ref: b5bcf2e7a3676b4dac35d73604d1ded5fba7ab5c
parent: e13af7f16f7c632d653222d58a61b2945ffe1da7
author: kvik <kvik@a-b.xyz>
date: Tue Nov 6 17:44:26 EST 2018
graceful error handling
--- a/clone.c
+++ b/clone.c
@@ -18,6 +18,7 @@
typedef struct {Dir;
WaitGroup wg;
+ Channel *errchan;
char *src, *dst;
int sfd, dfd;
} File;
@@ -27,6 +28,7 @@
vlong offset;
} Blk;
+int errors = 0;
int multisrc = 0;
int keepmode = 0;
int keepmtime = 0;
@@ -51,12 +53,12 @@
void wgwait(WaitGroup*);
char *filename(char*);
-Dir *mkdir(char*, Dir*, int);
+int mkdir(char*, char*, Dir*, Dir**);
int same(Dir*, Dir*);
void clone(char*, char*);
-void cloneattr(int, Dir*);
+int cloneattr(int, Dir*);
void clonedir(char*, char*);
-void clonefile(File*);
+int clonefile(File*);
File *filenew(char*, char*, Dir*);
void filefree(File*);
void fileproc(void*);
@@ -70,6 +72,19 @@
sysfatal("usage");}
+void
+error(char *fmt, ...)
+{+ va_list arg;
+ char err[ERRMAX];
+
+ errors = 1;
+ snprint(err, sizeof err, "%s: %s\n", argv0, fmt);
+ va_start(arg, fmt);
+ vfprint(2, err, arg);
+ va_end(arg);
+}
+
void *
emalloc(ulong n)
{@@ -145,27 +160,36 @@
return p + 1;
}
-Dir *
-mkdir(char *name, Dir *d, int dostat)
+int
+mkdir(char *src, char *dst, Dir *sd, Dir **dd)
{int fd;
- Dir dn;
- Dir *dd;
-
- dd = nil;
- dn = *d;
- dn.mode = dn.mode | DMDIR | 0200;
- fd = create(name, 0, dn.mode);
- if(fd < 0)
- sysfatal("can't create destination directory: %r");- cloneattr(fd, &dn);
- if(dostat){- dd = dirfstat(fd);
- if(dd == nil)
- sysfatal("can't stat: %r");+ Dir d;
+
+ if(!(sd->mode & 0400)){+ error("can't clone directory: '%s' permission denied", src);+ return -1;
}
- close(fd);
- return dd;
+ d = *sd;
+ d.mode = d.mode | DMDIR | 0200;
+ fd = create(dst, 0, d.mode);
+ if(fd < 0){+ error("can't create directory: %r");+ return -1;
+ }
+ if(cloneattr(fd, &d) < 0){+ close(fd);
+ return -1;
+ }
+ if(dd){+ *dd = dirfstat(fd);
+ if(*dd == nil){+ error("can't stat: %r");+ close(fd);
+ return -1;
+ }
+ }
+ return 1;
}
int
@@ -193,6 +217,7 @@
f->dst = estrdup(dst);
f->sfd = -1;
f->dfd = -1;
+ f->errchan = chancreate(sizeof(ulong), 0);
return f;
}
@@ -208,16 +233,17 @@
free(f->gid);
free(f->src);
free(f->dst);
+ chanfree(f->errchan);
free(f);
}
-void
+int
cloneattr(int fd, Dir *d)
{Dir dd;
if(!(keepmode || keepuser || keepgroup || keepmtime))
- return;
+ return 1;
nulldir(&dd);
if(keepmode)
dd.mode = d->mode & DMDIR ? d->mode|0200 : d->mode;
@@ -227,8 +253,11 @@
dd.uid = d->uid;
if(keepgroup)
dd.gid = d->gid;
- if(dirfwstat(fd, &dd) < 0)
- sysfatal("can't wstat: %r");+ if(dirfwstat(fd, &dd) < 0){+ error("can't wstat: %r");+ return -1;
+ }
+ return 1;
}
void
@@ -237,18 +266,23 @@
Dir *sd, *dd;
File *f;
+ dd = nil;
sd = dirstat(src);
if(sd == nil){- fprint(2, "clone: can't stat: %r\n");
+ error("can't stat: %r");return;
}
- dd = nil;
if(access(dst, AEXIST) >= 0){dd = dirstat(dst);
- if(dd == nil)
- sysfatal("can't stat: %r");- }else if(multisrc)
- dd = skipdir = mkdir(dst, sd, 1);
+ if(dd == nil){+ error("can't stat: %r");+ goto End;
+ }
+ }else if(multisrc){+ if(mkdir(src, dst, sd, &dd) < 0)
+ goto End;
+ skipdir = dd;
+ }
/* clone a file */
if(!(sd->mode & DMDIR)){@@ -256,17 +290,24 @@
dst = smprint("%s/%s", dst, filename(src));f = filenew(src, dst, sd);
sendp(filechan, f);
