This patch depends on: "tar: fix long names crashing tar archiving" https://lists.suckless.org/hackers/2402/19071.html
I just did the simplest possible implementation, in order to have at least something (it's a feature of 'tar' that I do actually use in my projects, so I needed it). Insights for more interesting approaches can be found here: https://lists.suckless.org/dev/2301/35084.html This should finally cover the specifications, although one might then want to support even longer paths (more than 150 (prefix) + 100 (name) for regular files, and more than 100 for links); but that should be discussed I think on dev. --- tar.c | 101 +++++++++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 90 insertions(+), 11 deletions(-) diff --git a/tar.c b/tar.c index a2dea4d..a54d66d 100644 --- a/tar.c +++ b/tar.c @@ -52,6 +52,16 @@ struct header { char prefix[155]; }; +/* List of encountered hardlinks. */ +struct hlink { + struct hlink *next; + dev_t dev; + ino_t ino; + char linkname[100]; +}; +struct hlink *hlinklist = NULL; +struct hlink *hlinktail = NULL; + static struct dirtime { char *name; time_t mtime; @@ -182,14 +192,15 @@ archive(const char *path) char b[BLKSIZ]; struct group *gr; struct header *h; + struct hlink *hlp; struct passwd *pw; struct stat st; size_t chksum, i; ssize_t l, r; int fd = -1; - size_t path_len; char tmp_prefix[PATH_MAX]; char *bsname; + int found_hlink = 0; if (lstat(path, &st) < 0) { weprintf("lstat %s:", path); @@ -205,14 +216,13 @@ archive(const char *path) h = (struct header *)b; memset(b, 0, sizeof(b)); - path_len = strlen(path); - if (path_len > 100 - 1) { + if (strlen(path) >= 100) { // Cover case where path name is too long (in which case we need // to split it to prefix and name). bsname = basename((char *)path); - strncpy(tmp_prefix, path, PATH_MAX); + estrlcpy(tmp_prefix, path, PATH_MAX); dirname(tmp_prefix); - // Could still be too long to fit in the struct. + // Could still be too long to fit in the fields. if (strlen(bsname) >= sizeof(h->name) || strlen(tmp_prefix) >= sizeof(h->prefix)) { eprintf("filename too long: %s\n", path); @@ -234,11 +244,55 @@ archive(const char *path) estrlcpy(h->gname, gr ? gr->gr_name : "", sizeof(h->gname)); if (S_ISREG(st.st_mode)) { - h->type = REG; - putoctal(h->size, (unsigned)st.st_size, sizeof(h->size)); - fd = open(path, O_RDONLY); - if (fd < 0) - eprintf("open %s:", path); + if (st.st_nlink > 1) { + /* It's an hardlink */ + for (hlp = hlinklist; hlp; hlp = hlp->next) { + if (hlp->ino == st.st_ino && + hlp->dev == st.st_dev) { + /* Found in our list. */ + found_hlink = 1; + h->type = HARDLINK; + putoctal(h->size, 0, sizeof(h->size)); + estrlcpy( + h->linkname, hlp->linkname, + sizeof(h->linkname)); + break; + } + } + if (!found_hlink) { + /* Never encountered this hardlink before. Let's + * store it in our list. */ + if (strlen(h->prefix) > 0) + eprintf( + "filename too long to be able to " + "store it as a hardlink: %s\n", + path); + struct hlink *new_hlink = + ecalloc(1, sizeof(struct hlink)); + new_hlink->next = NULL; + new_hlink->dev = st.st_dev; + new_hlink->ino = st.st_ino; + estrlcpy( + new_hlink->linkname, h->name, + sizeof(new_hlink->linkname)); + if (hlinklist == NULL) + hlinklist = new_hlink; + else + hlinktail->next = new_hlink; + hlinktail = new_hlink; + } + } + /* If it's a regular file OR if it is an hardlink but it's the + first time we encounter it, we need to dump the file content. + */ + if (!found_hlink) { + h->type = REG; + putoctal( + h->size, (unsigned)st.st_size, sizeof(h->size)); + fd = open(path, O_RDONLY); + if (fd < 0) + eprintf("open %s:", path); + } } else if (S_ISDIR(st.st_mode)) { h->type = DIRECTORY; } else if (S_ISLNK(st.st_mode)) { @@ -272,6 +326,20 @@ archive(const char *path) return 0; } +static void +freehlinklist() +{ + struct hlink *hlp = hlinklist; + struct hlink *next; + while (hlp != NULL) { + next = hlp->next; + free(hlp); + hlp = next; + } + hlinklist = NULL; + hlinktail = NULL; +} + static int unarchive(char *fname, ssize_t l, char b[BLKSIZ]) { @@ -383,8 +451,16 @@ skipblk(ssize_t l) static int print(char *fname, ssize_t l, char b[BLKSIZ]) { - puts(fname); + struct header *h = (struct header *)b; + + fputs(fname, stdout); + if (vflag && h->linkname[0]) { + fputs(" link to ", stdout); + fputs(h->linkname, stdout); + } + fputs("\n", stdout); skipblk(l); + return 0; } @@ -602,6 +678,9 @@ main(int argc, char *argv[]) eprintf("chdir %s:", dir); for (; *argv; argc--, argv++) recurse(AT_FDCWD, *argv, NULL, &r); + + freehlinklist(); + break; case 't': case 'x': -- 2.34.1
