ref: 2d7610a38eff20df2e243d797767135f8f62e019
parent: 427e868e2be75f24adccf7a509888e1b45d23052
author: Ori Bernstein <ori@eigenstate.org>
date: Fri Jul 18 10:02:58 EDT 2025
tar: add support for generating long file names our tar has had support for extracting long file names for a long time, but hasn't actually supported creating them; this stores long names via pax headers, and removes name splitting logic for midsize names. path= is the only pax attribute we added here, since we already support large file sizes via gnu/xstar's base256 encoding, and none of the others seem particularly useful.
--- a/sys/src/cmd/tar.c
+++ b/sys/src/cmd/tar.c
@@ -752,6 +752,8 @@
sysfatal("invalid delimiter in pax header: %c (%s)", *p, p);*lp++ = '\0';
len = atoi(lenbuf) - strlen(lenbuf) - 1;
+ if(len <= 0)
+ sysfatal("invalid attribute length in pax header (%s)", lenbuf);}
if (kvp == nil && (kvp = malloc(len)) == nil)
@@ -873,62 +875,88 @@
}
/*
- * if name is longer than Namsiz bytes, try to split it at a slash and fit the
- * pieces into bp->prefix and bp->name.
+ * In theory we could split names to fit them into a prefix/name pair,
+ * header,but we just take the simpler option and put it into a pax
+ * header if the name won't fit.
*/
static int
putfullname(Blk *bp, char *name)
{- int namlen, pfxlen;
- char *sl, *osl;
- String *slname = nil;
+ int n, dir;
- if (isdir(bp, name)) {- slname = s_new();
- s_append(slname, name);
- s_append(slname, "/"); /* posix requires this */
- name = s_to_c(slname);
+ n = strlen(name);
+ dir = isdir(bp, name);
+ if(dir)
+ n++;
+ if(n > Namsiz){+ fprint(2, "%s: name too long for tar header: %s\n", argv0, name);
+ return -1;
}
+ strncpy(bp->name, name, Namsiz);
+ if(dir)
+ bp->name[n-1] = '/'; /* posix requires this */
+ memset(bp->prefix, 0, sizeof(bp->prefix)); /* ustar paranoia */
+ return 0;
+}
- namlen = strlen(name);
- if (namlen <= Namsiz) {- strncpy(bp->name, name, Namsiz);
- bp->prefix[0] = '\0'; /* ustar paranoia */
- return 0;
- }
+static int
+mkpaxhdr(int ar, Dir *dir, char *file)
+{+ char *p, buf[Maxlongname + 512];
+ int n, nn, nf;
+ Blk *bp;
- if (!posix || namlen > Maxname) {- fprint(2, "%s: name too long for tar header: %s\n",
- argv0, name);
+ nf = strlen(file);
+ if(!posix)
return -1;
+ if(nf > Maxlongname){+ fprint(2, "%s: name too long for pax header: %s\n", argv0, file);
+ return -1;
}
+
/*
- * try various splits until one results in pieces that fit into the
- * appropriate fields of the header. look for slashes from right
- * to left, in the hopes of putting the largest part of the name into
- * bp->prefix, which is larger than bp->name.
+ * PAX headers require a length which includes
+ * the length of the length. We're not allowed
+ * to pad it. We need to find some n such that:
+ *
+ * n == strlen(n) + strlen(kvp)
+ *
+ * So, icky -- loop until it converges. We can
+ * only be off by 1 after our first guess, so
+ * this should be fast.
*/
- sl = strrchr(name, '/');
- while (sl != nil) {- pfxlen = sl - name;
- if (pfxlen <= sizeof bp->prefix && namlen-1 - pfxlen <= Namsiz)
- break;
- osl = sl;
- *osl = '\0';
- sl = strrchr(name, '/');
- *osl = '/';
+ n = 0;
+ nn = nf+1;
+ while(n != nn){+ n = nn;
+ nn = snprint(buf, sizeof(buf), "%d path=%s\n", n, file);
}
- if (sl == nil) {- fprint(2, "%s: name can't be split to fit tar header: %s\n",
- argv0, name);
- return -1;
+
+ bp = getblkz(ar);
+ bp->linkflag = LF_PAXHDR;
+ snprint(bp->name, sizeof(bp->name), "pax/romana");
+ snprint(bp->mode, sizeof(bp->mode), "%6lo ", dir->mode & 0777);
+ snprint(bp->uid, sizeof(bp->uid), "%6o ", aruid);
+ snprint(bp->gid, sizeof(bp->gid), "%6o ", argid);
+ snprint(bp->size, sizeof(bp->size), "%11uo ", n);
+
+ strncpy(bp->magic, "ustar", sizeof bp->magic);
+ strncpy(bp->version, "00", sizeof bp->version);
+ strncpy(bp->uname, dir->uid, sizeof bp->uname);
+ strncpy(bp->gname, dir->gid, sizeof bp->gname);
+
+ snprint(bp->chksum, sizeof(bp->chksum), "%6luo", chksum(bp));
+ putblk(ar);
+
+ p = buf;
+ while(n > 0){+ nn = (n < Tblock) ? n : Tblock;
+ bp = getblkz(ar);
+ memcpy(bp->data, p, nn);
+ p += nn;
+ n -= nn;
+ putblk(ar);
}
- *sl = '\0';
- strncpy(bp->prefix, name, sizeof bp->prefix);
- *sl++ = '/';
- strncpy(bp->name, sl, sizeof bp->name);
- if (slname)
- s_free(slname);
return 0;
}
@@ -960,7 +988,7 @@
sprint(bp->mtime, "%11luo ", dir->mtime);
bp->linkflag = (dir->mode&DMDIR? LF_DIR: LF_PLAIN1);
r = putfullname(bp, file);
- if (posix) {+ if(posix){strncpy(bp->magic, "ustar", sizeof bp->magic);
strncpy(bp->version, "00", sizeof bp->version);
strncpy(bp->uname, dir->uid, sizeof bp->uname);
@@ -1019,6 +1047,7 @@
int n, fd, isdir;
long bytes, blksread;
ulong blksleft;
+ char *hpath;
Blk *hbp;
Dir *dir;
String *name = nil;
@@ -1043,16 +1072,16 @@
if (dir == nil)
sysfatal("can't fstat %s: %r", file);+ hpath = file;
+ if(strlen(file) > Namsiz){+ if(mkpaxhdr(ar, dir, file) < 0)
+ goto Badhdr;
+ hpath = "PAXED";
+ }
hbp = getblkz(ar);
isdir = (dir->qid.type & QTDIR) != 0;
- if (mkhdr(hbp, dir, file) < 0) {- putbackblk(ar);
- free(dir);
- close(fd);
- if (name)
- s_free(name);
- return;
- }
+ if (mkhdr(hbp, dir, hpath) < 0)
+ goto Badhdr;
putblk(ar);
blksleft = BYTES2TBLKS(dir->length);
@@ -1060,7 +1089,7 @@
if (isdir)
addtreetoar(ar, file, shortf, fd);
- else {+ else{ for (; blksleft > 0; blksleft -= blksread) {hbp = getblke(ar);
blksread = gothowmany(blksleft);
@@ -1080,6 +1109,13 @@
if (verbose)
fprint(2, "%s\n", file);
}
+ if (name)
+ s_free(name);
+ return;
+Badhdr:
+ putbackblk(ar);
+ free(dir);
+ close(fd);
if (name)
s_free(name);
}
--
⑨