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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 | /* * linux/fs/readdir.c * * Copyright (C) 1995 Linus Torvalds */ #include <linux/types.h> #include <linux/errno.h> #include <linux/stat.h> #include <linux/kernel.h> #include <linux/sched.h> #include <linux/mm.h> #include <linux/smp.h> #include <linux/smp_lock.h> #include <asm/uaccess.h> /* * Traditional linux readdir() handling.. * * "count=1" is a special case, meaning that the buffer is one * dirent-structure in size and that the code can't handle more * anyway. Thus the special "fillonedir()" function for that * case (the low-level handlers don't need to care about this). */ #define NAME_OFFSET(de) ((int) ((de)->d_name - (char *) (de))) #define ROUND_UP(x) (((x)+sizeof(long)-1) & ~(sizeof(long)-1)) struct old_linux_dirent { unsigned long d_ino; unsigned long d_offset; unsigned short d_namlen; char d_name[1]; }; struct readdir_callback { struct old_linux_dirent * dirent; int count; }; static int fillonedir(void * __buf, const char * name, int namlen, off_t offset, ino_t ino) { struct readdir_callback * buf = (struct readdir_callback *) __buf; struct old_linux_dirent * dirent; if (buf->count) return -EINVAL; buf->count++; dirent = buf->dirent; put_user(ino, &dirent->d_ino); put_user(offset, &dirent->d_offset); put_user(namlen, &dirent->d_namlen); copy_to_user(dirent->d_name, name, namlen); put_user(0, dirent->d_name + namlen); return 0; } asmlinkage int old_readdir(unsigned int fd, void * dirent, unsigned int count) { int error; struct file * file; struct dentry * dentry; struct inode * inode; struct readdir_callback buf; lock_kernel(); error = -EBADF; if (fd >= NR_OPEN) goto out; file = current->files->fd[fd]; if (!file) goto out; dentry = file->f_dentry; if (!dentry) goto out; inode = dentry->d_inode; if (!inode) goto out; buf.count = 0; buf.dirent = dirent; error = -ENOTDIR; if (!file->f_op || !file->f_op->readdir) goto out; /* * Get the inode's semaphore to prevent changes * to the directory while we read it. */ down(&inode->i_sem); error = file->f_op->readdir(file, &buf, fillonedir); up(&inode->i_sem); if (error < 0) goto out; error = buf.count; out: unlock_kernel(); return error; } /* * New, all-improved, singing, dancing, iBCS2-compliant getdents() * interface. */ struct linux_dirent { unsigned long d_ino; unsigned long d_off; unsigned short d_reclen; char d_name[1]; }; struct getdents_callback { struct linux_dirent * current_dir; struct linux_dirent * previous; int count; int error; }; static int filldir(void * __buf, const char * name, int namlen, off_t offset, ino_t ino) { struct linux_dirent * dirent; struct getdents_callback * buf = (struct getdents_callback *) __buf; int reclen = ROUND_UP(NAME_OFFSET(dirent) + namlen + 1); buf->error = -EINVAL; /* only used if we fail.. */ if (reclen > buf->count) return -EINVAL; dirent = buf->previous; if (dirent) put_user(offset, &dirent->d_off); dirent = buf->current_dir; buf->previous = dirent; put_user(ino, &dirent->d_ino); put_user(reclen, &dirent->d_reclen); copy_to_user(dirent->d_name, name, namlen); put_user(0, dirent->d_name + namlen); ((char *) dirent) += reclen; buf->current_dir = dirent; buf->count -= reclen; return 0; } asmlinkage int sys_getdents(unsigned int fd, void * dirent, unsigned int count) { struct file * file; struct dentry * dentry; struct inode * inode; struct linux_dirent * lastdirent; struct getdents_callback buf; int error; lock_kernel(); error = -EBADF; if (fd >= NR_OPEN) goto out; file = current->files->fd[fd]; if (!file) goto out; dentry = file->f_dentry; if (!dentry) goto out; inode = dentry->d_inode; if (!inode) goto out; buf.current_dir = (struct linux_dirent *) dirent; buf.previous = NULL; buf.count = count; buf.error = 0; error = -ENOTDIR; if (!file->f_op || !file->f_op->readdir) goto out; /* * Get the inode's semaphore to prevent changes * to the directory while we read it. */ down(&inode->i_sem); error = file->f_op->readdir(file, &buf, filldir); up(&inode->i_sem); if (error < 0) goto out; lastdirent = buf.previous; error = buf.error; if (lastdirent) { put_user(file->f_pos, &lastdirent->d_off); error = count - buf.count; } out: unlock_kernel(); return error; } |