + strlen(dsp) + 1);
 
@@ -143,6 +145,11 @@ struct hexagonfs_dirent *construct_root_dir(const char *prefix, const char *dsp)
 		strcat(sns_reg_config, SNS_REG_CONFIG);
 	}
 
+	if (socinfo != NULL) {
+		strcpy(socinfo, prefix);
+		strcat(socinfo, SYSFS_SOCINFO);
+	}
+
 	if (dsp_libs != NULL) {
 		strcpy(dsp_libs, prefix);
 		strcat(dsp_libs, DSP_LIBS);
@@ -161,21 +168,11 @@ struct hexagonfs_dirent *construct_root_dir(const char *prefix, const char *dsp)
 				)
 		      );
 
-	return hfs_mkdir("/", 4,
-			hfs_mkdir("mnt", 1,
-				hfs_mkdir("vendor", 1,
-					persist_dir
-				)
-			),
-			persist_dir,
-			hfs_mkdir("usr", 1,
-				hfs_mkdir("lib", 1,
-					hfs_mkdir("qcom", 1,
-						hfs_map_or_empty("adsp", dsp_libs)
-					)
-				)
-			),
-			hfs_mkdir("vendor", 1,
+	/*
+	 * Some platforms need vendor in / and some need it in /system. Form
+	 * a hard link between both locations.
+	 */
+	vendor_dir = hfs_mkdir("vendor", 1,
 				hfs_mkdir("etc", 2,
 					hfs_mkdir("sensors", 2,
 						hfs_map_or_empty("config", sns_cfg),
@@ -183,6 +180,30 @@ struct hexagonfs_dirent *construct_root_dir(const char *prefix, const char *dsp)
 					),
 					hfs_map("acdbdata", acdbdata)
 				)
-			)
+			);
+
+	return hfs_mkdir("/", 6,
+			hfs_mkdir("mnt", 1,
+				hfs_mkdir("vendor", 1,
+					persist_dir
+				)
+			),
+			persist_dir,
+			hfs_mkdir("sys", 1,
+				hfs_mkdir("devices", 1,
+					hfs_map_or_empty("soc0", socinfo)
+				)
+			),
+			hfs_mkdir("system", 1,
+				vendor_dir
+			),
+			hfs_mkdir("usr", 1,
+				hfs_mkdir("lib", 1,
+					hfs_mkdir("qcom", 1,
+						hfs_map_or_empty("adsp", dsp_libs)
+					)
+				)
+			),
+			vendor_dir
 		);
 }

tests/meson.build

@@ -11,4 +11,18 @@ test_iobuffer = executable('test_iobuffer',
   include_directories : include,
 )
 
+sample_file = custom_target('sample_file',
+  input : 'sample_file.txt',
+  output : 'sample_file.txt',
+  command : ['cp', '@INPUT@', '@OUTPUT@']
+)
+test_hexagonfs = executable('test_hexagonfs',
+  'test_hexagonfs.c',
+  '../hexagonrpcd/hexagonfs.c',
+  '../hexagonrpcd/hexagonfs_mapped.c',
+  c_args : cflags,
+  include_directories : include,
+)
+
 test('iobuffer', test_iobuffer)
+test('hexagonfs', test_hexagonfs, args : [sample_file])

