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minix/servers/avfs/open.c
Thomas Veerman 203937456e Fix off-by-one errors and increase PATH_MAX to 1024 
In some places it was assumed that PATH_MAX does not include a
terminating null character.

Increases PATH_MAX to 1024 to get in sync with NetBSD. Required some
rewriting in AVFS to keep memory usage low (the stack in use by a thread
is very small).
2011-09-12 09:00:24 +00:00

735 lines
21 KiB
C
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/* This file contains the procedures for creating, opening, closing, and
* seeking on files.
*
* The entry points into this file are
* do_creat: perform the CREAT system call
* do_open: perform the OPEN system call
* do_mknod: perform the MKNOD system call
* do_mkdir: perform the MKDIR system call
* do_close: perform the CLOSE system call
* do_lseek: perform the LSEEK system call
* do_llseek: perform the LLSEEK system call
*/
#include "fs.h"
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/u64.h>
#include "file.h"
#include "fproc.h"
#include "dmap.h"
#include "lock.h"
#include "param.h"
#include <dirent.h>
#include <assert.h>
#include <minix/vfsif.h>
#include "vnode.h"
#include "vmnt.h"
#include "path.h"
PRIVATE char mode_map[] = {R_BIT, W_BIT, R_BIT|W_BIT, 0};
FORWARD _PROTOTYPE( int common_open, (char path[PATH_MAX], int oflags,
mode_t omode) );
FORWARD _PROTOTYPE( struct vnode *new_node, (struct lookup *resolve,
int oflags, mode_t bits) );
FORWARD _PROTOTYPE( int pipe_open, (struct vnode *vp, mode_t bits,
int oflags) );
/*===========================================================================*
* do_creat *
*===========================================================================*/
PUBLIC int do_creat()
{
/* Perform the creat(name, mode) system call. */
int r;
char fullpath[PATH_MAX];
if (fetch_name(m_in.name, m_in.name_length, M3, fullpath) != OK)
return(err_code);
r = common_open(fullpath, O_WRONLY | O_CREAT | O_TRUNC, (mode_t) m_in.mode);
return(r);
}
/*===========================================================================*
* do_open *
*===========================================================================*/
PUBLIC int do_open()
{
/* Perform the open(name, flags,...) system call. */
int create_mode = 0; /* is really mode_t but this gives problems */
int r;
char fullpath[PATH_MAX];
/* If O_CREAT is set, open has three parameters, otherwise two. */
if (m_in.mode & O_CREAT) {
create_mode = m_in.c_mode;
r = fetch_name(m_in.c_name, m_in.name1_length, M1, fullpath);
} else {
r = fetch_name(m_in.name, m_in.name_length, M3, fullpath);
}
if (r != OK) return(err_code); /* name was bad */
r = common_open(fullpath, m_in.mode, create_mode);
return(r);
}
/*===========================================================================*
* common_open *
*===========================================================================*/
PRIVATE int common_open(char path[PATH_MAX], int oflags, mode_t omode)
{
/* Common code from do_creat and do_open. */
int b, r, exist = TRUE, major_dev;
dev_t dev;
mode_t bits;
struct filp *filp, *filp2;
struct vnode *vp;
struct vmnt *vmp;
struct dmap *dp;
struct lookup resolve;
/* Remap the bottom two bits of oflags. */
bits = (mode_t) mode_map[oflags & O_ACCMODE];
if (!bits) return(EINVAL);
/* See if file descriptor and filp slots are available. */
if ((r = get_fd(0, bits, &m_in.fd, &filp)) != OK) return(r);
