init: create symlinks to block device nodes
eMMC block device names may change based on the detection order of
the eMMC device and any other SD bus devices, such as a removable SD
card.
This patch adds support to init for:
* Symlinks to block devices. When a block device uevent is
processed, if it starts with "/devices/platform", the platform
driver name is parsed out, and symlinks to the block device are
created in /dev/block/platform/<platform driver>/
* Symlinks based on partition name and number. If the uevent for
a block device contains information on the partition name or
number, symlinks are created under
/dev/block/platform/<platform driver>/by-num/p<partition>
and
/dev/block/platform/<platform driver>/by-name/<partition name>
init.rc can then use a device path like the following to mount an
eMMC device:
/dev/block/platform/<platform>/by-name/system /system ro
Change-Id: Id11bb7cdf1e2ada7752a5bd671cbf87237b34ae2
diff --git a/init/devices.c b/init/devices.c
index a9ed141..3263e5e 100644
--- a/init/devices.c
+++ b/init/devices.c
@@ -34,6 +34,7 @@
#include "init.h"
#include "devices.h"
+#include "util.h"
#define CMDLINE_PREFIX "/dev"
#define SYSFS_PREFIX "/sys"
@@ -47,6 +48,8 @@
const char *path;
const char *subsystem;
const char *firmware;
+ const char *partition_name;
+ int partition_num;
int major;
int minor;
};
@@ -346,6 +349,8 @@
uevent->firmware = "";
uevent->major = -1;
uevent->minor = -1;
+ uevent->partition_name = NULL;
+ uevent->partition_num = -1;
/* currently ignoring SEQNUM */
while(*msg) {
@@ -367,6 +372,12 @@
} else if(!strncmp(msg, "MINOR=", 6)) {
msg += 6;
uevent->minor = atoi(msg);
+ } else if(!strncmp(msg, "PARTN=", 6)) {
+ msg += 6;
+ uevent->partition_num = atoi(msg);
+ } else if(!strncmp(msg, "PARTNAME=", 9)) {
+ msg += 9;
+ uevent->partition_name = msg;
}
/* advance to after the next \0 */
@@ -379,11 +390,76 @@
uevent->firmware, uevent->major, uevent->minor);
}
+static char **parse_platform_block_device(struct uevent *uevent)
+{
+ const char *driver;
+ const char *path;
+ char *slash;
+ int width;
+ char buf[256];
+ char link_path[256];
+ int fd;
+ int link_num = 0;
+ int ret;
+ char *p;
+ unsigned int size;
+ struct stat info;
+
+ char **links = malloc(sizeof(char *) * 4);
+ if (!links)
+ return NULL;
+ memset(links, 0, sizeof(char *) * 4);
+
+ /* Drop "/devices/platform/" */
+ path = uevent->path;
+ driver = path + 18;
+ slash = strchr(driver, '/');
+ if (!slash)
+ goto err;
+ width = slash - driver;
+ if (width <= 0)
+ goto err;
+
+ snprintf(link_path, sizeof(link_path), "/dev/block/platform/%.*s",
+ width, driver);
+
+ if (uevent->partition_name) {
+ p = strdup(uevent->partition_name);
+ sanitize(p);
+ if (asprintf(&links[link_num], "%s/by-name/%s", link_path, p) > 0)
+ link_num++;
+ else
+ links[link_num] = NULL;
+ free(p);
+ }
+
+ if (uevent->partition_num >= 0) {
+ if (asprintf(&links[link_num], "%s/by-num/p%d", link_path, uevent->partition_num) > 0)
+ link_num++;
+ else
+ links[link_num] = NULL;
+ }
+
+ slash = strrchr(path, '/');
+ if (asprintf(&links[link_num], "%s/%s", link_path, slash + 1) > 0)
+ link_num++;
+ else
+ links[link_num] = NULL;
+