- return;
+ goto End;
}
/* clone a directory */
if(dd)
dst = smprint("%s/%s", dst, filename(src));- if(skipdir)
- mkdir(dst, sd, 0);
- else
- skipdir = mkdir(dst, sd, 1);
+ if(skipdir){+ if(mkdir(src, dst, sd, nil) < 0)
+ goto End;
+ }else{+ if(mkdir(src, dst, sd, &skipdir) < 0)
+ goto End;
+ }
clonedir(src, dst);
+
+End:
+ if(dd) free(dst);
+ free(sd); free(dd);
}
void
@@ -278,12 +319,19 @@
Dir *dirs, *d;
File *f;
+ dirs = nil;
+
fd = open(src, OREAD);
- if(fd < 0)
- sysfatal("can't open: %r");+ if(fd < 0){+ error("can't open: %r");+ return;
+ }
n = dirreadall(fd, &dirs);
- if(n < 0)
- sysfatal("can't read directory: %r");+ if(n < 0){+ error("can't read directory: %r");+ close(fd);
+ return;
+ }
close(fd);
for(d = dirs; n; n--, d++){@@ -293,7 +341,8 @@
sn = smprint("%s/%s", src, d->name); dn = smprint("%s/%s", dst, d->name); if(d->mode & DMDIR){- mkdir(dn, d, 0);
+ if(mkdir(sn, dn, d, nil) < 0)
+ continue;
clonedir(sn, dn);
}else{f = filenew(sn, dn, d);
@@ -329,20 +378,38 @@
return nblk;
}
-void
+int
clonefile(File *f)
{+ int ret;
vlong n;
Blk *blks, *b, *be;
+ enum {Anext, Aerr, Aend};+ Alt alts[] = {+ [Anext] {blkchan, &b, CHANSND},+ [Aerr] {f->errchan, nil, CHANRCV},+ [Aend] {nil, nil, CHANEND},+ };
+ ret = 1;
n = blklist(f, &blks);
if(n == 0)
- return;
- wginit(&f->wg, n);
+ return 1;
+ wginit(&f->wg, 0);
for(b = blks, be = b + n; b != be; b++)
- sendp(blkchan, b);
+ switch(alt(alts)){+ case Anext:
+ wgadd(&f->wg, 1);
+ break;
+ case Aerr:
+ ret = -1;
+ goto End;
+ }
+End:
+ chanclose(f->errchan);
wgwait(&f->wg);
free(blks);
+ return ret;
}
void
@@ -352,6 +419,7 @@
long n;
vlong off;
char *buf;
+ File *f;
Blk *b;
buf = emalloc(blksz);
@@ -360,15 +428,20 @@
if(b == nil)
break;
- sfd = b->f->sfd;
- dfd = b->f->dfd;
+ f = b->f;
+ sfd = f->sfd;
+ dfd = f->dfd;
off = b->offset;
- if((n = pread(sfd, buf, blksz, off)) < 0)
- sysfatal("blkproc: read error: %r");- if(n > 0)
- if(pwrite(dfd, buf, n, off) < n)
- sysfatal("blkproc: write error: %r");- wgdone(&b->f->wg);
+ if((n = pread(sfd, buf, blksz, off)) < 0){+ error("can't read: %r");+ sendul(f->errchan, ~0);
+ }
+ if(n > 0 && pwrite(dfd, buf, n, off) < n){+ error("can't write: %r");+ sendul(f->errchan, ~0);
+ }
+
+ wgdone(&f->wg);
}
}
@@ -385,14 +458,19 @@
break;
f->sfd = open(f->src, OREAD);
- if(f->sfd < 0)
- sysfatal("fileproc: can't open: %r");+ if(f->sfd < 0){+ error("can't open: %r");+ goto End;
+ }
f->dfd = create(f->dst, OWRITE, f->mode);
- if(f->dfd < 0)
- sysfatal("fileproc: can't create: %r");+ if(f->dfd < 0){+ error("can't create: %r");+ goto End;
+ }
- clonefile(f);
- cloneattr(f->dfd, f);
+ if(clonefile(f) > 0)
+ cloneattr(f->dfd, f);
+End:
filefree(f);
}
wgdone(wg);
@@ -443,5 +521,7 @@
chanclose(filechan);
wgwait(&filewg);
+ if(errors)
+ threadexitsall("errors");threadexitsall(nil);
}
--- a/clone.man1
+++ b/clone.man1
@@ -88,14 +88,6 @@
.IR pread(2),
.IR pwrite(2)
.SH BUGS
-No graceful error handling.
-An error encountered while copying a
-single file will simply axe all the
-.I clone
-processes, most certainly resulting in
-chaos. If there was an error, remove
-the destination and start all over again.
-.PP
Preserving the modification time of
directories does not work. Attributes are
cloned at directory creation time; meaning, if