lookup_init(&resolve, path, PATH_NOFLAGS, &vmp, &vp);
/* If O_CREATE is set, try to make the file. */
if (oflags & O_CREAT) {
omode = I_REGULAR | (omode & ALL_MODES & fp->fp_umask);
vp = new_node(&resolve, oflags, omode);
r = err_code;
if (r == OK) exist = FALSE; /* We just created the file */
else if (r != EEXIST) { /* other error */
if (vp) unlock_vnode(vp);
unlock_filp(filp);
return(r);
}
else exist = !(oflags & O_EXCL);/* file exists, if the O_EXCL
flag is set this is an error */
} else {
/* Scan path name */
resolve.l_vmnt_lock = VMNT_READ;
resolve.l_vnode_lock = VNODE_OPCL;
if ((vp = eat_path(&resolve, fp)) == NULL) {
unlock_filp(filp);
return(err_code);
}
if (vmp != NULL) unlock_vmnt(vmp);
}
/* Claim the file descriptor and filp slot and fill them in. */
fp->fp_filp[m_in.fd] = filp;
FD_SET(m_in.fd, &fp->fp_filp_inuse);
filp->filp_count = 1;
filp->filp_vno = vp;
filp->filp_flags = oflags;
/* Only do the normal open code if we didn't just create the file. */
if (exist) {
/* Check protections. */
if ((r = forbidden(vp, bits)) == OK) {
/* Opening reg. files, directories, and special files differ */
switch (vp->v_mode & I_TYPE) {
case I_REGULAR:
/* Truncate regular file if O_TRUNC. */
if (oflags & O_TRUNC) {
if ((r = forbidden(vp, W_BIT)) != OK)
break;
truncate_vnode(vp, 0);
}
break;
case I_DIRECTORY:
/* Directories may be read but not written. */
r = (bits & W_BIT ? EISDIR : OK);
break;
case I_CHAR_SPECIAL:
/* Invoke the driver for special processing. */
dev = (dev_t) vp->v_sdev;
r = dev_open(dev, who_e, bits | (oflags & ~O_ACCMODE));
if (r == SUSPEND) suspend(FP_BLOCKED_ON_DOPEN);
else vp = filp->filp_vno; /* Might be updated by
* dev_open/clone_opcl */
break;
case I_BLOCK_SPECIAL:
lock_bsf();
/* Invoke the driver for special processing. */
dev = (dev_t) vp->v_sdev;
r = dev_open(dev, who_e, bits | (oflags & ~O_ACCMODE));
if (r != OK) {
unlock_bsf();
break;
}
/* Check whether the device is mounted or not. If so,
* then that FS is responsible for this device. Else
* we default to ROOT_FS. */
vp->v_bfs_e = ROOT_FS_E; /* By default */
for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; ++vmp)
if (vmp->m_dev == vp->v_sdev &&
!is_nonedev(vmp->m_dev))
vp->v_bfs_e = vmp->m_fs_e;
/* Get the driver endpoint of the block spec device */
major_dev = major(vp->v_sdev);
if (major_dev < 0 || major_dev >= NR_DEVICES)
r = ENXIO;
else
dp = &dmap[major_dev];
if (r != OK || dp->dmap_driver == NONE) {
printf("VFS: driver not found for device %d\n",
vp->v_sdev);
r = ENXIO;
unlock_bsf();
break;
}
/* Send the driver endpoint (even when known already)*/
if (vp->v_bfs_e != ROOT_FS_E) {
/* but only when it's the ROOT_FS */
unlock_bsf();
break;
}
if ((r = req_newdriver(vp->v_bfs_e, vp->v_sdev,
dp->dmap_driver)) != OK) {
printf("VFS: error sending driver endpoint\n");
r = ENXIO;
}
unlock_bsf();
break;
case I_NAMED_PIPE:
/* Create a mapped inode on PFS which handles reads
and writes to this named pipe. */
tll_upgrade(&vp->v_lock);
r = map_vnode(vp, PFS_PROC_NR);
if (r == OK) {
vp->v_pipe = I_PIPE;
if (vp->v_ref_count == 1) {
vp->v_pipe_rd_pos = 0;
vp->v_pipe_wr_pos = 0;
if (vp->v_size != 0)
r = truncate_vnode(vp, 0);
}
oflags |= O_APPEND; /* force append mode */
filp->filp_flags = oflags;
}
if (r == OK) {
r = pipe_open(vp, bits, oflags);
}
if (r != ENXIO) {
/* See if someone else is doing a rd or wt on
* the FIFO. If so, use its filp entry so the
* file position will be automatically shared.
