9fsys.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include "stdinc.h"
#include "dat.h"
#include "fns.h"

#include "9.h"

typedef struct Fsys Fsys;

struct Fsys {
	VtLock* lock;

	char*	name;
	char*	dev;
	char*	venti;

	Fs*	fs;
	VtSession* session;
	int	ref;

	int	noauth;
	int	noperm;
	int	wstatallow;

	Fsys*	next;
};

static struct {
	VtLock*	lock;
	Fsys*	head;
	Fsys*	tail;

	char*	curfsys;
} sbox;

static char *_argv0;
#define argv0 _argv0

static char FsysAll[] = "all";

static char EFsysBusy[] = "fsys: '%s' busy";
static char EFsysExists[] = "fsys: '%s' already exists";
static char EFsysNoCurrent[] = "fsys: no current fsys";
static char EFsysNotFound[] = "fsys: '%s' not found";
static char EFsysNotOpen[] = "fsys: '%s' not open";

static Fsys*
_fsysGet(char* name)
{
	Fsys *fsys;

	if(name == nil || name[0] == '\0')
		name = "main";

	vtRLock(sbox.lock);
	for(fsys = sbox.head; fsys != nil; fsys = fsys->next){
		if(strcmp(name, fsys->name) == 0){
			fsys->ref++;
			break;
		}
	}
	vtRUnlock(sbox.lock);
	if(fsys == nil)
		vtSetError(EFsysNotFound, name);
	return fsys;
}

static int
cmdPrintConfig(int argc, char* argv[])
{
	Fsys *fsys;
	char *usage = "usage: printconfig";

	ARGBEGIN{
	default:
		return cliError(usage);
	}ARGEND

	if(argc)
		return cliError(usage);

	vtRLock(sbox.lock);
	for(fsys = sbox.head; fsys != nil; fsys = fsys->next){
		consPrint("\tfsys %s config %s\n", fsys->name, fsys->dev);
		if(fsys->venti && fsys->venti[0])
			consPrint("\tfsys %s venti %q\n", fsys->name, fsys->venti);
	}
	vtRUnlock(sbox.lock);
	return 1;
}

Fsys*
fsysGet(char* name)
{
	Fsys *fsys;

	if((fsys = _fsysGet(name)) == nil)
		return nil;

	vtLock(fsys->lock);
	if(fsys->fs == nil){
		vtSetError(EFsysNotOpen, fsys->name);
		vtUnlock(fsys->lock);
		fsysPut(fsys);
		return nil;
	}
	vtUnlock(fsys->lock);

	return fsys;
}

char*
fsysGetName(Fsys* fsys)
{
	return fsys->name;
}

Fsys*
fsysIncRef(Fsys* fsys)
{
	vtLock(sbox.lock);
	fsys->ref++;
	vtUnlock(sbox.lock);

	return fsys;
}

void
fsysPut(Fsys* fsys)
{
	vtLock(sbox.lock);
	assert(fsys->ref > 0);
	fsys->ref--;
	vtUnlock(sbox.lock);
}

Fs*
fsysGetFs(Fsys* fsys)
{
	assert(fsys != nil && fsys->fs != nil);

	return fsys->fs;
}

void
fsysFsRlock(Fsys* fsys)
{
	vtRLock(fsys->fs->elk);
}

void
fsysFsRUnlock(Fsys* fsys)
{
	vtRUnlock(fsys->fs->elk);
}

int
fsysNoAuthCheck(Fsys* fsys)
{
	return fsys->noauth;
}

int
fsysNoPermCheck(Fsys* fsys)
{
	return fsys->noperm;
}

int
fsysWstatAllow(Fsys* fsys)
{
	return fsys->wstatallow;
}

static char modechars[] = "YUGalLdHSATs";
static ulong modebits[] = {
	ModeSticky,
	ModeSetUid,
	ModeSetGid,
	ModeAppend,
	ModeExclusive,
	ModeLink,
	ModeDir,
	ModeHidden,
	ModeSystem,
	ModeArchive,
	ModeTemporary,
	ModeSnapshot,
	0
};

char*
fsysModeString(ulong mode, char *buf)
{
	int i;
	char *p;

	p = buf;
	for(i=0; modebits[i]; i++)
		if(mode & modebits[i])
			*p++ = modechars[i];
	sprint(p, "%luo", mode&0777);
	return buf;
}

int
fsysParseMode(char* s, ulong* mode)
{
	ulong x, y;
	char *p;

	x = 0;
	for(; *s < '0' || *s > '9'; s++){
		if(*s == 0)
			return 0;
		p = strchr(modechars, *s);
		if(p == nil)
			return 0;
		x |= modebits[p-modechars];
	}
	y = strtoul(s, &p, 8);
	if(*p != '\0' || y > 0777)
		return 0;
	*mode = x|y;
	return 1;
}

