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0
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1 //
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2 // File-system system calls.
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3 // Mostly argument checking, since we don't trust
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4 // user code, and calls into file.c and fs.c.
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5 //
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6
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7 #include "types.h"
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8 #include "defs.h"
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9 #include "param.h"
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10 #include "stat.h"
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11 #include "mmu.h"
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12 #include "proc.h"
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13 #include "fs.h"
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14 #include "file.h"
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15 #include "fcntl.h"
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16
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52
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17 #define __ncode __code
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18
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0
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19 // Fetch the nth word-sized system call argument as a file descriptor
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20 // and return both the descriptor and the corresponding struct file.
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21 static int argfd(int n, int *pfd, struct file **pf)
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22 {
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23 int fd;
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24 struct file *f;
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25
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26 if(argint(n, &fd) < 0) {
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27 return -1;
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28 }
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29
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30 if(fd < 0 || fd >= NOFILE || (f=proc->ofile[fd]) == 0) {
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31 return -1;
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32 }
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33
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34 if(pfd) {
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35 *pfd = fd;
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36 }
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37
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38 if(pf) {
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39 *pf = f;
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40 }
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41
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42 return 0;
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43 }
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44
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45 // Allocate a file descriptor for the given file.
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46 // Takes over file reference from caller on success.
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47 static int fdalloc(struct file *f)
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48 {
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49 int fd;
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50
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51 for(fd = 0; fd < NOFILE; fd++){
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52 if(proc->ofile[fd] == 0){
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53 proc->ofile[fd] = f;
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54 return fd;
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55 }
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56 }
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57
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58 return -1;
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59 }
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60
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61 int sys_dup(void)
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62 {
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63 struct file *f;
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64 int fd;
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65
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66 if(argfd(0, 0, &f) < 0) {
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67 return -1;
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68 }
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69
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70 if((fd=fdalloc(f)) < 0) {
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71 return -1;
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72 }
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73
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74 filedup(f);
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75
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76 return fd;
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77 }
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78
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52
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79 __ncode cbc_read(__code (*next)(int ret)){
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24
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80 struct file *f;
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81 int n;
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82 char *p;
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83
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84 if(argfd(0, 0, &f) < 0 || argint(2, &n) < 0 || argptr(1, &p, n) < 0) {
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85 goto next(-1);
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86 }
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87 goto cbc_fileread(f, p, n, next);
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88 }
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89
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88
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90 __code file_read(struct file *f, int n, char *p, __code next(...)){
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91 goto cbc_fileread(f, p, n, next);
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92 }
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93
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94 __code file_read_stub(struct Context* cbc_context){
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95 struct file *f;
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96 int n;
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97 char *p;
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98 if(argfd(0, 0, &f) < 0 || argint(2, &n) < 0 || argptr(1, &p, n) < 0) {
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99 goto next(-1);
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100 }
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101 goto cbc_fileread(f, p, n, next);
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102 }
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103
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0
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104 int sys_read(void)
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105 {
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106 struct file *f;
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107 int n;
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108 char *p;
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109
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110 if(argfd(0, 0, &f) < 0 || argint(2, &n) < 0 || argptr(1, &p, n) < 0) {
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111 return -1;
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112 }
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113
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114 return fileread(f, p, n);
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115 }
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116
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117 int sys_write(void)
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118 {
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119 struct file *f;
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120 int n;
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121 char *p;
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122
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123 if(argfd(0, 0, &f) < 0 || argint(2, &n) < 0 || argptr(1, &p, n) < 0) {
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124 return -1;
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125 }
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126
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127 return filewrite(f, p, n);
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128 }
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129
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130 int sys_close(void)
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131 {
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132 int fd;
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133 struct file *f;
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134
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135 if(argfd(0, &fd, &f) < 0) {
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136 return -1;
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137 }
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138
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139 proc->ofile[fd] = 0;
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140 fileclose(f);
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141
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142 return 0;
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143 }
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144
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145 int sys_fstat(void)
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146 {
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147 struct file *f;
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148 struct stat *st;
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149
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150 if(argfd(0, 0, &f) < 0 || argptr(1, (void*)&st, sizeof(*st)) < 0) {
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151 return -1;
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152 }
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153
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154 return filestat(f, st);
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155 }
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156
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157 // Create the path new as a link to the same inode as old.