*/
b = (bits & R_BIT ? R_BIT : W_BIT);
filp->filp_count = 0; /* don't find self */
if ((filp2 = find_filp(vp, b)) != NULL) {
/* Co-reader or writer found. Use it.*/
fp->fp_filp[m_in.fd] = filp2;
filp2->filp_count++;
filp2->filp_vno = vp;
filp2->filp_flags = oflags;
/* v_count was incremented after the
* vnode has been found. i_count was
* incremented incorrectly in FS, not
* knowing that we were going to use an
* existing filp entry. Correct this
* error.
*/
unlock_vnode(vp);
put_vnode(vp);
} else {
/* Nobody else found. Restore filp. */
filp->filp_count = 1;
}
}
break;
}
}
}
unlock_filp(filp);
/* If error, release inode. */
if (r != OK) {
if (r != SUSPEND) {
fp->fp_filp[m_in.fd] = NULL;
FD_CLR(m_in.fd, &fp->fp_filp_inuse);
filp->filp_count = 0;
filp->filp_vno = NULL;
put_vnode(vp);
}
} else {
r = m_in.fd;
}
return(r);
}
/*===========================================================================*
* new_node *
*===========================================================================*/
PRIVATE struct vnode *new_node(struct lookup *resolve, int oflags, mode_t bits)
{
/* Try to create a new inode and return a pointer to it. If the inode already
exists, return a pointer to it as well, but set err_code accordingly.
NULL is returned if the path cannot be resolved up to the last
directory, or when the inode cannot be created due to permissions or
otherwise. */
struct vnode *dirp, *vp;
struct vmnt *dir_vmp, *vp_vmp;
int r;
struct node_details res;
struct lookup findnode;
char *path;
path = resolve->l_path; /* For easy access */
lookup_init(&findnode, path, resolve->l_flags, &dir_vmp, &dirp);
findnode.l_vmnt_lock = VMNT_WRITE;
findnode.l_vnode_lock = VNODE_WRITE; /* dir node */
/* When O_CREAT and O_EXCL flags are set, the path may not be named by a
* symbolic link. */
if (oflags & O_EXCL) findnode.l_flags |= PATH_RET_SYMLINK;
/* See if the path can be opened down to the last directory. */
if ((dirp = last_dir(&findnode, fp)) == NULL) return(NULL);
/* The final directory is accessible. Get final component of the path. */
findnode.l_vmp = &vp_vmp;
findnode.l_vnode = &vp;
findnode.l_vnode_lock = (oflags & O_TRUNC) ? VNODE_WRITE : VNODE_OPCL;
vp = advance(dirp, &findnode, fp);
assert(vp_vmp == NULL); /* Lookup to last dir should have yielded lock
* on vmp or final component does not exist. */
/* The combination of a symlink with absolute path followed by a danglink
* symlink results in a new path that needs to be re-resolved entirely. */
if (path[0] == '/') {
printf("XXX: dangling symlink needs re-resolving\n");
unlock_vnode(dirp);
unlock_vmnt(dir_vmp);
put_vnode(dirp);
if (vp != NULL) {
unlock_vnode(vp);
put_vnode(vp);
}
return new_node(resolve, oflags, bits);
}
if (vp == NULL && err_code == ENOENT) {
/* Last path component does not exist. Make a new directory entry. */
if ((vp = get_free_vnode()) == NULL) {
/* Can't create new entry: out of vnodes. */
unlock_vnode(dirp);
unlock_vmnt(dir_vmp);
put_vnode(dirp);
return(NULL);
}
