xv6 实验1 Unix Utilities
Lab util: Uinx utilities
- https://pdos.csail.mit.edu/6.S081/2020/schedule.html
- https://pdos.csail.mit.edu/6.828/2020/labs/util.html
sleep
在 UPROGS 项中最后一行添加 $U/_sleep\1
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18UPROGS=\
$U/_cat\
$U/_echo\
$U/_forktest\
$U/_grep\
$U/_init\
$U/_kill\
$U/_ln\
$U/_ls\
$U/_mkdir\
$U/_rm\
$U/_sh\
$U/_stressfs\
$U/_usertests\
$U/_grind\
$U/_wc\
$U/_zombie\
$U/_sleep\
sleep.c1
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int
main(int argc, char *argv[])
{
if(argc == 2) {
fprintf(2, "(nothing happens for a little while)\n");
sleep(atoi((const char*) argv[1])); // convert ascii to integer and use system call sleep
exit(0);
}
else{
fprintf(2, "Usage:sleep number...\n"); // put the error masssage to the file descriptor 2
exit(1); // terminate the process,
// status = 1: indicates failure, and reported to wait()
}
}
pingpong
分析
通过fork、pipe和getpid系统调用，来实现pingpong
- fork在父进程中的返回值是pid，在子进程中的返回值是0
- pipe初始化的管道，其数组的第一个元素是读端，第二个元素是写端
实现
在 UPROGS 项中最后一行添加 $U/_pingpong\
pingpong.c1
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int
main(int argc, char *argv[])
{
int p1[2]; // parent -> child
int p2[2]; // child -> parent
char buffer[] = {'x'};
int length = sizeof(buffer);
if(argc != 1){
fprintf(2, "Usage: pingpong\n");
exit(1);
}
pipe(p1);
pipe(p2);
if(fork() == 0){ // child
close(p1[1]);
close(p2[0]);
if(read(p1[0], buffer, length) == 1){ // child receives the byte
printf("%d: received ping\n", getpid());
write(p2[1], buffer, length); // child sends the byte to child
close(p2[1]);
exit(0);
}
close(p2[1]);
exit(1);
}else{ // parent
close(p1[0]);
close(p2[1]);
write(p1[1], buffer, length); // parent sends a byte to the child
close(p1[1]);
wait((int *)0);
if(read(p2[0], buffer, length) == 1){ // parent receives the byte
printf("%d: received pong\n", getpid());
}
exit(0);
}
}
primes
分析
实现
在 UPROGS 项中最后一行添加 $U/_primes\
1 |
|
find
在 UPROGS 项中最后一行添加 $U/_find\
1 |
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xargs
在 UPROGS 项中最后一行添加 $U/_xargs\
1 |
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git查看修改记录
查看文件的变化1
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9grand@Lubuntu:~/xv6-labs-2020$ git diff origin/util util --stat
Makefile | 5 +++++
gradelib.pyc | Bin 0 -> 22972 bytes
user/find.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
user/pingpong.c | 40 ++++++++++++++++++++++++++++++++++++++++
user/primes.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
user/sleep.c | 17 +++++++++++++++++
user/xargs.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
7 files changed, 260 insertions(+)
查看具体修改内容git diff origin/util util1
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305diff --git a/Makefile b/Makefile
index 0fbaf7c..b2addd4 100644
--- a/Makefile
+++ b/Makefile
@@ -149,6 +149,11 @@ UPROGS=\
$U/_grind\
$U/_wc\
$U/_zombie\
+ $U/_sleep\
+ $U/_pingpong\
+ $U/_find\
+ $U/_xargs\
+ $U/_primes\
ifeq ($(LAB),syscall)
diff --git a/gradelib.pyc b/gradelib.pyc
new file mode 100644
index 0000000..634a0f3
Binary files /dev/null and b/gradelib.pyc differ
diff --git a/user/find.c b/user/find.c
new file mode 100644
index 0000000..8070f86
--- /dev/null
+++ b/user/find.c
@@ -0,0 +1,84 @@
+#include "kernel/types.h"
+#include "kernel/stat.h"
+#include "user/user.h"
+#include "kernel/fs.h"
+
+char*
+fmtname(char *path) // 将路径格式化为文件名
+{
+ static char buf[DIRSIZ+1];
+ char *p;
+
+ // Find first character after last slash. 从字符串末尾开始遍历，直到遇到'/'或者到字符串的头部为止
+ for(p=path+strlen(path); p >= path && *p != '/'; p--) ;
+ p++;
+
+ // Return blank-padded name.