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158 int sys_link(void)
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159 {
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160 char name[DIRSIZ], *new, *old;
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161 struct inode *dp, *ip;
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162
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163 if(argstr(0, &old) < 0 || argstr(1, &new) < 0) {
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164 return -1;
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165 }
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166
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167 if((ip = namei(old)) == 0) {
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168 return -1;
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169 }
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170
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171 begin_trans();
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172
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173 ilock(ip);
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174
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175 if(ip->type == T_DIR){
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176 iunlockput(ip);
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177 commit_trans();
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178 return -1;
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179 }
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180
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181 ip->nlink++;
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182 iupdate(ip);
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183 iunlock(ip);
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184
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185 if((dp = nameiparent(new, name)) == 0) {
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186 goto bad;
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187 }
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188
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189 ilock(dp);
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190
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191 if(dp->dev != ip->dev || dirlink(dp, name, ip->inum) < 0){
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192 iunlockput(dp);
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193 goto bad;
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194 }
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195
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196 iunlockput(dp);
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197 iput(ip);
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198
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199 commit_trans();
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200
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201 return 0;
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202
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203 bad:
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204 ilock(ip);
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205 ip->nlink--;
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206 iupdate(ip);
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207 iunlockput(ip);
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208 commit_trans();
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209 return -1;
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210 }
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211
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212 // Is the directory dp empty except for "." and ".." ?
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213 static int isdirempty(struct inode *dp)
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214 {
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215 int off;
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216 struct dirent de;
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217
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218 for(off=2*sizeof(de); off<dp->size; off+=sizeof(de)){
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219 if(readi(dp, (char*)&de, off, sizeof(de)) != sizeof(de)) {
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220 panic("isdirempty: readi");
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221 }
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222
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223 if(de.inum != 0) {
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224 return 0;
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225 }
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226 }
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227 return 1;
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228 }
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229
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230 //PAGEBREAK!
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231 int sys_unlink(void)
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232 {
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233 struct inode *ip, *dp;
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234 struct dirent de;
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235 char name[DIRSIZ], *path;
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236 uint off;
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237
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238 if(argstr(0, &path) < 0) {
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239 return -1;
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240 }
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241
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242 if((dp = nameiparent(path, name)) == 0) {
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243 return -1;
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244 }
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245
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246 begin_trans();
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247
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248 ilock(dp);
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249
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250 // Cannot unlink "." or "..".
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251 if(namecmp(name, ".") == 0 || namecmp(name, "..") == 0) {
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252 goto bad;
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253 }
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254
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255 if((ip = dirlookup(dp, name, &off)) == 0) {
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256 goto bad;
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257 }
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258
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259 ilock(ip);
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260
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261 if(ip->nlink < 1) {
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262 panic("unlink: nlink < 1");
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263 }
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264
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265 if(ip->type == T_DIR && !isdirempty(ip)){
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266 iunlockput(ip);
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267 goto bad;
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268 }
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269
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270 memset(&de, 0, sizeof(de));
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271
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272 if(writei(dp, (char*)&de, off, sizeof(de)) != sizeof(de)) {
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273 panic("unlink: writei");
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274 }
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275
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276 if(ip->type == T_DIR){
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277 dp->nlink--;
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278 iupdate(dp);
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279 }
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280
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281 iunlockput(dp);
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282
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283 ip->nlink--;
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284 iupdate(ip);
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285 iunlockput(ip);
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286
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287 commit_trans();
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288
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289 return 0;
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290
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291 bad:
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292 iunlockput(dp);
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293 commit_trans();
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294 return -1;
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295 }
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296
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297 static struct inode* create(char *path, short type, short major, short minor)
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298 {
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299 uint off;
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300 struct inode *ip, *dp;
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301 char name[DIRSIZ];
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302
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303 if((dp = nameiparent(path, name)) == 0) {
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304 return 0;
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305 }
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306
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307 ilock(dp);
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308
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309 if((ip = dirlookup(dp, name, &off)) != 0){
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310 iunlockput(dp);
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311 ilock(ip);
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312
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313 if(type == T_FILE && ip->type == T_FILE) {
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314 return ip;
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315 }
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316
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317 iunlockput(ip);
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318
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319 return 0;
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320 }
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321
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322 if((ip = ialloc(dp->dev, type)) == 0) {
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323 panic("create: ialloc");
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324 }
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325
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326 ilock(ip);
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327 ip->major = major;
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328 ip->minor = minor;
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329 ip->nlink = 1;
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330 iupdate(ip);
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331
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332 if(type == T_DIR){ // Create . and .. entries.
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333 dp->nlink++; // for ".."
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334 iupdate(dp);
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335
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336 // No ip->nlink++ for ".": avoid cyclic ref count.