File*
fsysGetRoot(Fsys* fsys, char* name)
{
	File *root, *sub;

	assert(fsys != nil && fsys->fs != nil);

	root = fsGetRoot(fsys->fs);
	if(name == nil || strcmp(name, "") == 0)
		return root;

	sub = fileWalk(root, name);
	fileDecRef(root);

	return sub;
}

static Fsys*
fsysAlloc(char* name, char* dev)
{
	Fsys *fsys;

	vtLock(sbox.lock);
	for(fsys = sbox.head; fsys != nil; fsys = fsys->next){
		if(strcmp(fsys->name, name) != 0)
			continue;
		vtSetError(EFsysExists, name);
		vtUnlock(sbox.lock);
		return nil;
	}

	fsys = vtMemAllocZ(sizeof(Fsys));
	fsys->lock = vtLockAlloc();
	fsys->name = vtStrDup(name);
	fsys->dev = vtStrDup(dev);

	fsys->ref = 1;

	if(sbox.tail != nil)
		sbox.tail->next = fsys;
	else
		sbox.head = fsys;
	sbox.tail = fsys;
	vtUnlock(sbox.lock);

	return fsys;
}

static int
fsysClose(Fsys* fsys, int argc, char* argv[])
{
	char *usage = "usage: [fsys name] close";

	ARGBEGIN{
	default:
		return cliError(usage);
	}ARGEND
	if(argc)
		return cliError(usage);

	return cliError("close isn't working yet; halt %s and then kill fossil",
		fsys->name);

	/*
	 * Oooh. This could be hard. What if fsys->ref != 1?
	 * Also, fsClose() either does the job or panics, can we
	 * gracefully detect it's still busy?
	 *
	 * More thought and care needed here.
	fsClose(fsys->fs);
	fsys->fs = nil;
	vtClose(fsys->session);
	fsys->session = nil;

	if(sbox.curfsys != nil && strcmp(fsys->name, sbox.curfsys) == 0){
		sbox.curfsys = nil;
		consPrompt(nil);
	}

	return 1;
	 */
}

static int
fsysVac(Fsys* fsys, int argc, char* argv[])
{
	uchar score[VtScoreSize];
	char *usage = "usage: [fsys name] vac path";

	ARGBEGIN{
	default:
		return cliError(usage);
	}ARGEND
	if(argc != 1)
		return cliError(usage);

	if(!fsVac(fsys->fs, argv[0], score))
		return 0;

	consPrint("vac:%V\n", score);
	return 1;
}

static int
fsysSnap(Fsys* fsys, int argc, char* argv[])
{
	int doarchive;
	char *usage = "usage: [fsys name] snap [-a] [-s /active] [-d /archive/yyyy/mmmm]";
	char *src, *dst;

	src = nil;
	dst = nil;
	doarchive = 0;
	ARGBEGIN{
	default:
		return cliError(usage);
	case 'a':
		doarchive = 1;
		break;
	case 'd':
		if((dst = ARGF()) == nil)
			return cliError(usage);
		break;
	case 's':
		if((src = ARGF()) == nil)
			return cliError(usage);
		break;
	}ARGEND
	if(argc)
		return cliError(usage);

	if(!fsSnapshot(fsys->fs, src, dst, doarchive))
		return 0;

	return 1;
}

static int
fsysSnapClean(Fsys *fsys, int argc, char* argv[])
{
	u32int arch, snap, life;
	char *usage = "usage: [fsys name] snapclean [maxminutes]\n";

	ARGBEGIN{
	default:
		return cliError(usage);
	}ARGEND

	if(argc > 1)
		return cliError(usage);
	if(argc == 1)
		life = atoi(argv[0]);
	else
		snapGetTimes(fsys->fs->snap, &arch, &snap, &life);

	fsSnapshotCleanup(fsys->fs, life);
	return 1;
}

static int
fsysSnapTime(Fsys* fsys, int argc, char* argv[])
{
	char buf[128], *x;
	int hh, mm, changed;
	u32int arch, snap, life;
	char *usage = "usage: [fsys name] snaptime [-a hhmm] [-s snapminutes] [-t maxminutes]";

