From 9e5970d596d7b1634200d50e96130886f593cede Mon Sep 17 00:00:00 2001
From: rtm <rtm>
Date: Sun, 13 Aug 2006 02:12:44 +0000
Subject: [PATCH] link()
---
Notes | 4 +--
defs.h | 1 +
fs.c | 89 ++++++++++++++++++++++++++++++++++++++---------------
ide.c | 2 --
main.c | 6 ----
proc.c | 3 --
syscall.c | 19 +++++++++++-
syscall.h | 1 +
user.h | 1 +
usertests.c | 61 ++++++++++++++++++++++++++++++++++++
usys.S | 1 +
11 files changed, 149 insertions(+), 39 deletions(-)
diff --git a/Notes b/Notes
index 7e3edd5..386bc2f 100644
--- a/Notes
+++ b/Notes
@@ -355,8 +355,6 @@ HMM maybe the variables at the end of struct cpu are being overwritten
OH! recursive interrupts will use up any amount of cpu[].stack!
underflow and wrecks *previous* cpu's struct
-better buffer cache replacement
-read/write of open file that's been unlinked
disk scheduling
mkdir
more than one directory content block
@@ -365,3 +363,5 @@ sh redirection
indirect blocks
two bugs in unlink: don't just return if nlink > 0,
and search for name, not inum
+is there a create/create race for same file name?
+ resulting in two entries w/ same name in directory?
diff --git a/defs.h b/defs.h
index 6a4f1c2..c8e1870 100644
--- a/defs.h
+++ b/defs.h
@@ -123,3 +123,4 @@ int writei(struct inode *ip, char *addr, uint off, uint n);
struct inode *mknod(char *, short, short, short);
int unlink(char *cp);
void iupdate (struct inode *ip);
+int link(char *file1, char *file2);
diff --git a/fs.c b/fs.c
index e01b4fb..7f0d2ea 100644
--- a/fs.c
+++ b/fs.c
@@ -439,14 +439,41 @@ namei(char *path, uint *ret_pinum)
}
}
+void
+wdir(struct inode *dp, char *name, uint ino)
+{
+ uint off;
+ struct buf *bp = 0;
+ struct dirent *ep = 0;
+ int i;
+
+ for(off = 0; off < dp->size; off += BSIZE) {
+ bp = bread(dp->dev, bmap(dp, off / BSIZE));
+ for(ep = (struct dirent *) bp->data;
+ ep < (struct dirent *) (bp->data + BSIZE);
+ ep++){
+ if(ep->inum == 0)
+ goto found;
+ }
+ brelse(bp);
+ }
+
+ panic("mknod: XXXX no dir entry free\n");
+
+ found:
+ ep->inum = ino;
+ for(i = 0; i < DIRSIZ && name[i]; i++)
+ ep->name[i] = name[i];
+ for( ; i < DIRSIZ; i++)
+ ep->name[i] = '\0';
+ bwrite (bp, bmap(dp, off/BSIZE)); // write directory block
+ brelse(bp);
+}
+
struct inode *
mknod(char *cp, short type, short major, short minor)
{
struct inode *ip, *dp;
- struct dirent *ep = 0;
- int off;
- int i;
- struct buf *bp = 0;
uint pinum = 0;
cprintf("mknod: %s %d %d %d\n", cp, type, major, minor);
@@ -469,27 +496,7 @@ mknod(char *cp, short type, short major, short minor)
iupdate (ip); // write new inode to disk
- for(off = 0; off < dp->size; off += BSIZE) {
- bp = bread(dp->dev, bmap(dp, off / BSIZE));
- for(ep = (struct dirent *) bp->data;
- ep < (struct dirent *) (bp->data + BSIZE);
- ep++){
- if(ep->inum == 0) {
- goto found;
