Initial Upload

pipe.c

@@ -0,0 +1,122 @@
+#include "types.h"
+#include "defs.h"
+#include "param.h"
+#include "mmu.h"
+#include "proc.h"
+#include "fs.h"
+#include "spinlock.h"
+#include "sleeplock.h"
+#include "file.h"
+
+#define PIPESIZE 512
+
+struct pipe {
+    struct spinlock lock;
+    char data[PIPESIZE];
+    uint nread;     // number of bytes read
+    uint nwrite;    // number of bytes written
+    int readopen;   // read fd is still open
+    int writeopen;  // write fd is still open
+};
+
+void cleanuppipealloc(struct pipe *p, struct file **f0, struct file **f1) {
+     if (p) {
+        kfree((char*)p);
+    }
+    if (*f0) {
+        fileclose(*f0);
+    }
+    if (*f1) {
+        fileclose(*f1);
+    }   
+}
+
+int pipealloc(struct file **f0, struct file **f1) {
+    struct pipe *p;
+
+    p = 0;
+    *f0 = *f1 = 0;
+    if ((*f0 = filealloc()) == 0 || (*f1 = filealloc()) == 0) {
+        cleanuppipealloc(p, f0, f1);
+        return -1;
+    }
+    if ((p = (struct pipe*)kalloc()) == 0) {
+        cleanuppipealloc(p, f0, f1);
+        return -1;
+    }
+    p->readopen = 1;
+    p->writeopen = 1;
+    p->nwrite = 0;
+    p->nread = 0;
+    initlock(&p->lock, "pipe");
+    (*f0)->type = FD_PIPE;
+    (*f0)->readable = 1;
+    (*f0)->writable = 0;
+    (*f0)->pipe = p;
+    (*f1)->type = FD_PIPE;
+    (*f1)->readable = 0;
+    (*f1)->writable = 1;
+    (*f1)->pipe = p;
+    return 0;
+}
+
+void pipeclose(struct pipe *p, int writable) {
+    acquire(&p->lock);
+    if (writable) {
+        p->writeopen = 0;
+        wakeup(&p->nread);
+    }
+    else {
+        p->readopen = 0;
+        wakeup(&p->nwrite);
+    }
+    if (p->readopen == 0 && p->writeopen == 0) {
+        release(&p->lock);
+        kfree((char*)p);
+    }
+    else {
+        release(&p->lock);
+    }
+}
+
+int pipewrite(struct pipe *p, char *addr, int n) {
+    int i;
+
+    acquire(&p->lock);
+    for (i = 0; i < n; i++) {
+        while (p->nwrite == p->nread + PIPESIZE) { //DOC: pipewrite-full
+            if (p->readopen == 0 || myproc()->killed) {
+                release(&p->lock);
+                return -1;
+            }
+            wakeup(&p->nread);
+            sleep(&p->nwrite, &p->lock);  //DOC: pipewrite-sleep
+        }
+        p->data[p->nwrite++ % PIPESIZE] = addr[i];
+    }
+    wakeup(&p->nread);  //DOC: pipewrite-wakeup1
+    release(&p->lock);
+    return n;
+}
+
+int piperead(struct pipe *p, char *addr, int n)     {
+    int i;
+
+    acquire(&p->lock);
+    while (p->nread == p->nwrite && p->writeopen) { //DOC: pipe-empty
+        if (myproc()->killed) {
+            release(&p->lock);
+            return -1;
+        }
+        sleep(&p->nread, &p->lock); //DOC: piperead-sleep
+    }
+    for (i = 0; i < n; i++) {  //DOC: piperead-copy
+        if (p->nread == p->nwrite) {
+            break;
+        }
+        addr[i] = p->data[p->nread++ % PIPESIZE];
+    }
+    wakeup(&p->nwrite);  //DOC: piperead-wakeup
+    release(&p->lock);
+    return i;
+}