+ return links;
+
+err:
+ free(links);
+ return NULL;
+}
+
static void handle_device_event(struct uevent *uevent)
{
char devpath[96];
char *base, *name;
+ char **links = NULL;
int block;
+ int i;
/* if it's not a /dev device, nothing to do */
if((uevent->major < 0) || (uevent->minor < 0))
@@ -404,6 +480,8 @@
block = 1;
base = "/dev/block/";
mkdir(base, 0755);
+ if (!strncmp(uevent->path, "/devices/platform/", 18))
+ links = parse_platform_block_device(uevent);
} else {
block = 0;
/* this should probably be configurable somehow */
@@ -441,12 +519,24 @@
if(!strcmp(uevent->action, "add")) {
make_device(devpath, block, uevent->major, uevent->minor);
- return;
+ if (links) {
+ for (i = 0; links[i]; i++)
+ make_link(devpath, links[i]);
+ }
}
if(!strcmp(uevent->action, "remove")) {
+ if (links) {
+ for (i = 0; links[i]; i++)
+ remove_link(devpath, links[i]);
+ }
unlink(devpath);
- return;
+ }
+
+ if (links) {
+ for (i = 0; links[i]; i++)
+ free(links[i]);
+ free(links);
}
}
diff --git a/init/util.c b/init/util.c
index 6f9a12e..a56ba0d 100644
--- a/init/util.c
+++ b/init/util.c
@@ -299,3 +299,81 @@
return ts.tv_sec;
}
+
+int mkdir_recursive(const char *pathname, mode_t mode)
+{
+ char buf[128];
+ const char *slash;
+ const char *p = pathname;
+ int width;
+ int ret;
+ struct stat info;
+
+ while ((slash = strchr(p, '/')) != NULL) {
+ width = slash - pathname;
+ p = slash + 1;
+ if (width < 0)
+ break;
+ if (width == 0)
+ continue;
+ if ((unsigned int)width > sizeof(buf) - 1) {
+ ERROR("path too long for mkdir_recursive\n");
+ return -1;
+ }
+ memcpy(buf, pathname, width);
+ buf[width] = 0;
+ if (stat(buf, &info) != 0) {
+ ret = mkdir(buf, mode);
+ if (ret && errno != EEXIST)
+ return ret;
+ }
+ }
+ ret = mkdir(pathname, mode);
+ if (ret && errno != EEXIST)
+ return ret;
+ return 0;
+}
+
+void sanitize(char *s)
+{
+ if (!s)
+ return;
+ while (isalnum(*s))
+ s++;
+ *s = 0;
+}
+void make_link(const char *oldpath, const char *newpath)
+{
+ int ret;
+ char buf[256];
+ char *slash;
+ int width;
+
+ slash = strrchr(newpath, '/');
+ if (!slash)
+ return;
+ width = slash - newpath;
+ if (width <= 0 || width > (int)sizeof(buf) - 1)
+ return;
+ memcpy(buf, newpath, width);
+ buf[width] = 0;
+ ret = mkdir_recursive(buf, 0755);
+ if (ret)
+ ERROR("Failed to create directory %s: %s (%d)\n", buf, strerror(errno), errno);
+
+ ret = symlink(oldpath, newpath);
+ if (ret && errno != EEXIST)
+ ERROR("Failed to symlink %s to %s: %s (%d)\n", oldpath, newpath, strerror(errno), errno);
+}
+
+void remove_link(const char *oldpath, const char *newpath)
+{
+ char path[256];
+ ssize_t ret;
+ ret = readlink(newpath, path, sizeof(path) - 1);
+ if (ret <= 0)
+ return;
+ path[ret] = 0;
+ if (!strcmp(path, oldpath))
+ unlink(newpath);
+}
diff --git a/init/util.h b/init/util.h
index 4f473ec..3dadfb9 100644
--- a/init/util.h
+++ b/init/util.h
@@ -24,4 +24,8 @@
time_t gettime(void);
unsigned int decode_uid(const char *s);
+int mkdir_recursive(const char *pathname, mode_t mode);
+void sanitize(char *p);
+void make_link(const char *oldpath, const char *newpath);
+void remove_link(const char *oldpath, const char *newpath);
#endif