	changed = 0;
	snapGetTimes(fsys->fs->snap, &arch, &snap, &life);
	ARGBEGIN{
	case 'a':
		changed = 1;
		x = ARGF();
		if(x == nil)
			return cliError(usage);
		if(strcmp(x, "none") == 0){
			arch = ~(u32int)0;
			break;
		}
		if(strlen(x) != 4 || strspn(x, "0123456789") != 4)
			return cliError(usage);
		hh = (x[0]-'0')*10 + x[1]-'0';
		mm = (x[2]-'0')*10 + x[3]-'0';
		if(hh >= 24 || mm >= 60)
			return cliError(usage);
		arch = hh*60+mm;
		break;
	case 's':
		changed = 1;
		x = ARGF();
		if(x == nil)
			return cliError(usage);
		if(strcmp(x, "none") == 0){
			snap = ~(u32int)0;
			break;
		}
		snap = atoi(x);
		break;
	case 't':
		changed = 1;
		x = ARGF();
		if(x == nil)
			return cliError(usage);
		if(strcmp(x, "none") == 0){
			life = ~(u32int)0;
			break;
		}
		life = atoi(x);
		break;
	default:
		return cliError(usage);
	}ARGEND
	if(argc > 0)
		return cliError(usage);

	if(changed){
		snapSetTimes(fsys->fs->snap, arch, snap, life);
		return 1;
	}
	snapGetTimes(fsys->fs->snap, &arch, &snap, &life);
	if(arch != ~(u32int)0)
		sprint(buf, "-a %02d%02d", arch/60, arch%60);
	else
		sprint(buf, "-a none");
	if(snap != ~(u32int)0)
		sprint(buf+strlen(buf), " -s %d", snap);
	else
		sprint(buf+strlen(buf), " -s none");
	if(life != ~(u32int)0)
		sprint(buf+strlen(buf), " -t %ud", life);
	else
		sprint(buf+strlen(buf), " -t none");
	consPrint("\tsnaptime %s\n", buf);
	return 1;
}

static int
fsysSync(Fsys* fsys, int argc, char* argv[])
{
	char *usage = "usage: [fsys name] sync";
	int n;
	
	ARGBEGIN{
	default:
		return cliError(usage);
	}ARGEND
	if(argc > 0)
		return cliError(usage);

	n = cacheDirty(fsys->fs->cache);
	fsSync(fsys->fs);
	consPrint("\t%s sync: wrote %d blocks\n", fsys->name, n);
	return 1;
}

static int
fsysHalt(Fsys *fsys, int argc, char* argv[])
{
	char *usage = "usage: [fsys name] halt";

	ARGBEGIN{
	default:
		return cliError(usage);
	}ARGEND
	if(argc > 0)
		return cliError(usage);

	fsHalt(fsys->fs);
	return 1;
}

static int
fsysUnhalt(Fsys *fsys, int argc, char* argv[])
{
	char *usage = "usage: [fsys name] unhalt";

	ARGBEGIN{
	default:
		return cliError(usage);
	}ARGEND
	if(argc > 0)
		return cliError(usage);

	if(!fsys->fs->halted)
		return cliError("file system %s not halted", fsys->name);

	fsUnhalt(fsys->fs);
	return 1;
}

static int
fsysRemove(Fsys* fsys, int argc, char* argv[])
{
	File *file;
	char *usage = "usage: [fsys name] remove path ...";

	ARGBEGIN{
	default:
		return cliError(usage);
	}ARGEND
	if(argc == 0)
		return cliError(usage);

	vtRLock(fsys->fs->elk);
	while(argc > 0){
		if((file = fileOpen(fsys->fs, argv[0])) == nil)
			consPrint("%s: %R\n", argv[0]);
		else{
			if(!fileRemove(file, uidadm))
				consPrint("%s: %R\n", argv[0]);
			fileDecRef(file);
		}
		argc--;
		argv++;
	}
	vtRUnlock(fsys->fs->elk);

	return 1;
}

static int
fsysClri(Fsys* fsys, int argc, char* argv[])
{
	char *usage = "usage: [fsys name] clri path ...";

	ARGBEGIN{
	default:
		return cliError(usage);
	}ARGEND
	if(argc == 0)
		return cliError(usage);

	vtRLock(fsys->fs->elk);
	while(argc > 0){
		if(!fileClriPath(fsys->fs, argv[0], uidadm))
			consPrint("clri %s: %R\n", argv[0]);
		argc--;
		argv++;
	}
	vtRUnlock(fsys->fs->elk);

	return 1;
}

/*
 * Inspect and edit the labels for blocks on disk.
 */
static int
fsysLabel(Fsys* fsys, int argc, char* argv[])
{
	Fs *fs;
	Label l;
	int n, r;
	u32int addr;
	Block *b, *bb;
	char *usage = "usage: [fsys name] label addr [type state epoch epochClose tag]";

	ARGBEGIN{
	default:
		return cliError(usage);
	}ARGEND
	if(argc != 1 && argc != 6)
		return cliError(usage);

	r = 0;
	vtRLock(fsys->fs->elk);

	fs = fsys->fs;
	addr = strtoul(argv[0], 0, 0);
	b = cacheLocal(fs->cache, PartData, addr, OReadOnly);
	if(b == nil)
		goto Out0;