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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 | /* * 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> 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); /* if there is a fs-specific handler, we can't just ignore it.. */ /* accept llseek() only for the signed long subset of long long */ if (file->f_op && file->f_op->lseek) { if (offset != (long) offset) return -EINVAL; return file->f_op->lseek(file->f_inode,file,offset,origin); } 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; } 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; } |