lock_vnode(vp, VNODE_OPCL);
if ((r = forbidden(dirp, W_BIT|X_BIT)) != OK ||
(r = req_create(dirp->v_fs_e, dirp->v_inode_nr,bits, fp->fp_effuid,
fp->fp_effgid, path, &res)) != OK ) {
/* Can't create inode either due to permissions or some other
* problem. In case r is EEXIST, we might be dealing with a
* dangling symlink.*/
if (r == EEXIST) {
struct vnode *slp, *old_wd;
/* Resolve path up to symlink */
findnode.l_flags = PATH_RET_SYMLINK;
findnode.l_vnode_lock = VNODE_READ;
findnode.l_vnode = &slp;
slp = advance(dirp, &findnode, fp);
if (slp != NULL) {
if (S_ISLNK(slp->v_mode)) {
/* Get contents of link */
r = req_rdlink(slp->v_fs_e,
slp->v_inode_nr,
VFS_PROC_NR,
path,
PATH_MAX - 1, 0);
if (r < 0) {
/* Failed to read link */
unlock_vnode(slp);
unlock_vnode(dirp);
unlock_vmnt(dir_vmp);
put_vnode(slp);
put_vnode(dirp);
err_code = r;
return(NULL);
}
path[r] = '\0'; /* Terminate path */
}
unlock_vnode(slp);
put_vnode(slp);
}
/* Try to create the inode the dangling symlink was
* pointing to. We have to use dirp as starting point
* as there might be multiple successive symlinks
* crossing multiple mountpoints. */
old_wd = fp->fp_wd; /* Save orig. working dirp */
fp->fp_wd = dirp;
vp = new_node(resolve, oflags, bits);
fp->fp_wd = old_wd; /* Restore */
if (vp != NULL) {
unlock_vnode(dirp);
unlock_vmnt(dir_vmp);
put_vnode(dirp);
*(resolve->l_vnode) = vp;
return(vp);
}
r = err_code;
}
if (r == EEXIST)
err_code = EIO; /* Impossible, we have verified that
* the last component doesn't exist and
* is not a dangling symlink. */
else
err_code = r;
unlock_vnode(dirp);
unlock_vnode(vp);
unlock_vmnt(dir_vmp);
put_vnode(dirp);
return(NULL);
}
/* Store results and mark vnode in use */
vp->v_fs_e = res.fs_e;
vp->v_inode_nr = res.inode_nr;
vp->v_mode = res.fmode;
vp->v_size = res.fsize;
vp->v_uid = res.uid;
vp->v_gid = res.gid;
vp->v_sdev = res.dev;
vp->v_vmnt = dirp->v_vmnt;
vp->v_dev = vp->v_vmnt->m_dev;
vp->v_fs_count = 1;
vp->v_ref_count = 1;
} else {
/* Either last component exists, or there is some other problem. */
if (vp != NULL) {
r = EEXIST; /* File exists or a symlink names a file while
* O_EXCL is set. */
} else
r = err_code; /* Other problem. */
}
err_code = r;
/* When dirp equals vp, we shouldn't release the lock as a vp is locked only
* once. Releasing the lock would cause the resulting vp not be locked and
* cause mayhem later on. */
if (dirp != vp) {
unlock_vnode(dirp);
}
unlock_vmnt(dir_vmp);
put_vnode(dirp);
*(resolve->l_vnode) = vp;
return(vp);
}
/*===========================================================================*
* pipe_open *
*===========================================================================*/
PRIVATE int pipe_open(register struct vnode *vp, register mode_t bits,
register int oflags)
{
/* This function is called from common_open. It checks if
* there is at least one reader/writer pair for the pipe, if not
* it suspends the caller, otherwise it revives all other blocked
* processes hanging on the pipe.
