minix/servers/vfs/scratchpad.h

#ifndef __VFS_SCRATCHPAD_H__
#define __VFS_SCRATCHPAD_H__

/* This is the per-process information.  A slot is reserved for each potential
 * process. Thus NR_PROCS must be the same as in the kernel.
 */
EXTERN struct scratchpad {
  union sp_data {
	int fd_nr;
	struct filp *filp;
  } file;
  struct io_cmd {
	vir_bytes io_buffer;
	size_t io_nbytes;
  } io;
} scratchpad[NR_PROCS];

#endif
AVFS: Use scratchpad instead of m_in to pass around file descriptors Some code relies on having the file descriptor in m_in.fd. Consequently, m_in is not only used to provide syscall parameters from user space to VFS, but also as a global variable to store temporary data within VFS. This has the ugly side effect that m_in gets overwritten during core dumping.* To work around this problem VFS now uses a so called "scratchpad" to store temporary data that has to be globally accessible. This is a simple table indexed by process number, just like fproc. The scratchpad allows us to store the buffer pointer and buffer size for suspended system calls (i.e., read, write, open, lock) instead of using fproc. This makes fproc a bit smaller and fproc iterators a bit faster. Moreover, suspension of processes becomes simpler altogether and suspended operations on pipes are now less of a special case. * This patch fixes a bug where due to unexpected m_in overwriting a coredump would fail, and consequently resources are leaked. The coredump was triggered with: $ a() { a; } $ a 2011-12-21 11:52:51 +01:00			`#ifndef __VFS_SCRATCHPAD_H__`
			`#define __VFS_SCRATCHPAD_H__`

			`/* This is the per-process information. A slot is reserved for each potential`
			`* process. Thus NR_PROCS must be the same as in the kernel.`
			`*/`
			`EXTERN struct scratchpad {`
			`union sp_data {`
			`int fd_nr;`
			`struct filp *filp;`
			`} file;`
			`struct io_cmd {`
Message type and related cleanup - Intorduce and use a message type for VFS_GETDENTS, VFS_READ, VFS_WRITE. - Some cleanup to related functions where vir_bytes are replaced (and casted to/from, in parameter definition and local variables as well. This allow to see more clearly which function receives unsafe (pointer) values, or at least values which are not supposed to be valid in the address space of VFS. The current patch does so only for the minimal amount of functions which are concerned with the introduction of the new message type. Change-Id: I0cdca97409c4016d02fae067b48bf55d37572c5c 2014-05-12 18:17:10 +02:00			`vir_bytes io_buffer;`
AVFS: Use scratchpad instead of m_in to pass around file descriptors Some code relies on having the file descriptor in m_in.fd. Consequently, m_in is not only used to provide syscall parameters from user space to VFS, but also as a global variable to store temporary data within VFS. This has the ugly side effect that m_in gets overwritten during core dumping.* To work around this problem VFS now uses a so called "scratchpad" to store temporary data that has to be globally accessible. This is a simple table indexed by process number, just like fproc. The scratchpad allows us to store the buffer pointer and buffer size for suspended system calls (i.e., read, write, open, lock) instead of using fproc. This makes fproc a bit smaller and fproc iterators a bit faster. Moreover, suspension of processes becomes simpler altogether and suspended operations on pipes are now less of a special case. * This patch fixes a bug where due to unexpected m_in overwriting a coredump would fail, and consequently resources are leaked. The coredump was triggered with: $ a() { a; } $ a 2011-12-21 11:52:51 +01:00			`size_t io_nbytes;`
			`} io;`
			`} scratchpad[NR_PROCS];`

			`#endif`