+ if(strlen(p) >= DIRSIZ) // 字符串太长了
+ return p;
+ memmove(buf, p, strlen(p)+1);
+ return buf;
+}
+
+void
+find(char *path, char *file)
+{
+ char buf[512], *p;
+ int fd;
+ struct dirent de;
+ struct stat st;
+
+ if((fd = open(path, 0)) < 0){ // 路径不存在
+ fprintf(2, "find: cannot open %s\n", path);
+ return;
+ }
+
+ if(fstat(fd, &st) < 0){ // 获取不了该路径的状态
+ fprintf(2, "find: cannot stat %s\n", path);
+ close(fd);
+ return;
+ }
+
+ switch(st.type){
+ case T_FILE: // 如果这是一个文件
+ if(strcmp(fmtname(path), file) == 0){
+ printf("%s\n", path);
+ }
+ break;
+
+ case T_DIR: // 如果这是一个目录
+ if(strlen(path) + 1 + DIRSIZ + 1 > sizeof buf){ // 路径太长，缓冲区装不下
+ printf("find: path too long\n");
+ break;
+ }
+ strcpy(buf, path);
+ p = buf+strlen(buf);
+ *p++ = '/'; // 在路径末尾添加'/'
+ while(read(fd, &de, sizeof(de)) == sizeof(de)){ // 从该路径读取出文件名或者目录名
+ if(de.inum == 0 || de.inum == 1)
+ continue;
+ if (strcmp(de.name, ".") == 0 || strcmp(de.name, "..") == 0)
+ continue;
+ memmove(p, de.name, DIRSIZ); // 在路径后面添加文件名or目录
+ p[DIRSIZ] = 0; // the end of string is '\0'
+ find(buf, file);
+ }
+ break;
+
+ default:
+ break;
+ }
+ close(fd);
+}
+
+
+int
+main(int argc, char *argv[])
+{
+ if(argc != 3){
+ fprintf(2, "Usage: find <path> <file>\n");
+ exit(1);
+ }
+ find(argv[1], argv[2]);
+ exit(0);
+}
diff --git a/user/pingpong.c b/user/pingpong.c
new file mode 100644
index 0000000..caecc4b
--- /dev/null
+++ b/user/pingpong.c
@@ -0,0 +1,40 @@
+#include "kernel/types.h"
+#include "kernel/stat.h"
+#include "user/user.h"
+
+int
+main(int argc, char *argv[])
+{
+ int p1[2]; // parent -> child
+ int p2[2]; // child -> parent
+ char buffer[] = {'x'};
+ int length = sizeof(buffer);
+ if(argc != 1){
+ fprintf(2, "Usage: pingpong\n");
+ exit(1);
+ }
+ pipe(p1);
+ pipe(p2);
+ if(fork() == 0){ // child
+ close(p1[1]);
+ close(p2[0]);
+ if(read(p1[0], buffer, length) == 1){ // child receives the byte
+ printf("%d: received ping\n", getpid());
+ write(p2[1], buffer, length); // child sends the byte to child
+ close(p2[1]);
+ exit(0);
+ }
+ close(p2[1]);
+ exit(1);
+ }else{ // parent
+ close(p1[0]);
+ close(p2[1]);
+ write(p1[1], buffer, length); // parent sends a byte to the child
+ close(p1[1]);
+ wait((int *)0);
+ if(read(p2[0], buffer, length) == 1){ // parent receives the byte
+ printf("%d: received pong\n", getpid());
+ }
+ exit(0);
+ }
+}
diff --git a/user/primes.c b/user/primes.c
new file mode 100644
index 0000000..6f9180e
--- /dev/null
+++ b/user/primes.c
@@ -0,0 +1,67 @@
+#include "kernel/types.h"
+#include "user/user.h"
+
+void
+close_pipe(int *p) {
+ close(p[0]);
+ close(p[1]);
+}
+
+void
+primes() {
+ int n, p, len;
+ int fd[2];
