Extend lc_open() to also being able to load overlay plugins.

For this it needs to look at the plugin header. Since lc_open() doesn't know
it's a plugin, the header needs to be changed slightly to include the new lc_header (which needs to be the first element in plugin_header so it can be casted savely).

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@28054 a1c6a512-1295-4272-9138-f99709370657

3 files changed, 72 insertions, 16 deletions

diff --git a/firmware/export/load_code.h b/firmware/export/load_code.h
index 6f5e5d0..55ce601 100644
--- a/firmware/export/load_code.h
+++ b/firmware/export/load_code.h
@@ -20,17 +20,21 @@
  ****************************************************************************/
 
 
+#ifndef __LOAD_CODE_H__
+#define __LOAD_CODE_H__
+
 #include "config.h"
 
 #if (CONFIG_PLATFORM & PLATFORM_NATIVE)
 #include "system.h"
 
-extern void *lc_open(const char *filename, char *buf, size_t buf_size);
+extern void *lc_open(const char *filename, unsigned char *buf, size_t buf_size);
 /* header is always at the beginning of the blob, and handle actually points
- * to the start of the blob */
+ * to the start of the blob (the header is there) */
 static inline void *lc_open_from_mem(void* addr, size_t blob_size)
 {
     (void)blob_size;
+    /* commit dcache and discard icache */
     cpucache_invalidate();
     return addr;
 }
@@ -48,14 +52,27 @@ static inline void lc_close(void *handle) { (void)handle; }
 #else
 #define _lc_open_char char
 #endif
-extern void *_lc_open(const _lc_open_char *filename, char *buf, size_t buf_size);
+extern void *_lc_open(const _lc_open_char *filename, unsigned char *buf, size_t buf_size);
 extern void *_lc_get_header(void *handle);
 extern void  _lc_close(void *handle);
 
-extern void *lc_open(const char *filename, char *buf, size_t buf_size);
-/* not possiible on hosted platforms */
+extern void *lc_open(const char *filename, unsigned char *buf, size_t buf_size);
 extern void *lc_open_from_mem(void *addr, size_t blob_size);
 extern void *lc_get_header(void *handle);
 extern void  lc_close(void *handle);
 extern const char* lc_last_error(void);
 #endif
+
+/* this struct needs to be the first part of other headers
+ * (lc_open() casts the other header to this one to load to the correct
+ * address)
+ */
+struct lc_header {
+    unsigned long magic;
+    unsigned short target_id;
+    unsigned short api_version;
+    unsigned char *load_addr;
+    unsigned char *end_addr;
+};
+
+#endif /* __LOAD_CODE_H__ */
diff --git a/firmware/load_code.c b/firmware/load_code.c
index 75bac8b..5b5307e 100644
--- a/firmware/load_code.c
+++ b/firmware/load_code.c
@@ -26,37 +26,77 @@
 #include "load_code.h"
 
 #if (CONFIG_PLATFORM & PLATFORM_NATIVE)
+
 /* load binary blob from disk to memory, returning a handle */
-void * lc_open(const char *filename, char *buf, size_t buf_size)
+void * lc_open(const char *filename, unsigned char *buf, size_t buf_size)
 {
     int fd = open(filename, O_RDONLY);
     ssize_t read_size;
+    struct lc_header hdr;
+    unsigned char *buf_end = buf+buf_size;
+    off_t copy_size;
 
     if (fd < 0)
     {
         DEBUGF("Could not open file");
-        return NULL;
+        goto error;
     }
 
 #if NUM_CORES > 1
     /* Make sure COP cache is flushed and invalidated before loading */
     {
         int my_core = switch_core(CURRENT_CORE ^ 1);
-        cpucache_invalidate();
+        cpucache_commit_discard();
         switch_core(my_core);
     }
 #endif
 
-    read_size = read(fd, buf, buf_size);
+    /* read the header to obtain the load address */
+    read_size = read(fd, &hdr, sizeof(hdr));
+
+    if (read_size < 0)
+    {
+        DEBUGF("Could not read from file");
+        goto error_fd;
+    }
+
+    /* hdr.end_addr points to the end of the bss section,
+     * but there might be idata/icode behind that so the bytes to copy
+     * can be larger */
+    copy_size = MAX(filesize(fd), hdr.end_addr - hdr.load_addr);
+
+    if (hdr.load_addr < buf || (hdr.load_addr+copy_size) > buf_end)
+    {
+        DEBUGF("Binary doesn't fit into memory");
+        goto error_fd;
+    }
+
+    /* go back to beginning to load the whole thing (incl. header) */
+    if (lseek(fd, 0, SEEK_SET) < 0)
+    {
+        DEBUGF("lseek failed");
+        goto error_fd;
+    }
+
+    /* the header has the addresses where the code is linked at */
+    read_size = read(fd, hdr.load_addr, copy_size);
     close(fd);
-    cpucache_invalidate();
 
     if (read_size < 0)
     {
         DEBUGF("Could not read from file");
-        return NULL;
+        goto error;
     }
-    return buf;
+
+    /* commit dcache and discard icache */
+    cpucache_commit_discard();
+    /* return a pointer the header, reused by lc_get_header() */
+    return hdr.load_addr;
+
+error_fd:
+    close(fd);
+error:
+    return NULL;
 }
 
 #elif (CONFIG_PLATFORM & PLATFORM_HOSTED)
@@ -85,12 +125,11 @@ static inline char *_dlerror(void)
 #include "rbpaths.h"
 #include "general.h"
 
-void * _lc_open(const _lc_open_char *filename, char *buf, size_t buf_size)
+void * _lc_open(const _lc_open_char *filename, unsigned char *buf, size_t buf_size)
 {
     (void)buf;
     (void)buf_size;
-    void* dl_handle = dlopen(filename, RTLD_NOW);
-    return dl_handle;
+    return dlopen(filename, RTLD_NOW);
 }
 
 void *lc_open_from_mem(void *addr, size_t blob_size)
diff --git a/firmware/target/hosted/android/lc-android.c b/firmware/target/hosted/android/lc-android.c
index 52ab08b..434e901 100644
--- a/firmware/target/hosted/android/lc-android.c
+++ b/firmware/target/hosted/android/lc-android.c
@@ -23,7 +23,7 @@
 #include "load_code.h"
 
 /* the load_code wrappers simply wrap, nothing to do */
-void *lc_open(const char *filename, char *buf, size_t buf_size)
+void *lc_open(const char *filename, unsigned char *buf, size_t buf_size)
 {
     return _lc_open(filename, buf, buf_size);
 }