tests/sample_file.txt

@@ -0,0 +1,91 @@
+/*
+ * FastRPC reverse tunnel - sample file for HexagonFS mapped file test
+ *
+ * Copyright (C) 2024 The HexagonRPC Contributors
+ *
+ * This file is part of HexagonRPC.
+ *
+ * HexagonRPC is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#![feature(io_error_more)]
+
+use std::collections::HashMap;
+use std::io::Error;
+use std::io::ErrorKind;
+use std::io::Result;
+use std::process::ExitCode;
+
+trait HexagonFSFile {
+	fn seek(&self) -> Result<u64>;
+	fn read(&self) -> Result<usize>;
+	fn openat<'a>(&'a self, name: &str) -> Result<Box<dyn HexagonFSFile + 'a>>;
+}
+
+trait HexagonFSDirent {
+	fn open<'a>(&'a self) -> Box<dyn HexagonFSFile + 'a>;
+}
+
+struct VirtDir<'a> {
+	def: &'a VirtDirDirent<'a>,
+}
+
+impl<'a> HexagonFSFile for VirtDir<'a> {
+	fn seek(&self) -> Result<u64>
+	{
+		Err(Error::new(ErrorKind::IsADirectory, "Is a directory"))
+	}
+
+	fn read(&self) -> Result<usize>
+	{
+		Err(Error::new(ErrorKind::IsADirectory, "Is a directory"))
+	}
+
+	fn openat<'b>(&'b self, name: &str) -> Result<Box<dyn HexagonFSFile + 'b>>
+	{
+		let resolution = self.def.files.get(name);
+
+		match resolution {
+			Some(dirent) => Ok(dirent.open()),
+			None => Err(Error::new(ErrorKind::NotFound, "No such file or directory"))
+		}
+	}
+}
+
+struct VirtDirDirent<'a> {
+	files: HashMap<&'a str, Box<dyn HexagonFSDirent>>
+}
+
+impl<'b> HexagonFSDirent for VirtDirDirent<'b> {
+	fn open<'a>(&'a self) -> Box<dyn HexagonFSFile + 'a>
+	{
+		Box::new(VirtDir {
+			def: self
+		})
+	}
+}
+
+fn main() -> ExitCode
+{
+	let root_dir = &VirtDirDirent { files: HashMap::from([
+		("sys", Box::new(VirtDirDirent { files: HashMap::from([
+
+		])}) as Box<dyn HexagonFSDirent>),
+	])};
+
+	let rootfd = root_dir.open();
+	let dirfd = rootfd.openat("");
+
+	return ExitCode::SUCCESS;
+}

tests/test_hexagonfs.c

@@ -0,0 +1,98 @@
+/*
+ * FastRPC reverse tunnel - tests for virtual filesystem
+ *
+ * Copyright (C) 2024 The HexagonRPC Contributors
+ *
+ * This file is part of HexagonRPC.
+ *
+ * HexagonRPC is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <fcntl.h>
+#include <libhexagonrpc/fastrpc.h>
+#include <stdbool.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "../hexagonrpcd/hexagonfs.h"
+
+static int test_mapped_seq_read(const char *path)
+{
+	struct hexagonfs_fd file = {
+		.is_assigned = true,
+		.up = NULL,
+		.ops = &hexagonfs_mapped_ops,
+	};
+	int ret, fd;
+	char *buf1, *buf2;
+
+	buf1 = malloc(256);
+	if (buf1 == NULL)
+		return 1;
+
+	buf2 = malloc(256);
+	if (buf2 == NULL)
+		return 1;
+
+	fd = open(path, O_RDONLY);
+	if (fd == -1)
+		return 1;
+
+	ret = hexagonfs_mapped_ops.from_dirent(path, false, &file.data);
+	if (ret)
+		return 1;
+
+	memset(buf1, 0, 6);
+	memset(buf2, 0, 6);
+
+	read(fd, buf1, 1);
+	read(fd, &buf1[1], 5);
+	hexagonfs_mapped_ops.read(&file, 1, buf2);
+	hexagonfs_mapped_ops.read(&file, 5, &buf2[1]);
+	if (memcmp(buf1, buf2, 6))
+		return 1;
+
+	memset(buf1, 0, 27);
+	memset(buf2, 0, 27);
+
+	lseek(fd, 819 - 6, SEEK_CUR);
+	read(fd, buf1, 27);
+	hexagonfs_mapped_ops.seek(&file, 819 - 6, SEEK_CUR);
+	hexagonfs_mapped_ops.read(&file, 27, buf2);
+	if (memcmp(buf1, buf2, 27))
+		return 1;
+
+	hexagonfs_mapped_ops.close(file.data);
+
+	close(fd);
+
+	free(buf2);
+	free(buf1);
+
+	return 0;
+}
+
+int main(int argc, const char **argv)
+{
+	int ret;
+
+	if (argc < 2)
+		return 1;
+
+	ret = test_mapped_seq_read(argv[1]);
+	if (ret)
+		return ret;
+
+	return 0;
+}