Revision 10:e58f6254f8a2, committed 2016-03-13

Comitter:

WiredHome

Date:

Sun Mar 13 19:11:54 2016 +0000

Parent:

9:4000fad3b21f

Child:

11:2f7ad4af3ec1

Commit message:

API changes to be more secure from buffer overruns.

Changed in this revision

--- a/FATFileSystem.cpp	Sun Mar 13 00:58:52 2016 +0000
+++ b/FATFileSystem.cpp	Sun Mar 13 19:11:54 2016 +0000
@@ -28,6 +28,19 @@
 #include "FATFileHandle.h"
 #include "FATDirHandle.h"
 
+// Define the maximum length for a filename. 
+//
+// Can accept the _MAX_LFN from ffconf, but this could be big (e.g. 255).
+//     Generally this only inflates the stack frame for these functions.
+//     Can also set a smaller number if you know the maximum is less.
+//     example: "0:/12345678.abc\0" would be 16.
+//     keep in mind that something 
+//        like "/usb/12345678.abc" is translated to "0:/12345678.abc"
+//
+//     Various APIs will return the failure code if you try to pass too long
+//     of a path/name in.
+//
+#define _MAX_FN_LEN _MAX_LFN
 
 //#define DEBUG "FtFS"
 // ...
@@ -111,8 +124,10 @@
 
 FileHandle *FATFileSystem::open(const char* name, int flags) {
     INFO("open(%s) on filesystem [%s], drv [%s]", name, _name, _fsid);
-    char n[_MAX_LFN];
-    sprintf(n, "%s/%s", _fsid, name);
+    char n[_MAX_FN_LEN];
+    int sn = snprintf(n, _MAX_FN_LEN, "%s/%s", _fsid, name);
+    if (sn < 0)
+        return NULL;
     INFO("  :: open(%s)", n);
     
     /* POSIX flags -> FatFS open mode */
@@ -146,8 +161,11 @@
 
 int FATFileSystem::remove(const char *name) {
     INFO("remove(%s) on filesystem [%s], drv [%s]", name, _name, _fsid);
-    char n[_MAX_LFN];
-    sprintf(n, "%s/%s", _fsid, name);
+    char n[_MAX_FN_LEN];
+    int sn = snprintf(n, _MAX_FN_LEN, "%s/%s", _fsid, name);
+    if (sn < 0)
+        return -1;
+
     INFO("  :: remove(%s)", n);
     FRESULT res = f_unlink(n);
     if (res) {
@@ -158,14 +176,17 @@
 }
 
 int FATFileSystem::rename(const char *oldname, const char *newname) {
-    char o[_MAX_LFN], n[_MAX_LFN];
-    sprintf(o, "%s/%s", _fsid, oldname);
-    sprintf(n, "%s/%s", _fsid, newname);
-    INFO("  :: rename(%s,%s)", o, n);
-    FRESULT res = f_rename(oldname, newname);
+    char o[_MAX_FN_LEN], n[_MAX_FN_LEN];
+    int sn = snprintf(o, _MAX_FN_LEN, "%s/%s", _fsid, oldname);
+    if (sn < 0)
+        return -1;
+    sn = snprintf(n, _MAX_FN_LEN, "%s/%s", _fsid, newname);
+    if (sn < 0)
+        return -1;
+    FRESULT res = f_rename(o, n);
     if (res) {
         INFO("f_rename() failed: %d", res);
-        return -1;
+        return -res;
     }
     return 0;
 }
@@ -181,8 +202,10 @@
 
 DirHandle *FATFileSystem::opendir(const char *name) {
     FATFS_DIR dir;
-    char n[_MAX_LFN];
-    sprintf(n, "%s/%s", _fsid, name);
+    char n[_MAX_FN_LEN];
+    int sn = snprintf(n, _MAX_FN_LEN, "%s/%s", _fsid, name);
+    if (sn < 0)
+        return NULL;
     FRESULT res = f_opendir(&dir, n);
     if (res != 0) {
         return NULL;
@@ -191,8 +214,10 @@
 }
 
 int FATFileSystem::mkdir(const char *name, mode_t mode) {
-    char n[_MAX_LFN];
-    sprintf(n, "%s/%s", _fsid, name);
+    char n[_MAX_FN_LEN];
+    int sn = snprintf(n, _MAX_FN_LEN, "%s/%s", _fsid, name);
+    if (sn < 0)
+        return -1;
     FRESULT res = f_mkdir(n);
     return res == 0 ? 0 : -1;
 }
@@ -209,3 +234,16 @@
     return res == 0 ? 0 : -1;
 }
 
+#if 0
+// I think this cannot work unless the FileSystemLike and other interfaces
+// are updated.
+int FATFileSystem::fstat(const char *path, FILINFO *fileinfo) {
+    char n[_MAX_FN_LEN];
+    int sn = snprintf(n, _MAX_FN_LEN, "%s/%s", _fsid, path);
+    if (sn < 0)
+        return -1;
+    FRESULT res = f_stat(n, fileinfo);
+    printf("f_stat(%s) returned: %d\r\n", n, res);
+    return res == 0 ? 0 : -res;
+}
+#endif
\ No newline at end of file

--- a/FATFileSystem.h	Sun Mar 13 00:58:52 2016 +0000
+++ b/FATFileSystem.h	Sun Mar 13 19:11:54 2016 +0000
@@ -82,6 +82,12 @@
      */
     virtual int unmount();
 
+    #if 0
+    // I think this cannot work unless the FileSystemLike and other interfaces
+    // are updated.
+    virtual int fstat(const char *path, FILINFO *fileinfo);
+    #endif
+    
     virtual int disk_initialize() { return 0; }
     virtual int disk_status() { return 0; }
     virtual int disk_read(uint8_t *buffer, uint32_t sector, uint32_t count) = 0;