- }
- }
- brelse(bp);
- }
- panic("mknod: XXXX no dir entry free\n");
-
- found:
- ep->inum = ip->inum;
- for(i = 0; i < DIRSIZ && cp[i]; i++)
- ep->name[i] = cp[i];
- for( ; i < DIRSIZ; i++)
- ep->name[i] = '\0';
- bwrite (bp, bmap(dp, off/BSIZE)); // write directory block
- brelse(bp);
+ wdir(dp, cp, ip->inum);
iput(dp);
@@ -541,3 +548,35 @@ unlink(char *cp)
iput(ip);
return 0;
}
+
+int
+link(char *name1, char *name2)
+{
+ struct inode *ip, *dp, *xip;
+ uint pinum = 0;
+
+ cprintf("link(%s, %s)\n", name1, name2);
+
+ if ((xip = namei(name2, &pinum)) != 0) {
+ cprintf(" failed %s exists\n", name2);
+ iput(xip);
+ return -1;
+ }
+
+ if ((ip = namei(name1, &pinum)) == 0){
+ cprintf(" failed %s does not exist\n", name1);
+ return -1;
+ }
+
+ ip->nlink += 1;
+ iupdate (ip);
+
+ dp = iget(rootdev, pinum);
+ wdir(dp, name2, ip->inum);
+ iput(dp);
+ iput(ip);
+
+ cprintf(" succeeded\n");
+
+ return 0;
+}
diff --git a/ide.c b/ide.c
index 3532121..331553f 100644
--- a/ide.c
+++ b/ide.c
@@ -52,14 +52,12 @@ ide_init(void)
}
ioapic_enable (IRQ_IDE, 1);
ide_wait_ready(0);
- cprintf ("cpu%d: ide_init:done\n", cpu());
}
void
ide_intr(void)
{
acquire(&ide_lock);
- // cprintf("cpu%d: ide_intr\n", cpu());
wakeup(&request[tail]);
release(&ide_lock);
}
diff --git a/main.c b/main.c
index c164c48..a2ee845 100644
--- a/main.c
+++ b/main.c
@@ -87,8 +87,6 @@ main0(void)
lapic_enableintr();
// Enable interrupts on this processor.
- cprintf("cpu%d: nlock %d before -- and sti\n",
- cpu(), cpus[0].nlock);
cpus[cpu()].nlock--;
sti();
@@ -98,7 +96,6 @@ main0(void)
//load_icode(p, _binary_userfs_start, (uint) _binary_userfs_size);
load_icode(p, _binary_init_start, (uint) _binary_init_size);
p->state = RUNNABLE;
- cprintf("loaded init\n");
scheduler();
}
@@ -123,7 +120,6 @@ mpmain(void)
cpus[cpu()].booted = 1;
// Enable interrupts on this processor.
- cprintf("cpu%d: initial nlock %d\n", cpu(), cpus[cpu()].nlock);
cpus[cpu()].nlock--;
sti();
@@ -139,7 +135,6 @@ load_icode(struct proc *p, uchar *binary, uint size)
// Check magic number on binary
elf = (struct elfhdr*) binary;
- cprintf("elf %x magic %x\n", elf, elf->magic);
if (elf->magic != ELF_MAGIC)
panic("load_icode: not an ELF binary");
@@ -151,7 +146,6 @@ load_icode(struct proc *p, uchar *binary, uint size)
for (i = 0; i < elf->phnum; i++, ph++) {
if (ph->type != ELF_PROG_LOAD)
continue;
- cprintf("va %x memsz %d\n", ph->va, ph->memsz);
if (ph->va + ph->memsz < ph->va)
panic("load_icode: overflow in elf header segment");
if (ph->va + ph->memsz >= p->sz)
diff --git a/proc.c b/proc.c
index 5f8769b..7290693 100644
--- a/proc.c
+++ b/proc.c
@@ -140,9 +140,6 @@ scheduler(void)
struct proc *p;
int i;
- cprintf("cpu%d: start scheduler jmpbuf %p\n",
- cpu(), &cpus[cpu()].jmpbuf);
-
if(cpus[cpu()].nlock != 0){
