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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 | /* * linux/fs/read_write.c * * Copyright (C) 1991, 1992 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 <asm/segment.h> /* * Count is now a supported feature, but currently only the ext2fs * uses it. A count value of 1 is supported for compatibility with * earlier libraries, but larger values are supported: count should * indicate the total buffer space available for filling with dirents. * The d_off entry in the dirents will then indicate the offset from * each dirent to the next, and the return value will indicate the * number of bytes written. All dirents will be written at * word-aligned addresses. [sct Oct 1994] */ asmlinkage int sys_readdir(unsigned int fd, struct dirent * dirent, unsigned int count) { int error; struct file * file; struct inode * inode; if (fd >= NR_OPEN || !(file = current->files->fd[fd]) || !(inode = file->f_inode)) return -EBADF; error = -ENOTDIR; if (file->f_op && file->f_op->readdir) { int size = count; if (count == 1) size = sizeof(*dirent); error = verify_area(VERIFY_WRITE, dirent, size); if (!error) error = file->f_op->readdir(inode,file,dirent,count); } return error; } asmlinkage int sys_lseek(unsigned int fd, off_t offset, unsigned int origin) { struct file * file; int tmp = -1; if (fd >= NR_OPEN || !(file=current->files->fd[fd]) || !(file->f_inode)) return -EBADF; if (origin > 2) return -EINVAL; if (file->f_op && file->f_op->lseek) return file->f_op->lseek(file->f_inode,file,offset,origin); /* this is the default handler if no lseek handler is present */ switch (origin) { case 0: tmp = offset; break; case 1: tmp = file->f_pos + offset; break; case 2: if (!file->f_inode) return -EINVAL; tmp = file->f_inode->i_size + offset; break; } if (tmp < 0) return -EINVAL; if (tmp != file->f_pos) { file->f_pos = tmp; file->f_reada = 0; file->f_version = ++event; } return file->f_pos; } asmlinkage int sys_llseek(unsigned int fd, unsigned long offset_high, unsigned long offset_low, loff_t * result, unsigned int origin) { struct file * file; loff_t tmp = -1; loff_t offset; int err; if (fd >= NR_OPEN || !(file=current->files->fd[fd]) || !(file->f_inode)) return -EBADF; if (origin > 2) return -EINVAL; if ((err = verify_area(VERIFY_WRITE, result, sizeof(loff_t)))) return err; offset = (loff_t) (((unsigned long long) offset_high << 32) | offset_low); /* there is no fs specific llseek handler */ switch (origin) { case 0: tmp = offset; break; case 1: tmp = file->f_pos + offset; break; case 2: if (!file->f_inode) return -EINVAL; tmp = file->f_inode->i_size + offset; break; } if (tmp < 0) return -EINVAL; file->f_pos = tmp; file->f_reada = 0; file->f_version = ++event; memcpy_tofs(result, &file->f_pos, sizeof(loff_t)); return 0; } asmlinkage int sys_read(unsigned int fd,char * buf,unsigned int count) { int error; struct file * file; struct inode * inode; if (fd>=NR_OPEN || !(file=current->files->fd[fd]) || !(inode=file->f_inode)) return -EBADF; if (!(file->f_mode & 1)) return -EBADF; if (!file->f_op || !file->f_op->read) return -EINVAL; if (!count) return 0; error = verify_area(VERIFY_WRITE,buf,count); if (error) return error; return file->f_op->read(inode,file,buf,count); } asmlinkage int sys_write(unsigned int fd,char * buf,unsigned int count) { int error; struct file * file; struct inode * inode; int written; if (fd>=NR_OPEN || !(file=current->files->fd[fd]) || !(inode=file->f_inode)) return -EBADF; if (!(file->f_mode & 2)) return -EBADF; if (!file->f_op || !file->f_op->write) return -EINVAL; if (!count) return 0; error = verify_area(VERIFY_READ,buf,count); if (error) return error; written = file->f_op->write(inode,file,buf,count); /* * If data has been written to the file, remove the setuid and * the setgid bits */ if (written > 0 && !suser() && (inode->i_mode & (S_ISUID | S_ISGID))) { struct iattr newattrs; newattrs.ia_mode = inode->i_mode & ~(S_ISUID | S_ISGID); newattrs.ia_valid = ATTR_MODE; notify_change(inode, &newattrs); } return written; } |