*/
vp->v_pipe = I_PIPE;
if((bits & (R_BIT|W_BIT)) == (R_BIT|W_BIT)) return(ENXIO);
/* Find the reader/writer at the other end of the pipe */
if (find_filp(vp, bits & W_BIT ? R_BIT : W_BIT) == NULL) {
/* Not found */
if (oflags & O_NONBLOCK) {
if (bits & W_BIT) return(ENXIO);
} else {
/* Let's wait for the other side to show up */
suspend(FP_BLOCKED_ON_POPEN); /* suspend caller */
return(SUSPEND);
}
} else if (susp_count > 0) { /* revive blocked processes */
release(vp, OPEN, susp_count);
release(vp, CREAT, susp_count);
}
return(OK);
}
/*===========================================================================*
* do_mknod *
*===========================================================================*/
PUBLIC int do_mknod()
{
/* Perform the mknod(name, mode, addr) system call. */
register mode_t bits, mode_bits;
int r;
struct vnode *vp;
struct vmnt *vmp;
char fullpath[PATH_MAX];
struct lookup resolve;
lookup_init(&resolve, fullpath, PATH_NOFLAGS, &vmp, &vp);
resolve.l_vmnt_lock = VMNT_WRITE;
resolve.l_vnode_lock = VNODE_READ;
/* Only the super_user may make nodes other than fifos. */
mode_bits = (mode_t) m_in.mk_mode; /* mode of the inode */
if (!super_user && (((mode_bits & I_TYPE) != I_NAMED_PIPE) &&
((mode_bits & I_TYPE) != I_UNIX_SOCKET))) {
return(EPERM);
}
bits = (mode_bits & I_TYPE) | (mode_bits & ALL_MODES & fp->fp_umask);
/* Open directory that's going to hold the new node. */
if (fetch_name(m_in.name1, m_in.name1_length, M1, fullpath) != OK)
return(err_code);
if ((vp = last_dir(&resolve, fp)) == NULL) return(err_code);
/* Make sure that the object is a directory */
if ((vp->v_mode & I_TYPE) != I_DIRECTORY) {
r = ENOTDIR;
} else if ((r = forbidden(vp, W_BIT|X_BIT)) == OK) {
r = req_mknod(vp->v_fs_e, vp->v_inode_nr, fullpath, fp->fp_effuid,
fp->fp_effgid, bits, m_in.mk_z0);
}
unlock_vnode(vp);
unlock_vmnt(vmp);
put_vnode(vp);
return(r);
}
/*===========================================================================*
* do_mkdir *
*===========================================================================*/
PUBLIC int do_mkdir()
{
/* Perform the mkdir(name, mode) system call. */
mode_t bits; /* mode bits for the new inode */
int r;
struct vnode *vp;
struct vmnt *vmp;
char fullpath[PATH_MAX];
struct lookup resolve;
lookup_init(&resolve, fullpath, PATH_NOFLAGS, &vmp, &vp);
resolve.l_vmnt_lock = VMNT_WRITE;
resolve.l_vnode_lock = VNODE_READ;
if (fetch_name(m_in.name1, m_in.name1_length, M1, fullpath) != OK)
return(err_code);
bits = I_DIRECTORY | (m_in.mode & RWX_MODES & fp->fp_umask);
if ((vp = last_dir(&resolve, fp)) == NULL) return(err_code);
/* Make sure that the object is a directory */
if ((vp->v_mode & I_TYPE) != I_DIRECTORY) {
r = ENOTDIR;
} else if ((r = forbidden(vp, W_BIT|X_BIT)) == OK) {
r = req_mkdir(vp->v_fs_e, vp->v_inode_nr, fullpath, fp->fp_effuid,
fp->fp_effgid, bits);
}
unlock_vnode(vp);
unlock_vmnt(vmp);
put_vnode(vp);
return(r);
}
/*===========================================================================*
* do_lseek *
*===========================================================================*/
PUBLIC int do_lseek()
{
/* Perform the lseek(ls_fd, offset, whence) system call. */
register struct filp *rfilp;
int r = OK;
long offset;
u64_t pos, newpos;
/* Check to see if the file descriptor is valid. */
if ( (rfilp = get_filp(m_in.ls_fd, VNODE_READ)) == NULL) return(err_code);
/* No lseek on pipes. */
if (rfilp->filp_vno->v_pipe == I_PIPE) {
unlock_filp(rfilp);
return(ESPIPE);
}
/* The value of 'whence' determines the start position to use. */
switch(m_in.whence) {
case SEEK_SET: pos = cvu64(0); break;
case SEEK_CUR: pos = rfilp->filp_pos; break;