+
+ // read the frist number from previous prime
+ if ((len = read(0, &n, sizeof(int))) <= 0 || n <= 0) {
+ close(1);
+ exit(0);
+ }
+
+ // print first number to console
+ printf("prime %d\n", n);
+
+ pipe(fd);
+ if (fork() == 0) { // child process
+ close(0);
+ dup(fd[0]); // link the std i/o 0 to fd[0]
+ close_pipe(fd);
+ primes();
+ } else { // parent process
+ close(1);
+ dup(fd[1]); // link the std i/o 1 to fd[1]
+ close_pipe(fd);
+ while ((len = read(0, &p, sizeof(int))) > 0 && p > 0) { // read the number from the prime
+ if (p % n != 0) {
+ write(1, &p, sizeof(int)); // filter the number
+ }
+ }
+ close(1);
+ wait((int *)0);
+ }
+ exit(0);
+}
+
+int
+main(void) {
+ int i;
+ int fd[2];
+
+ pipe(fd);
+ if (fork() == 0) { // child process
+ close(0);
+ dup(fd[0]); // link the std i/o 0 to the fd[0]
+ close_pipe(fd);
+ primes();
+ } else {
+ close(1);
+ dup(fd[1]); // link the std i/o 1 to the fd[1]
+ close_pipe(fd);
+ for (i = 2; i <= 35; i++) {
+ write(1, &i, sizeof(int));
+ }
+ close(1);
+ wait((int *)0);
+ }
+ exit(0);
+}
diff --git a/user/sleep.c b/user/sleep.c
new file mode 100644
index 0000000..1c4d51d
--- /dev/null
+++ b/user/sleep.c
@@ -0,0 +1,17 @@
+#include "kernel/types.h"
+#include "kernel/stat.h"
+#include "user/user.h"
+
+int
+main(int argc, char *argv[])
+{
+ if(argc == 2){
+ sleep(atoi((const char*) argv[1])); // convert ascii to integer and use system call sleep
+ exit(0);
+ }
+ else{
+ fprintf(2, "Usage:sleep number...\n"); // put the error masssage to the file descriptor 2
+ exit(1); // terminate the process,
+ //status = 1: indicates failure, and reported to wait()
+ }
+}
diff --git a/user/xargs.c b/user/xargs.c
new file mode 100644
index 0000000..1423af7
--- /dev/null
+++ b/user/xargs.c
@@ -0,0 +1,47 @@
+#include "kernel/types.h"
+#include "user/user.h"
+#include "kernel/param.h"
+
+int
+main(int argc, char *argv[])
+{
+ char *arguments[MAXARG];
+ char buff[255];
+ char *p = buff, *q = buff;
+ int i, offset;
+ if(argc <= 1){
+ fprintf(2, "Usage: xargc <command>...\n");
+ exit(1);
+ }
+
+ for(i = 1; i < argc; i++){ // get the command which is behind the "xargs"
+ arguments[i-1] = argv[i];
+ }
+ i = i - 1;
+ offset = i; // backup
+
+ while(read(0, p, 1)){
+ if(*p == '\n'){ // meet the '\n' and execute it with arguments
+ *p = '\0';
+ arguments[i] = q;
+ if(fork() == 0){
+ exec(arguments[0], arguments);
+ exit(0);
+ }else{
+ wait((int*)0);
+ p = buff;
+ q = p;
+ i = offset;
+ }
+ }else if(*p == ' ' || *p == '\t'){ // meet the ' ' or '\t', find an argument
+ *p = '\0';
+ arguments[i] = q;
+ i = i + 1;
+ p = p + 1;
+ q = p;
+ }else{
+ p = p + 1;
+ }
+ }
+ exit(0);
+}