cprintf("la %x lr %x\n", cpus[cpu()].lastacquire, cpus[cpu()].lastrelease );
panic("holding locks at first entry to scheduler");
diff --git a/syscall.c b/syscall.c
index 48da287..4505c89 100644
--- a/syscall.c
+++ b/syscall.c
@@ -303,7 +303,6 @@ sys_unlink(void)
return r;
}
-
int
sys_fstat(void)
{
@@ -325,6 +324,21 @@ sys_fstat(void)
return r;
}
+int
+sys_link(void)
+{
+ struct proc *cp = curproc[cpu()];
+ uint name1, name2;
+ int r;
+
+ if(fetcharg(0, &name1) < 0 || checkstring(name1) < 0)
+ return -1;
+ if(fetcharg(1, &name2) < 0 || checkstring(name2) < 0)
+ return -1;
+ r = link(cp->mem + name1, cp->mem + name2);
+ return r;
+}
+
int
sys_exec(void)
{
@@ -543,6 +557,9 @@ syscall(void)
case SYS_fstat:
ret = sys_fstat();
break;
+ case SYS_link:
+ ret = sys_link();
+ break;
default:
cprintf("unknown sys call %d\n", num);
// XXX fault
diff --git a/syscall.h b/syscall.h
index ca2855c..01d09ff 100644
--- a/syscall.h
+++ b/syscall.h
@@ -12,4 +12,5 @@
#define SYS_mknod 15
#define SYS_unlink 16
#define SYS_fstat 17
+#define SYS_link 18
diff --git a/user.h b/user.h
index 9dd1684..52b804b 100644
--- a/user.h
+++ b/user.h
@@ -16,6 +16,7 @@ int mknod (char*,short,short,short);
int unlink (char*);
struct stat;
int fstat (int fd, struct stat *stat);
+int link(char *, char *);
int puts(char*);
char* strcpy(char*, char*);
diff --git a/usertests.c b/usertests.c
index 3cb4a37..2d6b065 100644
--- a/usertests.c
+++ b/usertests.c
@@ -344,11 +344,72 @@ unlinkread()
puts("unlinkread ok\n");
}
+void
+linktest()
+{
+ int fd;
+
+ unlink("lf1");
+ unlink("lf2");
+
+ fd = open("lf1", O_CREATE|O_RDWR);
+ if(fd < 0){
+ puts("create lf1 failed\n");
+ exit();
+ }
+ if(write(fd, "hello", 5) != 5){
+ puts("write lf1 failed\n");
+ exit();
+ }
+ close(fd);
+
+ if(link("lf1", "lf2") < 0){
+ puts("link lf1 lf2 failed\n");
+ exit();
+ }
+ unlink("lf1");
+
+ if(open("lf1", 0) >= 0){
+ puts("unlinked lf1 but it is still there!\n");
+ exit();
+ }
+
+ fd = open("lf2", 0);
+ if(fd < 0){
+ puts("open lf2 failed\n");
+ exit();
+ }
+ if(read(fd, buf, sizeof(buf)) != 5){
+ puts("read lf2 failed\n");
+ exit();
+ }
+ close(fd);
+
+ if(link("lf2", "lf2") >= 0){
+ puts("link lf2 lf2 succeeded! oops\n");
+ exit();
+ }
+
+ unlink("lf2");
+ if(link("lf2", "lf1") >= 0){
+ puts("link non-existant succeeded! oops\n");
+ exit();
+ }
+
+ if(link(".", "lf1") >= 0){
+ puts("link . lf1 succeeded! oops\n");
+ exit();
+ }
+
+ puts("linktest ok\n");
+}
+
int
main(int argc, char *argv[])
{
puts("usertests starting\n");
+ linktest();
unlinkread();
createdelete();
twofiles();
diff --git a/usys.S b/usys.S
index f9565e5..73170c3 100644
--- a/usys.S
+++ b/usys.S
@@ -22,3 +22,4 @@ STUB(open)
STUB(mknod)
STUB(unlink)
STUB(fstat)
+STUB(link)
--
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