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337 if(dirlink(ip, ".", ip->inum) < 0 || dirlink(ip, "..", dp->inum) < 0) {
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338 panic("create dots");
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339 }
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340 }
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341
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342 if(dirlink(dp, name, ip->inum) < 0) {
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343 panic("create: dirlink");
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344 }
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345
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346 iunlockput(dp);
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347
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348 return ip;
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349 }
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350
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351 int sys_open(void)
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352 {
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353 char *path;
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354 int fd, omode;
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355 struct file *f;
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356 struct inode *ip;
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357
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358 if(argstr(0, &path) < 0 || argint(1, &omode) < 0) {
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359 return -1;
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360 }
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361
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362 if(omode & O_CREATE){
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363 begin_trans();
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364 ip = create(path, T_FILE, 0, 0);
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365 commit_trans();
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366
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367 if(ip == 0) {
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368 return -1;
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369 }
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370
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371 } else {
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372 if((ip = namei(path)) == 0) {
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373 return -1;
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374 }
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375
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376 ilock(ip);
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377
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378 if(ip->type == T_DIR && omode != O_RDONLY){
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379 iunlockput(ip);
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380 return -1;
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381 }
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382 }
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383
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384 if((f = filealloc()) == 0 || (fd = fdalloc(f)) < 0){
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385 if(f) {
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386 fileclose(f);
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387 }
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388
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389 iunlockput(ip);
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390 return -1;
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391 }
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392
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393 iunlock(ip);
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394
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395 f->type = FD_INODE;
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396 f->ip = ip;
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397 f->off = 0;
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398 f->readable = !(omode & O_WRONLY);
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399 f->writable = (omode & O_WRONLY) || (omode & O_RDWR);
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400
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401 return fd;
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402 }
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403
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404 int sys_mkdir(void)
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405 {
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406 char *path;
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407 struct inode *ip;
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408
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409 begin_trans();
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410
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411 if(argstr(0, &path) < 0 || (ip = create(path, T_DIR, 0, 0)) == 0){
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412 commit_trans();
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413 return -1;
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414 }
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415
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416 iunlockput(ip);
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417 commit_trans();
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418
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419 return 0;
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420 }
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421
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422 int sys_mknod(void)
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423 {
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424 struct inode *ip;
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425 char *path;
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426 int len;
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427 int major, minor;
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428
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429 begin_trans();
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430
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431 if((len=argstr(0, &path)) < 0 ||
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432 argint(1, &major) < 0 || argint(2, &minor) < 0 ||
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433 (ip = create(path, T_DEV, major, minor)) == 0){
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434
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435 commit_trans();
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436 return -1;
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437 }
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438
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439 iunlockput(ip);
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440 commit_trans();
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441
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442 return 0;
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443 }
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444
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445 int sys_chdir(void)
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446 {
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447 char *path;
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448 struct inode *ip;
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449
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450 if(argstr(0, &path) < 0 || (ip = namei(path)) == 0) {
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451 return -1;
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452 }
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453
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454 ilock(ip);
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455
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456 if(ip->type != T_DIR){
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457 iunlockput(ip);
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458 return -1;
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459 }
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460
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461 iunlock(ip);
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462
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463 iput(proc->cwd);
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464 proc->cwd = ip;
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465
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466 return 0;
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467 }
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468
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469 int sys_exec(void)
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470 {
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471 char *path, *argv[MAXARG];
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472 int i;
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473 uint uargv, uarg;
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474
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475 if(argstr(0, &path) < 0 || argint(1, (int*)&uargv) < 0){
|
|
|
476 return -1;
|
|
|
477 }
|
|
|
478
|
|
|
479 memset(argv, 0, sizeof(argv));
|
|
|
480
|
|
|
481 for(i=0;; i++){
|
|
|
482 if(i >= NELEM(argv)) {
|
|
|
483 return -1;
|
|
|
484 }
|
|
|
485
|
|
|
486 if(fetchint(uargv+4*i, (int*)&uarg) < 0) {
|
|
|
487 return -1;
|
|
|
488 }
|
|
|
489
|
|
|
490 if(uarg == 0){
|
|
|
491 argv[i] = 0;
|
|
|
492 break;
|
|
|
493 }
|
|
|
494
|
|
|
495 if(fetchstr(uarg, &argv[i]) < 0) {
|
|
|
496 return -1;
|
|
|
497 }
|
|
|
498 }
|
|
|
499
|
|
|
500 return exec(path, argv);
|
|
|
501 }
|
|
|
502
|
|
|
503 int sys_pipe(void)
|
|
|
504 {
|
|
|
505 int *fd;
|
|
|
506 struct file *rf, *wf;
|
|
|
507 int fd0, fd1;
|
|
|
508
|
|
|
509 if(argptr(0, (void*)&fd, 2*sizeof(fd[0])) < 0) {
|
|
|
510 return -1;
|
|
|
511 }
|
|
|
512
|
|
|
513 if(pipealloc(&rf, &wf) < 0) {
|
|
|
514 return -1;
|
|
|
515 }
|
|
|
516
|
|
|
517 fd0 = -1;
|
|
|
518
|
|
|
519 if((fd0 = fdalloc(rf)) < 0 || (fd1 = fdalloc(wf)) < 0){
|
|
|
520 if(fd0 >= 0) {
|
|
|
521 proc->ofile[fd0] = 0;
|
|
|
522 }
|
|
|
523
|
|
|
524 fileclose(rf);
|
|
|
525 fileclose(wf);
|
|
|
526
|
|
|
527 return -1;
|
|
|
528 }
|
|
|
529
|
|
|
530 fd[0] = fd0;
|
|
|
531 fd[1] = fd1;
|
|
|
532
|
|
|
533 return 0;
|
|
|
534 }
|