case SEEK_END: pos = cvul64(rfilp->filp_vno->v_size); break;
default: unlock_filp(rfilp); return(EINVAL);
}
offset = m_in.offset_lo;
if (offset >= 0)
newpos = add64ul(pos, offset);
else
newpos = sub64ul(pos, -offset);
/* Check for overflow. */
if (ex64hi(newpos) != 0)
r = EINVAL;
else {
rfilp->filp_pos = newpos;
/* insert the new position into the output message */
m_out.reply_l1 = ex64lo(newpos);
if (cmp64(newpos, rfilp->filp_pos) != 0) {
/* Inhibit read ahead request */
r = req_inhibread(rfilp->filp_vno->v_fs_e,
rfilp->filp_vno->v_inode_nr);
}
}
unlock_filp(rfilp);
return(r);
}
/*===========================================================================*
* do_llseek *
*===========================================================================*/
PUBLIC int do_llseek()
{
/* Perform the llseek(ls_fd, offset, whence) system call. */
register struct filp *rfilp;
u64_t pos, newpos;
int r = OK;
/* Check to see if the file descriptor is valid. */
if ( (rfilp = get_filp(m_in.ls_fd, VNODE_READ)) == NULL) return(err_code);
/* No lseek on pipes. */
if (rfilp->filp_vno->v_pipe == I_PIPE) {
unlock_filp(rfilp);
return(ESPIPE);
}
/* The value of 'whence' determines the start position to use. */
switch(m_in.whence) {
case SEEK_SET: pos = cvu64(0); break;
case SEEK_CUR: pos = rfilp->filp_pos; break;
case SEEK_END: pos = cvul64(rfilp->filp_vno->v_size); break;
default: unlock_filp(rfilp); return(EINVAL);
}
newpos = add64(pos, make64(m_in.offset_lo, m_in.offset_high));
/* Check for overflow. */
if (( (long) m_in.offset_high > 0) && cmp64(newpos, pos) < 0)
r = EINVAL;
else if (( (long) m_in.offset_high < 0) && cmp64(newpos, pos) > 0)
r = EINVAL;
else {
rfilp->filp_pos = newpos;
/* insert the new position into the output message */
m_out.reply_l1 = ex64lo(newpos);
m_out.reply_l2 = ex64hi(newpos);
if (cmp64(newpos, rfilp->filp_pos) != 0) {
/* Inhibit read ahead request */
r = req_inhibread(rfilp->filp_vno->v_fs_e,
rfilp->filp_vno->v_inode_nr);
}
}
unlock_filp(rfilp);
return(r);
}
/*===========================================================================*
* do_close *
*===========================================================================*/
PUBLIC int do_close()
{
/* Perform the close(fd) system call. */
return close_fd(fp, m_in.fd);
}
/*===========================================================================*
* close_fd *
*===========================================================================*/
PUBLIC int close_fd(rfp, fd_nr)
struct fproc *rfp;
int fd_nr;
{
/* Perform the close(fd) system call. */
register struct filp *rfilp;
register struct vnode *vp;
struct file_lock *flp;
int lock_count;
/* First locate the vnode that belongs to the file descriptor. */
if ( (rfilp = get_filp2(rfp, fd_nr, VNODE_OPCL)) == NULL) return(err_code);
vp = rfilp->filp_vno;
close_filp(rfilp);
rfp->fp_filp[fd_nr] = NULL;
FD_CLR(fd_nr, &rfp->fp_cloexec_set);
FD_CLR(fd_nr, &rfp->fp_filp_inuse);
/* Check to see if the file is locked. If so, release all locks. */
if (nr_locks > 0) {
lock_count = nr_locks; /* save count of locks */
for (flp = &file_lock[0]; flp < &file_lock[NR_LOCKS]; flp++) {
if (flp->lock_type == 0) continue; /* slot not in use */
if (flp->lock_vnode == vp && flp->lock_pid == rfp->fp_pid) {
flp->lock_type = 0;
nr_locks--;
}
}
if (nr_locks < lock_count)
lock_revive(); /* one or more locks released */
}
return(OK);
}
/*===========================================================================*
* close_reply *
*===========================================================================*/
PUBLIC void close_reply()
{
/* No need to do anything */
}
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